Effect of thermal aging on the crashworthiness of foam-filled CFRP composite tubes under lateral compression

Through the design process of automotive composite structures, the designer needs to meet the mechanical characteristics and consider the sensitivity of the design to the environmental factors, which control its safety and feasibility. The current experimental study presents the effect of thermal aging on the crashworthiness of carbon/epoxy composite tubes under lateral crushing. Tubes were subjected to thermal aging at 70 and 100 °C for 14 days. Both empty and foam-filled tubes were studied. In addition, foam specimens were compressed under the same conditions to understand the behavior of the foam-filled tubes. The outcomes demonstrated that the addition of the foam improved the load carrying capacity and energy absorption. The matrix's thermal degradation and debonding were the primary factors in the reduction of crashworthiness. For the foam-filled composites, the reduction in the crashworthiness is lower because of having the foam inside the tube. The average crushing force increases by 14% and 29% for the specimens exposed to 70 and 100 °C for 14 days, respectively, which result in higher energy absorption. The improvement in the foam-filled structures by aging is governed by the higher strength and energy absorbed of the foam after thermal exposure, which supports the use of polyurethane foam as a filler in energy absorption devices.