Energy absorption behaviors and optimization design of thin-walled double-hat beam under bending

Thin-walled hat-shaped structures have gained growing interest attributed to their excellent performance and wide application in the vehicle industry. However, few systematic studies have been conducted on the design of hat-shaped structures with irregular sectional shapes. In present research, thin-walled double-hat beam (DHB) with different sectional configurations under dynamic three-point-bending are investigated by performing numerical simulations. First, the energy absorption mechanism of DHB is explored, and then an in-depth parametric study, including shape parameters o, p, q and thickness parameter k, is performed. The results show that all DHBs deform in bending with indentation mode. And compared with single-hat beam (SHB), the DHB has a significant advantage in loading capacity. When the design space is held fixed, the shape parameter o has the greatest influence on the bending behaviors of DHB, followed by parameter p, while parameter q has the least influence. In addition, it is also found that a larger thickness of the top hat leads to the increase of the SEA and PCF and the decrease of the hammer displacement. Finally, a multi-objective optimization based on lower confidence bound matrix (LCBM) criteria is conducted to determine the optimal design of DHB. The numerical results of the optimal DHB suggest that increasing the initial impacting velocity will make the SEA and PCF increase while make the displacement decrease.