Crashworthiness Characteristic of Dynamically Expanded Circular Tubes Made of Light Alloys: Experimental and Theoretical Investigation

The paper presents the process of dynamic expansion of thin-walled pipes made of T6 temper 7075 aluminum alloy. The obtained results were related to the mass of tested elements, which allowed for calculating the specific energy absorption. The registered crushing force was in the range of 600–800 kN/kg. The obtained values were much greater than the crushing force of traditional crash boxes made of steel (80–120 kN/kg) or AZ31 magnesium alloy sheets (150 kN/kg). The analytical model for predicting crushing force depending on the thickness of the pipe wall was developed and proven to be correct by conducting real experiments and FEM simulation. The mathematical model for energy absorption named further as ETMEA (expanding tubes model for energy absorption) was developed based on calculated energy-deflection curves. It was proven that the energy absorption could be easily scaled. In cases where high energy absorption is needed, it can be easily achieved by increasing the thickness, while for lower energy absorption application, the thickness may be reduced and the goal may be achieved by selecting the appropriate length of the profile.