Browsing by Author "Chu, KH"

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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.
Fatigue of cracked plates repaired with single-sided composite patches
(1998-04-01)
Kam, TY
;
Chu, KH
;
Tsai, YC
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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
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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.
Reliability assessment of laminated composite plates with random strength parameters
(1999-12-01)
Kam, TY
;
Chu, KH
;
Chang, ES
;
機械工程學系
;
Department of Mechanical Engineering
A method is presented for the reliability assessment of transversely loaded laminated composite plates with random strength parameters. The proposed method is constructed on the basis of the first-ply failure method and the series system hypothesis. The first-ply failure analysis of a laminated plate is achieved via the use of a phenomenological failure criterion and the finite element method. In the reliability analysis, the independent (maximum stress) as well as the dependent (Tsai-Hill) failure criteria are used to establish the limit state equation; a direct numerical integration method together with the series system hypothesis are adopted to compute the reliability of the plate. Experimental investigations of lamina strength distributions and first-ply failure of laminated composite plates were performed. It has been found that lamina strengths and first-ply failure load can be well fitted by Weibull distributions. The baseline probability distributions of lamina strength parameters determined from the tests are then used in the reliability analysis of the laminated composite plates. The accuracy of the proposed method in reliability prediction of the laminated composite plates of different sizes is verified against the experimental results.