Browsing by Author "Kam, TY"

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Determination of elastic constants of composite laminates using measured natural frequencies
(2000)
Wang, WT
;
Kam, TY
;
機械工程學系
;
Department of Mechanical Engineering
The identification of material elastic constants of laminated composite plates using measured natural frequencies is studied. The first three natural frequencies of the lower resonant modes of the laminated composite plates were extracted from the modal testing data of the plates. The finite element method is used to perform the modal analysis of the laminated composite plates. An error function is established to measure the differences between the experimentally and theoretically predicted natural frequencies of the laminated composite plates. The identification of the material elastic constants of the laminated composite plates is formulated as a constrained minimization problem in which the elastic constants are determined by making the error function a global minimum. Test results of a number of laminated composite plates are used to illustrate the feasibility and applications of the proposed method.
Elastic constants identification of shear deformable laminated composite plates
(2001-11-01)
Wang, WT
;
Kam, TY
;
機械工程學系
;
Department of Mechanical Engineering
A constrained minimization method is presented for the identification of elastic constants of shear deformable laminated composite plates. Strains and/or displacements obtained from static testing of laminated composite plates are used in the proposed method to identify the elastic constants of the plates. In the identification process, the trial elastic constants of a laminated composite plate are used in a finite-element analysis to predict the strains and displacements of the plate. An error function is established to measure the differences between the experimental and theoretical predictions of strains and/or displacements. A constrained minimization technique is used to minimize the error function and update the trial elastic constants. The best estimates of the elastic constants of the plate are then determined by subsequently reducing the size of the feasible region of the elastic constants and making the error function a global minimum. The accuracy and applications of the proposed method are demonstrated by means of a number of examples. A sensitivity analysis is also performed to study the effects of variations of experimental data on the accuracy of the identified elastic constants.
Evaluation of buckling and first-ply failure, probabilities of composite laminates
(1998-05-01)
Lin, SC
;
Kam, TY
;
Chu, KH
;
機械工程學系
;
Department of Mechanical Engineering
A procedure for failure probability evaluation of composite laminates subjected to in plane loads is proposed. The material properties, fiber angles and layer thicknesses of the laminates are treated as random variables in the reliability analysis. The statistics of first-ply failure loads and buckling strengths of the laminates are determined via the stochastic finite element method. The failure probabilities of the laminates which are susceptible to buckling and first-ply failure are computed using the statistics obtained in the stochastic finite element analysis. The feasibility and accuracy of the present approach are validated using the results obtained via the Monte-Carlo method. A number of examples of reliability analysis of composite laminates subject to in-plane loads are given to illustrate the applications of the procedure. (C) 1998 Elsevier Science Ltd.
Experimental and theoretical predictions of first-ply failure strength of laminated composite plates
(1999-06-01)
Kam, TY
;
Lai, FM
;
機械工程學系
;
Department of Mechanical Engineering
Experimental and theoretical methods are presented to study the first-ply failure strength of laminated composite plates under different loading conditions. An acoustic emission technique is used to measure the energy released in the plates during the failure process. The first-ply failure strength of the plates is then identified via the energy vs load diagrams which are constructed on the basis of the measured acoustic emissions. A finite element analysis, which is constructed on the basis of the layerwise linear displacement theory, and the Tsai-Wu failure criterion are used to predict the first-ply failure strength of the plates. The comparison between the experimental and theoretical results shows good agreement. (C) 1999 Elsevier Science Ltd. All rights reserved.
External failure pressure of a frangible laminated composite canister cover
(1999-12-01)
Kam, TY
;
Wu, JH
;
Wang, WT
;
機械工程學系
;
Department of Mechanical Engineering
The static failure strength of a frangible laminated composite canister cover subjected to uniform external pressure is studied via both theoretical and experimental approaches. The frangible canister cover, which is fabricated with four plate-like laminated composite parts, which is designed in such a way that it will fail in a predetermined pattern when subjected to an impulsive internal pressure and its external Failure pressure is much higher than its internal failure pressure. The stress distribution in the canister cover is determined using the finite element method and the failure of the cover identified on the basis of an appropriate failure criterion. A number of laminated composite canister covers were fabricated and subjected to static external pressure testing. The failure modes of the frangible covers are studied and the experimental results are used to verify the theoretical predictions. Close agreements between the experimental and theoretical results have been observed. The present study shows that the design of frangible covers with external failure pressure much higher than the internal failure pressure can be achieved. (C) 2000 Elsevier Science Ltd. All rights reserved.
Failure analysis of a frangible laminated composite canister cover
(1999)
Wu, JH
;
Wang, WT
;
Kam, TY
;
機械工程學系
;
Department of Mechanical Engineering
The static burst strength of a frangible laminated composite canister cover subjected to uniform pressure is studied via both theoretical and experimental approaches. The frangible canister cover, which is fabricated with four plate-like laminated composite parts, is designed to fail in a predetermined pattern. The stress distribution in the canister cover is determined using the finite element method and the failure of the cover is identified on the basis of a failure criterion. A number of laminated composite canister covers were fabricated and subjected to static burst pressure testing. The failure modes of the frangible covers are studied and the experimental results are used to verify the theoretical predictions. Close agreements between the experimental and theoretical results have been observed. The canister covers that had been tested did fail in accordance with the predetermined pattern.
Fatigue of cracked plates repaired with single-sided composite patches
(1998-04-01)
Kam, TY
;
Chu, KH
;
Tsai, YC
;
機械工程學系
;
Department of Mechanical Engineering
Fatigue of cracked plates repaired with single sided composite patches is studied via both analytical and experimental approaches. A finite element model, which considers out-of-plane bending effects induced by asymmetric repair, is presented to determine the crack tip opening displacements of the repaired plates subjected to in-plane loading. The modified crack closure technique is used to calculate the stress intensity factor of the repaired plates. Fatigue life of the repaired plates is studied via the use of Paris tan for crack propagation. The effects of cracked plate and composite patch thicknesses on the fatigue track propagation of repaired plates containing different types of cracks are investigated. Fatigue tests of aluminum C-T specimens repaired with single-sided composite patches are performed, and the test data are used to validate the analytical approach. It has been shown that the repair of a cracked plate with a single-sided composite patch may have beneficial or adverse effects on the fatigue life of the repaired plate depending on the thicknesses of the patch and the cracked plate.
Fatigue reliability evaluation for composite laminates via a direct numerical integration technique
(1998-05-01)
Kam, TY
;
Chu, KH
;
Tsai, SY
;
機械工程學系
;
Department of Mechanical Engineering
A direct numerical integration technique for evaluating Fatigue reliability of composite laminates under varying stress amplitudes is presented. A number of cumulative damage models are adopted to construct the limit state equation for the laminates in the reliability analysis. Existing fatigue life distributions of composite laminates under cyclic stresses of constant amplitude are used in the reliability assessment of the composite laminates under varying stress amplitudes. The accuracy of the proposed method in fatigue reliability prediction is then verified by experimental Fatigue life data of varying stress amplitudes. A comparison between the present method and the modified beta-method is also made to illustrate the suitability of the present method in fatigue reliability prediction. (C) 1998 Elsevier Science Ltd.
Finite element analysis of foam-filled laminated composite sandwich plates
(1998)
Kam, TY
;
Lai, FM
;
機械工程學系
;
Department of Mechanical Engineering
A multi-layer plate element formulated on the basis of the layerwise lineal displacement theory is presented. The finite element together with an appropriate failure criterion are applied to the determination of stress distribution in and initial failure strength of foam-filled laminated composite sandwich plates. The accuracy of the present finite element in predicting stresses is verified by the existing solutions. Experimental results are used to verify the accuracy of the proposed method in failure load prediction. The effect of number of layer groups used in the finite element analysis and the suitability of the adopted failure criterion on first-ply failure strength prediction are investigated. The superiority of the present finite element over the first-ol der shear deformable (FOST) finite element on first-ply failure strength prediction is demonstrated via a comparative study.
First-ply failure strength of laminated composite pressure vessels
(1997-05-01)
Kam, TY
;
Liu, YW
;
Lee, FT
;
機械工程學系
;
Department of Mechanical Engineering
Strengths of laminated composite pressure vessels are studied via both analytical and experimental approaches. Experimental techniques are presented to determine the first-ply failure and burst strengths of laminated composite pressure vessels with different lamination arrangements. Different analytical methods, together with various failure criteria, are used to predict the first-ply failure strengths of the laminated pressure vessels. The accuracy of the theoretical prediction of first-ply failure strength is verified by the test data. The suitability of the failure criteria, as well as the limitations of the analytical methods are discussed. (C) 1997 Elsevier Science Ltd.
Identification of material constants of composite laminates using measured strains
(2000-10-01)
Kam, TY
;
Lin, CH
;
Wang, WT
;
機械工程學系
;
Department of Mechanical Engineering
A method for nondestructive evaluation of material constants of composite laminates is presented. An error function is established to measure the differences between the theoretically and experimentally predicted strains. The identification of the the material constants is formulated as a constrained minimization problem in which the material constants are determined to make the error function a global minimum. A global minimization method, together with an appropriate bounding technique for constraining the variations of the material constants, are used to solve the above minimization problem. The applications of the proposed method are demonstrated by means of several examples on the material constants identification of laminated composite cylindrical pressure vessels. [S0094-4289(00)02704-3].
Impact analysis of shear deformable laminated composite plates
(1995-09-01)
Kam, TY
;
Chang, WJ
;
機械工程學系
;
Department of Mechanical Engineering
A method for investigating the dynamic response of shear deformable laminated composite plates subject to low-speed impact is presented. The equations of motion of the impactor and the plate are derived via a virtual work approach. The contact force between the impactor and the plate is calculated by using an experimentally established contact law. The effects of existing in-plane forces, plate aspect ratio, length-to-thickness ratio, fiber angles, and number of layer groups on the contact force with or without the consideration of ply failure are studied. Optimal fiber angles and number of layer groups for angle-ply plates with maximum first-ply failure impact velocity are determined based on the maximum stress criterion.
Impact analysis of shear deformable laminated composite plates
(1995-09-01)
Kam, TY
;
Chang, WJ
;
交大名義發表
;
機械工程學系
;
National Chiao Tung University
A method for investigating the dynamic response of shear deformable laminated composite plates subject to low-speed impact is presented. The equations of motion of the impactor and the plate are derived via a virtual work approach. The contact force between the impactor and the plate is calculated by using an experimentally established contact law. The effects of existing in-plane forces, plate aspect ratio, length-to-thickness ratio, fiber angles, and number of layer groups on the contact force with or without the consideration of ply failure are studied. Optimal fiber angles and number of layer groups for angle-ply plates with maximum first-ply failure impact velocity are determined based on the maximum stress criterion.
Material characterization of flexibly supported shear deformable laminated composite plates
(2006)
Lee, CR
;
Kam, TY
;
機械工程學系
;
Department of Mechanical Engineering
This paper presents a method for nondestructively evaluating the system parameters of elastically restrained shear deformable laminated composite plates using measured natural frequencies. The proposed method is established on the basis of a multi-start global minimization method in which an objective function measuring the differences between the predicted and measured natural frequencies is constructed and a design variables normalization technique for expediting the convergence of the search of the solution is adopted. Vibration testing of several laminated composite plates with different boundary conditions was performed. Seven natural frequencies extracted from the vibration data of each of the plates were used in the proposed method to identify the system parameters of the plate. Excellent results have been obtained for the plates.
Material characterization off laminated composite plates via static testing
(2000-12-01)
Wang, WT
;
Kam, TY
;
機械工程學系
;
Department of Mechanical Engineering
A minimization method for material characterization of laminated composite plates using static test results is presented. Mechanical responses such as strains and displacements are measured from the static tests of the laminated composite plates. The finite element method is used to analyse the deformation of the laminated composite plates. An error function is established to measure the differences between the experimental and theoretical mechanical responses of the laminated composite plates. The identification of the material elastic constants of the laminated composite plates is formulated as a constrained minimization problem in which the elastic constants are determined by making the error function a global minimum. A number of examples are given to illustrate the feasibility and applications of the proposed method. (C) 2000 Elsevier Science Ltd. All rights reserved.
Minimum weight design of laminated composite plates subject to strength constraint
(1996-08-01)
Kam, TY
;
Lai, FM
;
Liao, SC
;
交大名義發表
;
機械工程學系
The minimum weight of laminated composite plates subject to strength and side constraints is studied via a constrained global optimization technique. The first-ply failure load that is treated as the strength of a laminated plate is determined by using a shear deformable finite element and one of the several commonly used phenomenological failure criteria. The optimal layer group parameters (fiber angles and thicknesses of layer groups) of the laminated composite plate are determined Via the proposed constrained global optimization technique for attaining the global minimum weight of the plate and satisfying the imposed constraints. A number of examples of the minimum weight design of symmetrically laminated composite plates with various aspect ratios, different number of layer groups, and different boundary conditions are given to illustrate the applications of the present constrained global optimal design method. The effects of the failure criteria on the optimal design parameters are also investigated via the examples. Finally, experimental investigation of the capability of the present method in obtaining global optima is performed. Failure tests of a number of graphite/epoxy laminates designed by different methods are performed, and the superiority of the present method over the other methods is demonstrated via the test results.
Minimum weight design of laminated composite plates subject to strength constraint
(1996-08-01)
Kam, TY
;
Lai, FM
;
Liao, SC
;
機械工程學系
;
Department of Mechanical Engineering
The minimum weight of laminated composite plates subject to strength and side constraints is studied via a constrained global optimization technique. The first-ply failure load that is treated as the strength of a laminated plate is determined by using a shear deformable finite element and one of the several commonly used phenomenological failure criteria. The optimal layer group parameters (fiber angles and thicknesses of layer groups) of the laminated composite plate are determined Via the proposed constrained global optimization technique for attaining the global minimum weight of the plate and satisfying the imposed constraints. A number of examples of the minimum weight design of symmetrically laminated composite plates with various aspect ratios, different number of layer groups, and different boundary conditions are given to illustrate the applications of the present constrained global optimal design method. The effects of the failure criteria on the optimal design parameters are also investigated via the examples. Finally, experimental investigation of the capability of the present method in obtaining global optima is performed. Failure tests of a number of graphite/epoxy laminates designed by different methods are performed, and the superiority of the present method over the other methods is demonstrated via the test results.
Mismatch analysis of TAB-on-Glass connection with ACF
(2000)
Hou, WF
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Kam, TY
;
Hsieh, A
;
Chen, JC
;
Chang, SM
Mismatch between outer lead bonds (OLBs) of a tape automated bonding (TAB) and a glass panel during fabrication is studied using the finite element method. A two-dimensional finite element model for the TAB-on Glass (TOG) connector is presented for determining the deformation of the connector. The deformation of the TOG connector induced by residual thermal stresses are determined via a two-stage approach. At the first stage, the TOG connector is under heat and pressure. The anisotropic conductive film (ACF) in-between the TAB and glass panel is assumed to be in a melting condition so that both TAB and glass panel can expand freely. At the second stage, the connector is cooled down to room temperature and the ACF becomes solidified. The deformations of the connector at the two stages are determined in the finite element analysis in which the temperature dependence of material properties is considered. Effects of particular parameters on the mismatch between the OLBs are studied by means of a number of numerical examples. A method for compensation design of the lead locations of the OLBs is proposed. It has been shown that the compensation design can produce results that will avoid the occurrence of unwanted mismatch.
Optimum design of laminated composite foam-filled sandwich plates subjected to strength constraint
(1999-07-01)
Kam, TY
;
Lai, FM
;
Chao, TM
;
機械工程學系
;
Department of Mechanical Engineering
Optimum design of laminated composite sandwich plates with both continuous (core thickness) and discrete (layer group fiber angles and thicknesses) design variables subjected to strength constraint is studied via a two-level optimization technique. The strength of a sandwich plate is determined in a failure analysis using the Tsai-Wu failure criterion and the finite element method which is formulated on the basis of the layerwise linear displacement theory. In the first level optimization of the design process, the discrete design variables are temporarily treated as continuous variables and the corresponding minimum weight of the sandwich plate is evaluated subject to the strength constraint using a constrained multi-start global optimization method. In the second level optimization, the optimal solution obtained in the first level optimization is used in the branch and bound method for solving a discrete optimization problem to determine the optimal design parameters and the final weight of the plate. Failure test of laminated composite foam-filled sandwich plates with different lamination arrangements are performed to validate the proposed optimal design method. A number of examples of the design of laminated composite foam-filled sandwich plates are given to demonstrate the feasibility and applications of the proposed method. (C) 1999 Elsevier Science Ltd. All rights reserved.
Predictions of deflection and first-ply failure load of thin laminated composite plates via the finite element approach
(1996-01-01)
Kam, TY
;
Sher, HF
;
Chao, TN
;
Chang, RR
;
機械工程學系
A nonlinear finite element method, which is based on the von Karman-Mindlin plate theory and the principle of minimum total potential energy, is used to study the deformation and first-ply failure of thin laminated composite plates. The load-displacement curves of a number of laminated composite plates are determined using the proposed finite element method. Stresses obtained from the linear and nonlinear finite element analyses are used to determine, respectively, the linear and nonlinear first-ply failure loads of the the laminated plates based on several phenomenological failure criteria. The accuracy of the finite element results is then verified by comparison with the available experimental data. It has been found that good agreement between the finite element and experimental load-strain curves before first-ply failure is observed. If the reduction in plate stiffness induced by failure of plies is taken into account in the finite element model, close agreement between finite element and experimental load-displacement curves from first-ply failure up to total failure may be obtained. Regarding the prediction of the first-ply failure load, it has been found that some of the phenomenological failure criteria may yield results of consistent accuracy for the laminated composite plates under consideration. Nevertheless, accurate prediction of the failure process after first-ply failure is still intractable. Hence, for reliability assurance further research on failure analysis of laminated composite plates subject to transverse loading is needed.