Evaluation and Research of Vehicle Body Stiffness and Strength for Car to Car Compatibility 2003-01-0908
In a CTC (car to car) crash, interaction between two vehicles is quite important. Interaction is primarily described by the contact area between two vehicles but interaction force (impact force) is also important for the entire crash phenomenon. In a frontal crash, impact force is resisted by the body structures, engine block, and tires. The resultant share of energy absorption, as well as the magnitude of body deformation, is greatly affected by the force profile. It is desired, therefore, to evaluate those factors of vehicle bodies in order to achieve CTC compatibility. There are some technical obstacles, however, in measuring those factors in testing. Impact force, for instance, cannot be measured directly in a CTC crash test unless load cells are installed in body frames. It is also difficult to analyze body deformation in a CTC crash test because both vehicles are moving. This study focused on methods to evaluate impact force and resultant deformation in a CTC frontal crash test, and proposes possible indicators to evaluate the interaction profile of the subject vehicle. First, a method has been developed to estimate the impact force and body deformation in a CTC test based on vehicle deceleration. The adequacy and consistency of the method were verified by using the principle of conservation of energy. By analyzing the estimated force-deformation curves, a possible mechanism in energy sharing between two vehicles was explained. Based on the mechanism, it was proposed to evaluate the interaction profile of the subject vehicle in a single vehicle test. The profile was well characterized by the stiffness of the front-end and the strength of the body. It was found that the interaction profile changes in CTC crashes. Barrier configurations and evaluation methods was also discussed to assess stability of the force profile.