Multi-scale crushing response of sandwich composite connecting rod based on thermal expansion molding technique

The lightweighting of automotive chassis structural components faces multiple challenges, including the selection of molding processes, the design of lightweight material structures, and the joining methods between metals and composites. In this study, a steel rear suspension link of an automotive chassis is taken as the research object, and a straight-type integrally molded sandwich composite connecting rod is designed and fabricated based on the thermal expansion molding technique. Compression tests are carried out on specimens with different joint molding methods and layup configurations. Digital image correlation (DIC) technology is employed to monitor the strain field in real time, and the load-displacement curves, damage evolution mechanisms, and compressive performance of the specimens are systematically analyzed. On this basis, a local ply optimization strategy is adopted to synergistically reinforce the weak load-bearing areas, further improving the compressive performance indicators of the sandwich composite connecting rod. The results show that the sandwich composite connecting rod exhibits excellent compressive strength and structural stability, and demonstrates a negative correlation in which the crushing force efficiency decreases with increasing peak load. This study provides key technical support and a practical basis for the engineering application of lightweight high-performance structural components in the automotive industry.