Dissertations / Theses on the topic 'Plates (Engineering)'
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1
Paulos, Yonas Kinfu. "Sedimentation between parallel plates." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/30055.
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Settling basins can be shortened by using a stack of horizontal parallel plates which develop boundary layers in which sedimentation can occur. The purpose of this study is to examine the design parameters for such a system and to apply this approach to a fish rearing channel in which settling length is strictly limited.
Flow between parallel rough and smooth plates has been modelled together with sediment concentration profile. Accurate description of boundary layer flow requires the solution of Navier-Stokes equations, and due to the complexity of the equations to be solved for turbulent flow some assumptions are made to relate the Reynolds stresses to turbulent kinetic energy and turbulent energy dissipation rate. The simplified equations are solved using a numerical method which uses the approach given by the TEACH code. The flow parameters obtained from the turbulent flow model are used to obtain the sediment concentration profile within the settling plates. Numerical solution of the sedimentation process is obtained by adopting the general transport equation. The lower plate is assumed to retain sediments reaching the bottom.
The design of a sedimentation tank for a fish rearing unit with high velocity of flow has been investigated. The effectiveness of the sedimentation tank depends on the uniformity
of flow attained at the inlet, and experiments were conducted to obtain the most suitable geometric system to achieve uniform flow distribution without affecting other performances of the fish rearing unit. The main difficulties to overcome were the heavy circulation present in the sedimentation tank and the clogging of the distributing system
by suspended particles. Several distributing systems were investigated, the best is discussed in detail.
It was concluded that a stack of horizontal parallel plates can be used in fish rearing systems where space is limited for settling sediments. Flow distribution along the vertical at the entrance to the plates determines the efficiency of the sediment settling process and a suitable geometrical configuration can be constructed to distribute the high velocity flow uniformly across the vertical. Numerical modelling of sediment removal ratio for flow between smooth and rough parallel plates has been calculated. The results show that almost the same pattern of sediment deposition occurs for both the smooth-smooth and rough-smooth plate arrangements.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
2
Jeong, Han Koo. "Reliability of laminated composite plates." Thesis, University of Southampton, 1999. https://eprints.soton.ac.uk/21869/.
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This thesis deals with reliability analysis of laminated composite plates subjected to transverse lateral pressure loads. Input parameters to strengths of the plates such as applied transverse lateral pressure loads, elastic moduli, geometric and ultimate strength values of the plates are treated as basic design variables, and specific probability distributions are applied to them to take into account the variability nature of these basic design variables. Based on the statistical information on the basic design variables, these variables are pseudo-randomly generated in accordance with the corresponding probability distributions by using statistical sampling techniques. Generated random values of the basic design variables corresponding to the applied loads, elastic moduli and geometric values are substituted into various laminated plate theories which can accommodate different lamination schemes and boundary conditions to assess the probabilistic strengths of the plates. The limit state equations are developed by using maximum stress, maximum strain, Tsai-Hill, Tsai-Wu, Hoffman and Azzi-Tsai-Hill failure criteria. Calculated probabilistic plate strengths and generated random values of the ultimate strength basic design variables of the plates are substituted into the developed limit state equations to define the failure or survival state of the plates. In solving the limit state equations, structural reliability techniques are adopted and evolved appropriately for the reliability analysis of the plates. Developed reliability analysing algorithms are applied to laminated plates from experiment to check its validity. Finally, the EUROCOMP Design Code is compared with the developed reliability analysis procedures by applying the both approaches to the strengths of laminated plates.
3
Putra, Azma. "Sound radiation from perforated plates." Thesis, University of Southampton, 2008. https://eprints.soton.ac.uk/63161/.
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Perforated plates are quite often used as a means of engineering noise control to reduce the sound radiated by structures. However, there appears to be a lack of representative models to determine the sound radiation from a perforated plate. The aim of this thesis is to develop such a model that can be used to give quantitative guidance corresponding to the design and effectiveness of this noise control measure. Following an assessment of various models for the radiation efficiency of an unbaffled plate, Laulagnet’s model is implemented. Results are calculated and compared with those for baffled plates. From this, simple empirical formulae are developed and give a very good agreement with the analytical result. Laulagnet’s model is then modified to include the effect of perforation in terms of a continuously distributed surface impedance to represent the holes. This produces a model for the sound radiation from a perforated unbaffled plate. It is found that the radiation efficiency reduces as the perforation ratio increases or as the hole size reduces. An approximate formula for the effect of perforation is proposed which shows a good agreement with the analytical calculation up to half the critical frequency. This could be used for an engineering application to predict the noise reduction due to perforation. The calculation for guided-guided boundary conditions shows that the radiation efficiency of an unbaffled plate is not sensitive to the edge conditions. It is also shown that perforation changes the plate bending stiffness and mass and hence increases the plate vibration. The situation is also considered in which a perforated unbaffled plate is located close to a reflecting rigid surface. This is established by modifying the Green’s function in the perforated unbaffled model to include an imaginary source to represent the reflected sound. The result shows that the presence of the rigid surface reduces the radiation efficiency at low frequencies. The limitation of the assumption of a continuous acoustic impedance is investigated using a model of discrete sources. The perforated plate is discretised into elementary sources representing the plate and also the holes. It is found that the uniform surface impedance is only valid if the hole distance is less than an acoustic wavelength for a vibrating rectangular piston and less than half an acoustic wavelength for a rectangular plate in bending vibration. Otherwise, the array of holes is no longer effective to reduce the sound radiation. Experimental validation is conducted using a reciprocity technique. A good agreement is achieved between the measured results and the theoretical calculation for both the unbaffled perforated plate and the perforated plate near a rigid surface.
4
CHAKRABARTI, SEKHAR KUMAR. "INELASTIC BUCKLING OF GUSSET PLATES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184188.
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The strength and behavior of gusset plates in buckling is evaluated herein based on data from the experimental investigations conducted by other researchers and the analytical work presented herein. A set of design guidelines has been recommended through the review of the current practice. Representative single and double brace gusset plates normally adopted for connections with compressive bracing/diagonal members in braced frames and trusses, were modeled and analyzed using linear and nonlinear finite element methods to determine the buckling loads. The buckling analysis data along with the test data indicated the occurrence of inelastic buckling of the gusset plates. Current design practice and a set of formulas for determination of gusset plate thickness have been reviewed. A set of guidelines has been recommended for the design and evaluating gusset plate buckling loads.
5
Lumpp, Dirk Manfred. "An experimental investigation of circular plates, beams and stiffened circular plates subjected to impulsive loading." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/9658.
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Bibliography: leaves 94-96.This primarily experimental investigation describes a series of experiments on fully-clamped circular plates, rectangular beams and stiffened circular plates. These test specimens were subjected to a uniformly distributed impulse. The impulse was provided by plastic explosive. This was arranged in such a way that a uniformly distributed impulse was imparted to the test specimens. The impulse was measured by means of a ballistic pendulum to which the test specimens were attached. The final mid-point deflections of the plates and beams were measured. The plate and beam results were compared to previous experimental work. A non-dimensional number for plates was modified to include an experimental mass scaling factor due to the ballistic pendulum mass. A non-dimensional number for rectangular beams was developed, including a similar experimental mass scaling factor. Comparing the beam and plate results from this study with those of previous work, using the respective non-dimensional numbers, showed good correlation. The results for the stiffened plates are compared with the plate results.
6
Abayakoon, Sarath Bandara Samarasinghe. "Large deflection elastic-plastic analysis of plate structures by the finite strip method." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26946.
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A solution procedure based on the finite strip method is presented herein, for the analysis of plate systems exhibiting geometric and material non-linearities. Special emphasis is given to the particular problem of rectangular plates with stiffeners running in a direction parallel to one side of the plate. The finite strip method is selected for the analysis as the geometry of the problem is well suited for the application of this method and also as the problem is too complicated to solve analytically.
Large deflection effects are included in the present study, by taking first, order non-linearities in strain-displacement relations into account. Material non-linearities are handled by following von-Mises yield criterion and associated flow rule. A bi-linear stress-strain relationship is assumed for the plate material, if tested under uniaxial conditions. Numerical integration of virtual work equations is performed by employing Gauss quadrature. The number of integration points required in a given direction is determined either by observing the individual terms to be integrated or by previous experience. The final set of non-linear equations is solved via a Newton-Raphson iterative scheme, starting with the linear solution.
Numerical investigations are carried out by applying the finite strip computer programme
to analyse uniformly loaded rectangular and I beams with both simply supported and clamped ends. Displacements, stresses and moments along the beam are compared with analytical solutions in linear analyses and with finite element solutions in non-linear analyses. Investigations are also extended to determine the response of laterally loaded square plates with simply supported and clamped boundaries. Finally, a uniformly loaded stiffened panel is analysed and the results are compared with finite element results. It was revealed that a single mode in the strip direction was sufficient to yield engineering accuracy for design purposes, with most problems.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
7
Mseikeh, Camille Hanna. "Wrinkling of membranes, plates, and shells." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30343.pdf.
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Ko, Kwang Hee 1971. "Laser measurement and reconstruction of curved plates." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91350.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2001.Includes bibliographical references (leaves 86-89).
by Kwang Hee Ko.
S.M.
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Malaret, Hiram A. (Hiram Anthony). "Mechanisms in thermal mechanical forming of plates." Thesis, Massachusetts Institute of Technology, 1987. http://hdl.handle.net/1721.1/14865.
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Mürk, Annely. "Optimization of inelastic plates with cracks /." Online version, 2006. http://dspace.utlib.ee/dspace/bitstream/10062/1226/5/murkannely.pdf.
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Oglesby, Keith Andrew. "Acoustic design optimization of thin plates." Thesis, Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/16375.
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Børvik, Tore. "Ballistic Penetration and Perforation of Steel Plates." Doctoral thesis, Norwegian University of Science and Technology, Department of Structural Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-466.
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Situations involving impact, i.e. the collision between two or more solids, were at one time primarily of concern to the military. Nowadays, as safety is highlighted within most branches of industry, the field of impact dynamics covers a wide range of situations and is of interest to engineers from a large number of different disciplines. This is in particular true for the oil, transport, space, military, nuclear and metal forming industry.
This thesis describes an experimental and numerical investigation on the ballistic penetration and perforation of Weldox 460F steel plates, and consists of eight independently published parts that are linked together through a synopsis. The thesis was generated from a project in progress on the behaviour of structural components subjected to impact loading conditions.
13
Koko, Tamunoiyala Stanley. "Super finite elements for nonlinear static and dynamic analysis of stiffened plate structures." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/30723.
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The analysis of stiffened plate structures subject to complex loads such as air-blast pressure waves from external or internal explosions, water waves, collisions or simply large static loads is still considered a difficult task. The associated response is highly nonlinear and although it can be solved with currently available commercial finite element programs, the modelling requires many elements with a huge amount of input data and very expensive computer runs. Hence this type of analysis is impractical at the preliminary design stage. The present work is aimed at improving this situation by introducing a new philosophy. That is, a new formulation is developed which is capable of representing the overall response of the complete structure with reasonable accuracy but with a sacrifice in local detailed accuracy. The resulting modelling is relatively simple thereby requiring much reduced data input and run times. It now becomes feasible to carry out design oriented response analyses.
Based on the above philosophy, new plate and stiffener beam finite elements are developed for the nonlinear static and dynamic analysis of stiffened plate structures. The elements are specially designed to contain all the basic modes of deformation response which occur in stiffened plates and are called super finite elements since only one plate element per bay or one beam element per span is needed to achieve engineering design level accuracy at minimum cost. Rectangular plate elements are used so that orthogonally stiffened plates can be modelled.
The von Karman large deflection theory is used to model the nonlinear geometric behaviour. Material nonlinearities are modelled by von Mises yield criterion and associated flow rule using a bi-linear stress-strain law. The finite element equations are derived using the virtual work principle and the matrix quantities are evaluated by
Gauss quadrature. Temporal integration is carried out using the Newmark-β method with Newton-Raphson iteration for the nonlinear equations at each time step.
A computer code has been written to implement the theory and this has been applied to the static, vibration and transient analysis of unstiffened plates, beams and plates stiffened in one or two orthogonal directions. Good approximations have been obtained for both linear and nonlinear problems with only one element representations for each plate bay or beam span with significant savings in computing time and costs. The displacement and stress responses obtained from the present analysis compare well with experimental, analytical or other numerical results.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
14
Tsikata, Sedina 1981. "Fresnel phase plates as reconfigurable microfluidic lenses." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/32792.
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Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaf 49).
In this study, Fresnel phase plates were tested as reconfigurable lenses. The lenses were constructed from a Fresnel pattern which was transferred to a silicon substrate via photolithography. A layer of PDMS was spin-coated on the substrate and cured to produce the lens. This lens was attached to a PDMS control layer which enabled specific regions of the lens to addressed, via the application of pressure. It was concluded that based on the limitations of the pressure-based Fresnel lenses, liquid-filled flow channels, while possessing slower response times, might be a more promising means of modulating phase.
by Sedina Tsikata.
S.B.
15
Farrow, Gary Herbert. "The response of impulsively loaded sandwich plates." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/18303.
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This thesis describes a numerical study of the response of impulsively loaded circular sandwich plates using the general purpose finite element programme called ABAQUS. The sandwich plate studied consists of three layers. The two outer layers are of mild steel and the centre layer, or core, is of air. Because of this configuration, the analysis is split into two sections. The first is the study of impulsively loaded circular single plates and the second is the study of the interaction of the outer layers of the sandwich plate on each other. The plates are analysed in the impulse range that results in large plastic deformations known as Mode I Failure. Mode II and III failure of the plates, where failure by tearing occurs, is omitted. The results of the single plate analysis are compared to experimental and analytical work. Criteria for comparison include mid-plate deflections, strain rate dependence, strain predictions, plate thinning, deformation shape and response time. The results of the sandwich plate analysis are compared to experimental data and the criteria for comparison include mid-plate deflections and the diameter of the contact area of the two outer layers. Other aspects of the plate behaviour such as response times and the amount of strain energy absorbed are also discussed. The explicit integration scheme is considered the best finite element solution method to use for this dynamic response problem. The pressure loading model is found to give the best correlation with experimental data while velocity loading models tend to result in instabilities in the explicit solution scheme. The presented results for both the single plates and the sandwich plates show good correlation with the experimental data. In the case of the sandwich plates, the predicted contact diameters show good correlation with the experimental work. The phases of deformation evident in the sandwich plate experimental work are not evident in the presented results, while the mid plate deflection predictions show correct trends, but over estimate the experimental data.
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Wang, Bohe. "The application of finite difference method and MATLAB in engineering plates." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1037.
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Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains iv, 87 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 86-87).
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Dandan, Razan A. "Self-consistent dynamical theory of composite laminated plates /." The Ohio State University, 1994. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487850665557227.
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Abdel-Khalk, Mohamed Farag. "The analysis of sandwich beams and plates." Thesis, University of Salford, 1990. http://usir.salford.ac.uk/26489/.
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This thesis is concerned with the linear and non-linear bending analysis of sandwich beams and plates with flexible cores and thick or profiled metal faces. the project commences with a review of previous work in structural aspects of sandwich construction. It reveals that analytical solutions have been obtained for a small number of simply supported and continuous sandwich beams with equal spans subjected to simple cases of loading. Due to the increasing popularity of such panels in the building industry, there have been demands for more general solutions. Therefore, the purpose of the first part of the present investigation is to find explicit solutions for both single and multispan sandwich beams subject to various cases of loading. The analysis of sandwich beams subject to combined uniform transverse load and compressive or tensile axial load is also presented. Furthermore, simple expressions are presented for the analysis of sandwich beams continuous over supports subject to settlement. This is followed by the derivation of more general solutions for sandwich beams with arbitrary loading and boundary conditions using the finite element technique. The method is exact because the solutions of the governing differential equations are used to derive the element stiffness matrices for sandwich beams subject to combined bending and axial loads. Attention is first confined to the general case of panels with profiled faces, followed by the analysis of panels with plane faces as a special case. Some tests for sandwich panels subject to axial compressive load are presented and the results compared with the theoretical values. In the second part of the investigation, the analysis of sandwich plates is considered. The general equations presented by Alien were first redeveloped in a different way. Then, the buckling and bending analysis of orthotropic rectangular sandwich panels with all edges simply supported and subject to uniform lateral and edge loads is presented. This analysis was based on a series solution of the governing differential equations. Expressions for determining the deflection, stress resultants and critical buckling load of such panels are also presented. This is followed by the linear and geometrically non-linear finite element analysis of multi-layer plates. The formulations were incorporated in existing, modified and new elements for the analysis of three and five layer plates. Finally, the thermal and flexural analysis of sandwich panels is carried out using a three dimensional composite element. Several illustrative examples are also presented to demonstrate the accuracy and versatility of the various formulations.
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Lim, B. S. "Buckling behaviour of asymmetric edge stiffened plates." Thesis, University of Strathclyde, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.371363.
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Zheng, Daihua. "Low Velocity Impact Analysis of Composite Laminated Plates." University of Akron / OhioLINK, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1194991384.
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McCarthy, Robert W. "Thermomechanical forming of steel plates using laser line heat." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/15261.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering; and, (M.S.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.
Bibliography: leaves 107-108.
by Robert W. McCarthy III.
M.S.
22
Achintha, Paththini Marakkala Mithila. "Fracture analysis of debonding mechanism for FRP plates." Thesis, University of Cambridge, 2010. https://www.repository.cam.ac.uk/handle/1810/240575.
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Inevitable flaws in the concrete-FRP interface govern plate debonding, and are not amenable to finite element analysis because the models require far more detail than will ever be available for the interface. This thesis describes a global-energy-balance based fracture-mechanics model for the debonding mechanism of externally bonded FRP plates attached to concrete beams. The model investigates the possible propagation of an existing interface crack by considering the energy balance of the beam during a small potential crack extension. The crack will extend if the energy release rate is greater than the interface fracture energy. Despite the fact that the crack-tip stress field is not amenable to precise analysis, its influence on the energy balance of the beam is insignificant because of the small volume of the "uncertain zone", whereas the crack tip stress field would solely govern an analysis based on linear elastic fracture mechanics. The plate end and the locations where the widening of flexural and flexural/shear cracks cause interface flaws are the most likely locations for the initiation of debonding. The model analyses debonding that initiates from either location. With the small extension of the interface crack the compatibility between the beam and the FRP alters, consequently causing changes in the stress states, and hence the energy states, of zones in the vicinity of the crack. The change in energy state of a beam section upon interface crack extension is determined from a modified version of Branson's model. The strain state when the FRP is fully or partly debonded needs to be considered. The mechanics of stress transfer from the concrete to the FRP differs from that with conventional steel reinforcing bars for which the accuracy of the original Branson's model was validated. So, the moment-curvature model considers the force in the FRP as an external compressive force on the concrete beam section; the separation of the effects of the axial force and the moment is achieved by defining an equivalent centroid. Debonding will propagate in whichever of the concrete, adhesive, or at an interface that provides the least resistance; thus, the interface fracture energy is that of the weakest phase. Experimental observations confirm that the concrete substrate just above the interface is most likely to fail, in particular when the FRP manufacturer-recommended adhesives are used with appropriate curing procedures. Fracture energy of concrete is determined from Hillerborg's cohesive-crack-model-based experimental and approximate theoretical models. Premature debonding propagation within the adhesive layer can also be analysed but the knowledge of that fracture energy is required. The energy release rate is calculated for assumed interface crack lengths and locations, from which the critical state is determined when it equals the interface fracture energy. Comparisons with test data reported in the literature demonstrate that the model is accurate for all modes of plate debonding. The analysis gives the critical plate curtailment location and the critical crack length which trigger debonding at the plate end and in the high moment zone respectively. The model allows for the inclusion of all properties of the concrete beam, adhesive, FRP and the loading arrangement and hence can be used as an optimisation tool in design. The model also provides a framework for the design of more complex real -life applications, and highlights subjects that require further research.
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Hua, Meng. "The mechanics of continuous roller bending of plates." Thesis, Aston University, 1986. http://publications.aston.ac.uk/11862/.
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This research initiates a study of the mechanics of four roll plate bending and provides a methodology to investigate the process experimentally. To carry out the research a suitable model bender was designed and constructed. The model bender was comprehensively instrumented with ten load cells, three torquemeters and a tachometer. A rudimentary analysis of the four roll pre-bending mode considered the three critical bending operations. The analysis also gave an assessment of the model bender capacity for the design stage. The analysis indicated that an increase in the coefficient of friction in the contact region of the pinch rolls and the plate would reduce the pinch resultant force required to end a plate to a particular bend radius. The mechanisms involved in the four roll plate bending process were investigated and a mathematical model evolved to determine the mechanics of four roll thin plate bending. A theoretical and experimental investigation was conducted for the bending of HP30 aluminium plates in both single and multipass bending modes. The study indicated that the multipass plate bending mechanics of the process varied according to the number of bending passes executed and the step decrement of the anticipated finished bend radius in any two successive passes (i.e. the bending route). Experimental results for single pass bending indicated that the rollers normally exert a higher bending load for the steady-continous bending with the pre-inactive side roll oper?tive. For the pre-bending mode and the steady-continous bending mode with the pre-active side roll operative, the former exerted the higher loads. The single pass results also indicated that the force on the side roll, the torque and power steadily increased as the anticipated bend radius decreased. Theoretical predictions for the plate internal resistance to accomplish finished bend radii of between 2500mm and 500mm for multipass bending HP30 aluminium plates, suggested that there was a certain bending route which would effectively optimise the bender capacity.
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Ho, Wai Yiu. "License Plate Recognition algorithms and their application to Macao license plates." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2182850.
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Teeling-Smith, R. Graeme. "An investigation into the deformation and tearing of thin circular plates subjected to impulsive loads." Master's thesis, University of Cape Town, 1990. http://hdl.handle.net/11427/14564.
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Includes bibliographical references.This investigation, primarily experimental, examines the failure of circular plates subjected to impulsive velocities. The experiments are conducted on fully clamped circular steel plates subjected to a uniformly distributed impulse. The strain-rate-sensitive mild steel plates fail with mode I (large ductile deformation), mode II (tensile-tearing and deformation) and mode III (transverse-shear) failure modes. The impulse is measured by means of a ballistic pendulum upon which the test plates are attached. During mode II and mode III failure the complete circumferential tearing of the test plate produces a circular disc. The velocity of this disc is recorded. An energy analysis is performed on the test results and an energy balance equation is formulated. Einput = Edeformation + Etearing + Edisc. The input and disc energies are obtained from the experimental measurements and the deformation energy is predicted by using the final deformed height and a shape function together with a rigid-plastic energy analysis adopted by Duffey. Etearing refers to the energy for tensile-tearing in mode II failure or the energy for transverse-shear in mode III failure. Good correlation is found and the experiments show good repeatability. The threshold velocities for the onset of failure modes II and III are given.
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Israr, Asif. "Vibration analysis of cracked aluminium plates." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/261/.
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This research is concerned with analytical modelling of the effects of cracks in structural plates and panels within aerospace systems such as aeroplane fuselage, wing, and tail-plane structures, and, as such, is part of a larger body of research into damage detection methodologies in such systems. This study is based on generating a so-called reduced order analytical model of the behaviour of the plate panel, within which a crack with some arbitrary characteristics is present, and which is subjected to a force that causes it to vibrate. In practice such a scenario is potentially extremely dangerous as it can lead to failure, with obvious consequences. The equation that is obtained is in the form of the classical Duffing equation, in this case, the coefficients within the equation contain information about the geometrical and mass properties of the plate, the loading and boundary conditions, and the geometry, location, and potentially the orientation of the crack. This equation has been known for just over a century and has in the last few decades received very considerable attention from both the analytical dynamics community and also from the dynamical systems researchers, in particular the work of Ueda, Thompson, in the 1970s and 1980s, and Thomsen in the 1990s and beyond. An approximate analytical solution is obtained by means of the perturbation method of multiple scales. This powerful method was popularized in the 1970s by Ali H.Nayfeh, and discussed in his famous books, ‘Perturbation Methods’ (1974) and ‘Nonlinear Oscillations’ (1979, with D.T.Mook), and also by J.Murdock (1990), and M.P.Cartmell et al. (2003) and has been shown to be immensely useful for a wide range of nonlinear vibration problems. In this work it is shown that different boundary conditions can be admitted for the plate and that the modal natural frequencies are sensitive to the crack geometry. Bifurcatory behaviour of the cracked plate has then been examined numerically, for a range of parameters. The model has been tested against experimental work and against a Finite Element model, with good corroboration from both. In all events, this is a significant new result in the field and one that if implemented within a larger damage detection strategy, could be of considerable practical use.
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Ghosh, Triguna. "Nondestructive characterization of plates with an emphasis on civil infrastructure." Diss., The University of Arizona, 1997. http://hdl.handle.net/10150/282426.
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This work is aimed at developing a methodology for inspecting large plates, used in civil infrastructure, by Lamb waves. The traditional methods inspecting infrastructure are based on scattering of elastic waves from internal defects and on time of flight measurements. The methods based on elastic wave scattering can only detect defects larger than the wavelength of ultrasound used. The time of flight measurements have proven to be unreliable for strength analysis. This work investigates the potential of the Lamb wave technique to detect small defects when Lamb waves propagate over large distances. An innovative transducer holder setup is developed, which is the key to how Lamb waves can be generated and received in large structures.
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Saliba, H. T. "Free vibration analysis of non-rectangular quadrilateral plates." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/5264.
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Mallakunta, Narendra. "Static and dynamic analysis of rectangular sandwich plates." Thesis, University of Ottawa (Canada), 1990. http://hdl.handle.net/10393/5984.
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The static and dynamic characteristics of homogeneous rectangular plates and rectangular sandwich plates are studied by the finite element method using a 8-node isoparametric rectangular element. A computer code utilizing the finite element method is developed to generate solutions for the static and dynamic analysis of homogeneous plates and sandwich plates for conditions of plane stress, plane strain, bending, and combined stress and bending for small deformation problems only. However, in this work, the scope is limited to bending problems only. Further, only the values for the center deflection are generated, in the static analysis, even though the code has the capability to generate the various stress components. In the dynamic analysis, the natural frequency and the associated mode shapes are determined. The boundary conditions are taken as free, simply supported, clamped edge constraints and their combinations. Uniformly distributed loads, concentrated loads or a combination of both can be applied. This study concentrates on free vibration problems in the case of the dynamic analysis. The effect of considering non-uniform shear distribution in the core of the sandwich plate is studied for both the static and dynamic analysis. The impact of considering two different orders of numerical integration is also studied. (Abstract shortened by UMI.)
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Li, Nong. "Vibration of laminated orthotropic composite plates and shells." Thesis, University of Ottawa (Canada), 1994. http://hdl.handle.net/10393/6946.
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Almost all of the analytical solution techniques presented for composite plates and shells deal with either simply supported conditions or boundary conditions with at least a pair of opposite edges simply supported. In the present study, an alternative general approach, combining superposition and state space techniques is developed for the free vibration analysis of laminated orthotropic composite plates and shells having arbitrary boundary conditions. This study concentrates on the antisymmetric angle-ply laminated plates and cross-ply laminated plates and shells. Three commonly adopted theories, i.e., classical theory, first-order shear deformation theory and third-order shear deformation theory, have been employed and compared with one another to investigate the influence of transverse shear deformation, structural aspect ratio, length-to-thickness ratio, degree of anisotropy and the number of layers on natural frequency. Convergence tests have been carried out to guarantee the accuracy of the closed-form solutions. Wherever possible, numerical results generated by the present approach are compared with those reported in the published references. Accurate non-dimensional fundamental frequencies are presented for laminated plates and shells with two adjacent edges, three edges and four edges clamped and other edges simply supported. Such analyses have not been reported in the literature previously. Also, vibration analysis of a cantilever angle-ply antisymmetric plate with a point support is conducted to demonstrate the applicability of the present technique. It has been shown that the method works extremely well and excellent agreements are found between the present results and those generated by previous researchers. It has also been shown that more complicated boundary-value problems can be solved by this technique without any difficulty.
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Alizadeh, Y. "Free vibration of partially supported plates and shells." Thesis, University of Ottawa (Canada), 1992. http://hdl.handle.net/10393/10751.
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First-order transverse shear-deformation Mindlin theory has been used to predict the free vibration frequencies and modal shapes for isotropic, laminated and composite plates or shells. A finite element model based on the small deflection linear theory has been developed to obtain numerical solutions for this class of problems. The results for some of the degenerate cases are compared with other results available in the literature. These analyses involve a wide number of variables, namely; material properties, aspect ratios, support conditions and also radius to base ratio. The cracked base plates, shells and blades are idealized as partially supported models with varying support lengths. The effects of the detached base length on natural frequencies, modal shapes and nodal lines of these types of structures are investigated. Although the expected decrease in frequency with increase in the detached base length is observed almost for all modes it is seen that this behavior is very pronounced for higher modes in both plates and shells. Analysis also showed that the variation of the detached base length has a small effect on the natural frequencies of plates and shells with large aspect ratios ( b/a > 2, r/a > 2).
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Bahous, André. "Plastic buckling of circular plates on elastic foundations." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123016.
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The thesis deals with the plastic bifurcation buckling of a full circular plate partially or fully bonded to an elastic foundation, and subjected to a uniform radial pressure at the periphery. The prebuckling state of stress in the plate is therefore a constant equibiaxial stress. Under this stress, the plate material undergoes strain-hardening, obeying an isotropically expanding J2 (von Mises) yield surface. The incremental constitutive relations, needed for the bifurcation analysis, are written in a way so as to incorporate behaviours according to both the J2 deformation and J2 -incremental theories of plasticity, and also to include the elastic theory. The governing equation and boundary conditions, suitable for non-axisymmetric or axisymmetric buckling, are derived using the principle of virtual work and Shanley's concept of bifurcation under increasing load. Exact analysis solves the fourth order partial differential equation, and obtains the buckling stresses for plates fixed and simply supported at the periphery, as a function of the radius to thickness ratio, and for various values of the foundation modulus.Four cases of foundation support are considered: (1) no foundation, (2) full foundation, (3) partial inside foundation for half the plate radius, and (4) partial outside foundation from half to the full radius. This is done for fixed as well as simply supported plates. Buckling stresses and the associated mode shapes, whether axisymmetric or nonaxisymmetric, are obtained for the investigated cases.Numerical results are presented for the bifurcation stress of Aluminum 24S-T3 plates and foam like foundation materials. The results show that the effect of foundation is less significant in the plastic range than in the elastic range. As expected, the buckling stresses for the incremental theory are always higher than the results for the deformation theory. For fixed plates the maximum difference is around 10% at the high end of the validity of the stress-strain curve. But, surprisingly for the simply supported plates, the results from the incremental theory are higher by less than 1%. This means, that for circular simply supported plates, the well-known plastic buckling paradox almost disappears, even in the presence of a foundation.Cette thèse traite du voilement plastique par bifurcation d'une plate circulaire qui est partiellement ou complètement liée à une fondation élastique, et qui est soumise à une pression radiale uniforme sur sa périphérie. Avant le voilement, la plaque se trouve dans un état de contraintes équibiaxiales constantes. Sous ces contraintes, le matériau de la plaque subit un écrouissage suivant une surface de plastification en expansion isotrope J2 (von Mises). Les lois constitutives incrémentales, requises pour l'analyse de bifurcation, sont écrites de façon à incorporer le comportement selon la théorie de déformation J2, les théories incrémentales de la plasticité J2 et la théorie élastique. L'équation régissant le comportement de la plaque et les conditions frontières, adaptés au voilement axisymétrique et non-axisymétrique, sont dérivés selon le principe du travail virtuel et le principe de bifurcation sous augmentation de charge de Shanley. L'analyse exacte de l'équation différentielle du 4e degré permet d'obtenir, en fonction du ratio rayon/épaisseur des plaques et du module de fondation, les contraintes de voilement pour les plaques encastrées et simplement supportées en leur périphérie.Quatre configurations de fondations sont considérées : (1) aucune fondation présente, (2) une fondation présente partout, (3) une fondation partielle présente uniquement à l'intérieur de la moitié du rayon de la plaque et (4) une fondation partielle présente à partir de la moitié du rayon jusqu'au bord de la plaque. Ces configurations sont appliquées pour des plaques simplement supportées et encastrées en périphérie. Les contraintes de voilement ainsi que les modes de déformations associés, qu'ils soient axisymétrique ou non-axisymétrique, sont obtenus pour chaque cas.L'analyse numérique présente des résultats de contraintes de bifurcation pour des plaques d'aluminium 24S-T3 et des matériaux de fondation peu rigides de type mousse synthétique. Il en ressort que l'effet de la fondation sur les contraintes de voilement est moins important dans le domaine plastique que dans le domaine élastique. Tel que prévu, les contraintes de voilement découlant de la théorie incrémentale de la plasticité J2 sont toujours supérieurs que celles basées sur la théorie de déformation J2. Pour les plaques encastrées, à l'extrémité de la courbe contrainte-déformation, la différence maximale est d'environ 10%. Étonnamment par contre, pour les plaques simplement supportées, les résultats de la théorie incrémentale de la plasticité sont plus importants par moins de 1%. Ceci veut dire que, pour les plaques simplement supportées, le paradoxe du voilement plastique ne s'applique pas et ce, même en présence d'une fondation.
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Anderson, Roger J. (Roger Jeffrey) 1976. "Experiments and simulation of line heating of plates." Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/80633.
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Pickering, Erik Green. "The response of quadrangular plates to buried charges." Master's thesis, University of Cape Town, 2011. http://hdl.handle.net/11427/12244.
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Includes abstract.Includes bibliographical references (leaves 155-162).
This dissertation reports on the results of an experimental and numerical investigation into the response of quadrangular plate structures to buried charges. The plate structure and PE4 explosive charge were scaled to the APC and the TM-57 Anti-tank mine respectively...
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Cherukunnath, Neeraj Narayanan. "Analysis of laminated plates using boundary element method." Thesis, University of Southampton, 2003. https://eprints.soton.ac.uk/45936/.
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Formulations and implementations of the Boundary Element Method (BEM) for bending, membrane stress, buckling and post-buckling analyses of laminated plates are presented. Symmetrically laminated plates are assumed for which the bending-stretching coupling is absent. From the generalized Rayleigh-Green identity corresponding to the plate-bending problem, boundary integral equations are derived using the appropriate fundamental solution. Integral equations are transformed into a system of equations in matrix form by introducing boundary element interpolation models. Linear and quadratic discontinuous boundary elements are employed combined with special schemes for the approximation of jump terms at corners. Singular integrals over elements containing the source point are evaluated from closed-form expressions derived through analytical integration. Using the stress function concept, it is shown that the membrane stress analysis due to arbitrary in-plane loading is mathematically equivalent to plate bending problem. Based on this similarity a new boundary element formulation is developed for the prediction of membrane stresses in a laminated plate. The same fundamental solution, which was used for plate bending problem, is used with the replacement of flexural coefficients with extensional compliance coefficients. A new formulation for the buckling analysis, which is similar to that for the plate bending problem, leads to integral equations with an irreducible domain integral depending on the plate deflection. Boundary modelling is combined with deflection modelling over the plate so that three integral equations are approximated as a discrete system of equations forming an eigenvalue problem from which the critical load is evaluated. This approach removes the need for integral equations involving the domain curvatures yielding directly the buckling mode of the plate. Formulations of membrane stress and bending analyses are expanded by including the nonlinear terms arising from large deflections and combined for the development of an incremental algorithm predicting the post-buckling behaviour of laminate plate. The C codes implementing the solution algorithms are applied to several benchmark problems involving orthotropic and general anisotropic plates and BEM predictions are compared with solutions available from the literature or obtainable through a general-purpose finite element package.
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Moazzami, Mehdi. "A higher order layer-wise theory of laminated plates." The Ohio State University, 1991. http://rave.ohiolink.edu/etdc/view?acc_num=osu1273001724.
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Han, Myoung Soo. "Fundamental studies on welding-induced distortion in thin plates /." The Ohio State University, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=osu1486402288262521.
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Warncke, Dale. "The response of quadrangular plates to buried encased charges." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/29194.
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This dissertation reports on a series of experiments and numerical simulations that were carried out to investigate the response of quadrangular plates to buried encased charges with a view of understanding landmine effects on simple structures. Different loading scenarios were carried out for comparison. In total, four loading scenarios were investigated; namely bare and encased charges detonated in air, and bare and encased charges detonated under sand. A vertical pendulum was used to measure the impulse imparted onto the target plates, and dry construction sand was used to bury the charges. The geometric scaling of the target plates and PE4 explosive charge was based on the Casspir APC and TM-57 Anti-tank mine respectively. The experiments were carried out under varying conditions, such as different standoff distances (50-90 mm) and depths of burial (0-10 mm). In general, the impulse and midpoint deflection decreased with an increase in total distance for all loading scenarios. Burn diameters were observed on plates loaded in air, with dissimilar scorch areas observed on plates subjected to buried charges. Scorched areas on plates subjected to encased charges indicated a focussing effect of the explosive products provided by the charge casing. Plates subjected to encased charges detonated in air typically resulted in ’capping’ in the central area, accompanied by significant shrapnel damage. In general, presence of a charge casing in buried charge tests resulted in more damage to the target plate. Larger impulses and midpoint deflections were measured for charges detonated under sand compared to bare charges detonated in air. Encased charges detonated under sand resulted in decreased impulse imparted onto the target plate, accompanied by an increased plate midpoint deflection when compared to bare charges detonated under sand. The presence of sand in encased charge tests tended to mitigate the shrapnel damage caused by the charge casing. ANSYS AUTODYN was used to perform numerical simulations on three variable standoff distance test series, one with no sand and a bare charge, one with a constant depth of burial and a bare charge, and the last with a constant depth of burial and an encased charge. These simulations mirrored the experimental test series. The simulations consisted of two-dimensional axisymmetric models, with lagrangian meshes representing the target plate and explosive casing, and an eulerian mesh used to model the behaviour of the PE4, sand and air. The blast was simulated in two phases, namely detonation of the explosive and loading of the structure. The casing mesh was only included in the detonation phase. Two separate models were used to simulate the impulse and the plate behaviour. The impulse model used a reflective boundary to represent the plate and pressure histories on the reflective boundary were used to calculate the impulse. The plate loading model included a lagrangian mesh to represent the plate and simulate its deformation. The plate loading model used and additional unloading phase to allow plate oscillations to subside. The numerical model was validated using the impulse, plate midpoint deflection and plate profile measured during the experiments. The numerical model showed good correlation with the results of the experiments in terms of midpoint deflections and impulse trends. The model provided insights into the experiments, such as how the gas products expanded after detonation and their interaction with the target plate.
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Das, Dhananjoy Kumar. "Finite strip analysis of sandwich panels." Thesis, University of British Columbia, 1989. http://hdl.handle.net/2429/30287.
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A finite strip analysis of sandwich wood panels is presented. The panels consist of upper and lower plates stiffened by beams (joists) in one direction only. The analysis considers a Fourier series expansion in the stiffeners' direction and a polynomial finite element approximation in the direction normal to the stiffeners. The number of degrees of freedom is 34, which includes also the lateral and torsional deformation of the joists. This permits consideration of the effect of joist bridging on the maximum deflection and bending stresses.
A maximum of 20 joists per panel can be analysed. The modulus of elasticity(E) of the joists may be selected randomly from a distribution, and controlled to be within a given range. The upper and lower plates may possess orthotropic properties. Nails connect the plates to the joists. Nailing may be considered either as a continuous or as discrete connectors. The loading may be in the form of an uniformly distributed load spread over the entire panel or over a maximum of 20 smaller (concentrated) areas of the top plate.
Numerical investigations have been carried out to verify the program. Parametric studies have been done to understand the behavior of the model. Lastly, the formula for shear lag given by CSA Standard CAN3-086.1-M84 is checked against the shear lag obtained from the current computer program.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Eriksson, Marcus. "Accelerated degradation of bipolar plates in the PEMFC." Thesis, KTH, Skolan för kemivetenskap (CHE), 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-207367.
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The aging of bipolar plates in the polymer electrolyte membrane fuel cell was evaluated using different accelerated degradation tests. From previous studies, it is well known that the startups and shutdowns of a polymer electrolyte membrane fuel cell is the primary cause of fuel cell component degradation. Therefore, the aim of these tests was to simulate the number of startups/shutdowns that normally occur during the lifetime of a polymer electrolyte membrane fuel cell, e.g. for automobile applications. The tests were carried out in situ in order to be as realistic and close to operational conditions in real applications as possible. Mechanical stress and degradation normally occurring during polymer electrolyte membrane fuel cell operation was thereby included. The accelerated degradation tests were designed for maximum fuel cell stress, including use of the no purge and the air purge strategy, short cycle duration as well as an increased number of startups/shutdowns. Since the no purge strategy avoids prevention of local H 2/O2 fronts, this strategy was implemented first. Other strategies e g the air purge strategy, where air is used to purge the anode, where also implemented. Parameters influencing the tests were varied and the cathode gas was changed between O2 and air depending on the test. Electrochemical methodology was implemented for the detection of corrosion in the tests and for analysis/ studies of the test results. These techniques include cell voltage/current readings, polarization curves, electrochemical impedance spectroscopy, contact resistance and current density decrease at constant cell voltage. In addition, scanning electron microscope was used to visualize the actual corrosion of the bipolar plates. It was found that implementation of the air purge strategy resulted in localized corrosion, i.e. oxide film formation, on the surface of the bipolar plates increasing both the corrosion resistance and the interfacial contact resistance.Åldrandet av bipolära plattor i polymerelektrolytbränslecellen undersöktes med hjälp av olika accelererade nedbrytningstest. Från tidigare studier är det känt att uppstarterna och avstängningarna av denna typ av bränslecell är den främsta orsaken till nedbrytningen av bränslecellskomponenterna. Av den anledningen var syftet med dessa test att simulera antalet uppstarter och avstängningar som normalt sker under en polymerelektrolytbränslecells livstid t ex för tillämpningar i fordon. Testen utfördes in situ för att vara så realistiska och så nära driftsförhållandena i verkliga tillämpningar som möjligt. Därmed inkluderades mekanisk påfrestning och nedbrytning som normalt sker under drift i en polymerelektrolytbränslecell. De accelererade nedbrytningstesterna utformades för maximal bränslecellspåfrestning. Detta åstadkoms bl a genom tillämpning av den s k "no purge"och "air purge " strategin, kort cykeltid samt ett utökat antal uppstarter/avstängningar. Eftersom "no purge" strategin eliminerar förebyggandet av H 2/O2 fronter, testades denna strategi först. Andra strategier tillämpades också som t ex "air purge" strategin, där luft fick "rena" anodsidan. Parametrar som påverkar testen varierades och katodgasen skiftades mellan O2 och luft beroende på experimentet. Elektrokemisk metodik användes för att detektera nedbryning i de olika testen och för att studera testresultaten. Dessa tekniker omfattade cellspänning/ -ström mätningar, polarisationskurvor, elektrokemisk impedans spektroskopi, kontaktresistens och strömtäthetsminskning vid konstant cellspänning. Svepelektronmikroskopi användes för att visualisera den fysiska nedbryningen av de bipolära plattorna. Det visade sig att "air purge" strategin gav upphov till korrosion i form av lokal oxidbildning på de bipolära plattornas yta. Detta ökade både korrosionsmotståndet och kontaktresistensen i gränsskiktet.
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Chow, Leung Choi. "Damping of plates with attached fluid or elastic layers." Thesis, University of Southampton, 1987. https://eprints.soton.ac.uk/52269/.
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The thesis is in three parts. The first is a theoretical and experimental investigation of squeeze-film damping on plates separated by gas, for example. air. For this study a thick excited plate was attached to an auxiliary plate parallel to the surface, thereby trapping a thin layer of air. Relative vibration of these two plates pumps this air at high velocities, resulting in energy loss due to air viscosity. The theory employs an impedance approach to predict the loss factor of the coupled plates. Below the excited plate critical frequency the damping is controlled by gas pumping, while above the critical frequency the plate couplings are the controlling factor. Theoretical predictions were compared with experimental measurements. A brief examination of the bolting effect on the loss factor was also conducted. The second part is a theoretical and experimental investigation of squeeze-film damping on plates separated by heavy fluid, for example, oil. The attached plate can be either perforated or unperforated. The ratio of fluid dynamic viscosity to density controls the losses. Viscosity was artificially increased by inserting porous materials into the oil layer. The properties of the porous materials were obtained from macroscopic flow resistance measurements. Theoretical modelling of the loss factor of these layered configurations with oil alone and with oil impregnated porous material were conducted using the impedance approach and compared with experimental measurements. The third part is a theoretical and experimental investigation of granular infill damping treatments on plates. Sand was used in the experiments and the bulk and shear elastic constants were measured when the sand was subjected to varying hydrostatic pressures. Both the dilatational and rotational motions in the granular layer were considered and the loss factor predictions were compared with measured results.
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Gatewitaya, Wonchai. "Optimal control of vibration of beams and plates." Ohio : Ohio University, 1995. http://www.ohiolink.edu/etd/view.cgi?ohiou1179345502.
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李華煜 and Wah-yuk Li. "Spline finite strip analysis of arbitrarily shaped plates and shells." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1988. http://hub.hku.hk/bib/B31231287.
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Li, Wah-yuk. "Spline finite strip analysis of arbitrarily shaped plates and shells /." [Hong Kong : University of Hong Kong], 1988. http://sunzi.lib.hku.hk/hkuto/record.jsp?B12350758.
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Salomon, Ami 1972. "An evaluation of finite element models of stiffened plates." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/91329.
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Lacruz, Alvarez Alfonso de. "Damage response of sandwich plates subject to dynamic loads." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/35040.
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Radford, Anthony Michael. "Thin circular metal plates subjected to localised impulsive loads." Master's thesis, University of Cape Town, 1995. http://hdl.handle.net/11427/21703.
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This thesis presents a theoretical model to predict the response of thin circular metal plates subjected to localised impulsive loads. These predictions are compared to experimental data and a finite element model. The theoretical model is described by two models where the first model predicts the plate deformation and the second model, using the deformation from the first, predict the strains in the plate. The first model or theoretical displacement model presents a stepwise velocity field approach, in which it is assumed that the explosive burns as a set of discretised rings spreading from the centre of the plate to the outer radius of the explosive. For each ring a velocity field for the plate is developed, and after including strain rate effects, a corresponding displacement is calculated. The total final displacement is determined by summing each of the individual displacements. The predictions are compared with all experimental data and a satisfactory correlation is found for both the mid-point displacements and the final plate shape. The second model or theoretical strain model uses the final displaced shape calculated using the theoretical displacement model to determine the strain in the deformed plates, with results being compared to uniaxial tensile strain and mean cap diameters obtained from experimentation. The maximum strain at failure calculated using the theoretical strain model gave good correlation to the uniaxial tensile strain and its position correlated well with the mean cap diameter.
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Nurick, Gerald N. "Large deformations of thin plates subjected to impulsive loading." Doctoral thesis, University of Cape Town, 1987. http://hdl.handle.net/11427/6923.
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Includes bibliographical references.The dynamic response of structures subjected to blast and impact loading has been obtained relatively simply using rigid-plastic or rigid-viscoplastic material idealisations. It is essential, however, that the predictions of these idealised theories should be checked against experimental results, and over the past twenty years several experimental studies have been carried out. This thesis describes a series of experiments on fully clamped Circular, square and rectangular steel plates. The final midpoint deflections measured were between 3 and 12 plate thicknesses: and the deflection time history was measured using a light interference technique. While the deflection-time history was being recorded. the impulse was simultaneously being measured by means of a ballistic pendulum upon which the plates were attached. The impulse was provided by sheet explosive which was arranged in such a way that the plate was subjected to a uniformly distributed impulse. In addition an extension of a mode approximation method, based on the assumption that membrane stresses predominate, is presented. This method assumes that the material behaviour can be modelled as rigid-viscoplastic. and that at any instant the shapes of the displacement and the velocity field are the same. Points on the plate surface were first assumed to displace perpendicular to the initial surface: this assumption was then relaxed to permit points to move perpendicular to the current surface. In both cases. the predicted transverse displacements agreed well with the experimental data. The predicted radial strain distribution exhibited trends similar to the experimental data in the case where lateral displacements were modelled.
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Bimha, Richard Ernest. "Response of thin circular plates to central blast loading." Master's thesis, University of Cape Town, 1996. http://hdl.handle.net/11427/8488.
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Includes bibliographical references.The large ductile deformation response and rupture of thin circular metal plates subjected to central blast loading is investigated using the ABAQUS general purpose finite element code. The finite element code incorporates non-linear geometry and material effects as well as strain rate sensitivity. A material failure model is also incorporated. The SA.XI axisymmetric sheet elements are used to model the plate. The shell element uses a theory that includes shear deformation effects but degenerates to the Kirchoff classical thin shell theory for thin shell elements. An explicit time integration scheme is considered more suitable than an implicit scheme for the analysis. A uniform mesh with 1000 elements is used in modelling the experiments. The mesh size is chosen to satisfy the conditions for numerical stability in the explicit analysis scheme. Two boundary conditions are considered; a plate clamped to its supports by bolts and a plate fully built-in. The pressure loading from the explosive charge is assumed to be uniform over the loaded area and decaying exponentially to the plate boundary. The pressure pulse is assumed to be rectangular. Material parameters are obtained from uniaxial quasi-static material tensile test results. The predicted plate responses; mid-plate permanent deflections, permanent deformation shape, strain rate dependence, strain predictions, response time and rupture are compared to experimental data and/or analytical and other numerical solutions. The predicted responses compare reasonably well with measured experimental results and/or with reported analytical and other numerical predictions.
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Lee, Ho Hyung. "Postbuckling failure of composite plates with central holes." Diss., This resource online, 1991. http://scholar.lib.vt.edu/theses/available/etd-10022007-145159/.
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