Abstract
In the impact models for determining the performance criteria of protection from head injury (HIC and maximum deceleration), it is essential to know the initial velocity of the occupant or dummy head impact with the dashboard. This parameter depends on the kinematics and dynamics of the occupant in the car interior which is linked to a number of factors related to automobile (frontal stiffness, characteristics of restraint systems, compartment geometry, etc.), to occupant (anthropometric characteristics - masses and dimensions, joints stiffness), as well as to frontal impact speed of the automobile. The paper presents the modeling of these phenomena using multi-body systems theory: the establishment of generalized coordinates, description of kinematic constraints, determination the equations of motion of the system by using Lagrange multipliers. These are integrated numerically using Matlab sequences and then is determined the head impact velocity with the dashboard. Numerical results are presented, obtained by considering the standard speed frontal impact and using anthropometric characteristics of frontal impact standard dummy Hybrid III 50%.
Keywords: multi-body system, generalized coordinates, kinematic constraints, Lagrange multipliers, head impact velocity