Motor vehicles on the market have been required to undergo the pedestrian head protection test since 2004 and engine-hoods need to meet the required standards for pedestrian head protection performance in addition to primary performance. The engine-hood of motor vehicles is evaluated by the pedestrian head protection performance test according to the Head injury criteria (HIC) which is calculated by 3-dimensional acceleration generated against the head. All car manufacturers are recently required to develop the engine-hood for the purpose of protecting pedestrian heads. It is important to control the acceleration time history at the initial stage and late stage for pedestrian head protection. The engine-hood for pedestrian head protection needs to control local rigidity and whole rigidity by just one structure. To solve this problem, we focus on inner panels which have a dominant role in absorbing energy. This study also aimed to evaluate that impact characteristics of inner panels adopting ZETA-stiffened panels improve pedestrian head protection by numerical analysis. As a result, it was found that the inner panel could complement the performance of outer panel. In addition, the ZETA-stiffened panel structure helped control the amount of displacement and it was effective in reduction of HIC.
