Automotive Science and Engineering

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This paper focuses on the optimization of initiating dimensions of groove bearing in association with de- sired design of vehicle’s front structure which is made up of low carbon steels in the case of frontal collision. Axial bearing analysis is done numerically using nonlinear finite element code LS-DYNA. In this analysis, changes of two main parameters including measure of energy absorption of structure and maximum force of structure collision are being considered. Square structure profile is being chosen and the groves are placed on two opposite sides. Tests of collision simulation are performed for steel samples and then a mathematical equation is derived next, the initiating dimensions are optimized using Genetic Algorithm. Desired case for design of this structure part is the one which provides maximum energy absorption measure and minimum collision force in this paper, the most optimal case is an initiator with groove depth of 4.5 mm and radius of 10 mm.

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In this article, vehicle cornering stability and brake stabilization via bifurcation analysis has been investigated. In order to extract the governing equations of motion, a nonlinear four-wheeled vehicle model with two degrees of freedom has been developed. Using the continuation software package MatCont a stability analysis based on phase plane analysis and bifurcation of equilibrium is performed and an optimal controller has been proposed. Finally, simulation has been done in Matlab-Simulink software considering a sine with dwell steering angle input, and the effectiveness of the proposed controller on the aforementioned model has been validated with Carsim model.

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Excitations from the vehicle engine and the road surface cause vibrations in the exhaust system and the exhaust noise and vibrations are transmitted through the vehcile body and structure to the cabin, causing distractions and discomfort for the driver and passengers. In this article the method of average driving degrees of freedom displacement (ADDOFD) has been used to determine and optimize the location of suspended hanger points. Based on this approach, a model of car exhaust system is used using ANSYS software to optimize the hanger installation points for reducing vibration and to select the best positions for these points. The optimum hanger positions must have a relatively lower ADDOFD value compared to adjacent points. Then the static and dynamic analysis of the exhaust system is illustrated and finally on the basis of the above analyses, the position is chosen for the exhaust system hangers to reduce the transmission of noise and vibrations into the car cabin. Results indicate that optimization of the locations has resulted in a significant decrease in hanger loads, significantly reducing the vibrations transmitted to the vehicle cabin and increasing the life of the rubber hangers. This study has practical significance for reducing the vibration of automobile exhaust systems and the vehicle cabin.

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Brake system performance significantly affects safety, handling and vehicle dynamics. Therefore, the objective of this paper is to discuss brake system characteristics and performance and component design parameters. We perform a detailed study of a specific brake system designed for Mercedes-AMG SLC-43, considering component design parameters and operational points, and finally conduct the vehicle braking system layout design. To this end, brake force and torque calculations and power dissipation modelling is performed. Then, ventilated brake discs are designed for the front and rear brakes. A main goal of the present article is to apply digital logic method to the material selection procedure among the candidate material proposed for brake components and rank the materials according to performance indices. The performance indices of five candidate materials were calculated and compared to select the best option for application in the brake disc. Finally, the calculations of the brake pedal, booster, cylinder, hoses and tubes are obtained.

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In this paper, the optimization of the suspension system’s parameters is performed using a combined Taguchi and TOPSIS method, in order to improve the car handling and ride comfort. The car handling and ride comfort are two contradictory dynamic indices; therefore, to improve both car handling and ride comfort, there is a need for compromising between these two indices. For this purpose, the criteria affecting these two are first identified. The lateral acceleration and the body roll angle were used to evaluate the handling, and the RMS of vertical acceleration of the vehicle body was used to evaluate the ride comfort. The design factors including stiffness of springs and damping coefficient of dampers in the front and rear suspension system were also taken into account. On this basis, the results obtained from the vehicle’s motion in the DLC test were evaluated in the CarSim software. Then, the ideal tests were identified using the combined entropy and TOPSIS technique; this method has been proposed for managing the handling and ride comfort criteria. Finally, the optimal level of the suspension system’s factors was extracted using Taguchi method. It is evident from the results that, for different speeds, the body roll angle was improved up to 6.5%, and the RMS of the vertical acceleration of the vehicle body was optimized up to 4% to 7%.

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