Optimization design for 3D-braided composite structure under thermo-mechanical load

In this work, a novel optimization method is proposed to pursue high-performance 3D-braided composite structure under thermo-mechanical loads, which optimizes structural topology and braiding parameters concurrently. To realize such design under affordable computational cost, we decompose the optimization method into offline and online stages. In the offline stage, a parameterized geometric model controlled by two braiding parameters, i.e., fiber volume fraction and braiding angle, is established to characterize the microstructure of composite. Subsequently Energy-based Homogenization Method is applied to calculate equivalent composite properties including elastic tensor, thermal conductivity tensor, and Coefficient of Thermal Expansion. A surrogate model based on Radial Basis Network is established to map braiding parameters to equivalent material properties. In the online stage, the surrogate model is integrated into Rational Approximation of Material Properties to build a systematic design scheme for structural topology and braiding parameters. Taking manufacturability into account, the proposed method is combined with stiffener layout design to obtain easy-to-manufacture braided composite structures. Finally, several numerical examples are provided to demonstrate the effectiveness of the proposed optimization method, indicating that braiding parameters have essential impacts on the composite structural design and performance.