Experimental and numerical investigation of a composite structure with frame and skin

A composite structure with frame and skin based on cabin structure in a large space telescope is studied in this paper. The frame is composed of longitudinal and transverse beams with hybrid bond- ed/bolted joints, and the skin is connected to the frame by bolts. Tensile tests are conducted on the structure by a set of test stand. It is observed that residual deformation occurs in the first test of the structure, which is attributed to the relative sliding between the skin and frame because of bolt-hole clearances. The high tightening torque and the increased number of the skin-frame bolts contribute to the high stiffness of the structure. A finite element model ( FEM) of this composite structure is es- tablished, and the simulation model is verified by the experimental results. The FEM is contrastively analyzed with different frame joints, and it is found that adhesive joining in the hybrid bonded/bol- ted joints enhances the stiffness of the structure significantly. Given that adhesive plays a leading role in the stiffness of the hybrid joints, Tie contact in FEM is proposed to simulate bonded or hybrid joints when studying the stiffness performance of undamaged structure.