Influence of shape, size and location of cutouts on crashworthiness performance of aluminium conical frusta under quasi-static axial compression

Abstract

Abstract The influences of different shape, size and number of lateral cutouts at various locations on the load-bearing capacity, buckling behaviour and energy absorption (Eabs) characteristics of aluminium conical frusta under quasi-static axial loading condition were studied from both experimental and numerical procedures. In this regard, 18° semi-apical angled aluminium conical (AC18) frusta were fabricated through the metal spinning process; and circular, square, and trapezoidal shapes of cutouts with required dimensions were introduced at various lateral locations of the frustum. These conical frusta were subjected to quasi-static axial loading at a rate of 2 mm/min using a universal testing machine (UTM), and the corresponding load-deformation characteristics were recorded for axial compression of 50 mm from its original height. In addition to that, similar to experimental studies, Finite Element Analysis (FEA) was performed with conical frusta having various cutouts using ABAQUS® finite element software to study the influence of cutouts on the changes on crashworthiness performance of conical frusta. From both studies, it is observed that the energy absorption capacity of 18° semi-apical angled aluminium conical frusta was found to be decreasing in the range of 3.67%–47.60% according to the shape, size, number and location of cutouts. Further, the load resistance parameters such as first peak load (Pfst), maximum peak load (Pmax) and average load (Pavg) also are found to be decreasing with an increase of cutout size. The change of cutout location from mid-height to three-fourth from the base of the frustum also resulted in a reduction of Eabs capacity, regardless of shape, size and number of cutouts. From these studies, it observed that the energy absorption characteristic of conical frusta having circular cutouts are found to be better than the conical frusta having square and trapezoidal cutouts at same locations. It is also observed that the Eabs capacity of conical frusta having cutouts was found to be non-linearly decreasing with the linear increase in the number, location, shape and size of cutouts. The specimens with a large-size of cutouts had exhibited large deformation over the cutout region that led to an unstable non-linear global buckling during axial compression. Consequently, their Eabs capacity was found to be decreased significantly as compared with the conical frusta with a small size of cutouts. The specimens with the small size of the cutouts exhibited progressive local buckling during axial compression, and they exhibited better energy absorption characteristics as compared with the conical frusta with large size of cutouts.