Optimization of curvilinear fiber orientation of composite plates and its experimental validation

Abstract

Variable stiffness composite (VSC) is a viable design extension of carbon fiber reinforced plastic (CFRP) laminates to obtain unique mechanical properties by changing the fiber orientation in a curvilinear manner. We optimized a VSC for open-hole tension laminates considering the automatic processing by the tow prepreg curve placement and evaluated the strength improvement with experiments. Multi-objective optimization using fracture criterion and mean curvature as objective functions resulted in higher strength gains for solutions with higher mean curvature and lower processability. Besides, by giving the molding conditions as constraints for optimization, the strength was improved while satisfying the molding conditions. The fabrication of optimum VSCs involved using a tabletop automated fiber placement. Strength tests showed a 34.3% improvement in the curvilinear prepreg path.