Search Results

This paper provides a theoretical explanation for the reported car size effect in frontal collisions. The frontal crush behaviour of the car population is examined arid shows that the specific energy absorption per unit mass propel-ties of the car population are independent of car size. Examination of single car crashes and car to car collisions in this context shows that the mean deceleration experienced by a car is inversely proportional to car length, is related to the square root of the collision closing speed arid to the inverse of the fourth I-oot of mass ratio and of crush depth. It is hypottiesised based on the Gadd severity index, for any specific car population and given degree of occupant protection within this population that Relative Injury Risk is proportional to the 2.3 power of mean deceleration.

This paper examines the deformation patterns of car fronts involved in both narrow object and offset frontal collisions and shows that the car side or sides not involved in direct crushing are pulled towards the centre of the car about a hinge point located 0.32 of the overall length to the rear of the front of the car. This corresponds with the location of the front of the car door/front bulkhead. The resulting crush profiles can be represented by simple geometric shapes. These are combined with a previously derived Specific Energy Absorption representation for the overall car population and applied to narrow object and pole impacts with car fronts. When compared with 19 staged pole impacts carried out by NHTSA high correlation is obtained and it is shown that the 95% confidence limits for calculated speed is +/- 9 km/hr.