Improve the Crashworthiness Properties of AA7075 Tube under Axial Impact Loading by Geometrical Change

Thin-walled sections absorb impact energy very efficiently that were considered in the studies in different shapes such as square profiles and cylindrical tubes by various methods as axial collapse or oblique loading. These structures are used in a variety of industries, such as aerospace, railways and road transport, especially to reduce road accident injuries in vehicles. To improve the crashworthiness properties of the structures, the peak load of the absorbers that ultimately shocks the occupant is also of importance. In this study, the cylindrical tubes of ultra-light aluminum alloys AA7075 that have a high-energy absorbing property were used for empirical tests. By considering the relationships of plastic hinge formation in thin-walled sections, a new geometry has been proposed that combined the axial and oblique loadings, then the peak load was controlled completely. By changing the end-cap of the tubes to the nozzled shape, after conducting empirical tests and validation of the finite element simulation results, according to analytical relation, the effect of this change was 30% reduction of initial peak load. Also, the effect of the geometry parameters has been studied. In this regard, to control the initial peak load, acceptable results are obtained. By changing the arc height by double and half, the peak load increased by 15% and decreased by 20%, respectively.