Numerical investigation into the collapse behaviour of an aluminium egg-box under quasi-static loading

Abstract

A wide range of energy absorbing structures and geometries have been researched upon and proposed for safety applications, particularly for automotive safety. Aluminium pressload panels are being researched to explore the energy absorption capabilities of the unique geometry so as to utilise them for automotive vehicle structures as energy absorbers. Preliminary research outputs describing the deformation of the egg-box under quasi-static loads were presented and the structure was proposed for a commercial vehicle front by the authors. Also the underlying reasons for the specific mode of deformation of the geometry were experimentally explored and research results were published. The current work serves as an extension to the recently published work as a numerical study using HYPERMESH and LS-DYNA software packages and validation against the experiments was carried out. The panel was experimentally tested to further explore the deformation pattern of the egg-box geometry. The effect of natural restraint that occurs due to the existence of the surrounding finite number of peaks/frusta and the flanges surrounding each frustum that comprises the panel's geometry was investigated as three separate cases: (1) single peak with free-free edges, (2) single peak with constrained edges and (3) single-peak in-situ, all tested quasi-statically. The egg-box geometry was modelled numerically and the simulated results were in good agreement with those from the experiment. The specific energy absorption of the single peak cut from the panel and edges left unconstrained was 300 J/kg and that with constrained four corner edges was 700 J/kg. The single peak in-situ absorbed as high as 775 J/kg of specific energy, which is nearly 2.6 times greater than that of for a single peak with free-free edges. This indicates the positive influence of the natural occurring restraint within the egg-box panel geometry to its energy absorption capability.

Keywords:

• crashworthiness
• energy absorber
• quasi-static
• egg-box
• aluminium panel
• finite element (FE) modelling

Acknowledgements

The authors would like to thank EU APROSYS project for financing this research work and Cellbond Composites (UK) Ltd for supplying the specimen material.