DESIGN AND EXPERIMENTAL VERIFICATION OF COMPOSITE BEND-TWIST COUPLED STRUCTURE BASED ON ASYMMETRIC STACKING SEQUENCE

The composite bend-twist coupled structure has important application value in the structural design of forward-swept wing aircrafts. The existing research mainly design bend-twist coupled structure based on symmetric composite materials, and there are some limitations such as narrow design domain and limited coupling effect. Asymmetric composite could solve the above problems, but because of its curing deformation, it has not been widely applied in engineering. In this paper, geometric factors and material constants of laminates are introduced to derive the analytical conditions of hygro-thermal stability of extension-shearing multi-coupled laminates. Secondly, a bend-twist coupled box structure model was constructed using extension-shearing multi-coupled laminates, and genetic algorithm-sequential quadratic program (GA-SQP) was used to complete the asymmetric optimization design of the box structure, which significantly improves the coupling effect of the structure. Then, the hygro-thermal stability and coupling effect of the bend-twist coupled structure is verified by numerical simulation, and its robustness is verified by Monte Carlo method. Finally, the experimental test of the coupling effect of the asymmetric bend-twist coupled structure is designed and completed, and the correctness of the theory is further verified. The results show that the asymmetric bend-twist coupled structure will not undergo curing deformation when the fiber angles meet conditions of hygro-thermal stability, and the introduction of asymmetry can significantly improve the coupling effect of bend-twist coupled structures and maximum increase is above 90%.