Energy absorption of an egg-box material

Abstract

Conical frustra made from leaded gun-metal have been compressed axially. Collapse is either by a travelling plastic hinge or by tearing. An analytical model is developed for the travelling plastic hinge in a rigid, ideally plastic solid; its predictions are compared with the observed response, and with those of an axisymmetric ÿnite element analysis. The travelling hinge mechanism is also observed in the compressive collapse of an egg-box material comprising a square array of conical frustra. Collapse mechanism maps are constructed for the egg-box material, and they show the regimes of dominance of elastic buckling, material tearing and the travelling plastic hinge. The maps are useful for selecting egg-box geometries that maximise the energy absorption per unit mass at any prescribed value of collapse stress. The optimisation indicates that the egg-box material has a similar energy absorption capacity to that of hexagonal honeycombs and is superior to that of metal foams. ?

Simplified analytical methods for the crashworthiness and the seismic design of lock gates

“…This assertion means that developing a theoretical solution to the present problem is not straightforward. Of course, one may argue that the concept of moving hinge has been successfully applied by many authors when dealing with plated structures, such as Simonsen [140], Amdahl [8] or Deshpande and Fleck [41] amongst others. However, it is worth bearing in mind that all these developments were based on the hypothesis that the bending moment and the axial force were decoupled within the yield criterion, i.e.…”

Low strain rate compressive behavior of high porosity closed-cell aluminum foams

“…Whilst sponge, polymer foam, airbag, soft paper and so like are commonly used to protect objects/structures under low failure limitation and weak impact energy conditions [27][28][29], wood or its sandwich structure is mainly designed as a special structure or box to package medium or large sized facilities [30,31]. However, the energy absorbing capabilities of these materials become insufficient when the imposed impact energy is intense, such as the landing of recovery capsule with astronauts or airdrop of heavy civil/military facilities.…”

Large deflections of metallic sandwich and monolithic beams under locally impulsive loading

“…The subsequent governing equations derived here for the motions of the sandwich beam can be shown to the transient solution of the sandwich beam impulsively loaded over a central patch in small deflection. In the dynamic response analysis, we will follow and extend the previous analysis [9] for the monolithic beam in small deflection to that of the sandwich beam at the end stage of core compression: it is assumed that the displacements occur only in the transverse direction and the shear effect is neglected, respectively. The motions of the sandwich beam are then split into three sequential phases based on a trial velocity field.…”

“…As a new member in the family of blast-resistance structures, metallic sandwich beam, plate and shell with various lightweight cores have been paid great attentions [1][2][3]. Several kinds of metallic cores are developed, such as metallic foams [3][4][5], lattice materials of pyramidal and tetrahedral arrangements [6][7][8], egg-box [9] and woven material [10]. Due to the excellent resistance to blast loading compared with solid monolithic structures with equal mass, sandwich structures possess potential engineering applications, e.g.…”