Numerical simulation of impact behaviour of multi-cell thin-walled structures with configurable thermal trigger design

Abstract

This study presents numerical results for thin-walled octagonal structures subjected to impact loading and analysed for different section and trigger solutions. Triggers are usually considered in crashworthiness applications as geometrical features introduced to promote crash initiation, reduction of peak loads and promotion of efficient energy absorption deformation modes. In this study, the improvement potential of the introduction of thermal triggers is analysed. These are obtained, in concept, through localized heat treatment in selected aluminium alloys wherein a softened region works as trigger area. The main objective of such approach is to absorb impact energy in a progressive and controlled manner with higher efficiency and moderate peak loads. In the present implementation, two different alternatives for section design complimented with geometric and thermal trigger options are analysed. The application is studied recurring to numerical simulation of representative base octagonal geometry and an alternative complex multi-cell section design that is suitable for extrusion manufacturing process. The alternative geometry is allowed for significant improvements in specific absorbed energy. Both geometric and thermal trigger solutions are allowed for reduction in peak loads while maintaining or improving energy absorption parameters.