Development of Crash Performance of the Front Bumper System by Adopting Target Cascading Scheme 2018-01-1054
A practical application of the Target Cascading scheme for the development of the front bumper system of a passenger car is investigated in this paper. The Target cascading in the crash performance of vehicle developments requires a systematic approach, propagating from the desired vehicle-level performance target to appropriate specifications in a system- and/or component-level. To define the values of design specification in the front bumper system, three physical variables are derived by analyzing the vehicle-level performance of the frontal impact under the high-speed (56kph NCAP frontal impact) and the low-speed (15kph RCAR structural test) crash conditions.
To ensure the sequential deformation in the high-speed frontal impact and to minimize the damage of the structural member in the low-speed crash, the maximum collapse load of a crash box should be smaller than the collapse load of a front side member. Under the low-speed crash condition, the maximum dynamic displacement of a front bumper beam should be smaller than the distance between the bumper beam and a cooling module. In addition, the deformation energy of the crash box should be greater than the initial kinetic energy of the vehicle under the low-speed crash condition, so as to prevent the damage of the structural part of the vehicle.
Within the feasible design space fulfilling these constraints, the system-level crash performance of the front bumper system can be developed from the early design stage of the vehicle. The effectiveness of the Target Cascading scheme is shown by applying the proposed design process on the front bumper system of a new vehicle development program.