Experiments on Crush Behavior of Three Thin Walled Basic Geometries

Different geometries and designs of crush tubes are employed in the frontal region i.e., crush zone of automobiles. The crush tubes undergo plastic deformation and absorb the impact energy in the case of vehicular collisions. In crashworthiness evaluation of crush tubes, out of several assessment parameters, the very important ones are crush force efficiency (CFE, the ratio between mean force and peak force), stroke efficiency (SE, the ratio between plastic crushed length and original length of crush tube), and specific energy absorption (SEA, the total energy absorption per unit mass of the crush tube). In design of crush tubes, significant research has been done so far to improve the CFE and SE close to 100% and maximise the SEA. While several varieties of geometries and configurations of crush tubes have been studied, the fundamental crush behaviour of standard basic geometries are not explored in detail. This research is focused on studying the crush behaviour of three basic geometries such as circular, triangular and square. The crush tube specimens of equal mass and 120 mm length have been prepared from Stainless Steel 304 (SS 304) material and subjected to axial crushing experiments in a universal testing machine. The crush force-crush displacement of all three crush tube specimens obtained from crush experiments are compared and their relative crashworthiness parameters are discussed. This study has revealed that the crush tube with a circular cross-section exhibited better crashworthiness parameters (CFE of 49.4% and SE of 80.5% and SEA of 18.4 kJ/kg) as compared to the square and triangular cross-sections.