The reconstruction of a road accident can be treated as the resolution of an “inverse problem” in mechanics using analytical or numerical models. In the road accident reconstruction research, an assumption is often made that a predominant part of the energy lost during vehicle collisions is consumed by permanent deformation of vehicle components. Other parts of the dissipated energy can be ignored due to their insignificant amount. In this article, this assumption will be verified for the front-to-side collision of passenger cars. The main objective of this paper is to determine the important components of the energy balance dissipated during the collision. These components were determined on the basis of experimental results, which included three crash tests with a front-to-side collision of motor vehicles of the same make and model, with the right-angle impact of one car against the side of another. The results of experiments were used to construct the model of the dynamics of the motor vehicle collision. The model was then used as a basis for the determination of the forces, displacements and velocities during vehicle collision. The above made it possible to determine vehicle force/deformation curves and then the key components of the dissipated energy in function of the duration of the contact phase of the vehicle collision. Based on the results of the model and crash tests, conclusions were formulated that provide an important insight into the reconstruction of the front-to-side collisions of motor vehicles.

The article is the third one of series of the authors' SAE Papers (other two: 2002-01-0619, 2005-01-1261) concerning modeling and simulation studies of strong non-linear processes in a car steering system. Here, attention is concentrated on the stick-slip phenomenon caused by the dry friction. The studies focus on the influence of different kinds of friction force characteristics (from Coulomb-type to Stribeck-type) on the steering system dynamics. We present mathematical models and simulation studies of the stick-slip phenomena in a typical steering mechanism. The simulations concern the open loop tests (sinusoidal input and combination of ISO maneuvers) and provide materials for a sensitivity analysis (different friction models and vehicle motion conditions). The presented models, example simulation results and conclusions may be interesting not only for specialists working on the car steering system problems but also for researchers working on the non-linear dynamics in multi-body systems.

The paper presents mathematical models and simulation studies of a car handling with regard the freeplay (backlash, clearance) and friction (viscous and dry friction with stiction) in a steering system. For description of these principal non-linearities in equations of motion a new method (basing on two piecewise-linear projections luz(…) and tar(…) as well as their special mathematical apparatus) has been used. Simulation models describe lateral dynamics of a passenger car with typical steering system including the freeplay and friction. Three types of open-loop car tests (parking like, lane change and sinusoidal test) have been used in the simulation. Some examples of results are presented. They show a sensitivity of car dynamics processes on the freeplay and friction in the steering system.

This paper continues a subject-matter of simulation studies of a car motion with inclusion of freeplay and dry friction, but in comparison to our SAE paper 2002-01-0619 (concerning to mechanical 2WS steering systems) in this paper also power assisted 2WS as well as 4WS steering systems are also the subjects of studies. The paper presents mathematical models and simulation studies of a car handling with regard to freeplay and friction in steering system. The models are customizable for several structures of steering system. Descriptions of freeplay and friction non-linearities base on special piecewise-linear projections. Elaborated models are used for digital simulation and sensitivity analyses concerning typical open road tests of passenger car. The paper describes these investigations and presents exemplary results. They show complexity of stick-slip phenomenon and car dynamics sensitivity on the freeplay and friction in the 2WS and 4WS structures. The presented models and results may be interesting and useful for researches working on non-linear dynamics and problems of vehicle active safety.