Frequency embedded box beam crash absorbers under oblique impacts

Among recent developments in automotive crash absorbers, box-section thin-walled beams with embedded sinusoidal patterns on wall surfaces have been proposed in literature and have shown promising results under axial impacts. To cater for real-life accident situations, an efficient automotive frontal crash absorber must be able to absorb high amounts of impact energy not only in the axial direction, but also during misaligned and oblique impacts. The purpose of this paper is to study and analyse the performance of beams with embedded sinusoidal patterns subjected to oblique impact loads which exert both an axial force and a bending moment. Two types of triggering mechanisms for these beams which have been recently proposed in literature, i.e. conventional notch triggers and progressive frequency triggers have been numerically studied under oblique impacts in this paper. The results obtained are compared with a plain reference specimen using the critical angle criterion. It is observed that patterned beams with notch triggers are only marginally better in oblique impacts as compared to plain beams with the same triggers. Progressive frequency triggers on the other hand, greatly improve the beam's performance under inclined tests.