MODELING OF AN INNOVATIVE FRONTAL CAR STRUCTURE: SIMILAR DECELERATION CURVES AT FULL OVERLAP, 40 PER CENT OFFSET AND 30 DEGREES COLLISIONS

摘要

The improved frontal crashworthiness of cars necessitates totally new design concepts, which take into account that the majority of collisions occur with partial frontal overlap and under off-axis load directions. Realistic crash tests with partial overlap have shown that conventional longitudinal structures are not capable of absorbing all the energy in the car front without deforming the passenger compartment. The reason for this is that the structure of the longitudinal members is specifically designed for meeting the more relaxed requirements of the compulsory full overlap test, in which both longitudinals are loaded axially. Increased protection for the entire collision spectrum can be obtained by a frontal structure consisting of two special longitudinal members, which combine a higher bending resistance without increasing the axial stiffness. In addition the longitudinal members are supported by a cable connection system for symmetric force distribution. If only one of the longitudinal members is loaded during a partial overlap crash, the cable connection system will force the other longitudinal member to crumple as well. This results in normal programmed energy absorption. With this revolutionary concept a complete frontal car structure is designed with almost the same stiffness for all overlap percentages and impact angles, resulting in one crash pulse which can be optimized for minimal injury of the occupants. The influence of various crash situations on the amount of energy absorbed by this total vehicle model and specified for important structural parts will be demonstrated by means of numerical simulations. Also important construction details, necessary for a well functioning of the designed cable supported frontal car structure, will be mentioned.