Applied Mechanics and Materials Vol. 822

Abstract: The aim of this paper is to present a comparison between the theoretical frameworks for the simulation of the movement of a vehicle in the linear case, one obtained using the exact solution of the equation of motion, and the other obtained with the solutions given by using homotopy analysis methods. Homotopy analysis methods allows the qualitative analysis of the dynamical system which is associated to a vehicle linear motion case, concerning the parameters involved in this equation of motion, for example, gears stages, adherence coefficient, aerodynamics coefficient, etc.

Abstract: The paper presents a possible practical application based on two 6R overconstrained mechanism, more precisely 6R Wohlhart overconstrained mechanism. Two of these mechanisms are put in a mirror position, in order to obtain a car jack. The mechanisms are disposed in other position than the original one, three non-adjacent joints being constrained to remain in a fixed plane.

Abstract: The steering system of a vehicle consists of two subsystems: the steering linkage, which correlates the steering angles of all the steerable road-wheels, and the actuation subsystem, which connects the driver's steering-wheel with one mobile element of the steering linkage. In the case of the vehicles with rigid steering axles, the most used steering linkage is a simple mechanism, composed of four bars (one being the base) connected with four joints. However, the design of the steering linkage isn't an easy task, mainly because the wanted correlation function is difficult to specify and because the packaging restrictions are very important. The present paper shows a possible approach to define the optimization function and the dimensions of the correlation steering mechanism.

Abstract: The present paper aims to identify the dynamic feedback of a steering mechanism in a vehicle, mainly under stationary conditions. The modal – dynamic analysis was established by applying two methods, the experimental method and the finite element modelling. For the experimental results concerning the proper frequencies of the steering box and of the tie rods assembly, a method of excitation with a measured and controlled linear momentum (impulse) force was implemented. The modal-based analysis aimed to measure the proper frequencies and the proper vibration modes. Therefore, the harmonic analysis obtained by using the finite element method is applied in order to determine the frequency variation diagrams of some nodes displacements, from some of the elements of the mechanism. Furthermore, the applied analysis seeks to identify the critical frequencies and the corresponding phase angles by investigating the displacements, the strains and the stresses of the mechanism elements, which correspond to critical frequencies and phase angles.

Abstract: In this paper the authors present the results of theoretical and experimental research in order to optimize suspension rigidity in case of Daewoo Nubira vehicle. The paper presents the mathematical model obtained by assimilating car with a dynamic system with 5 rigid solids with elastic and viscous linking between them. Theoretical results obtained based on this model and the experimental results are presented, and it is presented a solution to optimize suspension in order to remove the negative effects observed driving on gravel runways or damaged runaways. Theoretical results, compared with the experimental ones, allow us to say that it is possible to optimize suspension by analyzing specific parameters equivalent mathematical model.

Abstract: Abstract: The paper presents the possibility of generating a complex kinematic model that can be used to simulate various types of semi-independent rear axle used in the design of new cars. This model allows quick check for such axles of the interference that may occur in their functioning on the car. For application it was used the CATIA V5 software.

Abstract: Based on the ISO standards, that give the geometric definition and interpretation of tolerances, this paper propose o representation and interpretation for the geometric tolerances applied to the real pieces. In order to do that, based on the 2D layout of the part, a 3D model of the real piece (skin model) is developed. Then, the datum surface and tolerance zone are applied and explained.

Abstract: This paper presents a plane equivalent model of the vehicle and its mathematical model attached. The mathematical model is under a form of four differential equations system of order 1, in order to analyze the dynamic behaviour of the vehicle movement. Its goal is to determine the ranges of speed for that movement is stable or is unstable, or having chaotic character. The authors consider being necessary to know the conditions in which movements occur chaotic movements to avoid them through constructive or functional limitations. Speed ​​values ​​are identified for the behaviour of the system is placed in the quasiperiodic movements field or exceeding these movements trough chaos and are highlighted by the specific instruments: the trajectories in the phase plane, Poincare section and power spectra.

Abstract: In this paper is presented the development of a wheelchair intended to be use by the people with locomotors disabilities. They are presented various solutions of kinematics schemes proposed to be implemented as a mechanical transmission for the wheelchair. The developed wheelchair integrates a mechanical transmission which allows the movement in a straight line, and also in cornering. The mechanical transmission implemented contains a bevel gearbox. The purpose of the bevel gearbox is to multiply the moment transmitted to the motor wheels for movement on uneven terrain. They are presented aspects concerning the design of the wheelchair frame an of implemented bevel gearboxes.