1996 Fiscal Year Final Research Report Summary
Surface Buckling and Postbuckling of Composite Laminates with Delaminations
| Project/Area Number |
07651125
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Aerospace engineering
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
WANG Wen-Xue Research Institute for Applied Mechanics, Kyushu University, Associate Professor, 応用力学研究所, 助教授 (40240569)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAO Yoshihiro Research Institute for Applied Mechanics, Kyushu University, Professor, 応用力学研究所, 教授 (30108766)
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| Project Period (FY) |
1995 – 1996
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| Keywords | Composite laminates / Delamination / Local laminate asymmetry / Buckling and postbuckling / 3-D nonlinear FEM analysis |
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| Research Abstract |
Increasing demands for high performance and efficiency of various machines and vehicles lead to a series of developments and applications of advanced composite laminates due to their high stiffness, high strength and light weight. Conseuquently, the accurate evaluation of the mechanical behaviors and strength characteristics of composite laminates under various loading conditions becomes crucial. In this research, a finite deformation FEM program is developed based on the updated Lagrangian theory and numerical simulations and associated experiments are conducted to investigate the compressive response of delaminated laminated. Special attention is put on the effects of local asymmetry on the buckling and postbuckling behavior of delaminated laminates and following conclusions are obtained.
1.The local asymmetry of delaminated laminates may significantly reduce the global load carrying capacity of the laminate. For instance, the critical averaged compressive stress in the case of this r
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esearch is found to be reduced by nearly 12%.
2.The difference between the simple sums of energy release rates obtained from the three and two dimensional analyzes seems to be small. However, the distributions of energy release rates are non-homogeneous along the width direction due to the local asymmetry of the delaminated laminate, which implies that the delamination may not grow homogeneously along this direction.
3.The global bucking of the laminate is dominant for short delaminations. in this research, it is found that the critical load of the laminate with short delamination, (delamination length/laminate langth)<0.2, is almost the same with that of a laminate without delamination.
4.Nonhomogeneous delamination propagation and twist deformation due to the local asymmetry have been observed in the experimental research, which verifies the prediction of the numerical simulation qualitatively.
Further nemerical and experimental researches are still needed to accurately evaluate the damage and strength of delaminated laminates. Less
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