Automotive Science and Engineering
Volume:5 Issue: 1, Winter 2015

This paper introduces a technique that relates the coefficients of the Magic Formula tire model to the physical properties of the tire. For this purpose, the tire model is developed by ABAQUS commercial software. The output of this model for the lateral tire force is validated by available tire information and then used to identify the tire force properties. The Magic Formula coefficients are obtained from the validated model by using nonlinear least square curve fitting and Genetic Algorithm techniques. The loading and physical properties of the tire such as the internal pressure, vertical load and tire rim diameter are changed and tire lateral forces for each case are obtained. These values are then used to fit to the magic formula tire model and the coefficients for each case are derived. Results show the existing relationships between the Magic Formula coefficients and the loading and the physical properties of the tire. In order to investigate the effectiveness of the method, different parameter values are selected and the lateral force for each case are obtained by using the estimated coefficients as well as with the simulation and the results of the two methods are shown to be very close. This proves the effectiveness and the accuracy of the proposed method.

Car following process is time-varying in essence, due to the involvement of human actions. This paper develops an adaptive technique for car following modeling in a traffic flow. The proposed technique includes an online fuzzy neural network (OFNN) which is able to adapt its rule-consequent parameters to the time-varying processes. The proposed OFNN is first trained by an growing binary tree learning algorithm in offline mode, which produces favorable extrapolation performance, and then, is adapted to the stream of car following data, e.g. velocity and acceleration of the target vehicle, using an adaptive least squares estimation. The proposed approach is validated by means of real-world car following data sets. Simulation results confirm the satisfactory performance of the OFNN for adaptive car following modeling application.

7000 series Aluminum alloys are widely used in the automotive industries for structural lightweight components due to their exceptional high strength to weight ratio. However, this class of aluminum alloy is difficult to join by conventional fusion welding techniques so Friction stir welding (FSW) widely is used for welding this alloys. The process has been demonstrated to be effective and is currently industrially utilized for materials difficult to be welded or “un weldable”, especially aluminum and magnesium alloys. In this paper in order to predict the average grain size occurring in FSW of AA7050 plates due to the dynamic recrystallization (DRX) phenomena due to the welding process, a microstructure evolution model have been implemented in 3D fully coupled thermo-mechanical FEM in which the tool – work piece interaction in FSW of butt joint was investigated.

Cavitation and turbulence in a diesel injector nozzle has a great effect on the development and primary breakup of spray. However, the mechanism of the cavitation flow inside the nozzle and its influence on spray characteristics have not been clearly known yet because of the internal nozzle flow complexities. In this paper, a comprehensive numerical simulation is carried out to study the internal flow of nozzle and the cavitation phenomenon. The internal cavitation flow of the nozzle is simulated using the Eulerian-Eulerian two-fluid model. In this approach, the diesel liquid and the diesel vapor are considered as two continuous phases, and the governing equations of each phase are solved separately. Simulation method is validated by comparing the numerical results with experimental data and good correspondence is achieved. The effective parameters on the nozzle flow are investigated, including injection pressure, back pressure, inlet curvature radius of orifice, orifice iconicity and its length. Results clearly show the importance of nozzle geometrical characteristics and dynamic parameters on the internal nozzle flow. Discharge coefficient of nozzle and cavitation distribution in the nozzle are extremely dependent on these parameters, so the effect of cavitation on the primary breakup is not negligible.

The reason of this study is low cycle failure of cast iron cylinder head during the E5 standard durability test. The goal of the present investigation is durability test simulation and low cycle fatigue life evaluation of cast iron cylinder head. With uncouple structural analysis, preloads, thermal and mechanical load and boundary conditions are prescribed to finite element model of the cylinder head. To cover the durability test, the analysis steps repeated at five crack speed, 750, 1650, 2075, 2350 and 2600 rpm. The cylinder head is subjected to cyclic multi-axial non-proportional variable amplitude loads. In fatigue analysis, critical plane model with cumulative damage theory is applied to predict fatigue life. A general scripting is developed and validated to calculate fatigue life. The results show that the failure of critical cylinder head is the type of low cycle fatigue. The valve bridge region, where high temperature exists during operation of the engine, is the critical area in cast iron cylinder head in fatigue analysis approach. The simulation results are in accordance with the results of durability test.

Continuous radiation ovens are of widely used apparatuses in paint cure and coating industries. The most important issue that guarantee the quality of paint curing is suitable thermal condition. Designing of these ovens for curing paint on bodies of complex geometries has become a challenge for many years. In the present study a new designing approach is introduced and advised because of its acceptable capabilities as well as its high speed. This approach is based on cure window criterion and applies gradient optimization technique. The present work can be divided into two parts: first, geometric and thermal simulation of the curing body and second, preparing the design tool.Since a significant part of designing procedure usually devotes the iterations of optimization procedure, defining a proper objective function efficiently reduces the time consumed for designing procedure. Procedure of finding an appropriate objective function has been comprehensively discussed in the present article. In this regard a new approach, called Hybrid method, applying an objective function based on few number of elements on the curing body is introduced. That is more fast and capable relative to other methods addressed in this study. Capability of the proposed methods is then evaluated for a typical complicated geometry.