Optimization and verification of layup angles of carbon fiber-resin composites for stress concentration mitigation

Carbon fiber-resin composite multi-layer shells are widely used due to their light weight and high strength. However, traditional layup design heavily relies on empirical parameters, making it difficult to match the interlaminar mechanical properties with application requirements. Moreover, most existing studies on layup optimization only rely on simulation analysis and lack experimental verification for the reliability of optimization results. In this study, a finite element model is established based on COMSOL Multiphysics, and the BOBYQA (Boundary Optimization by Quadratic Approximation) algorithm is adopted to optimize the layup angles of a 6-layer composite shell, with the objective of minimizing the maximum Hashin failure index. Innovatively, the effectiveness of simulation optimization is indirectly verified by experimentally measuring the reduction in maximum normal stress, addressing the gap of missing experimental evidence in existing optimization studies. Numerical simulation and experimental verification are carried out on the experimental model of this work. Results show that the optimized model exhibits reductions of 28.9%, 16.1%, and 31.0% in maximum normal stress, von Mises stress, and Hashin failure index, respectively. Combined simulation and experimental evidence confirm that the optimization scheme significantly alleviates stress concentration, promotes uniform internal stress transfer, and improves structural strength.