Concurrent multi-scale optimization design of composite frame structures with maximum fundamental frequency

Glass or carbon fiber reinforced composite frames are ideal lightweight and high-span structures in the field of aerospace. Fundamental frequency is a key performance indicator in the process of the composite frame structure design. Increasing the value of fundamental frequency of the frames could avoid the phenomenon of structural resonance. Based on the structure and material concurrent optimization concept, the concurrent multi-scale optimization design for the maximum fundamental frequency of fiber reinforced frame structure is proposed. An optimization model based on the maximum structural fundamental frequency and the specified fiber material volume constraint has been established. The objective function sensitivity information about the two geometrical scales design variables are deduced with semi-analytical method. Numerical example in the paper shows that the concurrent multi-scale optimization for the maximum fundamental frequency can further explore the coupling effect between the macro-structure and micro-material to increase the fundamental frequency. The new two geometrical scales optimization model provides a choice for the design of composite frame structure in aerospace and other industries.