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1
Жигилій, Дмитро Олексійович, Дмитрий Алексеевич Жигилий, Dmytro Oleksiiovych Zhyhylii, Володимир Андрійович Хворост, Владимир Андреевич Хворост, and Volodymyr Andriiovych Khvorost. "Laminated composite plates." Thesis, Видавництво СумДУ, 2004. http://essuir.sumdu.edu.ua/handle/123456789/22944.
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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
Lazarus, Kenneth B. "Induced strain actuation of composite plates." Thesis, Massachusetts Institute of Technology, 1989. http://hdl.handle.net/1721.1/41235.
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Souza, Carlos Eduardo de. "Nonlinear aeroelasticity of composite flat plates." Instituto Tecnológico de Aeronáutica, 2012. http://www.bd.bibl.ita.br/tde_busca/arquivo.php?codArquivo=2243.
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This work presents a study on aeroelastic analyses of composite laminated flat plates subject to large displacements through the coupling of a nonlinear corotational shell finite element (FE) with an unsteady vortex-lattice method (UVLM) formulation. A FE implemented for the analysis of flat plates has been extended to model laminated composites with different lamina orientations. An UVLM formulation that is capable of coupling with this large displacement structural model is implemented. An explicit partitioned method is evaluated for the coupling of both models, using spline functions to interpolate information from the structural operator to the aerodynamic one, inside a Generalized-? time-marching solution. The resulting aeroelastic formulation provides a framework able of performing time marching simulation of structures made of composite material allowing the characterization of their nonlinear behavior and of the limit-cycle oscillation response. Laminated flat plates designed for high flexibility and low flutter speed onset are used as investigation models. To support the numerical studies, test specimens made of carbon fiber were used in experimental modal analysis and wind tunnel aeroelastic tests. Effects of nonlinearities are easily observed in the numerical results, which are promising for expansion of the work and application to the analysis of more refined and complex composite flexible wings.
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Simelane, Philemon Sphiwe. "Thermal buckling of laminated composite plates." Thesis, Peninsula Technikon, 1998. http://hdl.handle.net/20.500.11838/1240.
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Thesis (MTech (Mechanical Engineering))--Peninsula Technikon, 1998<br>However, studies were also conducted for the buckling of composite laminates
involving temperature distribution. Chen and Chen (1991) studied thermal buckling
of laminated plates under uniform and nonuniform temperature distribution using the
eight-node Serendipity finite element. Mathew, Singh and Rao (1992) investigated
thermal buckling of antisymmetric cross-ply composite laminates with a onedimensional
furite element having two nodes and six degrees of freedom.
Chandrashekhara (1992) accounted for transverse shear flexibility by using the
thermo-elastic version of the first-order shear deformation theory. This will also be
the case in this report. Literature on buckling and laminated composites abounds.
Brush and Aimroth (1975) published a book on Buckling of Bars, Plates, and Shells,
while Bushnell (1985) surveyed the Methods and Modes of Behaviour in Static
Collapse. The foundation for the study of composite materials was based on the
references [8], [10], [15] and [18]. The use of the Finite Element Method to analyse
the buckling behaviour of laminated structures comes from references [I], [4]. [I2].
[16], [24] and [32]. Reference [14] provided the basis for the formulation of the
variation of the governing equations. Most of the ideas in this report are based on
these publications and references.
Chapter I of this report introduces the concept of a composite. the formation of a
composite and a brief overview of the elements of a composite material. This chapter
also presents the concept of buckling that will form the basis of the development of
this project. At the end of this chapter the choice of the element that is used in this
study is justified. Chapter 2 provides the fundamentals of elasticity that relate to the
deformation of a loaded body. In this Chapter the stresses and strains are defined and
the temperature terms are introduced. In Chapter 3 the Mindlin plate theory is
presented with a view to laying the foundation for the analysis of laminated plates,
and as a starting point in the formulation of thermal buckling behaviour of laminated
plates. In Chapter 4 the elements of a composite material are discussed and the
constitutive equations of a laminated composite plate are built. Also the idea of
lamination is introduced and the various simplifications that can be introduced as a
result of lamination are discussed. The non-linear equilibrium equations and the
stability analysis of a composite plate are formulated in Chapter 5 using the
conventional anal}1ical method. The resulting equations justify the use of the Finite
Element Method as introduced in Chapter 6 and it is the method by which the
governing equations will be solved in ABAQUS computer analysis. The results for
various computer runs are presented for a normal plate, a plate with a square hole, and
the plate ""ith a circular cut-out in Chapter 7. Also in chapter 7 a comparison is made
between the laminate "ith a central hole and a normal plate to study the effect of a
cut-out on a critical buckling temperature. Appendices A deals the transverse shear in
plates, and Appendix B deals with the transformation of the laminate elastic constants
form the principal material direction to the general Cartesian co-ordinates. Also in
Appendix B the laminate stiffness matrices and these matrices are briefly evaluated
analytically. Appendix C is about the governing equations of laminated composites,
while Appendix D gives a full representation of the abbreviated finite element
equations of Chapter 6. Appendix E presents the list of ABAQUS input files that
were used in the computer simulation of Chapter 7.
6
Tiwari, Nachiketa. "Secondary Buckling of Laminated Composite Plates." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/37789.
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The postbuckling load carrying capacity of composite plates offers immense potential to their applications for loads exceeding their primary buckling load. However, such an efficient and economical usage of these plates can be reliable only if the nonlinear postbuckling behavior of these plates, which includes a good understanding of secondary buckling, is understood thoroughly. The present investigation is an attempt to understand secondary buckling of almost square composite clamped-simply supported plates, both unstiffened as well as stiffened, in some detail. With the help of the finite element method, a large number of numerical studies have been conducted to understand the secondary buckling characteristics. The sensitivity of these characteristics to variations in boundary conditions, lamination sequence, imperfections, and stiffener geometry has been considered. It has been found that the occurrence of secondary buckling in clamped-simply supported plates under uniform end shortening critically depends on the intensity of restrictions imposed on the inplane normal displacements along the unloaded simply supported edges of the plate. These restrictions could be due to the actual boundary conditions at these edges, or due to the presence of stiffeners along these edges. It has also been found that the presence of imperfections significantly delays the event of secondary buckling. Finally, it has been found that changes in lamination sequence of the plate alter its secondary buckling characteristics in ways that are, in general, quantitative in nature. The numerical investigations were followed by a limited number of experiments involving the testing of unstiffened as well as stiffened composite plates with the intent of augmenting the confidence in the numerical predictions made. Three different lamination sequences were considered during the testing phase of this investigation. It was found that the agreement between experimental data and numerical predictions was quite good. The occurrence of secondary buckling followed the predictions closely.<br>Ph. D.
7
Moorthy, Jayashree. "Dynamic instability of composite laminated plates." Thesis, Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/52090.
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Dynamic instability in a laminated composite plate is studied using the finite element technique. The governing equations are derived based on the first order shear deformation theory with a linear strain-displacement relationship. The regions of instability for the resulting set of coupled Mathieu equations are obtained using a method of simultaneous diagonalization. Boundary frequencies generated using a first subdeterminant approximation to the infinite determinant are compared with those obtained by using the more accurate second subdeterminant as well as with frequencies from an analytical solution. These values are verified by checking the nature of responses near the boundaries between stability and instability. Results are presented for plates with different laminations, boundary conditions, thicknesses, number of layers, etc. Some unstable regions for a damped plate are also shown. Results from the first order plate theory are compared with those from a higher order shear deformation theory.<br>Master of Science
8
Olsson, Robin. "Impact response and delamination of composite plates /." Stockholm, 1998. http://www.lib.kth.se/abs98/olss0528.pdf.
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Tippetts, Trevor 1977. "Modeling impact damage in laminated composite plates." Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/82782.
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Abdelnaser, Ahmad Shehadeh. "Random vibrations of composite beams and plates." Diss., Virginia Tech, 1992. http://hdl.handle.net/10919/37691.
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The response characteristics of beams and plates made from composite laminates are strongly affected by the shear deformations of their layers. However, incorporation of the shear deformation further complicates the equations of motion and their analysis. As a result the vibration analysis of such structures have been limited to simple free vibration studies such as determination of their frequencies. The forced vibration problems of these structures have been solved by exact methods for only some very simple cases. In this study, a generalized modal approach is presented to solve more general vibration problems of composite beams and plates. The coupled systems of partial differential equations, representing the equations of motion, are uncoupled into modal equations by utilizing the eigenfunctions of the system and its adjoint. A method is presented to obtain these eigenfunctions for beams with arbitrary boundary conditions and for plates with Levy-type boundary conditions. The forced vibration solutions obtained by this method are then used to calculate the random response characteristics of beams and plates subjected to spatially and temporally correlated random loads.
In the analysis of beams, both symmetric cross-ply and angle-ply configurations have been considered. In the symmetric cross-ply configuration with no torsional loads, of course, the warping effects are absent. The angle-ply case, however, includes torsion-warping effects and coupled bending-torsion motions. A simple displacement field is introduced to reflect warping in the third-order shear deformation theory. In the analysis of plates also two configurations of the laminates have been considered: symmetric cross-ply and antisymmetric angle-ply. At this time, these are the only two configurations which can be solved by the closed-form modal analysis approach for the Levy-type boundary conditions.
In both cases of the beams and plates, the numerical results with and without shear deformations are obtained and compared. The results for no shear deformation are obtained with the classical lamination theory. The results have also been obtained for the first-order shear deformation theory with a somewhat simpler displacement field which has been commonly used in the past by several investigators. The numerical results are obtained for the global response quantities such as frequencies, displacements and crossing rates as well as for the local response quantities such as normal and shear stresses across a cross section. The numerical results obtained with various deformation theories for the frequencies as well as response quantities are compared to evaluate the effect of the shear deformations. For thicker and rigid beams and plates, one observes large differences in the frequencies and responses obtained with (the first- and third-order shear deformation theories) and without consideration of shear deformations (classical theory). For the frequencies and global responses both the first- and third-order theories give about the same results. But for the local response quantities, the results obtained with the two shear deformation theories can also be quite different in some cases. In any case, the results clearly point out the importance of including the shear deformations in thick and rigidly constrained composite beams and plates.
Although, in this study only uniform cross section or uniform thickness beams and plates have been considered, it is felt that the eigenfunctions developed herein can also be conveniently utilized with advantage as comparison functions in approximate Rayleigh-Ritz type of approaches to analyze non uniform structures.<br>Ph. D.
11
Tang, Bruce S. "Lamb wave propagation in laminated composite plates." Diss., Virginia Polytechnic Institute and State University, 1988. http://hdl.handle.net/10919/80194.
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Low frequency Lamb waves in composite laminates were investigated theoretically and experimentally. To have a general solution for Lamb wave propagation in multilayered composite laminates is not practical due to a large number of boundary conditions needed to be satisfied at the interlaminar interfaces. Various approximate theories have been proposed to model low frequency Lamb wave propagation in composite laminates. In the present study, an approximate solution was derived from an elementary shear deformation plate theory and was shown to work well in the low frequency, long wavelength region.
A simple method, similar in configuration to the acousto-ultrasonic technique, was used to measure Lamb wave phase velocities. Low frequency Lamb waves, usually in the range of 10 kHz to 1 MHz, were generated. Dispersion curves of the lowest symmetric Lamb mode and the lowest antisymmetric Lamb mode were obtained. The experimental data were compared with the results obtained from the approximate solution for the lowest Lamb modes in the low frequency, long wavelength region for a unidirectional laminate, a symmetric cross-ply laminate, a symmetric quasi-isotropic laminate and an aluminum plate. There is good correlation between the data and the results obtained from the approximate solution, which suggests that the lowest Lamb modes are modeled adequately by the present theory in these cases. This experimental procedure of measuring phase velocities can be used to characterize laminated composite plates with and without damage since each material and stacking sequence gives distinct lowest symmetric and antisymmetric curves.
Stiffness reduction of composite laminates caused by damage can be related to the change in Lamb wave propagation speed. Damage in the form of transverse cracks in the 90° plies of a [90/90/90/0], graphite/epoxy laminate reduced the phase velocities of the Lamb modes. The lowest antisymmetric mode is sensitive to stiffness reduction in composite plates. Consequently, axial stiffness reduction in [0/45/0/45/0/45], and [0]₁₂ woven graphite/polyimide composite laminates was monitored by the lowest antisymmetric Lamb mode.<br>Ph. D.
12
Abdelnaser, Ahmad Shehadeh. "Random vibrations of composite beams and plates /." This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-05042006-164514/.
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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.
14
Kataoka, Filho Mário. "Optimization of nonhomogeneous facesheets in composite sandwich plates." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ27974.pdf.
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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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Huang, Haiying. "Single and multiple delamination behavior in composite plates." Diss., Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/12541.
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Madjidi, Saeid. "Low velocity impact of obliquely inclined composite plates." Thesis, University of the West of Scotland, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.535957.
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A study into the performance of CSM (Chopped Strand Mat) reinforced polyester laminates subject to low velocity impact at oblique angles is presented. The investigation encompasses both an experimental and theoretical assessment of the impact event, viz damage tolerance and residual material properties of flat, clamped composite plates. A short introduction is followed by a comprehensive review of the most relevant published literature on all aspects of impact induced damage. A theoretical analysis based on the use of damage toughness parameters is formulated to predict the residual tensile strength and stiffness properties of impact damaged plates. The analysis is further extended to determine the total internal stress distribution in the system. A combination of Hertzian contact, plate bending and finite element solution are used to establish the influence of plate inclination on the resulting stress state. Several common failure criteria were used to predict the extent of the damage. These predictions are compared with experimental data. Results from an extensive experimental programme are presented A fully instrumented test rig was used to assess the influence of imparted energy, impact force, and plate indentation with respect to surface indentation profiles, damage areas and micrographic evidence. The theoretical and experimental results are graphically presented, discussed in detail and exhibit good agreement. The study is finally concluded with comments summarising the most pertinent points derived from the present investigation together with recommendations for further work.
18
Chandiramani, Naresh K. "Dynamic stability of shear deformable viscoelastic composite plates." Thesis, Virginia Polytechnic Institute and State University, 1987. http://hdl.handle.net/10919/70917.
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Linear viscoelasticity theory is used to analyze the dynamic stability of composite, viscoelastic flat plates subjected to in-plane, biaxial edge loads. In deriving the associated governing equations, a hereditary constitutive law is assumed. In addition, having in view that composite-type structures exhibit weak rigidity in transverse shear, the associated governing equations account for the transverse shear deformations, as well as the transverse normal stress effect. The integro-differential equations governing the stability are solved for simply-supported boundary conditions by using the Laplace transform technique, thus yielding the characteristic equation of the system.
In order to predict the effective time-dependent properties of the orthotropic plate, an elastic behavior is assumed for tile fiber, whereas the matrix is considered as linearly viscoelastic.
In order to evaluate the nine independent properties of the orthotropic viscoelastic material in terms of its isotropic constituents, the micromechanical relations developed by Aboudi [24] are considered in conjunction with the correspondence principle for linear viscoelasticity. The stability behavior analyzed here concerns the determination of the critical in-plane normal edge loads yielding asymptotic stability of the plate. The problem is studied as an eigenvalue problem.
The general dynamic stability solutions are compared with their quasi-static counterparts. Comparisons of the various solutions obtained in the framework of the Third Order Transverse Shear Deformation Theory (TTSD) are made with its first order counterpart. Several special cases are considered and pertinent numerical results are compared with the very few ones available in the field literature.<br>Master of Science
19
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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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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Singhatanadgid, Pairod. "Buckling of composite plates subjected to biaxial loading /." Thesis, Connect to this title online; UW restricted, 2000. http://hdl.handle.net/1773/7067.
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An, Wei 1963. "Strengthening of concrete beams with composite plastic plates." Thesis, The University of Arizona, 1990. http://hdl.handle.net/10150/277246.
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This study investigates the feasibility of strengthening reinforced concrete beams with epoxy-bonded Glass-Fiber-Reinforced-Plastic (GFRP) plates. The composite plate is epoxy-bonded to the tension flange of the beam to increase its stiffness and strength. Seven rectangular and one T-beam, retrofitted with composite plates, were tested to failure under symmetrical 4-point bending. The load versus deflection and the load versus strain in the composite plate, steel rebar and the extreme compression fiber of concrete were measured and plotted for the midspan section throughout the entire range of loading up to failure. Analytical models based on the equilibrium of forces and compatibility of deformations were developed to predict the stresses and deformations of the beam in the linear and nonlinear regions. The predicted and measured results correlated well. The analytical models were used in a parametric study to investigate the effects of design variables such as, plate area, plate strength and stiffness, reinforcement ratio, etc., on the moment-curvature relationships of typical rectangular and T cross sections.
23
Awal, Mohammad A. 1959. "Transient response of delamination, intersecting and transverse cracks in layered composite plates." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/276955.
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A numerical method is developed to determine the dynamic behavior of delamination and transverse cracks in multilayered plates. The plate is subjected to a time dependent antiplane shear stress field which is acting on the plate surfaces. The interaction of waves diffracted at the crack tip with those reflected at the plate boundaries and transmitted at the material interface makes the problem very complicated, so analytical study of this problem cannot be carried out with our present state of knowledge; hence the problem is solved numerically. The finite element equations are obtained by variational calculus applied in the frequency domain. Thus time intregration schemes are avoided, but time dependent response can still be obtained after inverting the frequency dependent response spectra numerically by Fast Fourier Transform (FFT) routine. Another advantage of the frequency domain analysis is that the resonance frequency can be easily detected from the sharp peaks of the response spectra. The numerical difficulty associated with the singular behavior of the stress field near the crack tip has been avoided by using quarter point elements. The numerical results obtained from this investigation are compared with analytical results to verify the accuracy of the method.
24
Nayfeh, Jamal Faris. "Nonlinear dynamics of composite plates and other physical systems." Diss., This resource online, 1990. http://scholar.lib.vt.edu/theses/available/etd-07282008-135756/.
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Lee, Bok W. "Application of variational-asymptotical method to laminated composite plates." Diss., Georgia Institute of Technology, 1993. http://hdl.handle.net/1853/20695.
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Osman, Mahmoud Yassin. "Analysis of rectangular composite plates under static lateral loading." Thesis, Lancaster University, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305779.
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Nikoukar, Zanjani Farzad. "Strengthening of metallic structures using carbon fibre composite plates." Thesis, University of Southampton, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.404028.
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Saleh, Mohamed. "Electromechanical behaviour of three-dimensional (3D) woven composite plates." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/electromechanical-behaviour-of-threedimensional-3d-woven-composite-plates(cd06f8ef-88e0-45dd-be65-3911345212ba).html.
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Three dimensional (3D) woven composites have attracted the interest of academia and industry thanks to their damage tolerance characteristics and automated fabric manufacturing. Although much research has been conducted to investigate their out-of-plane "through thickness" properties, still their in-plane properties are not fully understood and rely on extensive experimentation. The aim of this work is to study the electromechanical behaviour of three different fibre architectures of 3D woven composites "orthogonal (ORT), layer-to-layer (LTL) and angle interlock (AI)" loaded, in three different orientations "warp (0º), weft (90º) and off-axis (45º)", in quasi-static tension. Stress/strain response is captured as well as damage initiation and evolution up to final failure. The ORT architecture demonstrated a superior behaviour, in the off-axis direction, demonstrated by high strain to failure (~23%) and high translaminar energy absorption (~40 MJ/m3). The z-binder yarns in ORT suppress delamination and allow larger fibre rotation during the fibre "scissoring motion" that enables further strain to be sustained. In-situ electrical resistance variation is monitored using a four-probe technique to correlate the resistance variation with the level of damage induced while loading. Monotonic and cyclic "load/unload" tests are performed to investigate the effect of piezo-resistivity and residual plasticity on resistance variation while damage is captured by X-ray scanning during interrupted tests at predefined load levels. In addition, this study investigates the potential of using 3D woven composites in joint assemblies through open-hole tension and "single fastener double-lap joint" bearing strength tests. 3D woven composites in the off-axis orientation, especially ORT, demonstrate a potential for overcoming some of the major challenges for composite joints' applications which are the pseudo-ductility, stress redistribution away from the notch and notch insensitivity. Finally, the study proposes a micro-mechanics based damage model to simulate the response of 3D orthogonal woven composites loaded in tension. The proposed model differs from classical damage mechanics approaches in which the evolution law is obtained by retrofitting global experimental observations.
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Sawicki, Adam John. "Damage tolerance of integrally stiffened composite plates and cylinders." Thesis, Massachusetts Institute of Technology, 1990. http://hdl.handle.net/1721.1/13615.
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Matsuhashi, Hiroto. "Nonlinear analysis of composite laminated plates subjected to impact." Thesis, Massachusetts Institute of Technology, 1992. http://hdl.handle.net/1721.1/42549.
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Ng, Chung Fai. "Dynamic behaviour of postbuckled composite plates under acoustic excitation." Thesis, University of Southampton, 1986. https://eprints.soton.ac.uk/52296/.
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Simple single-mode formulae are derived to present a general and straightforward understanding of the non-linear static and dynamic behaviour of postbuckled plates. The Rayleigh-Ritz method is used for multi-degrees-of-freedom analysis of postbuckled plates. A finite-element method using 16-nodes rectangular element is applied to postbuckling analysis of a composite plate with a central square hole. The magnitudes of multimodal linear response to random excitation are predicted using a simple formula based on results obtained by the Rayleigh-Ritz method and the trends of non-linear random responses are estimated using the single-mode formulae. Experimental techniques used include the Shadow Moire method to measure static displacement patterns, a point excitation test to find resonance frequencies and mode shapes, and acoustic testing to obtain random structural responses to sound pressure levels up to 163 dB. Experimental results were obtained for Aluminium alloy plates with two types of boundary conditions. These were compared with results from CFRP plates with similar types of boundary conditions. Finally, the acoustic response of a CFRP plate with a central square hole was examined. It was found that at high levels of acoustic exacitation, snap-through motion of amplitude larger than the oscillatory motion component can occur in the postbuckled plates and the overall r.m.s. strain value is comparable to the static strain value. In summary, the buckling of the plate changes the dominant deformations in the in-plane direction from those of in-plane effects to those of bending effects, whereas the large acoustic excitation changes the dominant dynamic deformations in the transverse direction from those of bending effects to those of in-plane effects.
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Majeed, Majed A. "Deformations of In-plane Loaded Unsymmetrically Laminated Composite Plates." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/26309.
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This study focuses on the response of flat unsymmetric laminates to an inplane compressive loading that for symmetric laminates are of sufficient magnitude to cause bifurcation buckling, postbuckling, and secondary buckling behavior. In particular, the purpose of this study is to investigate whether or not the concept of bifurcation buckling is applicable to unsymmetric laminates. Past work by other researchers has suggested that such a concept is applicable for certain boundary conditions. The study also has as an objective the determination of the response of flat unsymmetric laminates if bifurcation buckling does not occur. The finite-element program ABAQUS is used to obtain results, and a portion of the study is devoted to becoming familiar with the way ABAQUS handles such highly geometrically nonlinear problems, particularly for composite materials and particularly when instabilities and dynamic behavior are involved. Familiarity with the problem, in general, and with the use of ABAQUS, in particular, is partially gained by considering semi-infinite unsymmetrically laminated cross- and angle-ply plates, a one-dimensional problem that can be solve in closed form and with ABAQUS by making the appropriate approximations for the infinite geometry. In this portion of the study it is found that semi-infinite cross-ply laminates with clamped boundary conditions and semi-infinite angle-ply plates with simple-support boundary conditions remain flat under a compressive load until the load magnitude reaches a certain level, at which time the out-of-plane deflection become indeterminate, essentially an eigenvalue problem as encountered with classic bifurcation buckling analyses. Obviously, a linear analysis of such problems would not reveal this behavior and, in fact, there are other revealed significant differences between the predictions of linear and nonlinear analyses. Transversely-loaded and inplane-loaded finite isotropic plates are studied by way of semi-closed form Rayleigh-Ritz-based solutions and ABAQUS in a step to approaching the problem with unsymmetric laminates. A method to investigate the unloading behavior of postbuckled finite isotropic plates is developed that reveal multiple plate configurations in the postbuckled region of the response, and this method is then extended to the study of finite inplane-loaded unsymmetric laminates. To that end, two specific laminates, a symmetric and an unsymmetric cross-ply laminates, and a variety of boundary conditions are used to study the response of inplane-loaded unsymmetric laminates. The symmetric laminate is included to provide a familiar baseline case and a means of comparison. Plates with all four edges clamped and a variety of inplane boundary conditions are studied. Of course the symmetric cross-ply laminate exhibits bifurcation behavior, and when the tangential displacement on the loaded edges and the normal displacement on the unloaded edges are restrained, secondary buckling behavior occurs. For the unsymmetric cross-ply laminate, bifurcation buckling behavior does not occur unless the tangential displacement on the loaded edges and the normal displacement on the unloaded edges are restrained, or the tangential displacement on the loaded edges and the normal displacement on the unloaded edges are free. If either of these conditions are not satisfied, the unsymmetric cross-ply laminate exhibits what could be termed 'near-bifurcation' behavior. In all cases rather complex behavior occurs for high levels of inplane load, including asymmetric postbuckling and secondary buckling behavior. For clamped loaded edges and simply-supported unloaded edges, bifurcation buckling behavior does not occur unless the tangential displacement on the loaded edges and the normal displacement on the unloaded edges are restrained. For this case, rather unusual asymmetric bifurcation and associated limit point behavior occur, as well as secondary buckling. This is a very interesting boundary condition case and is studied further for other unsymmetric cross-ply laminates, including the use of a Rayleigh-Ritz-based solution in attempt to quantify the problem parameters responsible for the asymmetric response. The overall results of the study have led to an increased understanding of the role of laminate asymmetry and boundary conditions on the potential for bifurcation behavior, on the response of the laminate for loads beyond that level.<br>Ph. D.
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Gürdal, Zafer. "Automated design of composite plates for improved damage tolerance." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/52291.
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An automated procedure for designing minimum-weight composite plates subject to a local damage constraint under tensile and compressive loadings has been developed. A strain based criterion was used to obtain fracture toughness of cracked plates under tension. Results of an experimental investigation of the effects of simulated through-the-thickness cracks on the buckling, postbuckling, and failure characteristics of composite flat plates are presented. A model for kinking failure of fibers at the crack tip was developed - for compression loadings. A finite element program based on linear elastic fracture mechanics for calculating stress intensity factor (SIF) was incorporated in the design cycle. A general purpose mathematical optimization algorithm was used for the weight minimization. Analytical sensitivity derivatives of the SIF, obtained by employing the adjoint variable technique, were used to enhance the computational efficiency of the procedure. Design results for both unstiffened and stiffened plates are presented.<br>Ph. D.
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Meyers, Carol Ann. "Thermal buckling and postbuckling of symmetrically laminated composite plates." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/42238.
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This paper discusses an investigation into thermal buckling and post-buckling of symmetrically laminated composite plates. In this study, thermal buckling is investigated for laminates under two different simple support conditions, fixed and sliding. These laminates are subjected to the conditions of a uniform temperature change and a linearly varying temperature change along the length of the plate. Postbuckling in the presence of a uniform temperature change and nonlinear response to imperfections in the form of a thermal gradient through the thickness of the plate and a lack of initial flatness are also studied. The buckling response is studied using variational methods, specifically the Trefftz criterion. Postbuckling and responses to imperfections are studied using nonlinear equilibrium conditions. A Rayleigh-Ritz formulation is used to obtain numerical results from the formulations for the prebuckling response, the buckling response, and the post-buckling and imperfection responses. The analyses are applied to graphite-reinforced materials with (± 45/0₂)<sub>s</sub> and (± 45/0/90)<sub>s</sub> lamination sequences. Numerical results are obtained for these laminates and also for the case of these laminates being rotated 30° inplane. For the first laminate, for example, such a rotation results in a (+75/ — 15/30₂)<sub>s</sub>. stacking sequence. Such skewing of the principal material directions may be encountered when using fiber-reinforced materials in a structurally tailored design. In addition, the influence on thermal buckling of a lack of ideal boundary conditions in the form of boundary compliance and thermal expansion, which would occur in any real set-up, are investigated.<br>Master of Science
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Chern, Shue-Ming. "Analysis of notched composite plates under in-plane loading /." Thesis, Connect to this title online; UW restricted, 1999. http://hdl.handle.net/1773/7125.
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Allen, Aaron Andrew. "Stability results for damped multilayer composite beams and plates." [Ames, Iowa : Iowa State University], 2009.
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Kim, Young Soo. "Biaxial buckling of laminated composite plates." Thesis, 1995. http://spectrum.library.concordia.ca/2618/1/NN01284.pdf.
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"This research was motivated from a need to understand the buckling behaviour of laminated composites in structures such as aircraft fuselages and body-skin of automobiles or ships with various inplane loads and supporting mechanisms"
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CHEN, LAI-YI, and 陳來毅. "Thermal buckling of laminated composite plates." Thesis, 1988. http://ndltd.ncl.edu.tw/handle/27570781487886538908.
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Cheng, Shou-Hsiung, and 程守雄. "Buckling of Delaminated/Repaired Composite Plates." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/74147009836550695546.
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博士<br>國立中興大學<br>應用數學系<br>84<br>This dissertation presents four analytical modelsfor predicting
local buckling of delaminated composite plates,sandwichplates,
beam-plates with repairment fasteners, and laminated plates
withrepairment fasteners using continuous analysis.The
continuous analysis procedure can handle without difficulty
composite plates havingsingle and multiple through-the-width or
embedded delaminations of variousshapes and sizes at
anylocations.The method treats the discontinuous structure as a
body withoutdelamination but with a fictitious force system
added at a number of discrete points in thedelaminated region so
as to make the net interfacial tractions to vanish atthese
points. Hence, the procedure solves problems of delaminated
structuresdirectly as a continuous system.Results of the model
using such acontinuous analysis method should converge to
results of the original structurewhen the number of discrete
points taken in the delaminated region increases toa
sufficiently large number.A number of numerical
resultsaccounting for the effects of transverse normal
stiffnessesof the resin in the bond layer on the buckling load
of composite plates having delaminations of various shapes,
sizes, and at differentlocations are presented.A number of
numerical resultsaccounting for the effects of transverse normal
and shear stiffnessesof the core on the buckling load of
sandwich plates having delaminations of various shapes, sizes,
and at differentlocations are obtained.The illustrative examples
indicate that the present method is accurate and effective which
should be useful for practical applications.Based on the
continuous analysis mentioned above, a simple and
efficienttechnique for predicting the buckling load of the
delaminated plates repairedby fasteners is presented in this
dissertation.The effect of a fastener on the local
bucklingbehavior of the delaminated plates is modeled as axially
loaded elastic members which provide transversely inward
concentrated restraining forces on the upper and lowerparts of
the delaminated platesat the fastener positions.The method
presented in the study is straightforward,simple and accurate
for determining the buckling load of delaminated plates
withrepairing fasteners. For illustrative purposes, some
numerical examples accountingfor the effect of number and
locations offastener on the local buckling of delaminated
double-plates are presented.
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Chan, Ming-Shu, and 詹明樹. "Buckling of Circularly Delaminated Composite Plates." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/92535304818123948256.
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碩士<br>國立雲林科技大學<br>機械工程系碩士班<br>91<br>Due to their high strength, high modulus, and lightweight, composite materials are widely used in the engineering field. When compressive force is applied to delaminated composite plates, buckling may occur.
Delamination of composite materials often occurs due to laminated structure, manufacturing defects, or low-speed external impact. The buckling behavior of laminated plates with circular delamination under uniaxial compressive loading is studied here. Finite element methods are used to evaluate the buckling load and to determine the corresponding buckling modes.
In this study, the delaminated plate is modeled as a three dimensional problem. Three parameters, including radius of the delaminated region, the cross-sectional depth of the delaminated region, and plate width, are varied to evaluate the buckling load and the corresponding buckling modes. Uniform mesh refinement around the edge of the delaminated region is enforced to ascertain the singularity.
The results indicate that buckling loads decrease as the radius of delamination increases, and buckling modes change from a global type to a mixed type, then to a local type. The closer the position of the delamination to the plate surface, the more easily the plates buckle, and similarly, mixed and local buckling modes are easier to occur. Further, buckling loads increase slightly as plate width increases.
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劉孝偉. "Viscoelastic Analysis for Composite Sandwich Plates." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/76063187154569770502.
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碩士<br>國立中正大學<br>機械系<br>91<br>Owing to the advantage of the characteristics of low weight, high mechanical strength, high corrosion resistance, low heat conduction, high fatigue life endurance, many materials have been combined to form composite materials previously. The structure of composite sandwich plates is one kind of the most common composite material.
From the references, it is known that most of the researches do not consider the existence and viscoelasticity of adhesive layers in sandwich plates. Being on the premise that the adhesive layers have property of viscoelasticity, the objective of our research is to analysis the viscoelastic behavior of adhesive layers for a sandwich plate with five layers (including two layers of facing sheet, two layers of adhesive and one layer of core) in order to find the true theoretical deformation value of sandwich plate under loading. After getting numerical solution and trying to compare it with analytical solution, the validity of the analytical solution is then been proved.
When considering the adhesive layers to be viscoelastic, the sandwich plate will be effected and crept with time. The result of our research is expected to become one principle for designing and analyzing sandwich structure. The viscoelasticity of adhesive layers must be involved into the consideration of sandwich structure analysis. The result of this study could be one of the design criterions for advanced composite materials in the future.
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Lin, Geeng-Huei, and 林耿輝. "Vibration Analysis of Patched Composite Plates." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/26093547713799776822.
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Lin, Yuh-Hwa, and 林玉華. "Buckling of Rectanglly Delaminate Composite Plates." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/10338366537845717545.
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碩士<br>國立雲林科技大學<br>機械工程研究所<br>83<br>Due to laminated structure , manufacturing defects or external
impact , composite materials often contain delaminations . The
buckling behavior of laminated plates with rectangle delamination
under uniaxial compressive loading is studied here . Finite
element methods are used to evaluate the buckling load , and to
find out the corresponding buckling modes . Materials considered
include short fiber composite materials and long fiber composite
materials. For short fiber composite materials , the delaminated
plate is modelled as a two dimensional problem by neglecting the
effect of width. Two parameters , the size and the position along
the thickness direction of the delaminated region , are varied
to assess their influence on the buckling behavior of the plates .
In order to overcome the singularity of the crack tip , the
singular element is used around the crack tip to catch precise
stress distribution . For the long fiber composite materials ,
is considered also the influence of angle-ply and cross-ply on
the buckling behavior . Three parameters , including the size of
the delaminated region , the position of the delaminated region
in the thickness direction ,and the orientation of the fiber
direction , are varied to evaluate the buckling load and the
corresponding buckling modes . Uniform mesh refinement around
the delaminated reigon edge is enforced to overcome the singul-
arity of the crack tip . Whatever short fiber composite materials
or long fiber composite materials , the results indicate that the
buckling loads decrease as the delamination size increases , and
the buckling modes change from a global type to a mixed type ,
then to a local type .If the position of the delamination is closer
to the plate surface , the plates more easily buckle . Besides ,
for the long fiber composite materials , the buckling loads
decrease as the orientation of the fiber direction increases ,
and the buckling modes do not change . The influence of plate
width on the buckling behavior is not evident .
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Kuo, Shih-Yao, and 郭仕堯. "Aerothermoelastic Analysis of Composite Sandwich Plates." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/uw8y3p.
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博士<br>國立成功大學<br>航空太空工程學系碩博士班<br>90<br>By considering the total transverse displacement of a sandwich plate be the sum of the displacement due to bending of the plate and that due to shear deformation of the core, a 72 degree-of-freedom high precision high order triangular plate element is developed for aerothermoelastic analysis of composite sandwich plates. The Von Karman large deflection assumptions and quasi-steady supersonic aerodynamic theory are used for the aerothermoelastic analysis of composite sandwich panel consisting of two laminated face sheets and an orthotropic honeycomb core. The scope of this thesis includes thermal buckling and thermal postbuckling of composite sandwich plates; free vibration, linear flutter, and nonlinear flutter of thermally buckled composite sandwich plates. The effects of plate geometry, fiber orientation, boundary conditions, material properties, stacking sequence, and temperature distribution are discussed in details. The thermal buckling analysis has been represented as the standard eigenvalue problem. Numerical results show that the buckling mode that sandwich plate will buckle into is dependent on the fiber orientation in the plate and aspect ratio of the plate. In the thermal postbuckling analysis of composite sandwich plates. The nonlinear system equation is solved by Newton-Raphson method. Numerical results show that the buckle pattern that sandwich plate with angle-ply laminates faces will change is dependent on the fiber orientation in the plate and aspect ratio of the plate. The path of cooling down process is different from that of heating up process. The buckle pattern change will occur at lower temperature during cooling down process while it will occur at higher temperature in the heating up process. In the free vibration analysis of thermally buckled composite sandwich plates, the total response of the plate is assumed to be the sum of displacement due to static deformation and that due to dynamic deformation. The nonlinear governing equations can be written into two sets of equations. The static deflection of the thermally buckled plate is first solved by Newton-Raphson method. Then, another set of linear equation may determine the dynamic behavior of the thermally buckled plate in frequency domain. By examining the buckling and free vibration modes of the plate, a clear picture of buckle pattern change and lowest vibration mode shift is presented. Numerical results show that the order of the vibration mode is a function of the temperature rise. The higher vibration mode with multiple waves may become the fundamental vibration mode. Due to this buckle pattern change, the stiffness of the plate is also suddenly changed that in turn makes the natural frequency of the plate jump. The higher vibration mode may become the fundamental vibration mode after buckle pattern change. The temperature gradient induces thermal moments and makes the plate stiffer. None of the natural frequencies will drop to zero as the temperature is increased and lowest vibration mode shift induced by buckle pattern change will occur slowly. In the flutter analysis of thermally buckled composite sandwich plates, Newton-Raphson method and Newmark method are used to solve the nonlinear problem in frequency and time domains, respectively. Static condensation and modal reduction are adopted for saving computing time. In general, the coalescence pair usually is between natural modes (1,1) and (2,1). For longer or thicker plates, the flutter mode shape is the combination of (n,1) and (n+1,1) flutter modes. Numerical results show that the elevated temperature may not only decrease flutter boundary in general, but also increase flutter boundary due to the buckling pattern suddenly changes in some special cases. The corrugated deflection pattern will offer additional geometrical nonlinear stiffness. The critical aerodynamic pressure of the buckled plate with high temperature rise may be higher than the one without thermal effect. The temperature gradient makes the plates deflect under the critical buckling temperature and stabilized the dynamic behavior of the thermally buckled composite sandwich plates significantly. All five types of panel behavior such as flat, buckled, limit-cycle, periodic, and chaotic motions can be identified successively. The nonlinear behavior of composite sandwich plates subjected to aerodynamic loading and aerodynamic heating is extensively explored and reasonably understood. This dissertation provides aerothermoelastic analysis of composite sandwich plate that is still lacking. It is the first study devoted to the complete aerothermoelastic analysis of advanced composite sandwich plate.
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Sahu, Praseed. "Buckling analysis of Laminated Composite plates." Thesis, 2014. http://ethesis.nitrkl.ac.in/5685/1/110ME0327-3.pdf.
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Laminated composites have been used in many engineering structures from early time the recent advancements in material technology has led to the creation of a new composite with enhanced properties. Composite materials are generally used in many fields of engineering like buildings, bridges, boat hulls, swimming pool panels, race car bodies, shower stalls, bathtubs and storage tanks. In addition to that industries where weight reduction is of prime concern (aviation and spacecraft etc.). Composites are capable enough to take different types of loading both tensile and compressive based on the requirement. It is well known that the structural elements under compressive loads and/or due to thin built up they may be prone to buckle. In order to evaluate the buckling strength of laminated structures many studies has already been completed numerically and experimentally. A lab scale buckling test rig has been developed to obtain the critical load. In addition to that a simulation study has been done in ANSYS using ANSYS parametric design language. Some new results have been obtained for different parameter and discussed in detail
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Vijayaraju, K. "Analysis Of Delaminations In Tapered And Stiffened Laminated Composite Plates." Thesis, 1999. https://etd.iisc.ac.in/handle/2005/1617.
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Vijayaraju, K. "Analysis Of Delaminations In Tapered And Stiffened Laminated Composite Plates." Thesis, 1999. http://etd.iisc.ernet.in/handle/2005/1617.
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Wu, Jiun-Shiuan, and 吳俊炫. "Structural Behavior of Composite Cover Plates with Steel Rims and Base Plates." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/97778945176690153606.
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碩士<br>國立中興大學<br>土木工程學系<br>93<br>Composite cover plates are extensively used to engineering field. Generally speaking, the composite cover plates are constructed by various material of reinforcement concrete. Normally, it will be mounted on steel rims at the exterior and steel deck on the bottom of the composite plate. However, it ignores the effect of steel rims and base plate. Moreover, the joint effect between steel rims or steel deck and the composite plate are controversial. To answer the above question, it is decided to develop an experimental study of a series of 9 pieces of full-scale of composite cover plates with various steel rims or steel deck.
The final observation was found that the strength and stiffness of steel rims will increase about 5% and base plate will enhance approximately 2%. On the other hand, steel rims may provide an additional function to protect the composite plate. It is found that if the jointing effects between steel rims/steel deck and concrete are poor, the improvement for strength and stiffness are restrained.
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Akhlaque-E-Rasul, Shaikh. "Compressive Response of Tapered Curved Composite Plates." Thesis, 2010. http://spectrum.library.concordia.ca/7515/1/Akhlaque_PhD_S2011.pdf.
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Tapered laminated structures have considerable potential for creating significant weight savings in engineering applications. In the present thesis, the ply failure and global buckling failure of internally-tapered curved laminates are considered. For the buckling analysis, four different analytical approaches are employed: (1) classical shell theories using Ritz method, (2) first-order shear deformation shell theories using Ritz method, (3) linear finite element analysis based on first-order shear deformation shell theories, and (4) non-linear finite element analysis. Due to the variety of tapered curved composite plates and the complexity of the analysis, no closed-form analytical solution is available at present regarding their response to compressive loading. Therefore, the Ritz method is used for the global buckling analysis considering uniaxial compressive load. Linear buckling analysis of the plates is carried out based on eight classical shell theories and six first-order shear deformation shell theories. To apply the first-order shear deformation shell theories, an appropriate set of shear correction factors has been determined. The buckling loads obtained using Ritz method are compared with the existing experimental and analytical results, and are also compared with the buckling loads obtained using finite element method. The strength characteristics and load carrying capability of the tapered curved plates are investigated considering the first-ply failure and delamination failure. The commercial software ANSYS® is used to analyze these failures. Based on the ply failure and buckling analyses, the critical sizes and parameters of the tapered curved plates that will not fail before global buckling are determined.
Linear buckling analysis is insufficient to take into account the effect of large deflections on the buckling loads. This effect can only be considered in the non-linear buckling analysis. However, very large number of load steps is required to determine the buckling load based on the non-linear analysis in which the stability limit load is calculated from the non-linear load-deflection curve. In the present thesis, a simplified methodology is developed to predict the stability limit load that requires the consideration of only two load steps. The stability limit loads calculated using the present simplified methodology are shown to have good agreement with that calculated from the conventional non-linear load-deflection curve.
Parametric studies are carried out using the above mentioned four different types of analytical methods. In these studies, the effects of boundary conditions, stacking sequence, taper configurations, radius, and geometric parameters of the plates are investigated.
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Fan, Jung-He, and 范忠和. "Nonlinear Bending Analysis of Piezoelectric Composite Plates." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/65475118427612330753.
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碩士<br>淡江大學<br>機械與機電工程學系碩士班<br>93<br>A simple high-order theory is presented to examine the nonlinear analysis of the piezoelectric composite plates subjected electric field or voltage with elastically restrained boundary conditions in this thesis. The simple high-order theory employs parabolic shear strain variation across the thickness, and requires no correction factors because it satisfies shear free surface boundary conditions. Generalized double Fourier series are used to constitute a set of nonlinear algebra equations which solution is obtained by numerical method.The influences of aspect ratio, material properties, thickness-to-length, angle of orientation, elastically restrained coefficients, electric field, and voltage are particularly discussed in this thesis. Some special cases are compared with those given in the literature and good agreement is obtained.The research results should serve as references for designer and analysis of piezoelectric composite plates.