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1
Milčić, Dragan, Dragan Mitić, Nenad Radović, Miodrag Milčić, and Aleksija Đurić. "Characterization of welded joints with Partial penetration on S355N structural steel." Zavarivanje i zavarene konstrukcije 66, no. 4 (2021): 149–59. http://dx.doi.org/10.5937/zzk2104149m.
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Existing standards require welded joints with full penetration. It is considered that welded joints with complete penetration minimize the stress concentration in the root passage. However, there are numerous situations in the industry, in which the load-bearing capacity of the welded joint with partial penetration is satisfactory. If the tests of partially penetrated welds show satisfactory load capacity, the benefits compared to fully penetrated welds are reflected in lower costs, ie less time is required to prepare the joint, less additional material is needed, ie shorter time is required to make the welded joint. The paper presents the testing of butt welded joints of structural steel S355N, with partial penetration, achieved by the MAG welding in the overhead position (PD) in the protection of the gas mixture. The samples were welded with different welding parameters and with different joint preparation, and the tests were performed by non destructive methods (visual inspection, testing with penetrants and magnetic particles) and destructive methods - tension and bending tests, Vickers hardness testing.
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Zhang, Dongfang, Junhai Zhao, and Shuanhai He. "Cyclic Testing of Concrete-Filled Double-Skin Steel Tubular Column to Steel Beam Joint with RC Slab." Advances in Civil Engineering 2018 (July 26, 2018): 1–15. http://dx.doi.org/10.1155/2018/7126393.
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The design of composite joints for connecting concrete-filled double-skin tubular (CFDST) columns to steel beams supporting reinforced concrete (RC) slabs is presented in this paper. Five half-scale specimens were designed, including four composite joints with RC slab and one bare steel beam joint, and were tested under a constant axially compressive force and lateral cyclic loading at the top end of the column to evaluate their seismic behavior. The main experimental parameters were the construction of the joint and the type of the column. The seismic behaviors, including the failure modes, hysteresis curves, ductility, strength and stiffness degradation, and energy dissipation, were investigated. The failure modes of the composite joints depended on the joint construction and on the stiffness ratio of beams to columns. Joints of stiffening type had significantly higher load-bearing and deformation capacities than joints of nonstiffening type. Compared with the bare steel beam joint, the bearing capacities of the composite joints with RC slabs were markedly increased. The composite action was remarkable under sagging moments, resulting in larger deformation on the bottom flanges of the beams. Overall, most specimens exhibited full hysteresis loops, and the equivalent viscous damping coefficients were 0.282∼0.311. The interstory drift ratios satisfied the requirements specified by technical regulations. Composite connections of this type exhibit excellent ductility and favorable energy dissipation and can be effectively utilized in superhigh-rise buildings erected in earthquake zones.
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Barat, Vera, Artem Marchenkov, Vladimir Bardakov, Marina Karpova, Daria Zhgut, and Sergey Elizarov. "Features of Acoustic Emission in Tensile Testing of Dissimilar Welded Joints of Pearlitic and Austenitic Steels." Applied Sciences 11, no. 24 (December 14, 2021): 11892. http://dx.doi.org/10.3390/app112411892.
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This paper presents a study of acoustic emission (AE) during the deformation of dissimilar welded joints of austenitic steel to pearlitic steel. One of the specific problems in these welded joints is the presence of decarburized and carbide diffusion interlayers, which intensively increase in width during long-term high-temperature operation. The presence of wide interlayers negatively affects the mechanical properties of welded joints. Moreover, welded defects are difficult to diagnose in welded joints containing interlayers: due to the high structural heterogeneity, interlayers create structural noises that can hinder the detection of defects such as cracks, pores, or a lack of penetration. The AE method may become a complex decision for diagnosing dissimilar welded joints due to applicability to the testing of heterogenic materials with a complex microstructure. Specimens cut from dissimilar welded joints of austenitic steel to pearlitic steel were tested by tension to rupture, with parallel AE data registration. According to the research results, the characteristic features of the AE were revealed for specimens containing defects in the form of lack of penetration as well as for specimens with diffusion interlayers. The results obtained show that the AE method can be used to test both typical welding defects and diffusion interlayers in welded joints of steels of different structural classes.
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Bu, Yonghong, Qi Yang, Yihong Wang, and Dongfang Zhang. "Cyclic Testing of Bolt-Weld Joints Reinforced by Sleeves Connecting Circular CFST Columns to Steel Beams." Advances in Civil Engineering 2020 (January 28, 2020): 1–12. http://dx.doi.org/10.1155/2020/9674128.
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This study examined the design of joints reinforced by sleeves for connecting circular concrete-filled steel tube columns to steel beams. Six half-scale specimens, including four bolt-weld joints reinforced by sleeves and two bolt and stiffened end-plate joints, were designed and tested under cyclic loading to evaluate the seismic behavior of these joints. The joint construction and beam-column stiffness ratio were taken as the main parameters in the tests. The seismic behaviors, including the failure modes, hysteretic curves, ductility, strength and stiffness degradation, and energy dissipation, were investigated. The experimental results showed that no obvious bolt loosening, fracture, or widespread weld cracking appeared in the joints reinforced by sleeves. Furthermore, the joint strength and stiffness were markedly increased by the sleeves in the joint core area. Overall, most specimens exhibited full hysteresis loops and excellent ductilities, the equivalent viscous damping coefficients were 0.263∼0.532, and the ductility coefficients were 1.77∼3.42. The interstory drift ratios satisfied the requirements specified by technical regulations. The connections of these types exhibit favorable energy dissipations and can be effectively utilized for building construction in earthquake-prone areas. This research should contribute to the future engineering applications of concrete-filled steel tube to composite structure.
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Morelli, Piero. "An Experimental Study on the Shear Strength of Steel Structures Joints." Applied Mechanics and Materials 268-270 (December 2012): 279–82. http://dx.doi.org/10.4028/www.scientific.net/amm.268-270.279.
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The results of an experimental investigation on the shear strength of structural joints are presented and discussed. Joint typologies generally employed in structural frames of industrial warehouses and intermediate floors are taken into consideration. Specimens were supplied by an industrial shelving manufacturer, in two different configurations: the first one characterized by steel pressed geometrical connectors and the second one consisting in bolted fittings to angular welded supporting plates. A specific testing device has been designed in order to transfer axial loading into shear loading applied to a couple of joints in a symmetrical testing configuration. Quasi-static loads were applied with increasingly intensity steps, until the yielding of the material or the overall structure collapse were reached. Failure modes of the tested joints are analyzed and discussed.
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Berezovskaya, Vera V., A. V. Berezovskiy, and D. H. Hilfi. "Laser Welded Joints of High-Nitrogen Austenitic Steels: Microstructure and Properties." Solid State Phenomena 284 (October 2018): 344–50. http://dx.doi.org/10.4028/www.scientific.net/ssp.284.344.
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High nitrogen austenitic steels are used as structural materials required possessing high strength and fracture toughness. The present study is concerned with the characteristic features (shape, size, properties and structure) of the laser welded joints in Cr-Mn-, Cr-Mn-Mo-high nitrogen steels compared to the ones of Cr-Ni-steel joint. Butt welded joints were made using carbon dioxide laser with a maximum output of 5 kW in the continuous wave mode. The hardness and tensile tests of welded joints in the air and 3.5 vol.%-solution of NaCl, as well as the theoretical studies were carried out by optical and transmission electron microscopy (TEM). The results are achieved by testing that the welded joints of HNS had satisfactory weldability, adequately high mechanical and corrosion properties. The austenite of the investigated HNS retains high stability throughout the welding cycle.
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Jasiński, Radosław, and Iwona Galman. "Testing Joints between Walls Made of AAC Masonry Units." Buildings 10, no. 4 (April 2, 2020): 69. http://dx.doi.org/10.3390/buildings10040069.
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Joints between walls are very important for structural analysis of each masonry building at the global and local level. This issue has often been neglected in the case of traditional joints and relatively squat walls. At present, the issue of wall joints is becoming particularly important due to the continuous drive for simplifying structures, introducing new technologies and materials. Eurocode 6 and other standards (American, Canadian, Chinese, and Japanese) recommend inspecting joints between walls, but no detailed procedures have been specified. This paper presents our own tests on joints between walls made of autoclaved aerated concrete (AAC) masonry units. Tests included reference models composed of two wall panels joined perpendicularly with a standard masonry bond (six models), with classic steel and modified connectors (twelve models). The shape and size of test models and the structure of a test stand were determined on the basis of the analysis of the current knowledge, pilot studies and numerical FEM (Finite Element Method) - based analyses. The analyses referred to the morphology and failure mechanism of models. Load-displacement relationships for different types of joints were compared and obtained results were related to results for reference models. The mechanisms of cracking and failure was found to vary, and clear differences in the behaviour and load capacity of each type of joint were observed. The individual working phases of joints were determined and defined, and an empirical approach was proposed for the determination of forces and displacement of wall joints.
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Zhang, Zhaoqiang, Yanru Sa, Yong Yao, and Junhai Zhao. "Seismic Performance of Exterior Steel Ring-Stiffener Joint." Advances in Civil Engineering 2019 (November 7, 2019): 1–22. http://dx.doi.org/10.1155/2019/8107103.
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We study the seismic performance of the exterior steel ring-stiffener (ESRS) joint, a member that is used to connect a steel beam to a square steel tubular column filled with steel fibre recycled concrete for seismic resistance. To this end, the influence of seismic factors such as axial compression ratio and beam-column linear stiffness ratio on seven specimens is studied. A physical test is conducted on the specimens with a series of cyclic loadings. The testing and analysis of hysteretic loops and skeleton curves of the ESRS joints revealed the seismic performance characteristics including failure mode, rigidity, ductility, bearing-capacity degradation, and energy dissipation capacity. The results reveal (a) damage to the specimens at the beam-end near the joint, (b) no failure at the joints’ core area and column, (c) appearance of a plastic hinge at the beam-end near the joint, and (d) plump spindle-shaped hysteretic loops and normal rigidity degradation curves in the specimens. The specimens are then simulated with the finite element method (FEM) and the results are compared with those of the physical test.
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Alqaryouti, Yousef, Dilum Fernando, and Joseph Gattas. "Structural Behavior of Digitally Fabricated Thin-Walled Timber Columns." International Journal of Structural Stability and Dynamics 19, no. 10 (October 2019): 1950126. http://dx.doi.org/10.1142/s0219455419501268.
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This paper aims to investigate the structural behavior of digitally fabricated thin-walled timber sections with edge connectivity provided by integral mechanical press-fit joints. Experimental, numerical, and analytical investigations have been developed to accurately characterize the press-fit section behavior and their failure modes. Plywood fiber orientation, material thickness, and connection tightness are considered as potential factors that may affect the performance of the press-fit jointing system. Experimental testing of square hollow sections (SHSs) under uniaxial compressive loading showed failure of sections through both conventional crushing and novel pop-off bifurcation failures. Pop-off buckling behaviors were shown to be governed by the integral joint transverse stiffness and its magnitude relative to a critical edge stiffness value. Columns with joint transverse stiffness value less than the critical edge stiffness value exhibited pop-off failures. These joint stiffness values were obtained from testing of unloaded joints and were used to obtain accurate predictions of column failure modes. Joint stiffness values for loaded joints were then predicted with an interpolation model mapping axial strain to a tighter connection tolerance and these were used to obtain accurate estimations for column failure load in most of the tested column types. Comparative investigations showed thin-walled sections with integral joints only to be capable of matching the compressive capacities of glued sections, for instances where crushing governed. Similarly, the weight-specific compressive capacity of timber sections was found to be comparable to thin-walled steel sections when crushing governs.
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Hajro, Ismar, and Petar Tasić. "Properties mismatching and distribution on structural steels welded joints." Advanced Technologies & Materials 43, no. 2 (December 15, 2018): 15–20. http://dx.doi.org/10.24867/atm-2018-2-003.
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The paper presents results of combined, conventional and non-conventional, approach for evaluation of mechanical and technological properties of structural steel's welded joints. The selected structural steels are in the range of most common used strength level(s), as well as corresponding various chemical composition concept(s) and processing routes. A short review regarding weldability is presented based on recommendation provided in EN 1011-2, manufacturers recommendation, and own results. However, even it is a well-known fact, mismatching of properties is presented rather to provide sense of its level for particular steel grades. Moreover, the level of under-matching of weakest weld zone (coarse grained heat affected zone), provided by mean of welding thermo-cycle simulation is presented. This is due to the fact that such estimation is not possible with everyday conventional (standardized) testing. The most important design and technological properties of welded joint(s) are considered; e.g. strength, ductility, hardness, microstructure and toughness.
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Mitaľ, Dušan, Peter Michalik, Jozef Zivčak, Andrej Czan, Dana Stanceková, Svetlana Radchenko, and Jaroslav Vybostek. "Study the Quality of Welded Joints of Steel S235." Applied Mechanics and Materials 718 (December 2014): 88–92. http://dx.doi.org/10.4028/www.scientific.net/amm.718.88.
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Presented article is focused on welding of structural steel using coated electrode. Weld can be defines as a permanent join of two or more materials. Welder unit was Inventor 140 GC, where was weld 6 samples with different parameters of welding. Samples were tested by non-destructive methods such as visual control, capillary method and ultrasound method. Detection of defects in microstructures was made by destructive method – metallographic method. Testing of quality provide the most suitable welding parameters for welding constructions from structural steel S 235.
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Mironovs, Viktors, Vjaceslavs Zemcenkovs, Dmitrijs Serdjuks, Vjaceslavs Lapkovskis, Aleksejs Tatarinovs, and Viktors Kurtenoks. "Method and apparatus for dynamic testing of structural joints." Journal of Physics: Conference Series 2423, no. 1 (January 1, 2023): 012017. http://dx.doi.org/10.1088/1742-6596/2423/1/012017.
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Abstract The dynamic testing technique is used during the design phase of structures and series production. This test evaluates the structural capacity, especially of the assemblies, to withstand different forces and rates of impact encountered under realistic operational conditions. This study proposes a magnetic pulse exciter for high-speed impact loading in dynamic tests because of its capability to provide single and repeatable pulse loading over a wide range of force up to 20 kN and pulse durations from 10 up to 1000 ms. The method transforms accumulated electrical energy in a capacitor bank into mechanical energy. For experimental investigations, flat and cylindrical coil devices were used for a capacitor-type pulse current generator. The proposed method has been experimentally validated on timber beams in a specified volume of force loading. The technique demonstrated a potential for controlling force and energy parameters. The effects of operating voltage on coil and ‘metal plate - coil’ distance on the amplitude of dynamic loading have been investigated. Aluminium and steel plates fastened to the object at the point of impact were used to improve excitation efficiency. The developed technique can be used in experimental studies on model joints and real objects.
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Yu, Zeliang, Bin Yang, Bin Jia, Yuhong Yan, Shaowen Xiao, and Ke Lei. "Test and Numerical Study on Monotonic Behavior of Complex CFT Column Joints." Advances in Civil Engineering 2019 (September 24, 2019): 1–20. http://dx.doi.org/10.1155/2019/5105934.
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This paper presents a test and numerical investigation into the monotonic behavior of three different complex steel trusses to concrete-filled tubular (CFT) column joints. Based on an engineering structure, 1 : 4 reduced-scale specimens are manufactured and the three-dimensional subassembly testing system is designed to apply the monotonic load. Test phenomena and load-stress curves show that all three types of joints have a considerable load-carrying capacity and joint rigidity. Finite element (FE) analysis is adopted, and the stress distribution shows good agreement with test data. Both test and FE results show that local buckling and yielding in the root region of steel truss are the main failure modes of test joints and the core area of the CFT column remains intact which are in accordance with the design conception of “strong column and weak beam.” Design conception of proposed overlap joint form is then investigated based on the FE model, and results show that the optimized overlap joint can effectively reduce the stress concentration in the adjacent steel tube and beam member when compared to the traditional N-type overlap joint. Finally, the influence of the outer diaphragm on the stiffness of joint is analyzed. By comparing the end-displacement of the beam member, conclusion can be obtained that the beam flange thickness is suggested to be chosen as the outer diaphragm thickness. The forms of three different proposed joints and their design conceptions can provide good guidance for designers and engineers.
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Radu, Bogdan, Viorel Ungureanu, Ioan Both, Mircea Burcă, Ştefan Benzar, and Dan Dubină. "Experimental Researches on Using Resistance Spot Welding for Built-Up Cold-Formed Beams Made of Corrugated Galvanized Steel Sheets." Advanced Materials Research 1164 (June 23, 2021): 3–8. http://dx.doi.org/10.4028/www.scientific.net/amr.1164.3.
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The paper presents the results of researches carried out by a joint team from Department of Steel Structures and Structural Mechanics, together with Department of Materials Science and Engineering, from University Politehnica Timisoara, focused on the possibility of creating built-up cold-formed steel beams made of corrugated galvanized steel sheets by resistance welding, which will replace the similar beams built by self-drilling screws. Resistance spot welding technologies were developed and tested, together with mechanical testing of the welded joints, which were performed in our laboratories. The results obtained and presented confirm the good quality of the welded joints and, as a result, the good capability of this technology to be used in production, to replace the old type of beams.
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Wernicke, R., and R. Pohl. "Underwater Wet Repair Welding and Strength Testing on Pipe-Patch Joints." Journal of Offshore Mechanics and Arctic Engineering 120, no. 4 (November 1, 1998): 237–42. http://dx.doi.org/10.1115/1.2829546.
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The underwater wet welding method for repairing of submerged structural members has been intensively developed during the last years. It is an economical and especially more time-independent procedure. The shortened repair duration is a major advantage in regions with rough sea climate as the North Sea area. During research projects the weldability and fatigue performance of pipe-patch connections have been tested. These joints are in use for repairing of collision indents. The shape of the actual used repair patch was optimized to the requirements of underwater wet welding at high tensile strength steels as BS4360 Gr 50D. Steel materials in this grade show problems in regard to high hydrogen susceptibility, and therefore cold cracking. The fatigue behavior of the patch-welded pipe structural member has been investigated. First test series were carried out using as-welded joints. In a second part of the project, post-weld-treated connections were tested. The weld seams on these joints were partially ground or hammer peened. The test results have been evaluated by means of the hot-spot concept and then faced with actual code requirements. Extensive strain gage measurements and finite-element calculations have been carried out to provide the stress state in the structural details.
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Pascu, Doru Romulus, A. Bobic, G. Băltean, and Horia Mateiu. "Researches Regarding the Structural and Mechanical Characteristics of the C-Mn Steel within the Specific Thermal Circuits." Advanced Materials Research 23 (October 2007): 241–44. http://dx.doi.org/10.4028/www.scientific.net/amr.23.241.
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The paper presents the experimental results regarding the influence of the multiple thermal cycles on the structural and mechanical characteristics of the weldable C-Mn steel used in energetic. Macro- and microscopic examinations, and mechanical testing made on the intersection welds show that the structural and mechanical characteristics are within the reference range of CMn (type S355JR) steel. So, the hardness of the pearlitic – ferritic structures in the welded joints characteristic zones is less than 216 HB; the tensile strength of the welded joints is more than 430 [N /mm2], imposed value for the C-Mn steel. Also, the weld toughness is between 38 [J] and 52 [J] (at 20 °C), more than 27 [J], value what must be assured for the investigated steel. So, the tendency to brittle fracture of the welded joints is diminished. The presence of some imperfections within the intersection welds imposes a carefully monitoring of all these welded joints by adequate nondestructive examinations.
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Kałuża, Marta, Jacek Hulimka, and Arkadiusz Bula. "FEM Analysis as a Tool to Study the Behavior of Methacrylate Adhesive in a Full-Scale Steel-Steel Shear Joint." Materials 15, no. 1 (January 3, 2022): 330. http://dx.doi.org/10.3390/ma15010330.
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The use of adhesive to joint structural elements, despite many advantages of this technology, is not a method commonly used in engineering practice, especially in construction. This is mainly due to the poor recognition of the behavior, both in terms of testing and analysis, of joints made on a scale similar to the actual elements of building structures. Therefore, this paper presents the results of model tests and then numerical analyses of adhesively bonded joints made of high-strength steel elements in a full-scale (double-lap joint). In order to properly model the adhesive connection, material tests of the methacrylate adhesive were performed in the field of tensile, shear (in two versions: single lap joint test and thick adherent shear test) and bond properties. Comparison of the results of the model and numerical tests showed very good agreement in terms of the measurable values, which makes it possible to consider the results obtained in the adhesive layer as reliable (not directly measurable in model tests). In particular, the distribution of stresses inside the adhesive layer, the range of plastic zones and areas of loss of adhesion are presented and discussed. The results indicate the possibility of a reliable representation of the behavior of adhesively bonded joints of high-strength steel, thus providing a tool for the analysis of semirigid adhesive in large-size joints.
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Smirnov, A. N., N. A. Popova, N. V. Ababkov, K. V. Knyaz’kov, and E. L. Nikonenko. "Influence of deformation degree of austenitic steels welded joints on structural state and internal stresses felds in weld line zone." Izvestiya. Ferrous Metallurgy 64, no. 8 (September 2, 2021): 572–80. http://dx.doi.org/10.17073/0368-0797-2021-8-572-580.
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Nowadays initial assessment of welding quality is performed by testing equipment with increased loads (high pressure) at technical devices of hazardous production facilities. Test requirements are regulated by standardized documents of the Federal Service for Environmental, Technological and Nuclear Oversight of Russia (Rostekhnadzor). Recently, along with traditional tests, a “stress test” was used – the essence of which is to load pipeline section to the yield point, followed by leak test. However, in scientifc publications there is practically no information about physical processes occurring in the base metal and in welded joints during such tests. In addition, effect of preload (deformation) on the parameters of substructure and internal stresses feld in welded joints of austenitic steels and, consequently, on the further troublefree operation of the tested equipment was not evaluated. The paper analyzes changes in structural state and values of internal stresses in the samples of austenitic steel under the action of high loads. It substantiates the use of modulated current welding with automatic control of heat input process in molten weld pool. The admissible limits values of plastic deformation are argued when testing technical devices with high pressure for this type of steel. In order to reduce the risk of damage to austenitic steels welded joints of technical devices of hazardous industrial facilities, performed by pulsed welding with smalldrop transfer, and to exclude formation of microdefects in them, high pressure tests (stress test) can be performed under loads that create deformations in metal, not exceeding 5 %. For joints welded by manual arc welding, deformations should be less than 5 %. Welded joints made by pulsed welding with largedrop transfer (with and without defects) are not recommended to be tested with high pressure.
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Lan, Xiaoyi, Tak-Ming Chan, and Ben Young. "Testing, finite element analysis and design of high strength steel RHS T-joints." Engineering Structures 227 (January 2021): 111184. http://dx.doi.org/10.1016/j.engstruct.2020.111184.
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Ahmad, Bilal, and Michael E. Fitzpatrick. "Residual Stresses in Ultrasonically Peened Fillet Welded Joints." Advanced Materials Research 996 (August 2014): 755–60. http://dx.doi.org/10.4028/www.scientific.net/amr.996.755.
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Fatigue cracks mostly initiate at areas subjected to high tensile residual stress and stress concentration. Ultrasonic peening is a mechanical method to increase fatigue life by imparting compressive residual stress. In this study residual stresses are characterized in fillet welded ship structural steel plates with longitudinal attachments. As-welded, ultrasonically peened, and specimens peened then subjected to accelerated corrosion testing were measured. Residual stress characterization was performed by the contour method and neutron diffraction.
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Kowalski, Jakub, and Janusz Kozak. "Numerical Model of Plastic Destruction of Thick Steel Structural Elements." Polish Maritime Research 25, no. 2 (June 1, 2018): 78–84. http://dx.doi.org/10.2478/pomr-2018-0057.
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Abstract In the shipbuilding industry, the risk of brittle fracture of the structure is limited by using certified materials with specified impact strength, determined by the Charpy method (for a given design temperature) and by supervising the welding processes (technology qualification, production supervision, non-destructive testing). For off-shore constructions, classical shipbuilding requirements may not be sufficient. Therefore, the regulations used in the construction of offshore structures require CTOD tests for steel and welded joints with a thickness greater than 40 mm in the case of high strength steel and more than 50 mm in the case of other steels. Classification societies do not accept CTOD test results of samples with a thickness less than the material tested. For this reason, the problem of theoretical modeling of steel structure destruction process is a key issue, because laboratory tests for elements with high thickness (in the order of 100 mm and more) with a notch are expensive (large samples, difficulties in notching), and often create implementation difficulties due to required high load and range of recorded parameters. The publication will show results and conclusions from numerical modeling of elastic properties for steel typical for offshore applications. Calculations were carried out at the Academic Computer Centre in Gdańsk.
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Mou, Ben, Xu Liu, Fangying Wang, and Henglin Xiao. "Cyclic testing on prefabricated joints for steel beam to concrete-filled steel tubular column." Journal of Constructional Steel Research 194 (July 2022): 107345. http://dx.doi.org/10.1016/j.jcsr.2022.107345.
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Ali, Liaqat, Sikandar Khan, Salem Bashmal, Naveed Iqbal, Weishun Dai, and Yong Bai. "Fatigue Crack Monitoring of T-Type Joints in Steel Offshore Oil and Gas Jacket Platform." Sensors 21, no. 9 (May 10, 2021): 3294. http://dx.doi.org/10.3390/s21093294.
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Several approaches have been used in the past to predict fatigue crack growth rates in T-joints of the offshore structures, but there are relatively few cases of applying structural health monitoring during the non-destructive testing of jacket platforms. This paper presents an experimental method based on the sensing of the piezoelectric sensors and finite element analysis method for studying the fatigue cracks in the offshore steel jacket structure. Three types of joints are selected in the current research work: T-type plate, T-type tube-plate, and T-type tube joints. The finite element analysis model established in the current study computes and analyzes the high stress and high strain regions in the T-type joints. The fatigue damage in the T-type joints was successfully detected by utilizing both the finite element analysis and experimental methods. The results showed that fatigue cracks of the three types of joints are prone to appear at the weld toe and spread in the welding direction. The fatigue damage location of T-type plate and T-type tube-plate joints is more concentrated in the upper weld toe area, and the fatigue damage location of the T-type tube joint is closer to the lower weld toe area.
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Gusella, Federico, Maurizio Orlando, Andrea Vignoli, and Klaus Thiele. "Flexural Capacity of Steel Rack Connections Via The Component Method." Open Construction and Building Technology Journal 12, no. 1 (May 23, 2018): 90–100. http://dx.doi.org/10.2174/1874836801812010090.
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Background: In pallet rack structures, cold-formed steel (CFS) beams and columns are connected through dry joints, so beams can be easily disconnected according to changes of the rack geometric layout. Due to the great variety of connector types and member geometries, recent design codes recommend experimental tests on rack connections to assess their mechanical features. Nevertheless, tests only allow for the overall response of a joint to be evaluated, without providing information about the contribution of each component of the joint to its stiffness and strength. Objective: In this paper, a mechanical model is developed in order to provide useful information about the structural behaviour of rack beam-column connections. Methods: The proposed mechanical model is based on the application of the Component Method (CM) and it allows for the flexural resistance of steel rack connections to be analytically assessed. Analytical results are compared with experimental data from tests performed at the Structures and Materials Testing Laboratory of the Department of Civil and Environmental Engineering of Florence. Results: Results show a good agreement with experimental data, highlighting the accuracy of the proposed approach. The mechanical model allows for the weakest component of the joint and its failure mode to be evaluated, and it highlights the importance of an adequate welding between the beam-end section and the connector. Conclusion: The mechanical model provides fundamental information about the influence of structural details on the overall behavior of rack joints, it appears as a complementary method to expensive experimental tests and it can be used to improve the design of rack connections with the goal to increase their structural response.
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Francavilla, Antonella B., Massimo Latour, and Gianvittorio Rizzano. "The Design of a Real-Scale Steel Moment-Resisting Frame for Pseudo-Dynamic Earthquake Testing." Open Construction & Building Technology Journal 14, no. 1 (July 30, 2020): 174–84. http://dx.doi.org/10.2174/1874836802014010174.
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Background: Forthe reliable prediction of the non-linear response of structures, severe seismic events have proven to be a challenging task. Although much non-linear analysis software exists, the accuracy of the results depends on the assumptions made in the characterization of the members. Typically, the analytical models are calibrated using experimental observations. With this scope, experimental research remains the most reliable mean for the assessment of the seismic performance of structures, and it is crucial to target the development of new analytical models and design methods. Objective: Quasi-static tests can provide information on the non-linear behaviour of subassemblies, but it is often difficult to relate the imposed force or displacement histories to those that might occur during an earthquake. The pseudo-dynamic method combines an on-line computer simulation with experimental information about the tested structure, providing the application of realistic dynamic response histories. In this paper, the preliminary analysis and the design of a pseudo-dynamic testing facility for the experimental study of a real scale two storeys-two bays steel MRF, with classical and innovative joint details, are shown. Methods: Pushover and Incremental Dynamic Analyses carried out with Seismostruct software estimate the forces and displacements expected at each storey for the selected ground motions. These analyses have been performed by varying the structural detail of the beam-to-column connections. Results / Conclusion: In this paper, the analytical prediction of the performance of two bays-two storeys steel frames equipped with different solutions of beam-to-column joints is focused. Based on the performed analyses, it has been recognized that steel frames with partial strength joints can provide satisfactory performance under severe seismic actions provided that the joints are adequately designed.
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Huang, Chung-Hsing, Chang-Hsiang Hou, Tso-Sheng Hsieh, Liren Tsai, and Chia-Chin Chiang. "Investigation of distinct welding parameters on mechanical and corrosion properties of dissimilar welded joints between stainless steel and low carbon steel." Science Progress 105, no. 4 (October 2022): 003685042211267. http://dx.doi.org/10.1177/00368504221126795.
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The tensile strength and corrosion behavior of dissimilar welded joints are currently a subject of concern. In this work, gas metal arc welding (GMAW) and distinct welding parameters (welding current, arc voltage, and welding speed) were used to join 304 stainless steel (SUS304) and SS400 low carbon steel, and the ultimate tensile strength (UTS) of the dissimilar welded joints was investigated. A corrosion test was conducted by immersion in 3.5 wt.% sodium chloride (NaCl) solution for 7, 14, and 21 days. Based on tensile strength and Tafel testing, the welding parameters “Item 4” (welding current: 170 A, arc voltage: 20 V, welding speed: 40 cm/min) yielded good mechanical strength and low corrosion characteristics. The microstructure characterization showed that the area around the welded joints and SUS304 had more granular corrosion and corrosion tubercles with increasing immersion time. The chromium content gradually decreased. When exposed to the chloride environment, these welded joints easily underwent corrosion due to the loss of passivity. However, high-velocity oxygen-fuel (HVOF) spray used on the welded joints reduced the corrosion current density. Compared with the non-thermal spray sample (corrosion current density:7.49e − 05 A/cm2) while the corrosion current density (7.89e − 10 A/cm2) is five orders of magnitude lower. This spray effectively slowed down the corrosion rate of the welded joints and gave the structural objects good protection in the sodium chloride solution.
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Křivý, Vít, Zdeněk Vašek, Miroslav Vacek, and Lucie Mynarzová. "Corrosion Damage to Joints of Lattice Towers Designed from Weathering Steels." Materials 15, no. 9 (May 9, 2022): 3397. http://dx.doi.org/10.3390/ma15093397.
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The article dealt with the load-bearing capacity and durability of power line lattice towers designed from weathering steel. Attention was paid in particular to the bolted lap joints. The article evaluates the static and corrosion performance of bolted lap joints in long-term operating towers, and also presents and evaluates design measures that can be applied in the design of new lattice towers, or in the reconstruction of already operating structures. Power line lattice towers are the most extensive realization of weathering steel in the Czech Republic. On the basis of the inspections carried out to evaluate the working life of the transmission towers in operation, it can be stated that a sufficiently protective layer of corrosion products generally developed on the bearing elements of the transmission towers. However, the development of crevice corrosion at the bolted joints of the leg members is a significant problem. In this paper, the corrosion damage of bolted joints was evaluated considering two basic aspects: (1) the influence of crevice corrosion on the bearing capacity of the bolted joint was evaluated, using experimental testing and based on analytical and numerical calculations; (2) appropriate design measures applicable to the rehabilitation of developed crevice corrosion of in-service structures, or the elimination of crevice corrosion in newly designed lattice towers, was evaluated. Calculation analyses and destructive tests of bolted joints show that the development of corrosion products in the crevice does not have a significant effect on the bearing capacity of the joint, provided that there is no significant corrosion weakening of the structural elements, and bolts of class 8.8 or 10.9 are used. The results of the long-term experimental programme, and the experience from the rehabilitations carried out, show that, thanks to appropriate structural measures, specified in detail in the paper, the long-term reliable behaviour of the lattice towers structures is ensured.
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Wang, Yu, Yong Jun Liu, and Lin Qi. "Experimental Research of Corner Joints in Steel-Framed Structures under Fire Conditions." Applied Mechanics and Materials 578-579 (July 2014): 374–77. http://dx.doi.org/10.4028/www.scientific.net/amm.578-579.374.
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The research involved experimental testing of simple steel connections and components (structural 8.8 bolts) at elevated temperatures. High temperature tests on structural bolts demonstrated two modes of failure at elevated temperatures: bolt breakage and thread stripping. In order to prevent the thread stripping in a connection,the manufacturing process of bolts and nuts has been investigated and the ‘over tapping’ of nut threads to accommodate the (zinc) coating layer for corrosion resistance has been indentified as a primary reason resulting in this premature failure between bolts and nuts. Experimental tests on endplate connections revealed the ductility of these connections to decrease at high temperatures, which might hinder the development of catenary actions in fire if plastic hinges are attempted to be formed within the connection zones. Component-based modelling and finite element simulation have been utilized for investigation of the performance of these connections.
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Izzawati, Basirom, Mohd Afendi, S. Nurhashima, A. Nor, A. R. Abdullah, and R. Daud. "FE Modeling and Analysis of Structural Adhesive T-Joint at Elevated Temperature." Applied Mechanics and Materials 695 (November 2014): 635–38. http://dx.doi.org/10.4028/www.scientific.net/amm.695.635.
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Adhesive bonding is a joining technique that offers great design flexibility as it can be effectively integrated into practically available industrial sequences of single-piece work. Adhesive is seldom used in high-temperature structural applications that exposed to extreme environment, particularly in the granulation application. Granulator fluidization bed is a main component of urea granulator system in fertilizer plant. Perforated plate and frame structure are normally joined together using plug welding techniques. However, this technique has been proven unreliable. Plug welding technique requires specific amount of heat and welding speed to avoid excessive metal melting (304L Stainless Steel) due to a thin perforated plate, i.e. 1.25 mm. Moreover, fluidization bed is exposed to operating temperature of 95°C. This research aims to examine adhesively-bonded T-joints in tension at temperatures between room temperature and 100°C. This is also to identify the effective bond thickness at different temperatures by testing specimens with various bond thicknesses. The experimental result obtained used for validation by FE model of adhesive T-joint.
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Morano, C., F. Musiari, F. Moroni, GD Spennacchio, D. Di Lonardo, and M. Alfano. "Experimental analysis of steel joints bonded with automotive grade hot setting structural adhesives." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 233, no. 10 (December 12, 2018): 2084–93. http://dx.doi.org/10.1177/1464420718817860.
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Recent trends in car body manufacturing indicate that the use of a consistent mix of lightweight materials in conjunction with adhesive bonding, not only allows substantial weight reduction, but can also drive down costs and potentially enables more intelligent designs. Yet, presently, it is highly desirable that the introduction of structural adhesives is made with minimum impact on the automotive body framing systems. Adhesives commonly deployed in car body production (i.e. body-in-white) are applied without any prior surface preparation and final curing is carried out during the baking process that follows the electrophoretic coating. Several structural adhesives have been tailored to the conditions dictated by the automotive production process. The aim of this work is to assess the mechanical properties of adhesive joints bonded with automotive grade hot setting epoxy adhesives employed for the assembly of frame and panels. Single-lap and T-joints were fabricated and adhesive hardening was carried out following the typical curing cycle employed in the process chain of automobile production. The resulting mechanical properties were assessed before and after exposure to a standard accelerated thermal cycling under controlled humidity. The evaluation of the mechanical behavior was done through a combination of testing and analysis, which included the assessment of fracture surfaces using optical microscopy to resolve the locus of failure.
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Taranu, George, and Ionut-Ovidiu Toma. "Experimental Investigation and Numerical Simulation of C-Shape Thin-Walled Steel Profile Joints." Buildings 11, no. 12 (December 10, 2021): 636. http://dx.doi.org/10.3390/buildings11120636.
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The versatility of steel, its high resistance in relation to its low mass, as well as the easily accessible technology in the context of using recyclable materials and the low negative impact on the environment represent important arguments in using thin-walled steel profiles to make structures for buildings with a low height regime. This paper presents the results of an experimental program that investigated the behavior of three types of joints in a T-shape form made of thin-walled steel profiles to make shear wall panels or truss beam floors. Due to the small dimensions of the C-profiles of 89 × 41 × 12 × 1 mm, and of the technology of their joining, manufacturers prefer the hinged connections of elements with self-drilling screws. The purpose of the research presented in this paper is to assess the maximum capacity of the joints, the elastic and post-elastic behavior until failure, and also the mechanisms failure. The types of joints analyzed are commonly used in the production of structural systems for houses. The experimental program, which consisted of testing 5 specimens for each type of joint in tension (shear on screws), showed different behavior in terms of load-displacement. The experimental, tested models were analyzed by finite element simulations in an ANSYS nonlinear static structure with 3D solid models. The materials were defined by a bilinear true stress–strain curve obtained after some experimental tensile tests of the steel. The results of the experimental tests showed that the main failure mechanism is a yielding of the holes where the screws were mounted and a shearing of the profile walls. Adding an additional screw on each side increases the capacity of the joints, but not until a yield loss is obtained. In conclusion, it is shown that the solution is suitable for a low level of loading in a static manner; however, additional studies are necessary in order to develop and verify other solutions, thus improving the strength of the connection.
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Cai, Yancheng, Tak-Ming Chan, and Ben Young. "Chord plastification in high strength steel circular hollow section X-joints: Testing, modelling and strength predictions." Engineering Structures 243 (September 2021): 112692. http://dx.doi.org/10.1016/j.engstruct.2021.112692.
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Sisodia, Raghawendra Pratap Singh, and Marcell Gáspár. "An Approach to Assessing S960QL Steel Welded Joints Using EBW and GMAW." Metals 12, no. 4 (April 15, 2022): 678. http://dx.doi.org/10.3390/met12040678.
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In recent years, ultra-high-strength structural (UHSS) steel in quenched and tempered (Q+T) conditions, for example, S960QL has been found in wider application areas such as structures, cranes, and trucks due to its extraordinary material properties and acceptable weldability. The motivation of the study is to investigate the unique capabilities of electron beam welding (EBW) compared to conventional gas metal arc welding (GMAW) for a deep, narrow weld with a small heat-affected zone (HAZ) and minimum thermal distortion of the welded joint without significantly affecting the mechanical properties. In this study, S960QL base material (BM) specimens with a thickness of 15 mm were butt-welded without filler material at a welding speed of 10 mm/s using the high-vacuum (2 × 10−4 mbar) EBW process. Microstructural characteristics were analyzed using an optical microscope (OM), a scanning electron microscope (SEM), fractography, and an electron backscatter diffraction (EBSD) analysis. The macro hardness, tensile strength, and instrumented Charpy-V impact test were performed to evaluate the mechanical properties. Further, the results of these tests of the EBW joints were compared with the GMAW joints of the same steel grade and thickness. Higher hardness is observed in the fusion zone (FZ) and the HAZ compared to the BM but under the limit of qualifying the hardness value (450 HV10) of Q+T steels according to the ISO 15614-11 specifications. The tensile strength of the EBW-welded joint (1044 MPa) reached the level of the BM as the specimens fractured in the BM. The FZ microstructure consists of fine dendritic martensite and the HAZ predominantly consists of martensite. Instrumented impact testing was performed on Charpy-V specimens at −40 °C, which showed the brittle behavior of both the FZ and HAZ but to a significantly lower extent compared to GMAW. The measured average impact toughness of the BM is 162 J and the average impact toughness value of the HAZ and FZ are 45 ± 11 J and 44 ± 20 J, respectively.
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Hahnlen, Ryan, Gordon Fox, and Marcelo J. Dapino. "Fusion welding of nickel–titanium and 304 stainless steel tubes: Part I: laser welding." Journal of Intelligent Material Systems and Structures 24, no. 8 (October 29, 2012): 945–61. http://dx.doi.org/10.1177/1045389x12461075.
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Due to their large blocking stresses, high recovery strains, and solid-state operation, nickel–titanium actuators can offer substantial weight and space savings relative to traditional electric or hydraulic systems. A challenge surrounding NiTi-based actuators is integration of the NiTi components into a given system; this alloy is difficult and expensive to machine and challenging to weld to itself and structural materials. In this research, we join NiTi and 304 stainless steel tubes of 9.53 mm (0.375 in) in diameter through laser welding to create joints with weld depths up to 1.65 mm (0.065 in). By joining NiTi to a common structural material that is easily machined and readily welded to other materials, system integration is greatly improved. The joints prepared in this study were characterized through optical microscopy, hardness mapping, energy dispersive X-ray spectroscopy, mechanical testing, and analysis of the resulting fracture surfaces. The average ultimate shear strength of these joints is 429 MPa (62.2 103 lbf/in2) and the resulting fusion zone has a maximum width of 21.9 μm with a maximum hardness of 929 HV, while a possible heat-affected zone in NiTi is limited between 1 and 2 μm over most of the weld.
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Hlebová, Stanislava, and Ladislav Pešek. "Toughness of Ultra High Strength Steel Sheets ." Materials Science Forum 782 (April 2014): 57–60. http://dx.doi.org/10.4028/www.scientific.net/msf.782.57.
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Currently only few methods exist for thin steel sheet testing, especially based on fracture mechanics concept. Charpy impact test is one of the most used method for testing notch toughness and fracture behaviors because of the simplicity and the other advantages [. This article deals with toughness testing of automotive ultra high strength steel sheets (UHSS). Several standard types of toughness test that generate data for specific loading conditions and/or component design approaches exist. Two definition of toughness will be discussed: i) Charpy V-notch toughness, method includes joining of thin steel sheets to one compact unit and ii) material (tensile) toughness [. Two steels were used, DP1000 and 1400M of 1,8 mm thickness and two joining techniques: bonding with adhesives and joining with holders. Effect of material, joining technology, structural adhesives, and number of joined plates on the toughness values was quantified at the room temperature. Toughness of steels by the tensile test was added for comparison. Fracture surface was observed using scanning electron microscope analysis.
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Vasechkin, M. A., S. V. Egorov, A. B. Kolomensky, and E. D. Chertov. "Low-cycle fatigue of welded structures made from domestic and imported materials." Proceedings of the Voronezh State University of Engineering Technologies 80, no. 4 (March 21, 2019): 75–79. http://dx.doi.org/10.20914/2310-1202-2018-4-75-79.
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In various branches of modern engineering, corrosion-resistant steels and titanium alloys are widely used as structural materials. At the same time, it is possible to connect parts made from domestic and imported alloys using automatic argon-arc electric welding, which leads to the formation of a material with unexplored properties in the weld. Welded joints are stress concentrators and currently there is no information about low-cycle fatigue of welded joints obtained by fusing domestic and imported materials. In the course of the research, the modes of welding and heat treatment of butt welded joints obtained from sheet titanium alloys and corrosion-resistant steel of domestic and foreign production have been developed. Resource tests for low-cycle fatigue of samples of welded joints were carried out. Tests on low-cycle fatigue were carried out on the upgraded testing machine UMM-10 with repeated static stretching with an asymmetry factor of +0.1 and at a frequency of 0.6–0.8 Hz. The maximum tensile stress was 80% of the temporary tensile strength of the weakest alloy in the pair. The main stress axis from external loading in all cases was perpendicular to the weld. The tests were carried out until the destruction of the sample. As a result of research, it was established that all welded joints were destroyed along the fusion line, which is explained by the simultaneous action of geometric and structural stress concentrators. In this case, the destruction of the samples, as a rule, began near the seam from the side of the weakest alloy in the pair. It was also established that the use of temperatures of incomplete annealing in comparison with the full one allows to increase the cyclic durability for welded joints of titanium alloys by 1.3–2 times. From the results of comparative tests of samples of corrosion-resistant steels, it follows that domestic and imported steels, as well as their welded joints, have similar properties, both in strength and in re-static durability.
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Hernández-Belmontes, H., I. Mejía, V. García-García, and C. Maldonado. "Heat Input Effect on the Microstructure of Twinning-Induced Plasticity (TWIP) Steel Welded Joints Through the GTAW Process." MRS Advances 3, no. 64 (2018): 3949–56. http://dx.doi.org/10.1557/adv.2018.597.
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ABSTRACTHigh-Mn Twinning Induced Plasticity (TWIP) steels are an excellent alternative in the design of structural components for the automotive industry. The TWIP steels application allows weight reduction, maintaining the performance of vehicles. Nowadays the research works focused on TWIP steel weldability are relative scarce. It is well-known that weldability is one of the main limitations for industrial application of TWIP steel. The main goal of this research work was studied the effect of heat input on the microstructural changes generated in a TWIP steel microalloyed with Ti. A pair of welds were performed through Gas Tungsten Arc Welding (GTAW) process. The GTAW process was carried out without filler material, using Direc Current Electrode Negative (DCEN), tungsten electrode EWTh-2 and Ar as shielding gas. The microstructure and average grain size in the fusion (FZ) and heat affected zone (HAZ) were determined by light optical metallography (LOM). Elements segregation in the FZ was evaluated using point and elemental mapping chemical analysis (EPMA) by Scanning Electron Microscopy and Electron Dispersive Spectroscopy (SEM-EDS). Phase transformations were evaluated using X-ray diffraction (XRD). Finally, the hardness were measured by means of Vickers microhardness testing (HV500). The results show that the FZ is characterized by a dendritic solidification pattern. Meanwhile, the HAZ presented equiaxed grains in both weld joints. On the other hand, the TWIP-Ti steel weldments did not present austenite phase transformations. Nevertheless, the FZ exhibited variations in the chemical elements distribution (Mn, Al, Si and C), which were higher as the heat input increases. Finally, the heat input reduced the microhardness of TWIP-Ti steel weld joints. Although post-welding hardness recovery was detected, which is associated with precipitation of Ti second-phase particles.
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Barat, Vera, Artem Marchenkov, Vladimir Bardakov, Daria Zhgut, Marina Karpova, Timofey Balandin, and Sergey Elizarov. "Assessment of the Structural State of Dissimilar Welded Joints by the Acoustic Emission Method." Applied Sciences 12, no. 14 (July 18, 2022): 7213. http://dx.doi.org/10.3390/app12147213.
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In this study, we investigated defect detection in dissimilar welded joints by the acoustic emission (AE) method. The study objects were carbide and decarburized interlayers, which are formed at the fusion boundary between austenitic and pearlitic steels. Diffusion interlayers, as a structural defect, usually have microscopic dimensions and cannot be detected using conventional non-destructive testing (NDT) methods. In this regard, the AE method is a promising approach to diagnose metal objects with a complex structure and to detect microscopic defects. In this paper, the AE signatures obtained from testing defect-free specimens and specimens with diffusion interlayers are analyzed. We found that the AE signature for defective and defect-free welded joints has significant differences, which makes it possible to identify descriptors corresponding to the presence of diffusion interlayers in dissimilar welded joints.
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Hanus, Petr, and Eva Schmidová. "The Possibilities of Evaluating the Yield Strength in the Heat Affected Zones of a Weld through Indentation." Defect and Diffusion Forum 368 (July 2016): 20–24. http://dx.doi.org/10.4028/www.scientific.net/ddf.368.20.
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The research focuses on elastic-plastic behaviour of welded joints of materials which are commonly used in both constructional practice and the automotive industry. The examined welded joints are oriented to a common constructional S355 and a modern high-strength steel DOMEX 700MC.The main tool for the assessment of the elastic-plastic response was the methodology based on the instrumented penetration testing with the use of a cylindrical indenter. The indentation tool was applied into narrow zones of welded boundaries. These zones represent critical areas of welded constructions because of a changing structure and different mechanical properties than the basic material possesses. The indentation data were recalculated to the mechanical properties in shear with the help of Hencky ́s hypotheses about material behaviour. The correctness of the used methodology was verified by a tensile test. The aim of the work is to determine optimal methods for defining a yield strength and to find a hardening trend in the zones. The comparison of these steels revealed different changes due to the welding process. A substantial decrease of the yield strength of Domex700MC was observed, as a contrary to a stable, or partially increased, yield strength of the S355 steel. Structural analyses revealed a different material response of the evaluated steels, according to a different hardness in the heat affected zone.
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MIKI, Chitoshi, Kazuhiro NISHIKAWA, Hiromi SHIRAHATA, and Minoru TAKAHASHI. "ROUND ROBIN TEST OF TOFD ULTRASONIC TESTING SYSTEMS FOR WELDED JOINTS OF STEEL BRIDGES." Doboku Gakkai Ronbunshuu A 62, no. 4 (2006): 925–35. http://dx.doi.org/10.2208/jsceja.62.925.
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Liu, Xinhua, Jianren Zhang, Zihan Cheng, and Meng Ye. "Experimental and Numerical Studies on the Negative Flexural Behavior of Steel-UHPC Composite Beams." Advances in Civil Engineering 2021 (January 31, 2021): 1–15. http://dx.doi.org/10.1155/2021/8828175.
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The cracking of concrete in the negative moment region for a composite beam subjected to a negative bending moment reduces the beam’s strength and stiffness. To improve the cracking performance of composite beams, this paper presents an experimental investigation on applying ultrahigh-performance concrete (UHPC) instead of conventional concrete. Three steel-UHPC composite beams with different forms of joints were designed and tested through a unique rotation angle loading method using a spring displacement control testing setup. The crack distribution, rotation versus crack width, load versus spring displacement, and strains in the UHPC slab and steel girders were measured and studied. Nonlinear finite element analysis using ABAQUS based on the damaged plasticity model of concrete was carried out for comparison with the test results. The experimental and numerical results showed that the use of a UHPC slab can enhance the cracking performance of composite beams. Considering the convenience of construction, a reasonable joint form was suggested, and the appropriate UHPC longitudinal laying length in the negative moment region was proposed to be 0.1 L. Furthermore, a simplified formula for calculating the UHPC crack width was developed based on bond-slip theory.
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Kovács, Judit, and János Lukács. "Effect of the Welding Thermal Cycles Based on Simulated Heat Affected Zone of S1300 Ultrahigh Strength Steel." Key Engineering Materials 890 (June 23, 2021): 33–43. http://dx.doi.org/10.4028/www.scientific.net/kem.890.33.
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In the automotive industry there is an increasing demand for the wider application of high strength steels due to their favourable mechanical properties. The steel producers continuously developing new generations of high strength steels to insure higher strength and toughness properties. Since in most cases these steels are joined in welded structures, great attention must be taken to their weldability. The weldability of high strength steels has still challenges which are as follows: cold cracking sensitivity; reduction of strength and toughness of heat affected zone (HAZ); filler metal selection. Because the mechanical properties of ultrahigh strength steels are provided by using various alloying elements, micro alloys, and by different metallurgical methods, the steels may lose their outstanding properties during welding. In real welded joints the critical parts of the HAZ have small extent so their properties can be limitedly analysed by conventional material testing methods. With the help of physical simulators, the different parts of the heat affected zone can be produced in an adequate size for subsequent tests. In our research work the weldability, especially the HAZ properties of an ultrahigh strength structural steel (Rp0.2 = 1300 MPa) were investigated on thermal simulated samples with the help of Gleeble 3500 physical simulator. Three relevant technological variants for gas metal arc welding (GMAW), t8/5 = 5 s, 15 s and 30 s were applied during the HAZ simulations in the selected coarse-grained (CGHAZ), intercritical (ICHAZ) and intercritically reheated coarse-grained (ICCGHAZ) zones. Both the microstructure was studied by optical microscope and the mechanical properties were analysed by Vickers hardness tests and Charpy V-notch impact tests at -40 °C. According to the results the investigated ultrahigh strength steel was softened on account of the welding heat cycles, besides that the strength of the investigated ultrahigh strength steel can be better with the application of shorter t8/5 cooling time.
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Matlin, M. M., V. A. Kazankin, and E. N. Kazankina. "Shear strength diagnostics of machine parts." iPolytech Journal 26, no. 4 (December 29, 2022): 593–600. http://dx.doi.org/10.21285/1814-3520-2022-4-593-600.
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This study presents an effective non-destructive method for determining the ultimate shear strength of parts made of structural carbon and alloy steels. The shear strength was determined using the method of controlled part indentation. In addition, a new material characteristic – a shear hardening modulus – is proposed. The experimental study was carried out using an IR 5143-200 software and hardware complex for metal testing and a double-shear testing device. Steel samples of the following grades were examined: steel 10, 20, 35, 45, 20Kh, 40Kh, 25KhGT and 30KhGSA. The value of plastic hardness was used as a strength characteristic due to its advantages over other hardness values. The conducted experiments found a significant discrepancy (up to 20%) between the reference and experimental values of shear strength. Dependencies for determining the shear strength of structural carbon and alloy steel samples were obtained. The accuracy of these dependencies was determined to be sufficient for engineering calculations both according to the obtained experimental results and literature sources. The error associated with shear strength determination does not exceed ±5%. In addition, the paper provides some types of safety parts that can be destroyed by shear loads. The underestimated reference values of the ultimate strength can lead to increased unrealizable safety margins and, as a result, an increase in the specific metal amount of joints. The proposed non-destructive method for shear strength determination exhibits the accuracy sufficient for engineering practice and can be used when manufacturing, operating and repairing various machine parts and units.
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Sawa, Mateusz, Mirosław Szala, and Weronika Henzler. "INNOVATIVE DEVICE FOR TENSILE STRENGTH TESTING OF WELDED JOINTS: 3D MODELLING, FEM SIMULATION AND EXPERIMENTAL VALIDATION OF TEST RIG – A CASE STUDY." Applied Computer Science 17, no. 3 (September 30, 2021): 92–105. http://dx.doi.org/10.35784/acs-2021-24.
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This work shows a case study into 3D modelling, numerical simulations, and preliminary research of self-designed test rig dedicated for uniaxial tensile testing using pillar press. Innovative device was CAD modelled, FEM optimized, build-up according to the technological documentations. Then, the device utilization for tensile testing was validated via preliminary research. 3D model of the device was designed and FEM-analyzed using Solid Edge 2020 software. The set of FEM simulations for device components made of structural steel and stainless steel and at a workload equal 20 kN were conducted. This made it possible to optimize dimensions and selection of material used for individual parts of the device structure. Elaborated technical documentation allows for a build-up of a device prototype which was fixed into the pillar press. After that, the comparative preliminary experiments regarding tensile strength tests of X5CrNi18-10 (AISI 304) specimens were carried out. Tests were done using the commercial tensile strength machine and obtained results were compared with those received from an invented device. The ultimate tensile strength of X5CrNi18-10 steel, estimated using the commercial device (634 MPa) and results obtained from the patented device (620 MPa), were in the range of the standardized values. Findings confirm the utilization of the invented device for tensile strength testing.
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Bujnak, Jan, Peter Michalek, Frantisek Bahleda, Stefania Grzeszczyk, Aneta Matuszek-Chmurowska, and Arkadiusz Mordak. "Mechanical Testing of Composite Steel and Reactive Powder Concrete Structural Element." Materials 13, no. 18 (September 7, 2020): 3954. http://dx.doi.org/10.3390/ma13183954.
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Reactive powder concrete (RPC), typically with higher compressive strength, is particularly attractive to structural engineers to apply them in infrastructures for enhancing their resistance under severe environments and loads. The main objective of the initial study presented in the paper was to investigate the behavior of two types of these new cementitious materials differing in the nature of microfibers. The RPC mixes were reinforced with steel and then with basalt microfibers. To evaluate the structural performance of developed unconventional materials, properties were investigated experimentally and compared with the control normal concrete mix. Mechanical tests indicated that dispersing fine fibers for making RPC, a mean compressive strength of 198.3 MPa and flexural strength 52.6 MPa or 23.2 MPa, respectively, were developed after 28 days of standard curing at ambient temperatures. In composite structures consisting of steel girders and a concrete slab, it is necessary to prevent the relative slip at the steel and concrete interface using shear connectors. The very high RPC strength enabled a material saving, weight-reduced application of precast construction, and particularly effective joint to steel beams. The investigation of such shear connection efficiency, in the case of the higher strength concrete deck, using standard push-out test specimens was executed. Finite element numerical models were developed. The outputs of the studies are presented in the paper.
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Abokifa, Mohamed, and Mohamed A. Moustafa. "Experimental Behavior of Precast Bridge Deck Systems with Non-Proprietary UHPC Transverse Field Joints." Materials 14, no. 22 (November 18, 2021): 6964. http://dx.doi.org/10.3390/ma14226964.
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Full-depth precast bridge decks are widely used to expedite bridge construction and enhance durability. These deck systems face the challenge that their durability and performance are usually dictated by the effectiveness of their field joints and closure joint materials. Hence, commercial ultra-high performance concrete (UHPC) products have gained popularity for use in such joints because of their superior mechanical properties. However, the proprietary and relatively expensive nature of the robust UHPC mixes may pose some limitations on their future implementation. For these reasons, many research agencies along with state departments of transportation sought their way to develop cheaper non-proprietary UHPC (NP-UHPC) mixes using locally supplied materials. The objective of this study is to demonstrate the full-scale application of the recently developed NP-UHPC mixes at the ABC-UTC (accelerated bridge construction university transportation center) in transverse field joints of precast bridge decks. This study included experimental testing of three full-scale precast bridge deck subassemblies with transverse NP-UHPC field joints under static vertical loading. The test parameters included NP-UHPC mixes with different steel fibers amount, different joint splice details, and joint widths. The results of this study were compared with the results of a similar proprietary UHPC reference specimen. The structural behavior of the test specimens was evaluated in terms of the load versus deflection, reinforcement and concrete strains, and full assessment of the field joint performance. The study showed that the proposed NP-UHPC mixes and field joint details can be efficiently used in the transverse deck field joints with comparable behavior to the proprietary UHPC joints. The study concluded that the proposed systems remained elastic under the target design service and ultimate loads. In addition, the study showed that the use of reinforcement loop splices enhanced the load distribution across the specimen’s cross-section.
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Kim, Jong Seok, Yeong Min Park, Sang Yoon Kim, Mun Ki Bae, Dong Qi, Dong Chul Shin, and Tae Gyu Kim. "A study on the fretting wear characteristic of SCM415 alloy steel." International Journal of Modern Physics B 32, no. 19 (July 18, 2018): 1840055. http://dx.doi.org/10.1142/s0217979218400556.
Full textAbstract:
Fretting occurs at the contact area between two materials under load and in the presence of minute relative surface motion by vibration or external force. Bearings, clutches, riveted and bolted lap joints are subjected to fretting damage. Friction coefficient, materials of the specimen, contact surface pressure, relative slip amplitudes, temperatures and environment have an effect on the fretting. In this study, fretting wear test is conducted with SCM415 (Cr–Mo alloy steel) which are much used for making gears and shafts because of its excellent machinability, good mechanical properties and low cost, compared with those of the existing machine structural steels. In order to determine the fretting wear type, fretting wear fixture which can be attached to the servo hydraulic fatigue testing machine is made. And then, specimens and fretting pad with a constant curvature are made of SCM415 materials. Different normal forces and displacement amplitudes are applied to the fretting pad and diamond-like carbon (DLC) is coated on the fretting pad for fretting wear test.
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Siekierski, Wojciech. "Analysis of gusset plate of contemporary bridge truss girder." Baltic Journal of Road and Bridge Engineering 11, no. 3 (September 30, 2016): 188–96. http://dx.doi.org/10.3846/bjrbe.2016.22.
Full textAbstract:
Trussed structures in modern bridge building usually have “W” bracing. Structural joints are often based on application of gusset plates. Experimental tests of stress distribution in such gusset plates are rather sparse. Lab testing of scaled bridge truss girder was carried out in Poznań University of Technology in Poznań. Investigation into stress distribution in gusseted joint was carried out. Test results were put against results obtained from analyses of two finite element models: beam-element model and shell-element model. Normal stress and Huber-Mises equivalent stress distributions within gusseted joint were analysed. General conclusions are: a) normal stress distribution in gusseted joint cross-section, perpendicular to truss flange axis, is nonlinear and extreme stresses occur near cross-section edges, b) Huber-Mises equivalent stress distribution in the cross-section of gusset plate near its connection to truss flange is nonlinear and extreme stresses occur near centre of the cross-section, c) assessment of normal stresses in gusseted joints should not be carried out with an aid of beam-element modelling, d) it is possible to assess Huber-Mises equivalent stresses in gusset plate near its welded connection to rigid flange with an aid of beam-element modelling if non-uniform distribution of shear stress is taken into account, e) shell-element modelling of gusseted joint provides satisfactory accuracy of normal and equivalent stress assessment, f) beam-element modelling of friction grip bolts is sufficiently accurate for shell-element models of steel joints analysed within elastic range of behaviour.
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Arulsamy, Arun Negemiya, Gnanasekaran S, Bakkiyaraj Murugesan, Samson Jerold Samuel Chelladurai, Mohanraj Kishnan Selvaraj, Vijayakumar Palanivel, and Gizachew Balcha. "Experimental Investigation on Microstructure and Mechanical Properties of Friction Welded Dissimilar Alloys." Advances in Materials Science and Engineering 2022 (December 9, 2022): 1–15. http://dx.doi.org/10.1155/2022/5769115.
Full textAbstract:
High-temperature dissimilar connections built of Inconel 718 and AISI 410 martensitic stainless steel (MSS) are widely used in a range of industries, including boiler construction, the chemical industry, aerospace, and nuclear. When compared to other materials, Inconel 718 and AISI 410 martensitic stainless steel offer superior strength and corrosion resistance under a variety of environmental conditions. The rotational speed was adjusted between 1100 and 1500 RPM, while the friction pressure, friction time, forging pressure, and forging duration were all kept constant during the testing. Five sets of testing were performed, with the resultant tensile strength (both room temperature and hot tensile) and Vickers Hardness being recorded for each set of trials. To assess the structural integrity of the joints, a detailed microstructural investigation, SEM-EDS, and XRD were performed at their interfaces. Mechanical properties were revealed to be high at 1300 RPM due to the small grain size at the interface region; ultimate tensile strength and hardness were determined to be 571 MPa and 423 HV, respectively, due to the small grain size at the interface region. Additionally, a pitting corrosion study has been conducted on dissimilar welded joints at optimum conditions, and their results were discussed and compared with base metals.
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Zimmermann, Martina, Jörg Bretschneider, Gunter Kirchhoff, Uwe Stamm, Jens Standfuss, and Berndt Brenner. "Fatigue Behaviour of Laser Beam Welded Circular Weld Seams under Multi-Axial Loading." Advanced Materials Research 891-892 (March 2014): 1397–402. http://dx.doi.org/10.4028/www.scientific.net/amr.891-892.1397.
Full textAbstract:
With modern laser beam sources welding processes can be developed, that allow the joining of otherwise barely realisable material and geometrical constellations such as dissimilar welded, thick-walled shaft-hub joints for powertrain systems. Current design recommendations do not offer solutions to account for the cyclic strength under torsional loading for welded structures. In order to bridge the gap between cost and time consuming prototype testing and laboratory tests of basic homogeneous material samples, a test system combining axial and torsional loading was used. For this purpose application oriented test parts are designed to mimic the weld seam geometry, stiffness and heat dissipation conditions of the real structural part at its best. The dissimilar joints were realised for two material combinations: cast iron GJS-600-3 with case hardened steel 16MnCr5 and 42CrMo4 with 16MnCr5. The latter combination showed only a slightly higher cyclic strength compared to the cast iron/steel combination. A systematic optimization of the laser beam welding process leads to a fatigue behaviour under multi-axial loading conditions, where the cast iron/case hardened steel combination still met the strength specification required.