Stacking sequence optimization of the anti-buckled graphite/epoxy laminated composites for minimum weight using generalized pattern search algorithm

Abstract

Composite materials have been increasingly used during the last decades due to their properties such as low weight, high stiffness, superior fatigue and corrosion resistance. They have been used in aerospace, automobile, marine applications and etc. Composite materials being an expensive but efficient technology to get minimum weight structures, it is logical to make an attempt to find out how to design properly optimum laminated composite plates with no reduction in their strength. The aim of the thesis is to find the optimum stacking sequence to obtain the minimum thickness (weight) of laminated composite plates in different loadings and plate dimensions under buckling constraint. Moreover, a comparison study of conventional and continuous designs are performed to determine the effect of stacking sequence on weight. The objective function is the critical buckling load factor. Fiber angles of the composite plates are taken as continuous design variables and the plate is assumed to be balance and symmetric. Composite plates made of graphite/epoxy have been considered in this thesis. A combination of Generalized Pattern Search Algorithm (GPSA) and Genetic Algorithm (GA) has been considered as an optimization method. All the results show that the loading conditions and dimensions of composite plates are significant in stacking sequences optimization of laminated composite materials in terms of maximum critical buckling load factor and minimum thickness.