Besides functioning as an engine compartment cover, the hood of modern vehicles can also help manage the impact energy of a pedestrian's head in a vehicle-pedestrian impact. However, a hood's ability to absorb impact energy may be impeded by the proximity of the hood to components packaged inside the engine compartment, i.e., by its underhood clearance. For example, for a given hood design, the hood's ability to absorb impact energy through deformation can be significantly reduced when the hood and engine block are in close proximity. Therefore, a large underhood clearance would be preferred for pedestrian protection. However, it could negatively affect driver visibility, as well as a vehicle's aerodynamics and aesthetic appeal. This paper presents a sandwich hood design that has a potential to improvethe hood's ability to absorb the impact energy of a pedestrian's head with a relatively small underhood clearance. Using nonlinear finite element and the EEVC headform impactor models, a design analysis was conducted withan underhood clearance target of 60 mm and 75 mm for the child head impact area and the adult head impact area, respectively. A set of design parameters of the sandwich hood was optimized. The analysis shows that out of the 12 impact points covering the main hood area, about half of the impact points achieved Head Injury Criterion (HIC) values less than 800 and the others yielded HIC values between 800 and 1000. The full text of this papermay be found at: http://www-nrd.nhtsa.dot.gov/pdf/esv/esv21/09-0356.pdf For the covering abstract see ITRD E145407.
Samenvatting