Optimization Framework for the Design of Advanced Composite Structures

Abstract

Topology optimization is increasingly being used to generate efficient structural systems. To date, majority of the work has been limited to finding the optimal distribution of isotropic materials. The use of non-isotropic materials, such as Fibre Reinforced Polymer (FRP) composites, has become increasingly popular within the civil infrastructure industry. As such, there is a need to extend current topology optimization methods to handle non-isotropic materials and hence be applied in the design of composite structures. Topology optimization of orthotropic composite laminate structures is relatively more complex, as it requires the concurrent optimization of material distribution and material properties. For large-scale civil structures, the sizeable number of design variables means that simultaneous optimization may not be feasible. As such, a sequential framework is proposed, whereby the material distribution and material property optimization are decoupled in a multi-level approach. Based on the notion that the optimal distribution of material aligns with the trajectory of the structures load path, the topology optimization problem is first solved using a fixed isotropic material, and then the material properties optimized at the laminate element level. The validity of this approach has been addressed in existing literature however its pertinence has been shown to be dependent on the nature of the design variables as well as loading condition. This work will look to explore and validate the sequential optimization framework for civil structures.