Quasi Static Axial Crushing of Foam Filled Thin Walled Circular Tubes

Abstract

Objective: Thin walled circular tubes are used in many practical situations to absorb impact energy, the axial impact of these thin-walled tubes absorb deformation energy at nearly constant load resulting in high energy absorption. This paper investigates the dynamic progressive buckling response of empty and foam filled tubes under quasi static loading conditions and validation of results using non linear finite element code LS-DYNA. Method/Analysis: In the experimental study, aluminium 6063-T5 thin walled circular tubes are integrated with low density polyurethane foam and quasi static loading is conducted on both empty and foam filled tubes to determine the buckling response and deformation shape under impact. The load-displacement graph obtained is used to determine the energy absorbed by the thin walled structure. The numerical analysis of a similar loading condition is simulated using LS-DYNA and a systematic comparison between the finite element model and experimental deformed shapes, load-displacement, number of folds, energy absorption is done. Findings: The integration of low density foam in empty aluminium tube increased the energy absorption by 1.4% with an additional stability in the deformation and satisfactory agreements were achieved between the finite element model and experimental deformed shapes, load-displacement, number of folds, energy absorption with an error less than 15%. Applications/Improvements: One potential application of polyurethane foams is that it can be used as reinforcement in energy absorbing structures, hence an understanding of the response of the system in different loading condition is necessary to improve the crashworthiness. The experimental results are correlated to FEM to reduce the time spend on experimental testing.