This paper describes that a method has been developed to estimate the range of the scatter of Head Injury Criterion (HIC) values in pedestrian impact tests, which could help to reduce the range of the scatter of HIC values by applying the stochastic method for Finite Element (FE) analysis. A major advantage of this method is that it enables the range of scatter of HIC values to be estimated and to explain the mechanics of the behavior.
The test procedure of pedestrian impact allows some tolerances for the resultant conditions of impact such that the distance of actual impact location from the selected point is within 10 mm and the impact velocity is within ±0.7 km/h [1]. A HIC value calculated by impact simulation under a deterministic impact condition with the nominal input data does not necessarily represent the variation of measured data in impactor tests. However, it is difficult in physical tests to estimate the range of the scatter of the HIC values, which could vary as a result of variation in thickness of products, gap, test conditions and so on. Few studies have described methods to handle the range of the scatter of HIC values in impact tests.
On the other hand, the hood inner shape is a very important design factor for pedestrian head protection to reduce the HIC values. By using an optimization technique that has been developed by this study for the section geometry of the hood inner frame, a certainty of achieving the target HIC value has become highly probable in the case of certain hood impacts.