Self-protection of car occupant is a crucial topic all over the world. Restraint systems have to be designed to protect various sizes of occupants involved in several type of crash and therefore several types of crash pulses. Considering the additional constraints applied on the car design these days (CO2 emission and therefore mass reduction, or reduction of front overhang) improvements and optimisation on the car structure are needed to better control the pulse. Otherwise, if the pulse is too severe, it will be difficult to design adequate restraint systems.
PSA Peugeot Citroën launched a large programme with physical crash tests and modelling on the full-width rigid barrier test. This was applied to several types of cars and car architecture (small family, large family cars). The 8 x 16 (128) load cell wall was used in each crash test to get a lot of measurements essential for the correlation of the numerical models.
The physical crash tests permitted to identify the contribution of each load path on OLC and spüll (pulse severity). The load paths analysed are the subframe, the side members, the engine, the upper structure of the body in white... These tests were used to create correlated numerical model of each car size or architecture. Then, correlated crash simulations were used to carry out a parametric study via changing the impact speed, mass, subframe stiffness, longitudinals stiffness, engine size and position. This parametric study helped in defining the major contributors for each car size or architecture.
As expected, the influence of car mass and test velocity were highlighted to have a similar equivalent consequence on the severity of the crash (OLC and Spüll severity) whatever the car size or architecture. But for other parameters such as subframe stiffness, longitudinals stiffness, engine size and position, it was surprising to see that their influence is not as high as expected.
One last surprising result is to see that front end internal components have a low influence on the pulse severity with respect to the stiffness of the components in charge of transferring the load from the front end to the cockpit and subframe.