The complex part named main substructure is considered as free-interface, and the other branch substructures as fixed-interface.The computation of each substructure is entirely independent.

• 各子结构之间完全独立计算，并且通过计入主、从子结构的剩馀模态矩阵的办法来补偿所舍去的高阶模态分量，保证了计算精度。