Multi-objective optimization for snap-through deformation of bi-stable composite shell

Abstract

During fabrication process of laminated fibrous composites, asymmetric laminates result in skewed surfaces after curing due to strong anisotropy of each layer, and composites with specific lay-ups and dimensions show bi-stable states in terms of surface shapes. The present study performs a multi-objective optimization for the composite shell with bi-stable shapes. Objective functions are amount of averaged deformation between two stable shapes of shell (snap-thorough deformation) and critical temperature of surroundings which is the maximum temperature to keep the bi-stable characteristics. These properties indicate a trade-off relation each other and are maximized simultaneously by using an effective multi-objective genetic algorithm method, SPEA+. Shell shapes after curing are predicted by the thermal deformation analysis based on the Rayleigh-Ritz method with directly assumed strain functions. Calculated results agree well with those from experiments with respect to shell shapes, and the present multi-objective optimization reveals wide-ranging Pareto optimum solutions. The numerical results show that spirally laminated fiber orientation angles are effective to increase amount of snap-thorough deformation.