Applied Finite Element Procedure for Morphing Wing Design

Bistable composite laminates provide an appealing platform for morphing applications. On the other hand they exhibit geometrically nonlinear behavior and they are sensitive to imperfections. Their curing behavior dictates bifurcation buckling analysis while their actuation requires snapthrough buckling analysis. This work proposes a generalized finite element analysis procedure applying Koiter's asymptotic postbuckling theory to address their curing and actuation. Initially the postbuckling theory is discussed providing essential aspects required for its application into finite element analysis. A generalized scheme is established for the Koiter-based procedure to enable its incorporation into design optimization routines. To prove its generality, the procedure is implemented into three finite element commercial codes, namely, ABAQUS, ANSYS and LS-DYNA. Best practices for these implementations are provided, then their accuracies are assessed through multiple comparisons with published data. Moreover, Hyper-Elliptic Cambered Span (HECS) Wing design is developed utilizing bistable laminates. Stability characteristics of several design variations of the morphing HECS wing are assessed using the developed procedure. The Koiter-based finite element procedure is proven to be both general and suitable for implementation in different finite element codes to address designs with complex geometry. Therefore, this work provides a unique platform for novel designs employing bistable composites in various engineering applications. Furthermore, it presents a general framework to implement Koiter's asymptotic postbuckling theory in finite element codes for bifurcation buckling and post-buckling studies of imperfection-sensitive structures.