In this paper, the mechanical behavior and damage evolution of CFRP laminates under three-point bending loads were investigated. Based on the three-dimensional Hashin failure criterion and cohesive zone method, a progressive damage analysis model was constructed to predict seven different failure modes, and an improved stiffness matrix degradation law was proposed. Numerical simulations were performed using ABAQUS finite element software and UMAT user subroutines and verified by three-point bending tests. The experimental results show that the relative errors of the flexural strength and flexural modulus of the current model simulation results and the experimental data were −3.10% and −2.70%, respectively, and the damage evolution process after the ultimate load was accurately predicted. Meanwhile, the predicted final failure and damage modes were consistent with the micrographs of the failed specimens.

In this paper, a new optimization design strategy is explored to achieve a rapid design of lightweight structures for unmanned aerial vehicles (UAVs) using honeycomb sandwich panels. Based on the existing performance equivalent method of honeycomb core material, an effective mechanical property homogenization model of honeycomb material is proposed and applied to finite element analysis. A finite element model is established to analyze the mechanical response of honeycomb sandwich panels under different bending loads, and the rationality of the model is verified by mechanical tests. The error between the simulation results and the experimental results is about 10%. Based on the variable density method and rational approximation of material properties interpolation method, a topology optimization model with the minimum structural flexibility as the objective is constructed. By comparing with the experiment-based design scheme, it is found that the optimized design scheme has a more reasonable structure and better performance. The optimized design can effectively reduce the structural weight and improve the load transfer path while ensuring structural stiffness. In this way, the influence of stress concentration and large deformation on the structure is avoided, which is of great significance for the design of UAV structures.