Design Guidelines in Nonconventional Composite Laminate Optimization

Daniel Peeters, Mostafa Abdalla

Research output: Contribution to journalArticleScientificpeer-review

19 Citations (Scopus)
198 Downloads (Pure)


Nonconventional laminates, as defined in this paper, are laminates where ply angles are not restricted to a finite set: for example 0, 45, −45 −45 and 90 deg. Removing this restriction, structural behavior (for example, postimpact behavior) can be significantly improved. Nonconventional laminates are made of straight or steered fibers leading to constant- or variable-stiffness composites. In traditional composite design, empirical guidelines are imposed, guaranteeing the robustness of the composite. This paper presents a method to take design guidelines into account during nonconventional laminate optimization. The 10% rule is interpreted as a lower bound on the degree of isotropy and formulated as a positive-semidefinite matrix constraint. Other guidelines are interpreted as bounds on ply angle or angle difference, or the number of variables is reduced by fixing variables to user-defined values. Numerical results optimizing a plate under biaxial tension for strength demonstrate the optimizer generates nonconventional laminates obeying all guidelines, performing at least as well as conventional composites. For variable-stiffness laminates, a flat plate under uniaxial compression is optimized for buckling under a stiffness constraint. Applying the 10% rule, almost half of the improvement over conventional laminates is lost compared to the unconstrained case, demonstrating the importance of including design guidelines during nonconventional laminate optimization.

Original languageEnglish
Number of pages14
JournalJournal of Aircraft: devoted to aeronautical science and technology
Publication statusPublished - 2016


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