Optimization of transverse shear moduli for composite honeycomb cores

Effective transverse shear moduli of composite honeycomb cores are important material properties in analysis and design of sandwich structures. Based on a combined multi-objective optimization and homogenization approach, effective transverse shear moduli for composite honeycomb cores are optimized in this paper. An analytical approach using a two-scale homogenization technique is adopted to predict the effective transverse shear stiffnesses of thin-walled composite honeycomb cores with general configurations, and explicit formulas are given for three typical honeycomb cores consisting of sinusoidal, tubular, and hexagonal geometries. To maximize the performance of transverse shear behavior, a multi-objective method is employed to obtain optimal designs of periodic cellular cores. By assigning equal weighting (or penalty) factors to the transverse shear stiffnesses, the overall shear stiffness parameter is optimized. The optimization problem is solved using a sequential quadratic programming algorithm. The geometric and weighting factor effects on the optimal designs for the three cellular cores considered in this study are evaluated and discussed. An optimization procedure using finite element analysis and a response surface algorithm is also conducted to verify the proposed approach. The present combined homogenization and multi-objective optimization approach can be used to maximize transverse shear material properties of composite honeycomb structures.