Abstract: The numerical model of sandwich composite materials T-Joint is built by ANSYS. And, the damage formation, extension, failing process and optimization design of the T-Joint under bend displacement are investigated by numerical simulation. The Cantilever bending performance was tested to verify the simulation results. The test results show that the initial damage displacement is 30～32 mm, and the relative load is 7.5 kN~7.6 kN . The bearing capacity of T-Joint is increased and stiffness is reduced. The failure strength is increased by 41%~55% compared with initial damage strength. The results of experiment is consistent with the numerical simulation, indicating that the clapboard is the weak position of the structure. The initial damage is extrusion damage of composite material and appears to the connections between clapboard and enhancing area. With the increasing of bend displacement, the damage area is increased, leading to the failure of the whole T-Joint. By finite element optimization analysis, the improvement of the down-skin and core thickness of clapboard could lead to reduce the maximum stress and failure factor of down-skin of clapboard, and narrow failure factor difference of two clapboard skins, and give full play to the performance of overall structure.

Key words: sandwich composite, T-joint, cantilever bending experiment