Dissertations / Theses on the topic 'Plates (Engineering) Cracking Mathematical models'
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1
Akileh, Aiman R. "Elastic-plastic analysis of axisymmetrically loaded isotropic circular and annular plates undergoing large deflections." PDXScholar, 1986. https://pdxscholar.library.pdx.edu/open_access_etds/3559.
Full textAbstract:
The concept of load analogy is used in the elastic and elastic-plastic analysis of isotropic circular and annular plates undergoing moderately large deflection. The effects of the nonlinear terms of lateral displacement and the plastic strains are considered as additional fictitious lateral loads, edge moments, and in-plane forces acting on the plate. The solution of an elastic or elastic-plastic Von Karman type plate is hence reduced to a set of two equivalent elastic plate problems with small displacements, namely, a plane problem in elasticity and a linear elastic plate bending problem. The method of finite element is employed to solve the plane stress problem. The large deflection solutions are then obtained by utilizing the solutions of the linear bending problems through an iterative numerical scheme. The flow theory of plasticity incorporating a Von Mises layer yield criterion and the Prandtl-Reuss associated flow rule for strain hardening materials is employed in this approach.
2
Young, Andrew J. "Active control of vibration in stiffened structures." Title page, contents and abstract only, 1995. http://hdl.handle.net/2440/37722.
Full textAbstract:
Active control of vibration in structures has been investigated by an increasing number of researchers in recent years. There has been a great deal of theoretical work and some experiment examining the use of point forces for vibration control, and more recently, the use of thin piezoelectric crystals laminated to the surfaces of structures. However, control by point forces is impractical, requiring large reaction masses, and the forces generated by laminated piezoelectric crystals are not sufficient to control vibration in large and heavy structures. The control of flexural vibrations in stiffened structures using piezoceramic stack actuators placed between stiffener flanges and the structure is examined theoretically and experimentally in this thesis. Used in this way, piezoceramic actuators are capable of developing much higher forces than laminated piezoelectric crystals, and no reaction mass is required. This thesis aims to show the feasibility of active vibration control using piezoceramic actuators and angle stiffeners in a variety of fundamental structures. The work is divided into three parts. In the first, the simple case of a single actuator used to control vibration in a beam is examined. In the second, vibration in stiffened plates is controlled using multiple actuators, and in the third, the control of vibration in a ring-stiffened cylinder is investigated. In each section, the classical equations of motion are used to develop theoretical models describing the vibration of the structures with and without active vibration control. The effects of the angle stiffener(s) are included in the analysis. The models are used to establish the quantitative effects of variation in frequency, the location of control source(s) and the location of the error sensor(s) on the achievable attenuation and the control forces required for optimal control. Comparison is also made between the results for the cases with multiple control sources driven by the same signal and with multiple independently driven control sources. Both finite and semi-finite structures are examined to enable comparison between the results for travelling waves and standing waves in each of the three structure types. This thesis attempts to provide physical explanations for all the observed variations in achievable attenuation and control force(s) with varied frequency, control source location and error sensor location. The analysis of the simpler cases aids in interpreting the results for the more complicated cases. Experimental results are given to demonstrate the accuracy of the theoretical models in each section. Trials are performed on a stiffened beam with a single control source and a single error sensor, a stiffened plate with three control sources and a line of error sensors and a ring-stiffened cylinder with six control sources and a ring of error sensors. The experimental results are compared with theory for each structure for the two cases with and without active vibration control.Thesis (Ph.D.)--Mechanical Engineering, 1995.
3
Liu, Bing 1975. "FE analysis of plastic buckling of plates with initial imperfections and simulation of experiments." Thesis, McGill University, 2007. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=100251.
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The general problem of plastic buckling of flat metal plates is a fundamental area of investigation in mechanics not only because of its intrinsic importance in the design of engineering structures, but also because it still has not been settled in a satisfying manner. Which theory of plasticity is the correct one to predict the buckling loads in the plastic range is a long-argued problem.This thesis presents finite element analyses of plastic buckling and postbuckling behaviour of columns and plates, taking into account the presence of initial out-of-plane imperfections. The FE programs constructed by the author for this purpose are used to analyze the imperfection growth of such columns and plates under axial loading and simply supported edge conditions. The material behaviour is modeled according to both the incremental and the deformation theories of strain-hardening plasticity. The programs combine both the geometric and material nonlinearities to trace the load-deflection behaviours of these structures in prebuckling (up to the maximum load) as well as postbuckling ranges. The results of the analyses for plates show the extreme sensitivity of the incremental theory, and the relative insensitivity of the deformation theory, to the initial imperfections.
The programs are used to simulate the plastic buckling experiments on Aluminum tubes, taking into account their measured imperfections. The imperfection growth analyses demonstrate that the maximum load predictions of the incremental theory are quite close to those recorded in the experiments.
4
Robbins, Donald H. "Hierarchical modeling of laminated composite plates using variable kinematic finite elements and mesh superposition." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/40117.
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5
CHAKRABARTI, SEKHAR KUMAR. "INELASTIC BUCKLING OF GUSSET PLATES." Diss., The University of Arizona, 1987. http://hdl.handle.net/10150/184188.
Full textAbstract:
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.
6
Abel, Mary Sue M. "Four-bolt extended unstiffened moment end-plate connections." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-11242009-020221/.
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Montgomery, Darcy Thomas. "Milling of flexible structures." Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29689.
Full textAbstract:
Current manufacturing research aims at increasing productivity by optimal selection of process parameters. This is accomplished by understanding the fundamental physics of individual manufacturing processes.
In this thesis, peripheral milling of very flexible cantilevered plates is studied. The static and dynamic deflections of the plate under periodic milling forces are modelled. A new dynamic cutting force model is developed which considers five discrete zones of relative motion between the tool and the workpiece. The kinematics of both milling and vibratory motions are modelled, which is an original research contribution in this area. It is shown that the penetration of the tool into the workpiece during vibratory cutting has a strong influence on the damping and stiffness characteristics of the milling process.
A structural model of a discontinuous cantilevered plate is determined using the finite element method. A reduced order structural model at the tool-workpiece contact zone is implemented for discrete time response analysis of the plate under cutting force excitations during milling. The closed loop dynamic behaviour of the system is modelled and taken into account in the analysis. Simulations of plate machining are compared with experimental results. A model of the surface finish generation mechanism is deduced from the analysis and experimental results.
Applications of this research include peripheral milling of integral jet engine impellers, computer disk drives and other flexible mechanical components.Applied Science, Faculty of
Mechanical Engineering, Department of
Graduate
8
張啓軍 and Qijun Zhang. "The Galerkin Element Method and power flow in acoustic-structural problems with damped sandwich plates." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31239742.
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Nugroho, Widijanto Satyo. "Waves generated by a load moving on an ice sheet over water." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ32720.pdf.
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10
Yu, Wenbin. "Variational asymptotic modeling of composite dimensionally reducible structures." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/12225.
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11
Skeen, Michael Berling Mechanical & Manufacturing Engineering Faculty of Engineering UNSW. "An investigation of energy flow through coupled plate structures." Publisher:University of New South Wales. Mechanical & Manufacturing Engineering, 2008. http://handle.unsw.edu.au/1959.4/43277.
Full textAbstract:
This PhD thesis presents research aims to improving the dynamic modelling of coupled plate structures across a wide frequency range by using analytical, statistical and experimental methods. The analytical waveguide method is used to model the flexural displacement of coupled plate structures which are simply supported along two parallel edges. A method of quickly predicting the average energy level in a plate from details of the waveguide model is described, and used for comparison with SEA models. The Poynting and Impedance methods of predicting the energy flow in coupled plate structures are investigated. Transmission coefficients for coupled plate structures are evaluated using the analytical waveguide method for both semi-infinite and finite coupled plate structures. Finite transmission coefficients have traditionally been more difficult to evaluate due to the presence of a reverberant field, but in this work a novel method of separating the reverberant field using a scattering matrix method is presented. The transmission coefficients for semi-infinite and finite structures are then compared for L-shaped plates. A modal transmission coefficient is also defined and for the cases considered, and is used to develop an alternative method of deriving the transmission coefficient in a finite structure. Frequency averaged transmission coefficients are also considered, and the transmission coefficients derived for finite and semi-infinite structures are found to be very similar after frequency averaging. Statistical Energy Analysis models of coupled plates are evaluated using transmission coefficients derived from waveguide models. The results of the SEA models are compared to those predicted by the analytical waveguide method. A modal transmission coefficient based SEA model is also investigated. In an attempt to validate the numerical work presented in this thesis, experiments have been conducted. Using a wave extraction technique, both the wave amplitudes and plate properties have been evaluated from experimental data, and are subsequently used to experimentally measure the transmission coefficient for two plates coupled at different angles.
12
Sen, Sharma Pradeep Kumar. "Stress reduction in a plate with a hole by applied induced strains." Diss., Virginia Tech, 1993. http://hdl.handle.net/10919/27975.
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13
Liu, Xing Lu. "Some problems and analysis for thermal bending plates." Thesis, University of Macau, 2010. http://umaclib3.umac.mo/record=b2148242.
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14
Chandrashekhara, K. "Geometric and material nonlinear analysis of laminated composite plates and shells." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54739.
Full textAbstract:
An inelastic material model for laminated composite plates and shells is formulated and incorporated into a finite element model that accounts for both geometric nonlinearity and transverse shear stresses. The elasto-plastic material behavior is incorporated using the flow theory of plasticity. In particular, the modified version of Hill's initial yield criterion is used in which anisotropic parameters of plasticity are introduced with isotropic strain hardening. The shear deformation is accounted for using an extension of the Sanders shell theory and the geometric nonlinearity is considered in the sense of the von Karman strains. A doubly curved isoparametric rectangular element is used to model the shell equations. The layered element approach is adopted for the treatment of plastic behavior through the thickness. A wide range of numerical examples is presented for both static and dynamic analysis to demonstrate the validity and efficiency of the present approach. The results for combined nonlinearity are also presented. The results for isotropic results are in good agreement with those available in the literature. The variety of results presented here based on realistic material properties of more commonly used advanced laminated composite plates and shells should serve as references for future investigations.Ph. D.
15
SUBRAMANIAN, BALAKRISHNAN. "GEOMETRICALLY NONLINEAR ANALYSIS OF THIN ARBITRARY SHELLS USING DISCRETE-KIRCHHOFF CURVED TRIANGULAR ELEMENTS (FINITE)." Diss., The University of Arizona, 1985. http://hdl.handle.net/10150/188101.
Full textAbstract:
The research work presented here deals with the problems of geometrically nonlinear analysis of thin shell structures. The specific objective was to develop geometrically nonlinear formulations, using Discrete-Kirchhoff Curved Triangular (DKCT) thin shell elements. The DKCT elements, formulated in the natural curvilinear coordinates, based on arbitrary deep shell theory and representing explicit rigid body modes, were successfully applied to linear elastic analysis of composite shells in an earlier research work. A detailed discussion on the developments of classical linear and nonlinear shell theories and the Finite Element applications to linear and nonlinear analysis of shells has been presented. The difficulties of developing converging shell elements due to Kirchhoff's hypothesis have been discussed. The importance of formulating shell elements based on deep shell theory has also been pointed out. The development of shell elements based on Discrete-Kirchhoff's theory has been discussed. The development of a simple 3-noded curved triangular thin shell element with 27 degrees-of-freedom in the tangent and normal displacements and their first-order derivatives, formulated in the natural curvilinear coordinates and based on arbitrary deep shell theory, has been described. This DKCT element has been used to develop geometrically nonlinear formulation for the nonlinear analysis of thin shells. A detailed derivation of the geometrically nonlinear (GNL) formulation, using the DKCT element based on the Total Lagrangian approach and the principles of virtual work has been presented. The techniques of solving the nonlinear equilibrium equations, using the incremental methods has been described. This includes the derivation of the Tangent Stiffness matrix. Various Newton-Raphson solution algorithms and the associated convergence criteria have been discussed in detail. Difficulties of tracing the post buckling behavior using these algorithms and hence the necessity of using alternative techniques have been mentioned. A detailed numerical evaluation of the GNL formulation has been carried out by solving a number of standard problems in the linear buckling and GNL analysis. The results compare well with the standard solutions in linear buckling cases and are in general satisfactory for the GNL analysis in the region of large displacements and small rotations. It is concluded that this simple and economical element will be an ideal choice for the expensive nonlinear analysis of shells. However, it is suggested that the element formulation should include large rotations for the element to perform accurately in the region of large rotations.
16
Reddy, Yeruva S. "Numerical simulation of damage and progressive failures in composite laminates using the layerwise plate theory." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/38534.
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17
Stephens, Max Taylor. "Numerical and Experimental Analysis of Composite Sandwich Links for the LCF System." PDXScholar, 2011. https://pdxscholar.library.pdx.edu/open_access_etds/579.
Full textAbstract:
Shear links are used as fuse elements in lateral load resisting systems to provide ductility and dissipate seismic energy. These links have traditionally been employed in eccentrically braced frames, but have more recently been suggested for use in the innovative linked column frame system (LCF). Current design specifications for shear links require intermediate web stiffeners to provide out-of-plane web stability so ductility requirements can be achieved. This research focused on moving from discrete transverse web stiffening to continuously stiffened webs in built up shear links. Built up links were designed to yield in shear when subjected to severe cyclic loading, however the webs of the links were designed using two metal sheets joined by an elastic core. These composite "sandwich" webs allowed for an increase in web thickness (and inherent flexural rigidity) without increasing the shear strength of the links. Numerical and experimental investigations were conducted to assess the performance of composite sandwich links subjected to severe loading. Numerical results showed improved web behavior in sandwich links in which the core material was assigned an elastic modulus greater than 5000psi. Due to fabrication limitations, experimental specimens were fabricated with a core material elastic modulus of 1000psi. These specimens did not perform as well as unstiffened base case links in terms global hysteretic behavior or ductility.
18
Young, Andrew J. "Active control of vibration in stiffened structures." Thesis, 1995. http://hdl.handle.net/2440/37722.
Full textAbstract:
Active control of vibration in structures has been investigated by an increasing number of
researchers in recent years. There has been a great deal of theoretical work and some
experiment examining the use of point forces for vibration control, and more recently, the use
of thin piezoelectric crystals laminated to the surfaces of structures. However, control by
point forces is impractical, requiring large reaction masses, and the forces generated by
laminated piezoelectric crystals are not sufficient to control vibration in large and heavy
structures.
The control of flexural vibrations in stiffened structures using piezoceramic stack actuators
placed between stiffener flanges and the structure is examined theoretically and
experimentally in this thesis. Used in this way, piezoceramic actuators are capable of
developing much higher forces than laminated piezoelectric crystals, and no reaction mass is
required. This thesis aims to show the feasibility of active vibration control using
piezoceramic actuators and angle stiffeners in a variety of fundamental structures.
The work is divided into three parts. In the first, the simple case of a single actuator used to
control vibration in a beam is examined. In the second, vibration in stiffened plates is
controlled using multiple actuators, and in the third, the control of vibration in a ring-stiffened
cylinder is investigated.
In each section, the classical equations of motion are used to develop theoretical models
describing the vibration of the structures with and without active vibration control. The
effects of the angle stiffener(s) are included in the analysis. The models are used to establish
the quantitative effects of variation in frequency, the location of control source(s) and the
location of the error sensor(s) on the achievable attenuation and the control forces required
for optimal control. Comparison is also made between the results for the cases with multiple
control sources driven by the same signal and with multiple independently driven control
sources. Both finite and semi-finite structures are examined to enable comparison between
the results for travelling waves and standing waves in each of the three structure types.
This thesis attempts to provide physical explanations for all the observed variations in
achievable attenuation and control force(s) with varied frequency, control source location and
error sensor location. The analysis of the simpler cases aids in interpreting the results for the
more complicated cases.
Experimental results are given to demonstrate the accuracy of the theoretical models in each
section. Trials are performed on a stiffened beam with a single control source and a single
error sensor, a stiffened plate with three control sources and a line of error sensors and a ring-stiffened
cylinder with six control sources and a ring of error sensors. The experimental
results are compared with theory for each structure for the two cases with and without active
vibration control.Thesis (Ph.D.) -- University of Adelaide, Dept. of Mechanical Engineering, 1995.
19
Nahan, Matthew F. "A nonlocal damage theory for laminated plate with application to aircraft damage tolerance." Thesis, 1997. http://hdl.handle.net/1957/34015.
Full textAbstract:
Design of commercial aircraft structure, composed of composite material, requires the
prediction of failure loads given large scale damage. In particular, a fuselage of
graphite/epoxy lamination was analyzed for damage tolerance given a standard large
crack that severed both skin and internal structure. Upon loading, a zone of damage is
known to develop in front of a crack-tip in composite laminates; and, its material
behavior within the damage zone is characterized as strain softening. This investigation
sought to develop a computational model that simulates progressive damage growth and
predicts failure of complex laminated shell structures subject to combined tensile and
flexural load conditions. This was accomplished by assuming a macroscopic definition
of orthotropic damage that is allowed to vary linearly through the shell thickness. It was
further proposed that nonlocal plate strain and curvature act to force damage growth
according to a set of uniaxial criteria. Damage induced strain softening is exhibited by
degradation of laminate stiffness. An expression for the damage reduced laminated
plate stiffness was derived which assumed the familiar laminated plate [AM] stiffness
matrix format. The model was implemented in a finite element shell program for
simulation of fracture and evaluation of damage tolerance. Laminates were characterized
for damage resistance according to material parameters defining nonlocal strain and
the damage growth criteria. These parameters were selected using an inverse method to
correlate simulation with uniaxial strength and fracture test results. A novel combined
tension-plus-flexure fracture test was developed to facilitate this effort. Analysis was
performed on a section of pressurized composite fuselage containing a large crack.
Good agreement was found between calculations and test results.Graduation date: 1998
20
Tso, Y. (Yan). "A study of the transmission of vibration in structures characteristic of naval ships / Yan Tso." 1996. http://hdl.handle.net/2440/18755.
Full textAbstract:
Bibliography: leaves 159-169.xii, 170 leaves : ill. (some col.) ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
This thesis is concerned with the transmission and distribution of vibratory power in built-up structures, and in particular, structures characteristic of naval ships. The study consists of a detailed investigation of the wave transmission properties of structural junctions, followed by an analysis of the wave propagation through plates with periodic stiffeners. The results are used to develop Statistical Energy Analysis (SEA) models for the prediction of vibration levels in structures characteristic of naval ships.
Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 1996
21
Tso, Y. (Yan). "A study of the transmission of vibration in structures characteristic of naval ships / Yan Tso." Thesis, 1996. http://hdl.handle.net/2440/18755.
Full textAbstract:
Bibliography: leaves 159-169.xii, 170 leaves : ill. (some col.) ; 30 cm.
This thesis is concerned with the transmission and distribution of vibratory power in built-up structures, and in particular, structures characteristic of naval ships. The study consists of a detailed investigation of the wave transmission properties of structural junctions, followed by an analysis of the wave propagation through plates with periodic stiffeners. The results are used to develop Statistical Energy Analysis (SEA) models for the prediction of vibration levels in structures characteristic of naval ships.
Thesis (Ph.D.)--University of Adelaide, Dept. of Mechanical Engineering, 1996
22
Wu, Y. F. (Yu-Fei). "Seismic retrofitting of rectangular reinforced concrete columns with partial interaction plating." 2002. http://web4.library.adelaide.edu.au/theses/09PH/09phw9591.pdf.
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23
Wu, Y. F. (Yu-Fei). "Seismic retrofitting of rectangular reinforced concrete columns with partial interaction plating / by Yu-Fei Wu." Thesis, 2002. http://hdl.handle.net/2440/21836.
Full textAbstract:
"June 2002"Includes bibliographical references (leaves 349-374)
xxxix, 416 leaves : ill., plates ; 30 cm.
Thesis (Ph.D.)--University of Adelaide, Dept. of Civil and Environmental Engineering, 2002