Dissertations / Theses on the topic 'Sheet-steel'
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1
Shannon, Geoff. "Laser welding of sheet steel." Thesis, University of Liverpool, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.240883.
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Boyle, Kevin Patrick. "Cold work embrittlement of interstitial-free sheet steel /." *McMaster only, 2001.
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Ahmadi, Moghadam Parham. "Steel Sheet Applications and Integrated Heat Management." Thesis, Högskolan Dalarna, Energiteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:du-21446.
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Increasing energy use has caused many environmental problems including global warming. Energy use is growing rapidly in developing countries and surprisingly a remarkable portion of it is associated with consumed energy to keep the temperature comfortable inside the buildings. Therefore, identifying renewable technologies for cooling and heating is essential. This study introduced applications of steel sheets integrated into the buildings to save energy based on existing technologies. In addition, the proposed application was found to have a considerable chance of market success. Also, satisfying energy needs for space heating and cooling in a single room by using one of the selected applications in different Köppen climate classes was investigated to estimate which climates have a proper potential for benefiting from the application. This study included three independent parts and the results related to each part have been used in the next part. The first part recognizes six different technologies through literature review including Cool Roof, Solar Chimney, Steel Cladding of Building, Night Radiative Cooling, Elastomer Metal Absorber, and Solar Distillation. The second part evaluated the application of different technologies by gathering the experts’ ideas via performing a Delphi method. The results showed that the Solar Chimney has a proper chance for the market. The third part simulated both a solar chimney and a solar chimney with evaporation which were connected to a single well insulated room with a considerable thermal mass. The combination was simulated as a system to estimate the possibility of satisfying cooling needs and heating needs in different climate classes. A Trombe-wall was selected as a sample design for the Solar Chimney and was simulated in different climates. The results implied that the solar chimney had the capability of reducing the cooling needs more than 25% in all of the studied locations and 100% in some locations with dry or temperate climate such as Mashhad, Madrid, and Istanbul. It was also observed that the heating needs were satisfied more than 50% in all of the studied locations, even for the continental climate such as Stockholm and 100% in most locations with a dry climate. Therefore, the Solar Chimney reduces energy use, saves environment resources, and it is a cost effective application. Furthermore, it saves the equipment costs in many locations. All the results mentioned above make the solar chimney a very practical and attractive tool for a wide range of climates.
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Yu, Guowang. "Cold-formed Steel Framed Shear Wall Sheathed with Corrugated Sheet Steel." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc271921/.
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Incombustibility is one important advantage of the sheet steel sheathed shear wall over wood panel sheathed shear wall. Compared to shear wall sheathed with plywood and OSB panel, shear wall sheathed with flat sheet steel behaved lower shear strength. Although shear wall sheathed with corrugated sheet steel exhibited high nominal strength and high stiffness, the shear wall usually behaved lower ductility resulting from brittle failure at the connection between the sheathing to frames. This research is aimed at developing modifications on the corrugated sheathing to improve the ductility of the shear wall as well as derive practical response modification factor by establishing correct relationship between ductility factor ? and response modification factor R. Totally 21 monotonic and cyclic full-scale shear wall tests were conducted during the winter break in 2012 by the author in NUCONSTEEL Materials Testing Laboratory in the University of North Texas. The research investigated nineteen 8 ft. × 4 ft. shear walls with 68 mil frames and 27 mil corrugation sheet steel in 11 configurations and two more shear walls sheathed with 6/17-in.OSB and 15/32-in. plywood respectively for comparison. The shear walls, which were in some special cutting arrangement patterns, performed better under lateral load conditions according to the behavior of ductility and shear strength and could be used as lateral system in construction.
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Yan, Shu, and 閆澍. "Bolted and screwed connections of thin sheet steels at elevated temperatures." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2012. http://hub.hku.hk/bib/B47752828.
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The structural behaviour of single shear bolted connections, double shear bolted
connections and single shear screwed connections of thin sheet steels at elevated
temperatures has been investigated in this study. The current design rules on bolted
and screwed connections of thin sheet steels for cold-formed steel structures are
applicable for ambient temperature condition only. These design rules may not be
applicable for elevated temperature conditions. Therefore, design guidelines should
be prepared for bolted and screwed connections of cold-formed steel structures at
elevated temperatures.
A total of 30 tensile coupon tests were conducted to investigate the material
deterioration of the thin sheet steels at elevated temperatures, and also to determine
the critical temperatures for connection tests. A total of 510 tests on single shear
bolted connections, double shear bolted connections and single shear screwed
connections of thin sheet steels at elevated temperatures was performed in the
temperature ranged from 22 to 900?C using both steady state and transient state test
methods. The test results were compared with the predicted values calculated from
the North American, Australian/New Zealand and European specifications for coldformed
steel structures. In calculating the nominal strengths of the connections, the
reduced material properties of the thin sheet steels were used due to the deterioration
of material at elevated temperatures. It is shown that the design strengths predicted
by these specifications are generally conservative at elevated temperatures.
Finite element models for single shear bolted connections, double shear bolted
connections and single shear screwed connections were developed and verified
against the experimental results. Explicit dynamic analysis technique was used in the
numerical analyses. Extensive parametric studies that included 490 finite element
specimens were carried out using the verified finite element models to evaluate the
bearing strengths of bolted connections as well as the tilting and bearing strengths of
screwed connections of thin sheet steels at elevated temperatures.
Design equations for bearing strengths of bolted connections as well as design
equations for tilting and bearing strengths of screwed connections were proposed
based on both the experimental and the numerical results in the temperature ranged
from 22 to 900?C. The bearing strengths of bolted connections as well as the tilting
and bearing strengths of screwed connections obtained from the test specimens and
the finite element analyses were compared with the predicted strengths calculated
using the proposed design equations and also compared with the design strengths
calculated using the current North American, Australian/New Zealand and European
specifications with consideration of the reduced material properties at elevated
temperatures. It is shown that the proposed design equations are generally more
accurate and reliable in predicting the bearing strengths of bolted connections as well
as the tilting and bearing strengths of screwed connections of thin sheet steels at
elevated temperatures than the current design rules. The reliability of the current and
proposed design rules was evaluated using reliability analysis. The proposed design
equations are suitable for bolted and screwed connections assembled using thin sheet
steels of thickness ranged from 0.35 to 3.20mm.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
6
Shobaki, I. E. H. "The behaviour of profiled steel sheet/concrete slabs." Thesis, University of Salford, 2000. http://usir.salford.ac.uk/2056/.
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The work presented in this thesis is concerned with the effect of shear-bond on the behaviour of profiled steel sheet/concrete composite slabs. A review of the previous work carried out to investigate the influence of shear bond in composite construction and the factors which may affect shear bond resistance is presented and discussed. Also, the different empirical shear-bond equations proposed and design methods for composite slabs are reviewed. A description of push-off and pull-out tests follows and several examples of concrete/profiled steel sheeting units were tested and the results discussed. These small scale tests provided information on the load/slip relationship which was used in the subsequent modelling of the full-scale composite slabs. Fullscale composite slab tests are then considered together with a discussion of results. These are analysed using the regression approach of British Standards and the Eurocode 4. Comparison is made with the design values using the partial interaction method. The comparison indicates that both design methods are valid with the regression approach being slightly more conservative. Finite element methods and their advantages are reviewed and the ANSYS software is introduced together with it's proprietary elements, material models and contact elements. This is followed by a description of three-dimensional finite element modelling of composite slabs (small and full scale). The load versus deflection, and load versus slip provide a comparison between the numerical analysis and test results. The finite element analysis of the composite slabs was successful. The failure load of each slab was modelled satisfactorily using the contact stiffness from the small-scale tests modified by a small percentage (less than 10%). A close correlation between the experimental and finite element analysis predictions for the load/slip and load/deflection behaviour was also obtained. Three-dimensional finite element modelling of embossments with different parameters for the steel sheet and concrete was carried out and conclusions drawn. The general conclusions of the work follows together with recommendations for future research.
7
Billur, Eren. "Warm Hydroforming Characteristics of Stainless Steel Sheet Metals." VCU Scholars Compass, 2008. http://scholarscompass.vcu.edu/etd/1665.
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For numerical modeling and predictive analysis of warm hydroforming, better understanding of material properties (i.e. Flow curves) is required at elevated temperatures and high strains. Hydraulic bulge testing is a suitable method to obtain this information. However, analysis of the test data is not standardized as there are numerous approaches developed and adopted throughout the years. In this study, first, different approaches for hydraulic bulge analysis were compared with stepwise experiments to determine the best combination of approaches in obtaining accurate flow curves at different temperatures and strain rates. Then, three different grades of stainless steels (AISI 201, 301 and 304) were tested at various hydroforming conditions to determine the effect of pressure, temperature and strain rate on formability (i.e. cavity filling and thinning). These experimental findings were then used to be compared with predicted values from FEA. Results showed that material model works accurately in predicting the formability of materials in warm hydroforming.
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Quadir, Md Zakaria. "A microstructural study of warm rolled interstitial free steel." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2003. http://hub.hku.hk/bib/B31244683.
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Porrino, Alessandre. "Statistical analysis of deterministic textures in steel sheet production." Thesis, Brunel University, 2004. http://bura.brunel.ac.uk/handle/2438/4980.
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Textured surfaces are universally adopted in the steel sheet production industry, and manufacturers are continuously improving the quality of the finished products through intense research in the surface characterisation field. Deterministic Surfaces are textured with specifically designed rolls in order to present a certain degree of regularity, which allows better control over the functional behaviour of the metal sheets. The regularity of the texture impressed on the steel sheets also allows unconventional approaches to surface characterisation and to the assessment of the texture's structure. Statistical analysis is the most effective way to target the isolation of the deterministic part of the surface, which represents the desired product, from the stochastic part, called ‘noise’ and associated with the inaccuracies of production and measurement. This work addresses the problem of characterisation of deterministic textures through statistical analysis, proposing innovative filtering techniques aimed at the realisation of an On-line Process Control System. Firstly the techniques proposed are theoretically formulated and studied, addressing in particular the physical meaning of the geometrical parameters extracted through statistical analysis of highly correlated portions of the textures. A method for isolating the deterministic textures present on a surface, called the Statistical Surface Filter, is presented and discussed in detail, and tested on existing laboratory samples. Secondly the filter is applied to preliminary measurements acquired by an innovative on-line measurement system currently under development, and evidence is shown that the technique is effective in separating the information regarding the regular patterns from the stochastic noise. The possible applications to on-line Statistical Process Control are discussed. Thirdly, the Statistical Surface Filter is tested on a set of measurements representing texturing rolls and textured sheets with different characteristics; statistical analysis of the surface parameters extracted from the filtered surfaces show that the technique allows the assessment of the different contributions of the various stages of the texturing process to the final product. Finally, a software package is implemented for the practical application of the filtering techniques and the parameters extraction; the algorithms that perform the statistical filtering are described and discussed, concluding with the operations of optimisation and fine-tuning for production-line implementation.
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Hardin, Kenneth O. "Finite element analysis of cellular steel sheet pile cofferdams." Diss., Virginia Tech, 1990. http://hdl.handle.net/10919/39758.
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A cellular cofferdam represents a challenging soil-structure interaction problem. The cellular system consists of a combination of a flexible structure formed from interlocking sheet piles that is filled with soil. In the past, the cellular cofferdam has been viewed as a temporary structure, and the design procedures have been based on empirical concepts. Basic to these approaches are assumptions of soil and structural behavior that have, at best, only a rough accounting for soil-structure interaction.
In the last decade, work on cofferdams has improved our understanding of the behavior of these systems. Documentation of performance has increased, and in a few cases major instrumentation efforts have been undertaken. Concurrently, finite element methods have been introduced for the analysis of cofferdams. Where the finite element models have been properly calibrated by field performance, they have reasonably predicted the principal aspects of cofferdam behavior. Results of the finite element models have also served to help explain some aspects of the soil-structure interaction process in the cofferdam system.
Two finite element programs are used in this research, AXISHL and GPS. The first of these is an axisymmetric analysis tool which is applicable to the case of filling of a main cell. The second program provides a simplified means of analyzing the main/arc cell and common wall system. Both programs are used in a series of parameter studies with the objective to provide information that will allow improvement of the state-of-the-art of design for cofferdams. An analytical solution is proposed which allows an insight to be developed as to how the clamping effect at the dredge line affects the behavior of the system. A simplified calculation procedure which has some of the characteristics of the finite element analysis is developed to supplement the need for a finite element analysis.Ph. D.
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Rautenbach, Elana. "Finite element modelling of thin sheet steel screw connections." Diss., University of Pretoria, 2016. http://hdl.handle.net/2263/60017.
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This study focused on the non-linear finite element modelling procedure, utilising the explicit dynamic analysis technique, and how the various modelling parameters affect the accuracy. The computer modelling of screwed connections is a complex task, and the objective was to investigate the different modalities of finite element modelling to effectively analyse thin sheet steel screwed connections, through calibration against test data found within existing literature. Several aspects of the modelling procedure were examined, including contact definitions, the effective control of the applied load and how it affects the energy output of the finite element model. The final calibrated model was utilised in subsequent parametric studies, which investigated the effect of the steel sheet thickness, as well as the number of the screws used. Results concluded that the finite element model could effectively simulate the expected experimental behaviour of these connections.Disseration (MEng)--University of Pretoria, 2016.
Civil Engineering
MEng
Unrestricted
12
Sederstrom, Jack Hunter. "Spot friction welding of ultra high-strength automotive sheet steel / /." Diss., CLICK HERE for online access, 2007. http://contentdm.lib.byu.edu/ETD/image/etd1724.pdf.
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Ye, Jianjun. "Compression strength of unstiffened elements in cold-reduced high strength steel." Thesis, The University of Sydney, 2005. https://hdl.handle.net/2123/27906.
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Compression strength of unstiffened elements in cold—reduced high strength
steel G550 and G450 steel to Australian Standard AS 1397-1993 are
investigated experimentally and theoretically in this thesis.
The thesis describes two series of tests. The first one is material property tests
performed on tension and compression coupons cut from high strength steel
sheet in 0.6 mm or 1.0 mm thickness with nominal yield stress of 550 MPa and
1.5 mm thickness with nominal yield stress of 450 MPa. The second is
compression tests performed on stub angles cut from high strength steel sheet
in 0.6 mm and 1.0 mm thickness with nominal yield stress of 550 MPa.
A numerical simulation on the angle compression tests using the commercial
finite element computer program ABAQUS is also presented as part of this
thesis. The effect of changing variables, such as geometric imperfections and
end boundary conditions is also investigated. The ABAQUS analysis gives
accurate simulations of the tests and is in good agreement with the experimental
results.
The results of the column tests and ABAQUS simulation have been compared
with the design procedures in the Australian/New Zealand Standard for Cold-
Formed Steel Structures (AS/NZS 4600). The stub column tests show that the
current design rules give too conservative predictions of the compressive
section capacities of the column members used in their current form for G550
steel.
A design proposal is presented in this thesis to account for the effects peculiar to
high strength thin steels on the section and member capacities.
14
Weimer, William Eugene. "Corrosion of Magnesium, Aluminum, and Steel Automotive Sheet Metals Joined by Steel Self-Pierce Rivets." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1420818436.
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Shah, S. Rehan H. "The deformation behaviour of zinc-rich coatings on steel sheet." Thesis, Cardiff Metropolitan University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314778.
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Gustafsson, Emil. "Design and application of experimental methods for steel sheet shearing." Doctoral thesis, Högskolan Dalarna, Materialteknik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:du-23382.
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Shearing is the process where sheet metal is mechanically cut between two tools. Various shearing technologies are commonly used in the sheet metal industry, for example, in cut to length lines, slitting lines, end cropping etc. Shearing has speed and cost advantages over competing cutting methods like laser and plasma cutting, but involves large forces on the equipment and large strains in the sheet material. The constant development of sheet metals toward higher strength and formability leads to increased forces on the shearing equipment and tools. Shearing of new sheet materials imply new suitable shearing parameters. Investigations of the shearing parameters through live tests in the production are expensive and separate experiments are time consuming and requires specialized equipment. Studies involving a large number of parameters and coupled effects are therefore preferably performed by finite element based simulations. Accurate experimental data is still a prerequisite to validate such simulations. There is, however, a shortage of accurate experimental data to validate such simulations. In industrial shearing processes, measured forces are always larger than the actual forces acting on the sheet, due to friction losses. Shearing also generates a force that attempts to separate the two tools with changed shearing conditions through increased clearance between the tools as result. Tool clearance is also the most common shearing parameter to adjust, depending on material grade and sheet thickness, to moderate the required force and to control the final sheared edge geometry. In this work, an experimental procedure that provides a stable tool clearance together with accurate measurements of tool forces and tool displacements, was designed, built and evaluated. Important shearing parameters and demands on the experimental set-up were identified in a sensitivity analysis performed with finite element simulations under the assumption of plane strain. With respect to large tool clearance stability and accurate force measurements, a symmetric experiment with two simultaneous shears and internal balancing of forces attempting to separate the tools was constructed. Steel sheets of different strength levels were sheared using the above mentioned experimental set-up, with various tool clearances, sheet clamping and rake angles. Results showed that tool penetration before fracture decreased with increased material strength. When one side of the sheet was left unclamped and free to move, the required shearing force decreased but instead the force attempting to separate the two tools increased. Further, the maximum shearing force decreased and the rollover increased with increased tool clearance. Digital image correlation was applied to measure strains on the sheet surface. The obtained strain fields, together with a material model, were used to compute the stress state in the sheet. A comparison, up to crack initiation, of these experimental results with corresponding results from finite element simulations in three dimensions and at a plane strain approximation showed that effective strains on the surface are representative also for the bulk material. A simple model was successfully applied to calculate the tool forces in shearing with angled tools from forces measured with parallel tools. These results suggest that, with respect to tool forces, a plane strain approximation is valid also at angled tools, at least for small rake angles. In general terms, this study provide a stable symmetric experimental set-up with internal balancing of lateral forces, for accurate measurements of tool forces, tool displacements, and sheet deformations, to study the effects of important shearing parameters. The results give further insight to the strain and stress conditions at crack initiation during shearing, and can also be used to validate models of the shearing process.
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Sederstrom, Jack H. "Spot Friction Welding of Ultra High-Strength Automotive Sheet Steel." BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/842.
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Spot friction welding (SFW) was performed on ultra high strength steel (UHSS) steel sheet commonly used in automobile manufacturing. Alloys studied included DP780, DP780EG, DP980, and DF140T sheet steel of varying thickness from 1.2 mm to 1.4 mm. Welding was accomplished using a PCBN standard tool. Weld strengths were then compared to a proposed AWS standard. Initial hardness readings were taken in cross sectioned samples. Grain structure in a SFW is presented. Resistance spot welds were created in three steels. This study focuses on the strength of SFW joints as compared to traditional resistance spot welding (RSW) in welding like materials to one another. Cycle times of SFW were also evaluated and compared to production rate cycle times of RSW.
18
Yanagi, Noritsugu. "Analytical Model of Cold-formed Steel Framed Shear Wall with Steel Sheet and Wood-based Sheathing." Thesis, University of North Texas, 2013. https://digital.library.unt.edu/ark:/67531/metadc271920/.
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The cold-formed steel framed shear walls with steel sheets and wood-based sheathing are both code approved lateral force resisting system in light-framed construction. In the United States, the current design approach for cold-formed steel shear walls is capacity-based and developed from full-scale tests. The available design provisions provide nominal shear strength for only limited wall configurations. This research focused on the development of analytical models of cold-formed steel framed shear walls with steel sheet and wood-based sheathing to predict the nominal shear strength of the walls at their ultimate capacity level. Effective strip model was developed to predict the nominal shear strength of cold-formed steel framed steel sheet shear walls. The proposed design approach is based on a tension field action of the sheathing, shear capacity of sheathing-to-framing fastener connections, fastener spacing, wall aspect ratio, and material properties. A total of 142 full scale test data was used to verify the proposed design method and the supporting design equations. The proposed design approach shows consistent agreement with the test results and the AISI published nominal strength values. Simplified nominal strength model was developed to predict the nominal shear strength of cold-formed steel framed wood-based panel shear walls. The nominal shear strength is determined based on the shear capacity of individual sheathing-to-framing connections, wall height, and locations of sheathing-to-framing fasteners. The proposed design approach shows a good agreement with 179 full scale shear wall test data. This analytical method requires some efforts in testing of sheathing-to-framing connections to determine their ultimate shear capacity. However, if appropriate sheathing-to-framing connection capacities are provided, the proposed design method provides designers with an analytical tool to determine the nominal strength of the shear walls without conducting full-scale tests.
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Chen, Yujie. "Nominal Shear Strength and Seismic Detailing of Cold-formed Steel Shear Walls using Steel Sheet Sheathing." Thesis, University of North Texas, 2010. https://digital.library.unt.edu/ark:/67531/metadc30444/.
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In this research, monotonic and cyclic tests on cold-formed steel shear walls sheathed with steel sheets on one side were conducted to (1) verify the published nominal shear strength for 18-mil and 27-mil steel sheets; and (2) investigate the behavior of 6-ft. wide shear walls with multiple steel sheets. In objective 1: this research confirms the discrepancy existed in the published nominal strength of 27-mil sheets discovered by the previous project and verified the published nominal strength of 18 mil sheet for the wind design in AISI S213. The project also finds disagreement on the nominal strength of 18-mil sheets for seismic design, which is 29.0% higher than the published values. The research investigated 6-ft. wide shear wall with four framing and sheathing configurations. Configuration C, which used detailing, could provide the highest shear strength, compared to Configurations A and B. Meanwhile, the shear strength and stiffness of 2-ft. wide and 4-ft. wide wall can be improved by using the seismic detailing.
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Varadarajan, Ashok. "Dross formation mechanism and development of wear resistant scraper in 55Al-1.5Si-Zn coating bath." Morgantown, W. Va. : [West Virginia University Libraries], 2008. https://eidr.wvu.edu/etd/documentdata.eTD?documentid=6022.
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Thesis (Ph. D.)--West Virginia University, 2008.Title from document title page. Document formatted into pages; contains xi, 106 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 101-106).
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Harris, I. D. "High-speed GMAW and laser GMAW hybrid welding of steel sheet." Thesis, Cranfield University, 2009. http://dspace.lib.cranfield.ac.uk/handle/1826/4571.
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Arc welding is the most widely used set of joining technologies in industry today. The automotive tier supplier network and light manufacturing are significant users of arc welding, particularly gas metal arc welding (GMAW) and pulsed GMAW (GMAW-P). For sheet metal welding the majority of welds are single pass fillet welds on T-butt, lap, or edge joints. A fundamental problem and limitation to the use of higher travel speeds in GMAW is the phenomenon of weld bead humping, a weld profile defect with a wavelike profile to the weld bead that has peaks and troughs in the longitudinal direction.
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Holliday, R. J. "Mechanism of electrode growth during spot welding of coated sheet steel." Thesis, Swansea University, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637291.
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It has been found that growth of the electrode tip is the dominant electrode degradation process controlling electrode life. Three distinct mechanisms then contribute to overall growth of the electrode tip. The relative contribution of these mechanisms is dependent on coating type and welding process details. In general, electrode tip growth rate is governed by the current and force density at the electrode contact face, but is independent of electrode material. Alloying between the electrode contact face and the coating is considered to be a secondary factor influencing electrode life. Techniques have been developed for measuring the change in resistance during weld formation at the electrode/sheet and sheet/sheet interfaces. The electrode/sheet interfacial resistance has been found to be significantly greater than that measured at the sheet/sheet interface. It has been established that the electrode degradation processes affect these resistance values. In particular, the resistance across the welding electrodes is inversely related to electrode tip contact area. Improvements in electrode life are thus possible through the use of current stepping techniques. In the present investigation, a number of criteria for establishing optimum rates of current increase have been evaluated. The most significant improvements in life were obtained using a rate of current increase based on the rate of electrode tip growth. An iterative technique has been derived for establishing an optimum non-linear current stepping programme. The implications of the results to manufacturing procedures have been considered, including the recommendation of preferred electrode geometry, practices for electrode dressing and current stepping. These practical considerations should lead to a more efficient mode of operation in modern manufacturing plants operating at high production rates.
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Mawer, Richard William. "Analysis of reduced modulus action in U-section steel sheet piles." Thesis, University of Southampton, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.431934.
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Too, Jonah Kiptanui Arap. "Development and application of new joints in steel pipe sheet piles." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145361.
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Hirsch, Michael Robert. "Fretting behavior of AISI 301 stainless steel sheet in full hard condition." Thesis, Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24759.
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Zhao, Congxiao. "Investigations on structural interaction of cold-formed steel roof purlin-sheet system." Thesis, University of Birmingham, 2014. http://etheses.bham.ac.uk//id/eprint/5199/.
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When used as secondary roof purlins, cold-formed steel (CFS) sections are often attached to trapezoidal sheets through self-drilling screws to form a complete roofing system. The load application points are often eccentric to the shear centre, and thus inevitably generate a torsional moment that will induce twisting and/or warping deformations in addition to bending deflection. The connections between purlin and roof sheeting provide a restraining effect on purlin members by preventing such lateral and twisting movements, and hence have a beneficial effect on the load-carrying capacity. In this thesis the interactional behaviour of CFS purlin-sheeting system have been investigated through the following steps: (1) A F-test is carried out to measure the rotational stiffness at the connections, an engineering-orientated model is developed for quantifying the rotational stiffness regardless to purlin and sheet geometry and loading directions; (2) A set of loading tests on Z- and Σ- roof system are conducted to investigate the impact of rotational stiffness on the overall structural performance, load-carrying capacity and buckling behaviour of the system; (3) Finite element simulations of the existing tests are carried out and successfully validated; (4) Numerical parametric studies are established to study other factors that could affect the rotational stiffness.
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Beaumont, Richard Adrian. "Determining the effect of strain rate on the fracture of sheet steel." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/56768/.
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A key challenge for the automotive industry is to reduce vehicle mass without compromising on crash safety. To achieve this, it is necessary to model local failure in a material rather than design to the overly conservative criteria of total elongation to failure. The current understanding of local fracture is limited to quasi-static loading or strain rates an order of magnitude too high for automotive crash applications. This thesis studies the local fracture properties of DP800 sheet steel at the macroscopic scale from strain rates of to for the first time. Geometries for three stress states, namely plane-strain, shear and uniaxial tension, were developed to determine a fracture locus for DP800 steel using optical strain measurement. These geometries were developed using Finite Element Analysis and validated experimentally for strain rate and stress state. Thermal imaging was used to determine the effect of strain rate on temperature rise and its associated effect on fracture. Fractography was used to examine the specimens’ failure modes at different strain rates. The geometries were applied to the advanced high strength steel grade DP800. Despite prior evidence from simple tensile test data, DP800 showed no significant variation in fracture strain with strain rate in all three stress states. Non-contact thermal measurements showed that the high strain rate tests ( ) were non-isothermal with temperature rises of up to being observed. As a result of this it is difficult to decouple the effect of strain rate from the effect of temperature and requires further investigation. The test geometries were also applied to the deep draw steel DX54 and the aluminium alloy AA5754 where a strain rate effect was observed. Both materials are significantly more ductile than DP800 whish exposed a limitation in the test procedures. At high fracture strains the stress state deviates from its intended value and can invalidate the test. Therefore, a method was developed for determining the validity of a test for each geometry and material from experimental data. The preliminary data from DX54 indicates significantly greater strain rate sensitivity across one order of magnitude than was observed in five orders of magnitude in DP800.
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Blandford, Peter. "Through-thickness inhomogeneity of steel-sheet texture and its affect on material properties." Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59295.
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The work of this thesis centres around two related themes, the first being the characterization of the through-thickness inhomogeneity found in rolled sheet at various stages in its production. The second is involved with attempting to understand how and to what extent the existing inhomogeneity affects the correlations with the anisotropies of some physical or mechanical properties. For this, the inhomogeneity of six steels were measured.Three were specimens removed from the sheet during the early processing of conventional grain-oriented ferrosilicon steel, one sample taken after the first cold rolling stage, another taken after the intermediate anneal, while the last was taken after the following stage, i.e. after the second cold rolling.
To contrast the extensive inhomogeneity expected in the ferrosilicon steels, the remaining three steels consisted of two continuous-annealed, interstitial-free, extra-low-carbon steels and one aluminum-killed, batch-annealed, low-carbon steel, all three of which are commercial final product, deep drawing steels.
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W, Lindvall Fredrik. "On tool steel, surface preparation, contact geometry and wear in sheet metal forming." Licentiate thesis, Karlstads universitet, Avdelningen för maskin- och materialteknik, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-8883.
Full textAbstract:
In sheet metal forming operations the life length of the production equipment islargely dependent on the wear of the tools that are in direct contact with the sheet.One form of adhesive wear where some sheet material gets transferred to the tool, alsoknown as galling, is the most common cause of tool failure. The transferred materialsticks firmly to the tool and will scratch subsequent sheets and increase friction, renderingthem anywhere from aesthetically unsightly to completely ripped apart. Withcareful combination of several parameters the tools production life can be significantlyextended. The surface preparation of the tools has a large influence on the tool life, thesurface has to be smooth and yet not without texture. It was shown in strip reductiontesting that the orientation as well as the depth of the surface texture left by polishinginfluenced the tool life and that a texture perpendicular to the sliding direction was toprefer. The geometry of the forming tool is also a parameter to take into account as itinfluences the tool life not only by changing the contact pressure but also in itself. Ina sliding against flat sheet test rig a lower contact pressure increased the sliding distanceto galling. When two different geometries were compared at the same contactpressure it was found that there was a difference in tool life. As to the tool itself thematerial it’s made of influences the wear rate and tool life. Different tool steels wasinvestigated in sliding wear against metal sheets; Vancron 40 performed better thanVanadis 6 and S290PM performed better than a AISI M2 grade steel.
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Kuleib, M. M. A. "The analysis and behaviour of composite space frames with profiled steel sheet floors." Thesis, University of Salford, 1989. http://usir.salford.ac.uk/2055/.
Full textAbstract:
The objective of this research was to analyse and investigate the behaviour of a composite space frame. The space frame is assembled from individual inverted square-based pyramids. Each pyramid consists of a steelangle section top-tray and diagonals. When the top trays are connected together, they form the top-chord members of a double-angle section connected back to back. The investigation is primarily concerned with the composite section within the space frame system which comprises the top chord members, profiled steel sheeting and a concrete slab. This composite section is also assumed to work as a system of intersecting composite Tbeams. Each composite T-beam comprises of a top chord member, a certain width of profiled steel sheet and a concrete slab. The composite action is ensured by a series of self-tapping screws. The experimental work is based on two-unit space frame specimens. Each specimen represents two adjacent units with their top chord member which carries the highest compressive axial load in the real structure. Each unit is tested in a situation which simulates its position and loading within the real structure. In addition to the composite T-beams being tested, steel struts composed of the top chord member double-angles were tested. In the theoretical section, the real structure is analysed as composite beam elements and thin steel plate elements which all represent the top composite T-beams. The diagonals and the ties were considered as truss elements. A successful method of analysis was developed using matrix and finite element methods resulting in the force distribution and deformations for a full composite space frame. Additionally, the experimental work yielded useful information on the behaviour of composite struts of this type. Recommendations for future work are made. The investigation of the behaviour of the composite T-beams with different locations and numbers of shear connectors together with the analysis of the structure comprise the main part of this work.
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DeMania, Deborah Ann. "The influence of martensitic transformation on the formability of 304L stainless steel sheet." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/11488.
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Els-Botes, Annelize. "Material characterisation of laser formed dual phase steel components." Thesis, Nelson Mandela Metropolitan University, 2005. http://hdl.handle.net/10948/176.
Full textAbstract:
The nature and scope of this thesis can be divided into four categories: • FORMING PARAMETERS • Identification of various laser forming parameters in order to produce specimens of similar dimension (radius of curvature). • TEMPERATURE AND MICROSTRUCTURE • To study the effect of maximum temperature reached during the forming operation on the microstructure of the various specimens. • FATIGUE LIFE • Compare the fatigue life of the specimens produced by various laser parameters to that of the original material, and also the fatigue life of mechanical formed specimens. • RESIDUAL STRESS PROFILE Determine if the laser forming process induces detrimental residual stress magnitudes in the specimens. The main objective of this thesis was to gain an understanding of the way in which laser forming affects the fatigue performance and residual stress magnitude / distribution of dual phase steel. Although lasers have been used successfully in various manufacturing processes (welding, cutting, marking, etc.), little information is available on the influence of laser forming on many automotive alloys such as dual phase steel. The first part of the work involved a literature review of the process and factors affecting the laser forming process. It became clear from the literature overview that laser forming of sheet material thicker than 1mm is complex in nature. The variables that can influence the process are complicated and their interaction with each other is not easily controlled. The main parameters that were thus controlled in this study are as follows: • Laser power (P) • Laser head travel speed (v) • Laser beam size (mm) The chapters that follow the literature review, deals with the laser forming process of dual phase steel and the production of fatigue specimens using various laser parameters. It was found that the following laser parameters resulted in specimens with approximately the same radius of curvature: Laser power KW Beam diameter mm Interval spacing % Overlap Scanning velocity m/min Line Energy J/m 5 20 10 50 2,5 2000 3,1 14 10,5 25 2 1550 1,5 7,5 7,5 0 1,2 1250 From the results obtained from fatigue testing specimens produced with the above settings, it is clear that the laser forming process has the potential to be employed as a production stage in the manufacture of wheel centre discs while maintaining adequate fatigue strength. Large beam diameters which cause heat penetration through the thickness of the specimen and hence microstructure breakdown should be avoided, since it was shown that these specimens exhibited impaired mechanical properties than those produced with a smaller laser beam diameter. The microstructural changes observed during the forming process needs to be considered since the mechanical properties of the material changes with a change in microstructure. A dramatic change in microstructure was observed; therefore it is of crucial importance that microstructural evaluation plays an important part in deciding optimum laser parameters for the forming process of ferrous alloys. During residual stress analysis, trends were observed between measurements taken at the same location of the samples; regardless whether measurements were taken on the laser irradiated side or the reverse side of the specimen. The only difference was the magnitude of the relieved residual stress. In most cases the obtained relieved residual stress was much smaller in magnitude than that of the original plate (in the bulk of the material). The surface indicated a slight tensile residual stress for most samples evaluated. A good correlation in distribution profile was obtained between microhardness and relieved residual stress distribution at the ‘middle of sample’ location. This indicates that an increase in hardness indicates an increase in residual stress magnitude for the laser formed specimens. In conclusion, this research has proved that it is possible to deform metal plate of a 3,5mm thickness with a CO2 laser system. The research also established the effect of process parameters on the final product’s shape/bend angle and characterised the effect of the laser forming process on the material’s mechanical properties and structural integrity.
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Becque, Jurgen. "The interaction of local and overall buckling of cold-formed stainless steel columns." Thesis, The University of Sydney, 2008. http://hdl.handle.net/2123/3772.
Full textAbstract:
Abstract: The objective of this research is to investigate the interaction of local and overall flexural buckling in cold-formed stainless steel columns. Literature study exposes a lack of understanding of this subject and a need for experimental data, particularly on the local-overall interaction buckling of stainless steel open sections. Two separate experimental programs were therefore carried out. The first program included 36 tests on pin-ended lipped channel columns. Three alloys were considered: AISI 304, AISI 430 and 3Cr12. The specimens were designed to fail by local-overall interaction buckling in the inelastic stress range, thus highlighting the non-linear behaviour of stainless steel. Half of the specimens were tested under a concentric load. The other half had the load applied with a nominal eccentricity of Le/1500. The test results demonstrate the imperfection sensitivity of local-overall interaction buckling and illustrate the shift in effective centroid in pin-ended columns with singly symmetric cross-section. The second experimental program studied local-overall interaction buckling in 24 pin-ended stainless steel I-section columns. The specimens consisted of plain channels connected back-to-back using sheet metal screws. Two alloys were considered: AISI 304 and AISI 404. Local and overall imperfections were carefully measured in both experimental programs. Extensive material testing was carried out on the alloys employed in the experimental program, in order to determine tensile and compressive material properties, anisotropic parameters and enhanced corner properties. A detailed finite element model is presented, which includes non-linear material behaviour, anisotropy, increased material properties of the corner areas and local and overall imperfections. The model was verified against the two aforementioned experimental programs and against additional data available in literature on stainless steel SHS columns. The model yielded excellent predictions of the specimen failure mode, ultimate strength and load-deformation behaviour. The finite element model was used to generate additional data for stainless steel columns with lipped channel, plain channel, SHS and I-shaped cross-section, failing by local-overall interaction buckling. The parametric studies covered the practical ranges of overall and cross-sectional slenderness values. The Australian/New Zealand, European and North American standards for stainless steel were evaluated using the available data. The comparison reveals an inability of the design codes to properly account for the interaction effect as the cross-sectional slenderness increases. Predictions are unsafe for I-section columns with intermediate or high cross-sectional slenderness. A direct strength method is proposed for stainless steel columns, accounting for the local-overall interaction effect. The method offers a simple design solution which fits within the framework of the current Australian and North-American standards.
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Becque, Jurgen. "The interaction of local and overall buckling of cold-formed stainless steel columns." University of Sydney, 2008. http://hdl.handle.net/2123/3772.
Full textAbstract:
PhDAbstract: The objective of this research is to investigate the interaction of local and overall flexural buckling in cold-formed stainless steel columns. Literature study exposes a lack of understanding of this subject and a need for experimental data, particularly on the local-overall interaction buckling of stainless steel open sections. Two separate experimental programs were therefore carried out. The first program included 36 tests on pin-ended lipped channel columns. Three alloys were considered: AISI 304, AISI 430 and 3Cr12. The specimens were designed to fail by local-overall interaction buckling in the inelastic stress range, thus highlighting the non-linear behaviour of stainless steel. Half of the specimens were tested under a concentric load. The other half had the load applied with a nominal eccentricity of Le/1500. The test results demonstrate the imperfection sensitivity of local-overall interaction buckling and illustrate the shift in effective centroid in pin-ended columns with singly symmetric cross-section. The second experimental program studied local-overall interaction buckling in 24 pin-ended stainless steel I-section columns. The specimens consisted of plain channels connected back-to-back using sheet metal screws. Two alloys were considered: AISI 304 and AISI 404. Local and overall imperfections were carefully measured in both experimental programs. Extensive material testing was carried out on the alloys employed in the experimental program, in order to determine tensile and compressive material properties, anisotropic parameters and enhanced corner properties. A detailed finite element model is presented, which includes non-linear material behaviour, anisotropy, increased material properties of the corner areas and local and overall imperfections. The model was verified against the two aforementioned experimental programs and against additional data available in literature on stainless steel SHS columns. The model yielded excellent predictions of the specimen failure mode, ultimate strength and load-deformation behaviour. The finite element model was used to generate additional data for stainless steel columns with lipped channel, plain channel, SHS and I-shaped cross-section, failing by local-overall interaction buckling. The parametric studies covered the practical ranges of overall and cross-sectional slenderness values. The Australian/New Zealand, European and North American standards for stainless steel were evaluated using the available data. The comparison reveals an inability of the design codes to properly account for the interaction effect as the cross-sectional slenderness increases. Predictions are unsafe for I-section columns with intermediate or high cross-sectional slenderness. A direct strength method is proposed for stainless steel columns, accounting for the local-overall interaction effect. The method offers a simple design solution which fits within the framework of the current Australian and North-American standards.
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Tavrou, Chrysostomos Kyriacou, and stavrou@swin edu au. "Evaluation of adhesively bonded steel sheets using ultrasonic techniques." Swinburne University of Technology, 2005. http://adt.lib.swin.edu.au./public/adt-VSWT20060306.085412.
Full textAbstract:
Adhesives have presently reached a stage where they have become part of everyday
life both in a professional sense as well as for household applications. They offer
advantages that in many respects surpass other joining processes such as bonding
of large areas, joining a wide range and dissimilar materials; and without the need for
special tooling or operator training, that is often required by many other joining
processes. They are of course not a panacea to all fastening applications, but they
can easily be described as the most versatile and most widely used joining method at
present.
Engineering applications have also benefited from the advantages offered by
adhesives, but they are not as liberally used due to the severe consequences that
may result from bond failure. Although adhesives can demonstrate their ability to
fulfil the joining strength requirements under laboratory conditions, their application in
industry proved to be not as reliable as expected. A number of parameters that can
easily be controlled under laboratory conditions such as temperature, humidity,
surface preparation and uniform adhesive application are not as easily observed in
industry. Quality assurance during manufacturing can achieve excellent results;
however even in these cases the probability of having adhesive bond defects is still
present. Therefore, there is a need for post process inspection of adhesive bonds
where risk levels require higher reliability than what is offered though process quality
control.
Adhesive bond inspection is a well researched area with respectable outcomes. Non
destructive inspection techniques such as x-ray, thermal, and ultrasonic are well
utilised in the inspection of adhesive bonds. However, despite all the effort in this
area for more than forty years, there is still no singular technique that can achieve the
confidence level required in some engineering applications. Therefore, the need for
continuing research in the area of non-destructive evaluation of adhesive bonds is as
necessary today as it�s ever been. The research presented in this thesis, continues
in the same endeavour as many other researchers; that of achieving the ultimate
technique in adhesive bond inspection, capable of reaching the confidence level
required for all engineering applications.
The research in the thesis commenced with coverage of adhesives used for
engineering applications and a study of the adhesion science that was considered
necessary to enable an informed approach to the problem. Adhesive bond failure is
also analysed through a literature survey as well as experimental tests on standard
specimens. At the completion of the literature survey and preliminary tests, a
decision was taken to follow the ultrasonic path of non-destructive testing of adhesive
bonds. The reasons for this, are clearly outlined in the main body of this thesis but in
summary, the literature has shown that ultrasonic evaluation is the most widely used
technique by industry. Therefore, improvements on data analysis using existing
techniques that exploit ultrasonic inspection have the potential to reach the widest
spectrum of industrial applications.
Ultrasonic inspection equipment was sourced that was capable of achieving
experimental results to the accuracy level required in this research. A precision test
rig was designed and constructed that was subsequently calibrated using computer
based statistical techniques to ensure the validity of all results. Other ancillary
equipment, such as a portable tensile testing device were also designed and
constructed during the research as it became necessary.
Research concentrated on techniques found to be inadequately researched in this
domain. The first technique evaluated was to measure bond quality through the
stress distribution in adherent and adhesive. Computer based Finite Element
Analysis showed that the ability to detect variation in stress distribution at the
adhesion interface is capable of revealing the local bond strength. Having found that
there is no technique available at present that can measure the stress distribution at
the interface, a different direction was taken that showed potential in achieving
excellent quantitative results in the analysis of ultrasonic signals from adhesive
bonds. This technique was rigorously evaluated and the results are systematically
reported in this work.
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Dogar, Attiq Ur Rahman. "Post Elastic Behaviour and Moment Redistribution in a Double Span LTP200 Steel Trapezoidal Sheet." Thesis, Luleå tekniska universitet, Byggkonstruktion och brand, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-68306.
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Wan, Muhammad Wan Mujtahiddin. "FEM assisted analyze of the spring-back phenomena for steel sheet with complex microstructure." Master's thesis, Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2010. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-38165.
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Essex, Stephen. "Ultrasonic characterisation of rolled aluminium and steel sheet correlated with electron backscatter diffraction measurements." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/3147/.
Full textAbstract:
This thesis is based on the characterization of material properties of interest in rolled aluminium and steel sheet, both popular materials used across a wide-range of applications. The forming processes involved in producing rolled sheet metal depend on plastic deformation, inducing elastic anisotropy as a consequence. These changes result in a variation from the simple isotropic and cubic symmetry systems possessed by steel and aluminium prior to cold-working. The most significant changes include the introduction of crystallographic texture and the morphology of the crystallographic grains in size and shape to accommodate the plastic deformation. It is desirable in industries that use rolled product for manufacturing components to quantify such changes. The literature has postulated links between plastic and elastic properties, and hence any quantification of the elasticity, crystallographic texture and grain morphology can aid in the prediction of future formability behaviour. This thesis presents non-destructive, rapid ultrasonic measurements to characterize some of the changes that are evident in rolled aluminium and steel sheet. These ultrasonic results have then been correlated to crystallographic orientation measurements generated from using a microscopic technique called electron backscatter diffraction (EBSD). The level of agreement between the two contrasting methods has been analysed and is presented here. The non-destructive ultrasonic measurements include quantifying crystallographic texture utilising theory linking the S0 Lamb wave velocity and the direction of propagation in a rolled sheet with respect to the rolling direction. This leads to the determination of texture coefficients known as orientation distribution coefficients (ODC). Through-thickness linearly polarized SH waves have then been used to analyse grain morphology using attenuation data, and elasticity measurements from velocity data. EBSD datasets have been manipulated to produce predictions of the effective elastic stiffness constants, which in turn can be used to generate comparable S0 Lamb wave velocity predictions to be directly compared to the ultrasonic measurements. This process has required a novel method to generate such ultrasonic velocity predictions as a function of angle, together with predictions for the nine effective elastic stiffness constants inherent to rolled orthorhombic sheet. The facility to measure grain size and shape accurately from EBSD data has been utilized. The thesis starts with a general introduction in non-destructive testing and microscopy, with focussed discussion on ultrasound, electromagnetic acoustic transducers (EMATs), EBSD and metallurgy in the subsequent chapters. Chapter 6 introduces the development of correlation methods between the ultrasound and EBSD results, with chapters 7 and 8 displaying the empirical ultrasound and EBSD data respectively. Chapter 9 compares the data from the two methods, with the final conclusions given in chapter 10.
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Waterworth, Adelle. "Quantitative characterisation of surface finishes on stainless steel sheet using 3D surface topography analysis." Thesis, University of Huddersfield, 2006. http://eprints.hud.ac.uk/id/eprint/385/.
Full textAbstract:
The main aim of this project was to quantitatively characterise the developed surface topography of finishes on stainless steel sheet using three-dimensional surface analysis techniques. At present surface topography is measured using (mainly) stylus profilometry and analysed with 2D parameters, such as Ra, Rq and Rz. These 2D measurements are not only unreliable due to a lack of standardised measurement methodology, but are also difficult to relate directly to the actual shape of the topography in 3 dimensions. They bear little direct relation to the functional properties of the surface of stainless steel, making them less useful than their 3D counterparts. Initially it is crucial to ensure that the surface topography data collected is correct, accurate and relevant, by defining a measurement strategy. Models of the surface topography are developed encompassing the usual features of the topography and variations in the topography caused by production or 'defects'. The functional features are discussed and predicted relevant parameters are presented. The protocol covers the selection of the correct measuring instrument based on the surface model and the size of the relevant functional features so that the desired lateral and vertical resolution and range is achievable. Measurement data is then analysed using Fast Fourier Transforms (FFTs) to separate the different frequencies within the spatial frequencies detected on the surface. The frequency of the important features shows up dominantly on a Power Spectral Density (PSD) plot and this is used to find the correct sampling interval to accurately reconstruct the 3D surface data. The correct instrument for further measurements is then selected using a Steadman diagram. Operational details of the measuring instruments available for this project are given and variables for these instruments are discussed. Finally, measurement method recommendations are made for each of the four finishes modelled. Based on this surface characterisation an attempt is made to identify the 3D parameters that give a quantitative description of common stainless steel sheet finishes with respect to some aspects of their production and functional performance. An investigation of the differences in manufacturing processes, gauge and grade of material is presented, providing an insight into the effect on topography of such divergences. The standardised 3D parameter set is examined to determine its sensitivity to common variations in the topography of the 2B finish and therefore their potential relevance. A new data separation technique of the material probability curve for use on the 3D datasets establishes a cut-off (transition point) between the two main functionally relevant features of the 2B surface (plateaus and valleys) by finding the intersection of the asymptotes of a fitted conic section, giving a non subjective methodology to establish the section height. The standardised 3D parameters are then used on the separated data, with the aim of being more functionally relevant to the main surface studied. Functional tests to rate capability of these parameters in the areas of optical appearance, lubricant retention and corrosion are carried out and the appropriate topography parameters are related to their performance.
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Debray, Bruno. "Microstructure and mechanical properties of an as-hot rolled carbon manganese ferrite-bainite sheet steel." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69713.
Full textAbstract:
By means of torsion testing, the microstructures and mechanical properties produced in a 0.14%C-1.18%Mn steel were investigated over a wide range of hot rolling conditions, cooling rates and coiling temperatures. The reheating temperature was varied between 800$ sp circ$C and 1050$ sp circ$C, and strains between 0 and 0.8 were applied. This led to austenite grain sizes ranging from 10 to 150$ mu$m. Two cooling rates, 55$ sp circ$C/s and 90$ sp circ$C/s, were applied and cooling was interrupted at coiling temperatures ranging from 550$ sp circ$C to 300$ sp circ$C.Optical microscopy and TEM were used to study the microstructures. The mechanical properties were studied by means of tensile testing. A method developed by IRSID for deducing the transformation kinetics from the cooling data was adapted to the present context and used successfully to interpret the observed influence of the process parameters. (Abstract shortened by UMI.)
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Sherry, Samuel Thomas. "Carbon Fiber Reinforced Polymer Retrofits to Increase the Flexural Capacity of Deteriorated Steel Members." Diss., Virginia Tech, 2021. http://hdl.handle.net/10919/104986.
Full textAbstract:
The load-carrying capacity of aging bridge members may at times be found insufficient due to deterioration and a historical trend towards increased truck axle loads beyond their design capacity. Structurally deficient bridges are problematic for bridge owners and users because they restrict traffic usage and require bridges to be posted (operate at less than their ideal capacity). Structural deficiency is the primary motivation for bridge owners to retrofit bridges to meet a specified operating demand. It may be required to replace or retrofit a portion or all of a deficient bridge. The replacement of an entire bridge or even a part of the bridge is generally less desirable than a retrofit solution because retrofits are generally a cheaper alternative to the entire replacement of a structure and usually do not require the bridge's closure. Standard strengthening solutions for corroded members include bolting or welding steel cover plates, replacing sections of the girder, or adding external prestressed tendons. However, these methods also have several challenges, including required lane closures, high installation costs, increased dead weight, and continuing corrosion issues.
One alternative to conventional retrofits is the use of carbon fiber-reinforced polymer (CFRP) laminates, which can be adhered to increase both strength and stiffness. CFRPs are a highly tailorable material with an extremely high strength-to-weight ratio, ease of installation and can potentially mitigate further corrosion concerns. Fiber Reinforced Polymers (FRPs) have already been widely accepted as a means of retrofitting reinforced concrete structures (AASHTO 2012, 2018a; ACI 2002, 2017; National Academies of Sciences, Engineering 2010, 2019) but have not yet been widely adopted in the steel industry due to the retrofit's material limitations (lower elastic modulus [less than 29,000 ksi], unanswered questions related to debonding, and no unified design or installation guides). However, newly developed materials and manufacturing processes have allowed for the economic development of stiffer CFRP materials suitable for steel structures, such as the high modulus (HM) CFRP strand sheet.
This research analytically and experimentally investigates how newly developed HM strand sheets perform in small scale tensile testing and large scale flexural testing (laboratory and in situ testing). During the laboratory testing, these HM strand sheets were compared against normal modulus (NM) CFRP plates to draw conclusions on these different retrofitting materials (strength, stiffness, bond behavior, and applicability of the retrofit). Another central point in examing these different retrofit materials is how CFRPs perform when attached to structural steel with significant corrosion damage. Corrosion damage typically results in a variable surface profile, which may affect a CFRP retrofit's bond behavior. While limited laboratory testing has been conducted on CFRP attached to steel structures with simulated deterioration, the surface profile does not represent realistic conditions. The effects of a variable surface profile on the NM plate material and HM strand sheet were investigated using small scale tensile testing and large scale flexural testing. All the variable surface profiles tested for bond strength were fabricated based on "representative" simulated corrosion samples or on specimens with significant corrosion.
Once all the variables pertaining to the new materials and the effect of a variable surface profile on CFRP retrofits had been examined in a laboratory setting, these retrofitting techniques were implemented on deteriorated in-service steel bridge structures. This research was the first to retrofit deteriorated in-service bridge structures with HM CFRP strand sheets in the United States. This in situ testing was used to compare the laboratory test data of an individually retrofitted girder to the behavior of a single girder that had been retrofitted in a bridge structure. This information was used to verify results on the behaviors of strengthening, stiffening, effects on live load distributions, and modeling assumptions of retrofitted bridge structures.
The results from the laboratory testing and in situ testing of CFRP retrofits on corroded steel structures were synthesized to provide information on performance and design guidance for future retrofits. This dissertation provides additional information on CFRP retrofits applied to variable surface profiles and provides data on new CFRP materials (HM strand sheets). With this information, Departments of Transportation (DOT) can be confident as to where and when different types of CFRPs are a suitable retrofit material for corroded or uncorroded steel structures.Doctor of Philosophy
The capacity of aging bridges may at times be found insufficient due to deterioration and a trend towards increased loading. Structurally deficient bridges are problematic for bridge owners and users because they restrict traffic usage and require bridges to operate at less than their intended capacity. Inadequate capacity are the primary motivation for bridge owners to repair (retrofit) bridges to meet specified traffic demands. Repairs usually do not require the bridge's closure to traffic. Standard repairs for corroded steel members include bolting or welding steel cover plates, replacing sections of the girder, or adding external prestressed tendons. However, these methods also have several challenges, including required bridge closures, high installation costs, increased weight, and continuing corrosion issues. One alternative to conventional repairs is the use of carbon fiber-reinforced polymer (CFRP) laminates, which can be adhered to the deteriorated members to increase strength and stiffness. CFRPs are an extremely versatile material with high strength, high stiffness, ease of installation and can potentially mitigate concerns about further corrosion. Fiber Reinforced Polymers (FRPs) have already been widely accepted as a means of retrofitting reinforced concrete structures(AASHTO 2012, 2018a; ACI 2002, 2017; National Academies of Sciences, Engineering 2010, 2019) but have not yet been widely adopted in the steel industry due to the lack of literature and economical implementation of the CFRPs on steel. However, over the past 20 years, research has been completed on the application of CFRPs on steel, and newly developed materials were created for the economic implementation of CFRP materials suitable for steel structures. In particular, this material is a high modulus (HM) CFRP strand sheet, which has a higher stiffness than a conventional CFRP. This research investigated how newly developed HM strand sheets perform in small-scale laboratory testing and large-scale laboratory testing. Where material strengths, bondability, and the efficacy of different repairs were examined against conventional means on steel structures with and without corrosion deterioration. Once all the variables pertaining to the new materials and the effects corrosion had on CFRP retrofits had been examined in a laboratory setting, these retrofitting techniques were implemented on a deteriorated in-service steel bridge structure (field study) that required repair. This research was the first to repair deteriorated in-use bridge structures with HM CFRP strand sheets in the United States. This information was used to verify results on the material's behavior. The laboratory testing and field testing of CFRP retrofits on corroded steel structures were summarized to provide information on performance and design guidance for future retrofits. This dissertation provides additional information on CFRP repairs applied to corroded steel and provides data on new CFRP materials (HM strand sheets). With this information, Departments of Transportation (DOT) can be confident as to where and when different types of CFRPs are a suitable retrofit material for corroded or uncorroded steel structures.
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Snow, Gregory L. "Strength of Arc Spot Welds Made in Single and Multiple Steel Sheets." Thesis, Virginia Tech, 2008. http://hdl.handle.net/10919/33200.
Full textAbstract:
The objective of this research was to establish a relationship between arc spot weld shear strength and the arc time used to form the weld. Lap shear tests were performed on both 3/4 in. and 5/8 in. nominal diameter welds. Each weld was formed in one-, two-, or four-layers of sheet steel ranging from 22 gauge (0.028 in.) to 16 gauge (.057 in.). Three distinct time series were tested for each unique weld size, thickness of sheet steel and layer configuration. The first of these series were the full-time welds. The two remaining series, 2/3-time and 1/3-time welds, had arc times equal to 2/3 and 1/3 of the average full-time weld arc time, respectively.
Both weld shear strength tests and weld sectioning were performed for each series of weld. Strength tests were performed on a minimum of three specimens from every weld series. If the strength of any specimen deviated by over ten percent from the mean strength, an additional specimen was tested, helping to better understand the true behavior of the weld. Comparisons were made between the strengths of full-time, 2/3-time and 1/3-time welds. Comparisons were also made between the observed strength of each weld and the strengths calculated using the 2001 AISI Specification.
Each sectioning test involved measuring and documenting the visual diameter, average diameter and effective diameter of the weld. Weld penetrations were also documented as sufficient or insufficient and any porosity was noted. A single sectioning test was performed for each full-time series, while three were performed for every 2/3-time and 1/3-time series.
The data taken from the strength tests and the sectioning samples proved that welds formed using reduced arc times were considerably smaller and weaker than full-time welds. The tests also proved that proper penetration is not dependent on the arc time, but is instead a function of the welding current and sheet steel thickness.Master of Science
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Richards, D. C. "A study of the contaminants on the surface of sheet steel important to its corrosion performance." Thesis, Swansea University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.638663.
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The aim of this work has been to study the contamination on the surface of sheet steel and its influence on autobody paint systems. The findings showed that the contamination did have an effect when considering some paint systems. However, when using other systems (e.g. a cathodic electroprimer), or including a top coat, the results showed little association with steel surface contamination, especially in outdoor corrosion tests. The mechanism for paint system failure was investigated and found to be closely associated with the porosity of the zinc phosphate coating normally applied before priming. This was influenced by the presence of carbon in either the amorphous or graphitic form. Using Glow Discharge-Optical Emission Spectroscopy and a combination of plant and laboratory based experiments, it was confirmed that graphitisation was the result of the decomposition of a metastable iron carbide (cementite) at temperatures in excess of 680oC during annealing. In agreement with other workers, strong carbide formers such as Cr and Mn, which form stable mixed carbides with Fe, were found to control the extent of graphite formation. Sulphur bearing species, such as those present in rolling lubricants, also reduced graphitisation. The mechanism was consistent with the formation of an unstable intermediate compound from FeO and CO gas at active surface sites. Other elements were also found to segregate during annealing (such as Mn,Cr,Si,S and P), the driving force probably being oxidation at the surface. Cr appears to be the principal graphite moderator. This, and the presence of an oil film on the pre-anneal surface, were the only two controllable factors which influenced graphitisation. The formation of amorphous carbon from rolling oils was also studied. The breakdown of the synthetic ester molecules was consistent with a free radical oxidation, the rate being strongly influenced by the extent of unsturation present. Radical scavengers were therefore effective antioxidants. The formation of surface carbon was probably the result of polymerisation via the free radical intermediates, which carbonised on the steel surface during the heating phase of annealing.
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JIANG, ZHUOYING. "A Study of the Fate and Effect of Steel Sheet Surface Oxides on Galvanizing Bath Management." Case Western Reserve University School of Graduate Studies / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=case1395924244.
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Ritthiruth, Pawin. "Flexural Behavior of Cold-Formed and Hot-Rolled Steel Sheet Piling Subjected to Simulated Soil Pressure." Thesis, Virginia Tech, 2021. http://hdl.handle.net/10919/101845.
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Hot-rolled sheet piling has long-been believed to have a better flexural performance than cold-formed sheet piling based on a test conducted by Hartman Engineering twenty years ago. However, cold-formed steel can have similar strength to the hot-rolled steel This experimental program studied the flexural behavior of hot-rolled and cold-formed steel sheet pilings. This program quantified the influence of transverse stresses from soil pressures on the longitudinal flexural strength. Four cross-sections with two pairs of equivalent sectional modulus were investigated. Sheet-piling specimens were subjected to simulated soil pressure from an air bladder loaded transversely to their longitudinal axis. The span lengths were varied, while the loading area remains unchanged to examine the effect of different transverse stresses. Lateral bracings were provided at discrete locations to establish a sheet piling wall behavior and allow the development of transverse stresses. Load-pressure, load-deflection, load-strain, and moment-deflection responses were plotted to demonstrate the behavior of each specimen. The moment-deflection curves were then normalized to the corresponding yield stress from tensile coupon tests to make a meaningful comparison. The results indicate that transverse stresses influence the flexural capacity of the sheet pilings. The longer span length has less amount of transverse strains, resulting in a higher moment capacity. The hot-rolled sheet pilings have better flexural performance also because of less transverse strains.Master of Science
Sheet piling wall is an essential structure used during the excavation process. Sheet piling can be hot-rolled and cold-formed. Hot-rolled sheet piling has long-been believed to have a better bending performance based on a test conducted by Hartman Engineering twenty years ago. However, cold-formed steel can have similar strength to hot-rolled steel. This experimental program studied the bending behavior of hot-rolled and cold-formed steel sheet pilings. This program quantified the influence of lateral loading from soil pressure on the moment capacity of the sheet piling. Four cross-sections with two pairs of equivalent bending properties were investigated. Sheet-piling specimens were set up as beam members and subjected to simulated soil pressure from an air bladder. The span lengths of the specimens were varied, while the loading area remains unchanged to examine the effect of different amounts of load. Lateral bracings were provided at discrete locations to establish a sheet piling wall behavior and allow local deflection of the cross-section. Load-pressure, load-deflection, load-strain, and moment-deflection responses were plotted to demonstrate the behavior of each specimen. The moment-deflection curves were then normalized to the corresponding material property of each specimen to make a meaningful comparison between different specimens. The results indicate that lateral loading of the soil pressure influences the bending capacity of the sheet pilings. The longer span length has less amount of transverse strains, resulting in a higher bending capacity. The hot-rolled sheet pilings have better bending performance also because of less transverse strains.
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Ahlgren, Peters Adam. "A SIMULATION WITH FINITE ELEMENTS TO MODEL STEEL SHEET SLITTING : A Master Thesis in Engineering Physics." Thesis, Uppsala universitet, Tillämpad mekanik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-385495.
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A steel slitting process is simulated using FEM (Finite Element Method) in order to see potential defects along the edge in a steel sheet after it has been cut. The model's results were compared to microscope images of the steel sheet in order to verify accuracy. The purpose is conceptual and to find a model that successfully simulates a steel cutting process and (hopefully) how the edge depends on different parameters. The model developed seems to achieve this task, and a more thorough calibration of the model could result in (more) optimal parameters for the machine to use.
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Gardner, Rebecca. "An Experimental Investigation of Friction Bit Joining in AZ31 Magnesium and Advanced High-Strength Automotive Sheet Steel." BYU ScholarsArchive, 2010. https://scholarsarchive.byu.edu/etd/2159.
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Friction Bit Joining (FBJ) is a recently developed spot joining technology capable of joining dissimilar metals. A consumable bit cuts through the upper layer of metal to be joined, then friction welds to the lower layer. The bit then snaps off, leaving a flange. This research focuses on FBJ using DP980 or DP590 steel as the lower layer, AZ31 magnesium alloy as the top layer, and 4140 or 4130 steel as the bit material. In order to determine optimal settings for the magnesium/steel joints, experimentation was performed using a purpose-built computer controlled welding machine, varying factors such as rotational speeds, plunge speed, cutting and welding depths, and dwell times. It was determined that, when using 1.6 mm thick coupons, maximum joint strengths would be obtained at a 2.03 mm cutting depth, 3.30 mm welding depth, and 2500 RPM welding speed. At these levels, the weld is stronger than the magnesium alloy, resulting in failure in the AZ31 rather than in the FBJ joint in lap shear testing.
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Zalieskis, Ramūnas. "Plonalakščio plieno gaminių ir jų gamybos procesų projektavimo integravimas." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2006. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2006~D_20060614_110611-68899.
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Zalieskis R. Integration of designing sheet steel products and their manufacturing processes : Master thesis of mechanical engineer / research advisor associate prof. habil. dr. A.Bargelis, Šiauliai university, department of technologic, department of mechanical engineering. – Šiauliai, 2006. – 38 p. Sheet steel is used wide in a modern manufacturing. In this paper I researched the work one of the factories manufacturing sheet steel products. It was analysed all manufacturing operations and equipment needed to make a box. I researched the designing of sheet steel products and their manufacturing processes on purpose to improve designing process. The designer can use results obtained from this paper and estimate outlay of newly designed product in early design stage. Scientific novelty of the work In this paper method of mathemamatical statistics was used and firstly created classificator of sheet steel products on purpose to estimate outlay of manufacturing.
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Dingle, Matthew, and mikewood@deakin edu au. "Elastic behaviour in mechanical draw presses." Deakin University. School of Engineering and Technology, 2001. http://tux.lib.deakin.edu.au./adt-VDU/public/adt-VDU20051017.150247.
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This thesis explores the elastic behaviour of the mechanical double action press and draw die system commonly used to draw sheet metal components in the automotive industry. High process variability in production and excessive time spent in die try-out are significant problems in automotive stamping. It has previously been suggested that the elastic behaviour of the system may contribute to these problems. However, the mechanical principles that cause the press system to affect the forming process have not been documented in detail. Due to a poor understanding of these problems in industry, the elasticity of the press and tools is currently not considered during the die design. The aim of this work was to explore the physical principles of press system elasticity and determine the extent to which it contributes to problems in try-out and production. On the basis of this analysis methods were developed for controlling or accounting for problems during the design process.
The application of frictional restraining force to the edges of the blank during forming depends on the distribution and magnitude of the clamping force between the binders surfaces of the draw die. This is an important control parameter for the deep drawing process. It has been demonstrated in this work that the elasticity of the press and draw die can affect clamping force in two ways. The response of the press system, to the forces produced in the press during forming, causes the magnitude of clamping force to change during the stroke. This was demonstrated using measured data from a production press. A simple linear elastic model of the press system was developed to illustrate a definite link between the measured force variation and the elasticity of the press and tools. The simple model was extended into a finite element model of the complete press system, which was used to control a forming simulation. It was demonstrated that stiffness variation within the system could influence the final strains in a drawn part. At the conclusion of this investigation a method is proposed for assessing the sensitivity of a part to clamping force variation in the press during die design. A means of reducing variation in the press through the addition of a simple linear spring element is also discussed.
The second part of the work assessed the influence of tool structure on the distribution of frictional restraining forces to the blank. A forming simulation showed that tool stiffness affects the distribution of clamping pressure between the binders. This was also shown to affect the final strains in a drawn part. However, the most significant influence on restraining force was the tendency of the blank to increase in thickness between the binders during forming. Using a finite element approximation of the try-out process it was shown that the structure of the tool would also contribute to the problems currently experienced in try-out where uneven contact pressure distributions are addressed by manually adjusting the tool surfaces.
Finally a generalised approach to designing draw die structures was developed. Simple analysis methods were combined with finite element based topology optimisation techniques to develop a set of basic design guidelines. The aim of the guidelines was to produce a structure with uniform stiffness response to a pressure applied at the binder surface.
The work concludes with a recommendation for introducing the methods developed in this thesis into the standard production process.
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Carlsson, Per. "Surface Engineering in Sheet Metal Forming." Doctoral thesis, Uppsala University, Department of Materials Science, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4764.
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In recent years, surface engineering techniques have been developed in order to improve the tribological performance in many industrial applications. In sheet metal forming processes, the usage of liquid lubricants can be decreased by using self lubricated tribo surfaces which will result in more environmentally friendly workshops. In the present work two different concepts, i.e. the deposition of thin organic coatings on the steel sheet and PVD coatings on the tool, have been evaluated. The sheet materials investigated include Zn and 55%Al-Zn metal coated steel sheet, which in general are difficult materials to form under dry conditions since they are sticky and thus have a high tendency to adhere to the tool surface. The PVD coatings include CrN, TiN and various DLC coatings. The work comprises tribo testing and post test characterisation using surface analytical techniques in order to evaluate the tribological properties of the tribo surfaces. The tribological tests of different tribo couples were conducted by using modified scratch testing and ball-on-disc testing. From these test results different friction and wear mechanisms have been identified.
The deposition of thin organic coatings on the steel sheet metal has been found to be promising in order to control the friction and to avoid metal-metal contact resulting in galling. However, it has been found that the tribological characteristics of organic coated steel sheet are strongly influenced by coating chemical composition, the substrate surface topography and the coating thickness distribution.
The performance of the PVD coatings depends mainly on the chemical composition and topography of the coated surface. By choosing PVD coatings such as diamond like carbon (DLC) low and stable friction coefficients can be obtained in sliding contact against Zn. Surface irregularities such as droplet-like asperities may cause an initial high friction coefficient. However, after a running in process or by polishing the PVD coating low friction coefficients can be obtained resulting in a stable sliding contact.
The combination of imaging (optical profilometry, LOM, SEM) and chemical analytical techniques (EDS, AES, ToF-SIMS) gave valuable information concerning the friction and wear properties of the tribo surfaces investigated.