Dynamic Response and Energy Absorption Characteristics of Expansion Tubes Under Axial Impact

The expansion tube is normally used in impact-resistant components, owing to the stable expansion force, and high specific energy-absorption capacity. This paper reports the deformation mechanism and energy absorption characteristics of expansion tube subject to impact velocity ranging from 0.083 m/s to 48.84 m/s. The effects of cone piston semi angle, tube wall thickness, and impact velocity on expansion tube performance were studied via experimental measurements and numerical modeling. The mechanical responses of the expansion tube were measured using a universal gas gun setup. The energy absorption capacity of the expansion tube absorber was identified to be different under quasi-static and dynamic compressions. The dynamic expansion force is lower than the quasi-static expansion force, which is about 62.2%-76.6% of the static expansion force, but the deformation mechanisms of the tube under quasi-static loading and dynamic impact are same. A finite element numerical model was built and validated with the experimental data. The finite element predictions were in good agreement with the experimental measurements. It was shown that the decrease in the friction coefficient is the main reason for the dynamic expansion force lower than the quasi-static expansion force. The influence of cone piston semi angle and tube wall thickness are significant on the energy absorption capacity of the tube. The dynamic expansion response does not change significantly when the impact velocity is less than 50 m/s. Under dynamic impact, the change of energy absorption efficiency is negligible, and the plastic deformation energy is about 64%-71.5% of the total kinetic energy of striker.