Design of variable stiffness panels for maximum strength using lamination parameters

Tailoring of laminated composite structures by changing ply angle and thickness locally provides a unique opportunity to take full advantage of anisotropic properties of composite materials. Variable stiffness design has become more attractive with the development of industrial fibre placement machi...

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Bibliographic Details
Published in:	Composites. Part B, Engineering Vol. 42; no. 3; pp. 546 - 552
Main Authors:	Khani, A., IJsselmuiden, S.T., Abdalla, M.M., Gürdal, Z.
Format:	Journal Article
Language:	English
Published:	Kidlington Elsevier Ltd 01-04-2011 Elsevier
Subjects:	A. Plates B. Strength B. Stress concentrations composite materials Criteria Exact sciences and technology Failure Fibre Fundamental areas of phenomenology (including applications) hybrids industrialization Lamination parameters Mathematical analysis Mathematical models Panels Physics Solid mechanics Static elasticity (thermoelasticity...) Stiffness Strength Structural and continuum mechanics B. Strength A. Plates B. Stress concentrations Lamination parameters Stacking sequence Laminate Fiber reinforced material Theoretical study Fracture criterion Modeling Composite material Optimization Finite element method Panel Numerical simulation Stiffness
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Summary:	Tailoring of laminated composite structures by changing ply angle and thickness locally provides a unique opportunity to take full advantage of anisotropic properties of composite materials. Variable stiffness design has become more attractive with the development of industrial fibre placement machines. Strength design is one of the areas where fibre steering is advantageous. Design methods that consist of directly optimising fibre angles or fibre path coefficients can lead to local optima and/or non-continuous solutions. These problems can be alleviated by using lamination parameters as design variables, which provide a compact definition of laminate stiffness. Additionally these parameters are continuous and the design space has shown to be convex. Dependency of strength failure criteria on ply angles may preclude using lamination parameters as design variables. Here, a recently developed method which incorporates the strength failure criteria in the lamination parameter space by using a conservative failure envelope for all ply angles is utilised. A hybrid approximation for the failure index is developed and is guaranteed to be convex using a convexifying approach. As an example strength maximisation of a panel with a central hole under uniaxial tension is investigated. Numerical results show improvements in strength with respect to the quasi-isotropic design. Although there is a common belief that design for stiffness can be served as a surrogate for strength design, it is shown that considering the strength as a design criteria especially for structures with large stress gradients is very important.
Bibliography:	http://dx.doi.org/10.1016/j.compositesb.2010.11.005 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 ObjectType-Article-2 ObjectType-Feature-1
ISSN:	1359-8368 1879-1069
DOI:	10.1016/j.compositesb.2010.11.005