Deformation pattern and energy absorption characteristics of a four-tube nested system under lateral and oblique loadings

The present research introduces a new configuration of thin-walled nested tube structure as a possible energy absorber subjected to lateral compression. The nested-tube structures were configured in a system comprising of four tubes arranged in different ways. All the nested systems were quasi-statically compressed in the lateral direction on a universal mechanical tester to obtain their energy absorption characteristics. Two modes of deformation, asymmetric mode referred to as “overlap” and symmetric mode referred to as “side-by-side”, were identified in the four-tubes nested systems. The specific energy absorbed by the inverted four-tubes systems was larger than that of the three-tubes nested systems by 20%. The experiments were also modelled using ABAQUSv6.13. Good correlations were obtained for the deformation modes and the corresponding lateral crush force-displacement. The validated model was thereafter used in parametric study to investigate the effectiveness of the nested system under two different boundary conditions; rotation of the specimen by different angles and impact at different angles.