Crushing of energy absorption connectors with polyurethane foam and asymmetric pleated plates

In this paper, the dynamic crushing responses of polyurethane foam-filled energy absorption connectors with asymmetric pleated plates were studied through drop-weight impact tests and FE simulations, from which three deformation stages were identified according to the formation and rotation of plastic hinges of asymmetric pleated plates. The effects of polyurethane foam filler as well as thickness and geometric parameter k of pleated plate on the energy absorption characteristics of connectors were analyzed quantitatively. The results indicated that filling polyurethane foam and increasing parameter k could result in higher energy absorption and specific energy absorption. In addition, thicker pleated plate could also increase energy absorption and crushing force. The results also showed that filling polyurethane foam and decreasing parameter k could reduce the peak force before densification and thus, improving crush force efficiency. Moreover, a theoretical model, considering strain rate effects of polyurethane foam and steel, was also proposed to predict energy absorption–displacement relationships of the polyurethane foam-filled connectors subjected to impact loading and its correctness was validated by comparing the calculations with experimental results.