Numerical Evaluation of Ultimate Strengths of Composites Considering Both In-Plane Damage and Delamination


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Traditional laminate strength analysis only considers face failure under in-plane loads. In fact, owing to the mismatch of the mechanical properties of the adjacent layers, a three-dimensional interlaminar singular stress fields develop in a small boundary region in the vicinity of the free edges of the laminate under mechanical load, which may lead to interlaminar delamination failure. Neglecting this interlaminar failure mode, the failure strength of laminate will be overestimated. In this paper, face failure and interlaminar failure are both considered. So for a lamina, three major failure modes are considered: matrix failure, fiber breakage and delamination. Finite element method is used to obtain the stresses in a laminate under mechanical loads. Stress-based criterions are adopted to predict the failure mode of laminas. When a lamina is failed, the lamina stiffness is reduced according to the corresponding failure mode, and the stresses of the laminate are re-analyzed. This procedure is repeatedly performed until the whole laminate fails and thus the ultimate strength is determined. The predicted ultimate strengths are in good agreement with experiment results in the open literature.



Key Engineering Materials (Volumes 324-325)

Edited by:

M.H. Aliabadi, Qingfen Li, Li Li and F.-G. Buchholz




W. J. Peng and J. Q. Chen, "Numerical Evaluation of Ultimate Strengths of Composites Considering Both In-Plane Damage and Delamination", Key Engineering Materials, Vols. 324-325, pp. 771-774, 2006

Online since:

November 2006




[1] P. Pal, C. Ray. Progressive failure analysis of laminated composite plates by finite element method. �Journal of reinforced plastics and composites, Vol. 21 (2002), pp.1505-1513.


[2] X.Y. Wang, J.Q. Chen. Robust design of laminated composite plates based on the last-ply failure criterion (in Chinese). Journal of Mechanical Strength, Vol. 6 (2004), pp.675-679.

[3] Th. Lorriot, G. Marion. Onset of free-edge delamination in composite laminates under tensile loading. Composite: Part B, Vol. 34 (2003), pp.459-471.


[4] F. Lecuyer, D. Engrand. A methodology for the identification of a criterion for delamination initiation. JNC 8 (1992).

[5] S.B. Singh, Ashwini Kumar. Post-bucking response and strength of laminates under combined in-plane loads. Composites Science and Technology, Vol. 59 (1999), pp.727-736.


[6] Z. Hashin. Failure criteria for unidirectional fiber composites. Journal of Applied Mechanics, Vol. 47 (1980), pp.329-334.

[7] G. Kress. Free-Edge influence on CFRP-Laminate Strength. International Journal of Damage Mechanics, Vol. 3 (1994), pp.194-211.