Weight Optimization of All-Composite Sandwich Structures for Automotive Applications

Lightweight composite sandwich structures are widely used in the automotive industry, particularly in vehicle body applications, due to their advantageous properties, e.g. low density, high stiffness and high strength-to-weight ratio. The goal of the research was the elaboration of an optimization method for a totally Fiber Reinforced Plastic (FRP) sandwich structure in order to construct a minimal weight structure. The all-composite sandwich panel consists of a hexagonal FRP honeycomb core and laminated FRP face sheets. The article investigates the optimization of the FRP composite layers of the cell wall of the honeycomb core and the face sheets simultaneously. The Classical Lamination Theory (CLT) with analytical expressions was adopted to calculate the stiffness and strength of the sandwich components. The minimization of the total weight of the sandwich structure was the main goal during the structural optimization. Therefore, the design variables were the following: the orientation of the FRP layer for the cell wall of the core; furthermore the number and orientation of the face sheets' layers. During the optimization, 5 design constraints which related to structure strength criteria were considered. I-sight software was used in conjunction with Excel software to perform the optimization process. Some of the feasible design points were numerically modelled using Abaqus Cae software and showed good agreement with the optimization result. The main added value of the research is the elaboration of the single weight optimization method for a totally FRP sandwich structure.