Automotive Science and Engineering

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In this article, rubber bumpers of Double - Wishbone suspension system have been modeled and analyzed. The objective of the present work is to predict the performance of these products during deformation, represent an optimum method to design, obtain stiffness characteristic curves and utilize the results in the automotive suspension dynamic analysis. These parts are nonlinear and exhibit large deformation under loading. They have an important role to limit the motion of wheels and absorb energy. In this study, nonlinear FE model using ABAQUS software was used to obtain the bumper load - displacement curve. Then a laboratory test was done on the bumper to get this curve. The comparison between numerical and experimental results shows a good adaptation. A less than 2 percent difference has been observed between them. Thus, we can use this numerical method to simulate bumpers easily and accurately.

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In this paper, Front Engine Accessory Drive (FEAD) system of automotive engine is modeled with ADAMS software. The model is validated using engine test data. It is then used to investigate the effect of design parameters on the system performance such as belt vibration and loads on the idlers. Three alternative layouts were developed in order to improve the performance of original EEAD system. The validated model was used to study the effect of changes made to the layouts on the reduction of vibration and loads. Several system outputs indicated that for the modified layouts, large reductions in vibration and loads were achieved. It was concluded that one of proposed layouts was more appropriate and could be a useful substitution to the original layout. The developed model also proved useful for the design of engine FEAD systems and could be used for further developments.

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In recent years, the balanced score card (BSC) has been the focus of considerable methodology for strategic cost management in management accounting area since it was originally proposed by Kaplan ,R.S. and Norton, D.P. in 1992. BSC is an approach to performance measurement based on both financial and nonfinancial information from four perspectives which are called financial, customer, internal business process, and learning and growth, in order to balance the traditional financial performance system by several grouping of performance measures: short-term and long-term, internal and external, and current and future. Over time, it has been developed to a strategic management system from a comprehensive performance measure, and used in many organizations such as business, hospital, and autonomy in many countries. In this paper, we propose a general model based on BSC by introducing fuzzy inference mechanism. From this, specialists’ knowledge and experience can be effectively reflected during the construction of the practical model. Then we illustrate a practical example for an Automotive Manufacturing Co.

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In the present paper, a complete literatures review of thermal barrier coating applications in diesel engines is performed to select a proper type and to find coating effects. The coating system has effects on the fuel consumption, the power and the combustion efficiency, pollution contents and the fatigue lifetime of engine components. Usually there are several beneficial influences by applying ceramic layers on the combustion chamber, including the piston, the cylinder head, the cylinder block, intake and exhaust valves by using a plasma thermal spray method. Several disadvantages such as producing nitrogen oxides also exist when a coating system is used. In this article, all effects, advantages and disadvantages of thermal barrier coatings are investigated based on presented articles.

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In this study, stability control of a three-wheeled vehicle with two wheels on the front axle, a three-wheeled vehicle with two wheels on the rear axle, and a standard four-wheeled vehicle are compared. For vehicle dynamics control systems, the direct yaw moment control is considered as a suitable way of controlling the lateral motion of a vehicle during a severe driving maneuver. In accordance to the present available technology, the performance of vehicle dynamics control actuation systems is based on the individual control of each wheel braking force known as the differential braking. Also, in order to design the vehicle dynamics control system the linear optimal control theory is used. Then, to investigate the effectiveness of the proposed linear optimal control system, computer simulations are carried out by using nonlinear twelvedegree- of-freedom models for three-wheeled cars and a fourteen-degree-of-freedom model for a fourwheeled car. Simulation results of lane change and J-turn maneuvers are shown with and without control system. It is shown that for lateral stability, the three wheeled vehicle with single front wheel is more stable than the four wheeled vehicle, which is in turn more stable than the three wheeled vehicle with single rear wheel. Considering turning radius which is a kinematic property shows that the front single three-wheeled car is more under steer than the other cars.

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By new advancements in vehicle manufacturing vehicle quality evaluation and assurance has become a more critical issue. In present work, the vibration transfer path analysis and vibration path ranking of a car interior has been performed. The method is similar to classical multilevel TPA methods but has distinct differences. The method is named VIVS which stands for Vehicle Interior Vibration Simulation. Performance of some tests like chassis dyno test, virtual mass function test and body transfer function test are required in this approach. The accelerations on both sides of the engine mounts are measured on chassis dyno by which the virtual mass and body transfer functions are measured at engine mounts. Using the concept of multilevel TPA, the vibration share from each path is calculated. The overall vibration magnitude at target point is calculated by summing the shares. Path ranking can be done by having the share of each path from overall vibration magnitude. Using this method on a sample vehicle, some modification has been proposed to decrease the vibration at target point, and the side effect of the modifications on the powertrain dynamic behavior has been evaluated. The proposed method needs less analysis time than classical TPA methods and its ability in optimization of vibration magnitude at target points is proven.

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The dissipated energy from periodic deformation is regarded as the main reason for heat generation and temperature rise inside the tire domain. However, the mechanical behavior of rubber parts is highly temperature dependent. In most performed investigations, the influence of thermal effects on stress/ deformation fields of pneumatic tires is ignored and just temperature distribution is considered. Hence in this study, using a series of 2D and 3D finite element models, a robust and efficient numerical study is presented for thermo-mechanical analysis of pneumatic tires specially 115/60R13 radial tire. Finally, the effects of loading condition s and ambient temperature on the thermo-mechanical properties of tire are investigated in detail. Comparing the obtained results with the available results in literature, shows a good agreement of the presented studies with related published works.

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The subjects of heat transfer and cooling system are very important topics in the Internal Combustion Engines (ICE). In modern cooling systems, low weight, small size and high compactness are the critical designing criteria that requires heat transfer enhancement. Boiling phenomenon which is occurred in the water jacket of the ICE is one of the methods to increase heat transfer in the coolant system of an ICE. A research has been shown that parameters such as material, temperature, and roughness of the heated surface have direct effect on the rate of heat transfer in a boiling phenomenon. In this paper the potential of boiling phenomenon and the effect of the surface roughness on the amount of heat flux removed by the coolant flow in the engine water jacket is investigated experimentally. For this purpose the experiments was carried out in three different flow velocities and also three different surface roughnesses. Results show that the boiling and roughness of a hot surface will increase the heat removal significantly.

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Shot peening applies a residual compressive stress field (RCSF) on the surface of parts. It also shifts “crack nucleation sites” to sub-surface locations. A nondestructive method of measuring the stresses, Sin2ψ was utilized here and the stress values introduced to Ansys software. For this purpose, uniform stress in all directions was applied on the con rod. Loading on the rod in Ansys had three steps: RCSF caused by shot peening (measured by XRD), and tensile and compressive stresses caused by inertial and gas forces, respectively (calculated). Fatigue Macro of Ansys was resumed carrying out the cyclic loading and thereby, improvement of powder forged connecting rods' fatigue life, caused by shot peening was obtained.

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In this paper, a numerical study is performed to provide the combustion and emission characteristics resulting from fuel-reactivity controlled compression ignition (RCCI) combustion mode in a heavy-duty, single-cylinder diesel engine with gasoline and diesel fuels. In RCCI strategy in-cylinder fuel blending is used to develop fuel reactivity gradients in the combustion chamber that result in a broad combustion event and reduced pressure rise rates (PRR). RCCI has been demonstrated to yield low NOx and soot with high thermal efficiency in light and heavy-duty engines. KIVA-CHEMKIN code with a reduced primary reference fuel (PRF) mechanism are implemented to study injection timings of high reactivity fuel (i.e., diesel) and low reactivity fuel percentages (i.e., gasoline) at a constant engine speed of 1300 rpm and medium load of 9 bar indicated mean effective pressure (IMEP). Significant reduction in nitrogen oxide (NOx), while 49% gross indicated efficiency (GIE) were achieved successfully through the RCCI combustion mode. The parametric study of the RCCI combustion mode revealed that the peak cylinder pressure rise rate (PPRR) of the RCCI combustion mode could be controlled by several physical parameters – PRF number, and start of injection (SOI) timing of directly injected fuel.

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The natural frequencies and mode shapes of pneumatic tires are predicted using a geometrically accurate, three-dimensional finite element modeling. Tire rubber materials and cord layers are represented independently using “shell element” available in COSMOS. The effects of some physical parameters such as the inflation pressure tread pattern, thickness of belts and ply angles to the natural frequencies of tires are investigated. By imposing equivalent centrifugal forces, the effect of translational speed on vibrating behavior of the tire is also studied in this work. Comparisons of numerical and experimental results are given to show the validity of the proposed model.

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If an air flow is injected into a liquid fluid, many ambulant air bubbles are formed inside the fluid. Air bubbles move inside the liquid fluid because of the buoyancy force, and the mobility of these air bubbles makes sizable commixture and turbulence inside the fluid. This mechanism was employed to enhance the heat transfer rate of a horizontal double pipe heat exchanger in this paper. However it can be used in any other type of heat exchanger. Especially, this method can be expanded as a promising heat transfer improvement technique in automotive cooling system, for instance in radiator which contains of water or other liquid fluid. Bubbles were injected via a special method. Present type of air bubbles injection and also the use of this mechanism for double tube heat exchanger have not been investigated before. Results are reported for varying bubble inlet parameters. The main scope of the present work is to experimentally clarify the effect of air bubble injection on the heat transfer rate and effectiveness through a horizontal double pipe heat exchanger.

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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.

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The viscoelastic effect of rubber material on creation of rolling resistance is responsible for 10-33% dissipation of supplied power at the tire/road interaction surface. So, evaluating this kind of loss is very essential in any analysis concerned with energy saving. The transient dynamic analysis for including the rolling effects of the tire requires long CPU time and the obtained results are prone to considerable numerical oscillations. By adding the equivalent loads to static interaction of tire with the road, an efficient 3D FE analysis is presented for evaluating the dissipated energy of a rolling tire. The results closely match the related experimental and numerical investigations.

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Paint cure oven is one of the most important parts of automobile production line. The cure speed and the magnitude of energy consumption are significant in auto manufacturing industry. The radiation oven has been of the interest by cure industry due to the reduction in energy consumption and appropriate cure. The design process of these ovens is really complex specially for bodies with complex geometry and bodies which especially delicate to specific temperature condition. According to the progress of computation equipment abilities and design algorithms, the utilization of these ovens has gained considerable attention from auto manufacturing industry in recent years. This study considers the benefits and defects of the radiation oven and shows that replacement of the convection ovens with radiation ovens in Iran Auto manufacturing industry would lead to 32% energy saving. The design process of convection continuous ovens is easier than radiation ovens but the associated numerical modeling is complicated and computationally intensive. In this study, the moving boundary method and its application to convection continuous ovens are discussed. The numerical results based on the moving boundary method are compared with the experimental results.

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<span style="line-height: 115%; font-size: 10pt; font-style: normal; mso-bidi-font-size: 12.0pt; mso-ascii-font-family: " times="" new="" roman";="" mso-hansi-font-family:="" "times="" mso-bidi-language:="" fa;"="">This paper concentrates on a new procedure which experimentally recognises gears and bearings faults of a typical gearbox system using a least square support vector machine (LSSVM). Two wavelet selection criteria Maximum Energy to Shannon Entropy ratio and Maximum Relative Wavelet Energy are used and compared to select an appropriate wavelet for feature extraction. The fault diagnosis method consists of three steps, firstly the six different base wavelets are considered. Out of these six wavelets, the base wavelet is selected based on wavelet selection criterion to extract statistical features from wavelet coefficients of raw vibration signals. Based on wavelet selection criterion, Daubechies wavelet and Meyer are selected as the best base wavelet among the other wavelets considered from the Maximum Relative Energy and Maximum Energy to Shannon Entropy criteria respectively. Finally, the gearbox faults are classified using these statistical features as input to LSSVM technique. The optimal decomposition level of wavelet is selected based on the Maximum Energy to Shannon Entropy ratio criteria. In addition to this, Energy and Shannon Entropy of the wavelet coefficients are used as two new features along with other statistical parameters as input of the classifier. Some kernel functions and multi kernel function as a new method are used with three strategies for multi classification of gearboxes. The results of fault classification demonstrate that the LSSVM identified the fault categories of gearbox more accurately with multi kernel and OAOT strategy.

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Heat transfer in internal combustion engines is one of the most significant topics. Heat transfer may take place through thermal conduction and thermal convection in spark ignition engines. In this study, valve cover heat transfer and thermal balance of an air-cooled engine are investigated experimentally. The thermal balance analysis is a useful method to determine energy distribution and efficiency of internal combustion engines. In order to carry out experiments, a single cylinder, air-cooled, four-stroke gasoline engine is applied. The engine is installed on proper chassis and equipped with measuring instruments. Temperature of different points of valve cover and exhaust gases is measured with the assistance of K-type thermocouples. These experiments are conducted in various engine speeds. Regarding to the first law of thermodynamics, thermal balance is investigated and it is specified that about one-third of total fuel energy will be converted to effective power. It is also evaluated that for increasing brake power, fuel consumption will increase and it is impossible to prevent upward trends of wasted energies. In addition, it is resulted that, there is a reduction heat transfer to brake power ratio by increasing engine speed. Furthermore, it is found that, at higher engine speed, lower percentage of energy in form of heat transfer will be lost.

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Due to the extensive use of cars and progresses in the vehicular industries, it has become necessary
to design vehicles with higher levels of safety standards. Development of the computer aided design and
analysis techniques has enabled employing well-developed commercial finite-element-based crash
simulation computer codes, in recent years. The present study is an attempt to optimize behavior of the
structural components of a passenger car in a full-frontal crash through including three types of energy
absorptions: (i) structural damping of the car body, (ii) viscoelastic characteristics of the constituent
materials of the bumper, and (iii) a proposed wide tapered multi-cell energy absorber. The optimization
technique relies on the design of experimental (DOE) method to enables finding the absolute extremum
solution through the response surface method (RSM) in MINITAB software. First, the car is modeled in
PATRAN and meshed in ANSA software. Then, the full-scale car model is analyzed in ABAQUS/CAE
software. The optimization has been accomplished through a multi-objective function to simultaneously,
maximize the observed energy and minimize the passenger’s deceleration. Results are verified by the
experimental results and effects of using non-equal importance coefficients for the absorbed energy and
passenger’s deceleration in the multi-objective function are also evaluated. Influence of the optimized
parameters on the frontal crash behavior of the vehicle body structure and passenger’s deceleration is
investigated, too.

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In this paper, a three-axle bus rollover threshold and the effective parameters are studied. The rollover threshold is a speed that automotive is passing without occurring rollover. The objective is a determination of the heavy vehicle rollover critical speed while turning. For this purpose, a three-axle bus is studied. The dynamic equations related to rollover is extracted, and then rollover criterion, which is LTR (Load Transfer Ratio) in this paper, is obtained. The governing equations are simulated in MATLAB software and then the effect of the parameters such as steering rate, road curvature radius, road bank slope and automotive effective parameters on the rollover critical speed is studied. Prior to the investigation of these parameters, due to validation of the simulation model in MATLAB, a three-axle bus with specific parameters values is placed under various maneuvers with different conditions in TruckSim software then results are recorded. In order to validate, these results are compared with the results which are achieved from MATLAB. After validation, the relation between effective parameters in rollover stability and vehicle speed for desire maneuvers is obtained and it is illustrated in form of function. The results of this research work can be used in road threshold speed without huge computation costs and expensive tests.