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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 88
PROCEEDINGS OF THE NINTH INTERNATIONAL CONFERENCE ON COMPUTATIONAL STRUCTURES TECHNOLOGY
Edited by: B.H.V. Topping and M. Papadrakakis
Paper 10

Effect of the Failure Criterion on the Minimum Weight of Laminated Composites

R.H. Lopez1, M.A. Luersen2 and E.S. Cursi1

1Mechanical Engineering Department, National Institute of Applied Sciences (INSA), Rouen, France
2Mechanical Engineering Department, Federal Technological University of Paraná (UTFPR), Curitiba, Brazil

Full Bibliographic Reference for this paper
R.H. Lopez, M.A. Luersen, E.S. Cursi, "Effect of the Failure Criterion on the Minimum Weight of Laminated Composites", in B.H.V. Topping, M. Papadrakakis, (Editors), "Proceedings of the Ninth International Conference on Computational Structures Technology", Civil-Comp Press, Stirlingshire, UK, Paper 10, 2008. doi:10.4203/ccp.88.10
Keywords: laminated composite materials, optimisation, genetic algorithm, Puck failure criterion.

Summary
A laminated composite can be tailored accordingly to the designer's needs, the orientation of the laminas, the thickness and the number of layers usually being the design variables. In order to achieve the best results, optimisation techniques have been developed. Among them, the genetic algorithm (GA) has been extensively used to pursue the optimisation of a given composite structure [1,2,3,4].

Regarding failure criteria, it seems surprising that many scientists, when implementing failure criteria for composites, which the failure behaviour is similar to brittle materials, decided to follow the yield criteria of von Mises or Hill which are more suitable to ductile materials [5]. It seems much more appropriate to use the failure criteria of Mohr as guidelines, these having been developed for materials that exhibit brittle fracture characteristics. A criterion which accomplishes it is the Puck's failure criterion (PFC) [5,6].

Therefore, the purpose of the present work is to analyse the effect of the choice of the failure criterion on the minimum weight of a laminated plate subjected to in-plane loads. The GA was employed as an optimization tool. Three different failure criteria were independently tested as constraints: Maximum Stress, Tsai-Wu and PFC. A focus is given on PFC because it seems to be a more realistic criterion and it has been little explored in composite structures design problems.

From the analysis pursued, it can be concluded that the optimal weight depends on the failure criterion as well as the load conditions (especially for the negative-negative load condition). It must be stressed that the same failure criterion not necessarily generated the lightest or heaviest structure for each load condition.

One important conclusion is that the choice of the failure criterion must agree with the real behaviour of the type of laminate which is being used, once during the optimisation process the structure will be taken to the limit. If this choice is not made properly, the structure may be too costly or even (extremely dangerously) under dimensioned.

References
1
R. Le Riche, R. Haftka, "Optimization of laminate stacking sequence for buckling load maximization by genetic algorithm", AIAA Journal, 31, 951-956, 1993. doi:10.2514/3.11710
2
S. Nagendra, D. Jestin, Z. Gurdal, R. Haftka, L. Watson, "Improved genetic algorithm for the design of stiffened composite panels", Computers & Structures, 58, 543-555, 1994. doi:10.1016/0045-7949(95)00160-I
3
A. Todoroki, R. Haftka, "Stacking sequence optimization by a genetic algorithm with a new recessive gene like repair strategy", Composites Part B, 29, 277-285, 1998. doi:10.1016/S1359-8368(97)00030-9
4
B. Liu, R. Haftka, M Akgun, A. Todoroki, "Permutation genetic algorithm for stacking sequence design of composite laminates", Computer Methods in Applied Mechanics and Engineering, 186, 357-372, 2000. doi:10.1016/S0045-7825(99)90391-2
5
A. Puck, H. Schürmann, "Failure analysis of FRP laminates by means of physically based phenomenological models", Composites Science and Technology, 58, 1045-1067, 1998. doi:10.1016/S0266-3538(96)00140-6
6
A. Puck, "Festigkeitsanalyse von Faser-Matrix-Laminaten: Modelle für die Praxis", München, Wien, Hanser, 1996.

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