Experimental and Numerical Study on Plastic Behavior of Expansion Tubes Subjected to Impact

Aiming to study the plastic behavior of expansion tubes, this paper presents experimental studies on Q420 and S2205 steel tubes and investigates the influence of key parameters on the responses of the expansion tube. A finite element model is established and validated by comparing the numerical results with experimental results. Based on both experimental and numerical approaches, the effects of the coefficient of friction, geometric parameters, tube material and impact velocity are revealed. The results show that the steady-state force increases linearly with increasing friction coefficient and tube thickness. As expansion value increases, the growth rate of steady-state force decreases, and local buckling and splitting become more likely. Numerical simulations examine the response and failure modes under low- to high-speed impacts. The steady-state force is insensitive to impact velocity and expansion angle, but the failure mode under high-speed impact is more severe than that under low-speed impact. Four failure modes and typical deformation stages of the failure process were obtained based on test observations and numerical simulations. The empirical formula for predicting the steady-state force of Q420 steel tubes under quasistatic and low-speed impact expansion is proposed based on similarity criteria and dimensional analysis.