MODELLING AND ANALYSIS OF DYNAMIC RESPONSE OF OCCUPANT RESISTANCE SYSTEM IN A CAR CRASH

Abstract

In this research work, the seatbelt is modelled for a linear and dynamic condition under side impact situation. A two degree of freedom lumped mass spring is used to describe the detail interaction of occupant and seatbelt. Seat belt modelled using single degree of freedom for frontal impact become redundant for side impact condition. Therefore, such models do not justify the realistic condition of accident, as impact may occur from any direction. To model such situation, a 3-point seatbelt is divided into two parts namely shoulder belt and lap belt. Shoulder belt majorly resists the forward motion of occupant due to impact while lap belt resists the sliding motion in the side directions. The impact may occur either from the far side or from the near side direction. Moreover occupant is free to move in any the direction (i.e. toward right or left). Here, in the proposed model, all these situation is considered and thus shoulder belt is modelled using a single spring to resist forward motion and lap belt is modelled using two springs to resist the side motion in the either direction. Finally the model is simulated for the various other impact condition to find its versatility. An airbag is also modelled using the primary forces on the occupant such as the inertia force due to vehicle deceleration and restraint force due to airbag. After modelling the airbag, the behavior of occupant under impact condition is studied and occupant’s deceleration is computed