Static and dynamic axial crushing of square thin-walled aluminium extrusions

An experimental investigation was carried out to study the behaviour of square thin-walled aluminium extrusions in alloy AA6060 subjected to axial loading. Both static and dynamic tests were performed and the primary variables were the wall thickness and temper of the square tubes and the impact velocity of the projectile. The mass of the projectile in the dynamic tests was 56 kg, while the impact velocity was in the range 8-20 m/s. The experimental results show that a symmetric deformation mode is formed for the static tests with a lobe number that is a function of the temper. In the dynamic tests a mixture of modes is found. The experimental results also show that the dynamic mean force is significantly higher than the corresponding static force for the same axial displacement, which indicates a strong inertia effect. For initially straight square tubes, the mean load ratio between a dynamic and a static test is a decaying function with respect to the axial displacement. However, by introducing initial geometrical imperfections prior to dynamic testing an almost constant ratio is found. Copyright (C) 1996 Elsevier Science Ltd.