Loreta Simniceanu

Fatigue Analysis for the Primary Shaft of a Mechanical Gearbox of a Car

The paper presents the fatigue analysis of the primary shaft of a mechanical gearbox with three axles for a SUV car. For the analytical fatigue calculation the Soderberg method was used for finding the global fatigue safety factor. The numerical fatigue analysis was performed using Ansys software for the maximum load case of the primary shaft using Soderberg mean stress theory from Ansys Fatigue Tool.

Mathematic Model for Analysing the Dynamic Behavior of a Vehicle in the Field of Chaotic Movements

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.

Influence of Carburizing Time of Iron Powder Samples on the Carbon Content after Gas-Carburizing - Sintering Process

The paper presents experimental results of the influence of carburizing time of iron powder samples on the carbon content in the sample’s depth by layers, subjected to a GCS (Gas-Carburizing Sintering) method. Sintered steel elaboration by GCS method consist of enriching the Fe powder with carbon in gas medium in a single thermal cycle including the carburising operation followed by sintering, thereby achieving the sintered carbon steel. Numerical simulations were made using Abaqus/CAE software for mass diffusion analysis in order to find the appropriate diffusion coefficient value.

Analysis about Influence of the Mechanical Vibrations on the Function of Shaping-Machine

In this paper, it is analyzed the effect of shocks on the kinematical parameters, linear and angular courses and accelerations, of shaping-mechanism at the function with shocks. In this scope, with experimentally recorded data it is plotted the diagram of variation (in time) of mentioned parameters obtained for the different regimes of processing for the component elements of the shaping mechanism in the case of function with shocks. It is made a comparative analysis of the laws of variation for kinematical parameters obtained for the different regimes with shocks in the conditions imposed, resulting, finally, the effect of shocks.

Nonlinear differential system applied of a mechanical plan model of the automotives used for the nonlinear stability analysis

This paper proposes a plan mechanical model for the vehicles with two axles, taking into account the lateral deflection of the tire. For this mechanical model are determined two mathematical models under the nonlinear differential equations systems form without taking into account the action of the driver and taking into account. The analysis of driver-vehicle system consists in the mathematical description of vehicle dynamics, coupled with the possibilities and limits of the human factor. Description seeks to emphasize the significant influence of the driver in handling and stability analyzes of vehicles and vehicle-driver system stability until the advent of skidding. These mathematical models are seen as very useful tools to analyzing the vehicles stability. The paper analyzes the influence of some parameters of the vehicle on its behavior in terms of stability of dynamic systems.

THEORETICAL AND EXPERIMENTAL RESEARCH ON THE TORQUE VARIATION OF THE BODY PASSING THROUGH LANDMARKS

This paper presents analytical expressions of the vertical reactions of the car wheels. These mathematical expressions take into account the inertia forces which are expressed by two main components of acceleration of the reference system chosen. The vertical reactions of the wheels and the torque acting on the body are determined by analytical and experimental methods in case of movement among the landmarks when the vehicle speed is 25 km/h. Theoretical results are compared with data obtained from experimental tests. Approximation values of the two data sets validates the theoretical model adopted.

The Simulation of the Vehicle Motion Based on Generalized Mathematical Model of Vehicle Motion

The paper presents a numerical simulation of the motion of a car based on a mathematical model that takes into account the lateral and longitudinal forces from the contact stain, forces given by suspension system, aero-dynamical force and weight force. In the paper is also presented the mechanical model for a vehicle upon which it was built a mathematical model. Considering the mechanical model and the mathematical model vehicle dynamics numerical simulations were made using the computing environment Matlab. Numerical simulations presented in this paper are obtained at relatively constant speeds of the car, taking into consideration a sinusoidal variation of the steering angle of the wheel: the variation of steering angle was with amplitude equal to 5° and period equal to 3 s. The results refers to the linear and angular movement and velocity, linear and angular accelerations, deformations of the tires, lateral forces.

The Modal Analysis for the Helicoidally Spring of the Macpherson Automotive Suspension

The paper presents a modal analysis for the helicoidally spring from the compound of the Macpherson automotive suspension. In the first part, it is described the device used for the experimental study and then, the measurement equipment used, too. First of all, it is represented the kinematical scheme and 3D representation for the device mechanism included the helicoidally spring necessary to the dynamic analysis. After this, are made some measurements of different parameters of the helicoidally spring obtaining the experimental values which are compared finally with the simulation results.

Theoretical and Experimental Researches Regarding the Influence of the Suspension Car Stiffness on the Dynamic Behavior of Vehicles

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.

Design Optimization of the Rear Wing of a Sports Car

In this paper it is presented the design optimization of the rear wing of a sports car. The wing profile was parameterized with three variables, the angle of attack was the fourth variable and the objective function was to minimize the lift over drag ratio. Three virtual models were considered: a model without rear wing, a model with a rear wing with initial profile and position and a model with optimized rear wing. For these three models the drag and lift coefficients were calculated for comparison along with drag and lift forces.