Crash performance of notch triggers and variable frequency progressive-triggers on patterned box beams during axial impacts

Embedding complex sinusoidal patterns on the wall surfaces of box beam impact absorbers has been recently proposed in literature and demonstrated to significantly improve energy absorption capability of box beams during axial impacts. However, no suitable trigger has yet been devised for these absorbers. This paper evaluates the viability of using conventional notch triggers on patterned beams. A progressive triggering mechanism on box beams with embedded patterns is also proposed by a novel idea of using a variable pattern throughout the length of the beam. In the proposed progressively triggered beams, the reaction force slightly increases with each progressive collapse buckle formation throughout the collapse. An extensive FEM study is performed using the commercial pre-processor HyperCrash™ and the commercial explicit FEM solver RADIOSS™. It is found that, as opposed to point triggers, progressive triggering through variable pattern formulation effectively triggers and initiates a more stable collapse. More importantly, progressive triggers cause less stray deformations elsewhere along the beam and are consequently much more robust against global bending.