Identifying Vehicle and Collision Impact by Applying the Principle of Conservation of Mechanical Energy

Abstract

Various methodologies and tools applied to identification of vehicle and collision impact seek to present more and more accurate solutions to reproduce, restore, recreate and investigate the casualty. Modern computer technology and software provide the tools to solve specific problems developing mathematical modelling of complex mechanical systems involving vehicles and other objects in a road accident. Scientists generally utilize the Standard Test Method for Impact Testing calculating the energy of deformation of both vehicles, however, one of its limitations is the evaluation of the kinetic energy of the vehicles in post-collision taking into consideration vehicle rotation and linear displacement. To improve the analysis, dynamic traffic simulation is used, taking into account the variations in the coefficient of friction, suspension elasticity and damping. The proposed method is based on a system of two equations derived from two principles: the Principle of Conservation of Mechanical Energy and the Principle of Conservation of Momentum in the impact phase. The new approach is conducted on mathematical modelling and computer simulation of vehicle motion after the impact, wherefrom the linear and angular velocities are analysed. This is achieved by the numerical solution of the differential equations of motion of the cars after the impact, and the given initial conditions that satisfy the solution are used to solve the system of equations. The main findings of the study can be grouped as follows: 1) The positions of the vehicles prior to the moment of first impact and the post-impact orientation of velocity vectors are more precise. 2) The variability of the tire-road friction coefficient is taken into consideration. 3) The value of coefficient of restitution according to Newton’s theory of impact is unnecessarily determined.

Impact of Inertial Forces on Car Occupants in a Vehicle-Fixed Barrier Front Crash

“…The aim of the present paper is to design and come up with a dynamic model of a vehicle-fixed barrier front crash in three separate motion phases and to investigate the inertial forces' impact on occupant behavior in the passenger compartment. While predicting dynamically changing values and inertial forces, the impact of passive safety systems has been also determined [7][8][9][10][11][12].…”

An Update on the Momentum 360 Method of Vehicle Impact Reconstruction through 3D Modeling and Computer Simulation

“…In order to determine the quantities involved in expressions ( 8) and ( 9), mechanomathematical modeling and computer simulation of the movement of vehicles after the impact are applied [2,[14][15][16]. According to the available traces and findings in a first approximation, the position of the cars at the moment of impact is selected, corresponding to the phase of maximum deformation, respectively, when forming the maximum impact force.…”

“…We have been working for a long time on a new approach, which is described in [14][15][16]. In [14], a research method is proposed, which is based not only on the theorem for the change in the amount of movement of each car for the time of the impact but also on the theorem for the change in the kinetic moment.…”

“…In [14], a research method is proposed, which is based not only on the theorem for the change in the amount of movement of each car for the time of the impact but also on the theorem for the change in the kinetic moment. The movement of the cars after the impact is identified by a spatial dynamic model and computer simulation [15,16].…”

Systems Engineering Information Model of Vehicle-Pedestrian Collisions

“…10. On the other hand, it is generally assumed that the steady motion of the pedestrian is according to the dependence (9) 𝐿 p = 𝑉 p . 𝑡 p , where: 𝑉 p is the pedestrian velocity of the center of mass; 𝑡 pthe pedestrian time of motion; 𝑎 pthe acceleration at the start of the pedestrian.…”