Free material stiffness design of laminated composite structures using commercial finite element analysis codes

In this work optimum stiffness design of laminated composite structures is performed using the commercially available programs ANSYS and MATLAB. Within these programs a Free Material Optimization algorithm is implemented based on an optimality condition and a heuristic update scheme. The heuristic update scheme is needed because commercially available finite element analysis software is used. When using a commercial finite element analysis code it is not straight forward to implement a computationally efficient gradient based optimization algorithm. Examples considered in this work are a clamped-clamped 2D plate loaded in two load cases and a point loaded six layered 3D double curved corner hinged shell. The first example displays the effect of varying the size of patches having the same parametrization, and the second illustrates the benefit of using a layered free material parametrization. The results provide information concerning topology, material anisotropy, and the direction having the maximum stiffness. The obtained results are compared to gradient based optimization solutions using Discrete Material Optimization and Continuous Fiber Angle Optimization implemented in a research code, where full access to the finite element analysis core is granted. This comparison displays the possibility of using commercially available programs for stiffness design of laminated composite structures.