Integrated design optimization of composite frames and materials for maximum fundamental frequency with continuous fiber winding angles

Fiber reinforced composite frame structure is an ideal lightweight and large-span structure in the fields of aerospace, satellite and wind turbine. Natural fundamental frequency is one of key indicators in the design requirement of the composite frame since structural resonance can be effectively avoided with the increase of the fundamental frequency. Inspired by the concept of integrated design optimization of composite frame structures and materials, the design optimization for the maximum structural fundamental frequency of fiber reinforced frame structures is proposed. An optimization model oriented at the maximum structural fundamental frequency under a composite material volume constraint is established. Two kinds of independent design variables are optimized, in which one is variables represented structural topology, the other is variables of continuous fiber winding angles. Sensitivity analysis of the frequency with respect to the two kinds of independent design variables is implemented with the semi-analytical sensitivity method. Some representative examples in the manuscript demonstrate that the integrated design optimization of composite structures can effectively explore coupled effects between structural configurations and material properties to increase the structural fundamental frequency. The proposed integrated optimization model has great potential to improve composite frames structural dynamic performance in aerospace industries.