Automotive Science and Engineering

Electric vehicles (EVs) have gained the attention of many authorities, automakers and researchers due to their considerable energy saving and emission reduction. One of the main issues that must be considered in design of a road vehicle is the calculation of aerodynamic forces. This issue also must be scrutinized in the design of EVs. Installation of rear spoiler is one of the solutions proposed for reduction of aerodynamic drag in racing cars and consequently increasing their maximum speed. This study focuses on the effects of installing a rear spoiler on an EV. The vehicle's drag and lift coefficients are determined by solving a 3D steady-state incompressible solution of Navier-Stokes equations with computational fluid dynamic (CFD) analysis in ANSYS FLUENT. In order to verify the effects of installing a rear spoiler on an EV, all the components were modelled in MATLAB /SIMULINK also, practical tests were performed to confirm and verify the simulation results. The results show that installing a rear spoiler on an EV, not only improves the aerodynamic characteristics of vehicle but also improves operating efficiency of electric motor and some operational aspects of batteries. In addition, it is shown that an EV with a rear spoiler is able to travel more in comparison with an EV without rear spoiler.

Loading conditions and complex geometry have led the cylinder heads to become the most challenging parts of diesel engines. One of the most important durability problems in diesel engines is due to the cracks valves bridge area. The purpose of this study is a thermo-mechanical analysis of cylinder heads of diesel engines using a two-layer viscoplasticity model. In this article, mechanical properties of A356.0 alloy, obtained by tensile tests at 25 and 200°C. The results of the thermo-mechanical analysis indicated that the maximum temperature and stress occurred in the valves bridge. The results of the finite element analysis of cylinder heads correspond with the simulation results, carried out by researchers.

In this study, the fluid flow around a Pride vehicle was solved in a two-dimensional design using numerical methods. To do so, a two-dimensional figure of a Pride was modeled and gridded, and different surfaces were introduced. Then, governing equations the fluid flow was solved for the standard K-ε model and the appropriate boundary conditions. Areas that increased lift and drag forces were specified through studying the results and observing flow lines, pressure distribution, and vortices created around the automobile. In this way, the ideal height for different speeds was determined through examining the changes in those forces at different heights. In this study, the Pride was examined at different heights 80, 120, 160 (standard), 200, and 250 mm for the speeds 10, 20, 33, and 40 m/s. The results showed that lift and drag forces depended on the height of the automobile and changed at different heights

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.

<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.

Nowadays, due to increasing the complexity of IC engines, calibration task becomes more severe and the need to use surrogate models for investigating of the engine behavior arises. Accordingly, many black box modeling approaches have been used in this context among which network based models are of the most powerful approaches thanks to their flexible structures. In this paper four network based modeling methods are used and compared to model the behavior of an IC engine: neural networks model (NN), group method of data handling model (GMDH), a hybrid NN and GMDH model (NN-GMDH), and a GMDH model whose structure is determined by genetic algorithm (Genetic-GMDH). The inputs are engine speed, throttle angle, and intake valve opening and closing timing, and the output is the engine brake torque. Results show that NN has the best prediction capability and Genetic-GMDH model has the most flexible and simplest structure and relatively good prediction ability.

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This study aims to numerically investigate on the crashworthiness of thin-walled square tubes by consideration of 3-D oblique loading. In this type of loading, direction of loading is defined by using two spatial angles relative to the position of the tube. To this aim, finite element (FE) analysis is employed to simulate the loading for 8 different numerical models with different loading orientation. Subsequently, load-displacement diagrams as well as deformation shapes during the loading are derived for each model. Moreover, a study is done on the tube collapse mode for each case. Effect of loading orientation and tube thickness on the maximum crushing load and energy absorption are also studied via a parametric study on the FE simulations. Results indicated a different trend for all cases of 3D oblique loading compared to axial loading. This study highlights the significance of consideration of a 3D orientation in analysis of crushing behavior of thin-walled tubes.

According to the Global Fuel Crisis, it seems necessary to use alternative fuel instead of gasoline. Since the natural gas is cheaper, have higher frequency than gasoline and less pollution, it is a suitable fuel. Many efforts have been done in order to replace gasoline with natural gas. One of the methods is to inject natural gas and gasoline fuel simultaneously and to use the benefits of both fuels. The purpose of this paper is studying natural gas and gasoline blend effect on engine power, torque and emissions. The simulated model was validated in different engine RPMs for gasoline and natural gas, were separately injected into the engine at full load condition. The results of simulation was had good agreement with experiments. The results show that by natural gas and gasoline Simultaneous injection power and torque have been reduced. NOX, HC and CO2 Pollutants change periodically, but their production level is generally lower than gasoline mode, but the CO pollutant increases.

Modern diesel engines should have higher pollutant emissions standards with better performance and by using split injection strategies which could optimize the air – fuel mixture, this purpose could be achieved. After achieving the successful validation between modeling and experimental results for both single and double injection strategies, for the first time and in this paper, double injection strategies with new nozzle configuration were used in which number of nozzle holes were doubled and located below the previous holes and then double injection strategies were implemented in a case that for each pulse of injections upper or below holes were used, then this study focused on the effects of the new nozzle configuration holes angle in each pulse of injections. This study confirms that split injection could decrease Nox emission, because it has lower maximum in-cylinder temperature than single injection case due to its separate second stage of combustion, also results showed that using new nozzle configuration with two rows of holes could be more effective in decreasing pollutant emissions without any significant effects on engine performance.

In this paper, a two-surfaces sliding mode controller (TSSMC) is proposed for the voltage tracking control of a two input DC-DC converter in application of electric vehicles (EVs). The imperialist competitive algorithm (ICA) is used for tuning TSSMC parameters. The proposed controller significantly improves the transient response and disturbance rejection of the two input converters while preserving the closed-loop stability. The combination of the proposed controller and ICA, realizes a fast transient response over a wide transient load changes and input voltage disturbances. For modeling the equations governing the system, state-space average modeling technique is used. In order to analyzing the results, the two input converter equipped with the proposed controller, was modeled in MATLAB/SIMULINK environment. Simulation results are reported to validate the theoretical predictions and to confirm the superior performance of the proposed nonlinear controller when it is compared with a conventional pure SMC.

In recent years due to improvements of technology within automobile industry, design process of advanced driver assistance systems for collision avoidance and traffic management has been investigated in both academics and industrial levels. Detection of traffic signs is an effective method to reach the mentioned aims. In this paper a new intelligent driver assistance system based on traffic sign detection with Persian context is designed. The main goal of this system is to assist drivers to choose their path based on traffic signs more precisely. To reach this purpose, a new framework by using of fuzzy logic was used for detection of traffic signs in videos which have has been captured from a vehicle path in highways. Fuzzy logic increases inference and intelligent capabilities in smart systems to make correct decision making in online conditions. Then, the combination of Maximally Stable Extermal Regions (MSER) and Canny Edge Detector Algorithms are used to detect road sign’s texts detection. MSER algorithm is aimed at assists to detect regions in an image that differ in properties, for example in brightness or color, compared to surrounding regions. Also, canny edge detector uses a multi-stage algorithm to detect a wide range of edges in the images. Thereafter, morphological mask operator is used to join individual characters for final detection of texts in the traffic signs. Finally, MATLAB Optical Character Recognition (OCR) is employed to recognize the detected texts. This new framework gives an overall text detection and recognition rate of . .

In this study, a numerical computational fluid dynamics study is conducted in order to predict the aerodynamic forces on the NP car. The turbulent air flow around the car is modeled using the realizable k-ε model. First, results are validated against those presented for the Ahmed’s body. Next, the fluid flow around the car is simulated for different car speeds ( to mph) and flow directions ( to degree) and the drag and lift forces and coefficients are calculated. Increasing the car speed leads to increase of the drag and lift forces. While, the drag and lift coefficients of the car for all studied speeds are almost constant and are respectively equal to . and . . In addition, for different flow directions the drag coefficient would increase up to . . Also, the effect of mirrors on the drag force is investigated. Results reveal that removing the mirrors leads to approximately reduction in the drag force with no significant reduction in the drag coefficient. Furthermore, the effect of car elevation on the drag and lift forces is analyzed. It has been shown that when the car elevation decreases up to mm, the drag force will decrease more than , and the drag and lift coefficients are still constant. Keywords: road sign detection, text detection, object detection from video, fuzzy logic, MSER

Loading conditions and complex geometry have led the cylinder heads to become the most challenging parts of diesel engines. One of the most important durability problems in diesel engines is due to the cracks valves bridge area. The purpose of this study is a thermo-mechanical analysis of cylinder heads of diesel engines using a two-layer viscoplasticity model. In this article, mechanical properties of A alloy, obtained by tensile tests at and C. Tensile tests were simulated by abaqus software and very good agreement was shown between experimental and simulation results of tensile tests. The results of the thermo-mechanical analysis indicated that the maximum temperature and stress occurred in the valves bridge. The results of the finite element analysis showed that when the engine is running the stress in the region is compressive caused by the thermal loading and combustion pressure. When the engine shut off the compressive stress turned into the tensile stress because of assembly loads. The valves bridge was under the cyclic tensile and compressive stress and then is under low cycle fatigue. After several cycles the fatigue cracks will appear in this region. The results of the thermo-mechanical analysis of cylinder heads correspond with the simulation results, carried out by researchers. Viscous strain was significant and its amount is not negligible.

New product development (NPD) is described in the literature as the transformation of a market opportunity into a product available for sale [ ]. In the automotive industry, within the context of ISO/TS (the automotive quality management system international standard), consists of Three main phases such as planning, Implementation and sales. There are also five sub phases called “Planning”, “Product Design”, “Process Design and Development”, “Product and Process Verification and Validation”, and “Production”. These phases may be done concurrently and have correlated activities.

Our analysis shows that most of domestic researches about the new product development success factors are based on the Western literature and use them as the theoretical platform in the design of their own research strategy and research questions design. The paper proposes a contribution of measuring indicators extracted from literature review and completed by several industry and university experts’ interviews to finalizing the weighting indictors that could be useful in performance measuring on Auto new product development gates.

The constitutive relationships of the rubber materials that act as the main spring of a hydraulic engine mount are nonlinear. In addition to material induced nonlinearity, further nonlinearities may be introduced by mount geometry, turbulent fluid behavior, temperature, boundary conditions, decoupler action, and hysteretic behavior. In this research all influence the behavior of the system only certain aspects are realistically considered using the lumped parameter approach employed. The nonlinearities that are readily modeled by the lumped parameter approach constitute the geometry and constitutive relationship induced nonlinearity, including hysteretic behavior, noting that these properties all make an appearance in the load-deflection relationship for the hydraulic mount and may be readily determined via experiment or finite element analysis. In this paper we will show that under certain conditions, the nonlinearities involved in the hydraulic mounts can show a chaotic response.

Excavators are heavy construction equipment consisting of a boom, dipper (or stick), bucket and cab on a rotating platform known as the "house". In this paper the hydraulic shovel excavator is analyzed through the D-H method. The shovel working device with the bucket capacity of 36m3 is optimized. The determination of the objective function, variables and constraints are described in detail. The position of optimized shovel is achieved. Also Bucket trajectory and envelope drawing are designed. These are carried on the analysis and comparison. Optimum design is proved rationality.

The usage of turbochargers in diesel engines has led to the downsizing of the motors as well as usage of the waste gates in turbochargers. Any dimensional reduction in turbochargers and appurtenant leads to an enhancement on the performance of internal combustion engines and in environmental problems in terms of aerodynamic, thermodynamic and mechanical specifications for both engines and turbochargers. For this reason, the efforts need to be focused on the design of turbochargers and their waste gates accurately, in order to maintain its benefits as much as possible. The extent of waste gate opening, from full opened to closed valve, is demonstrated by the limiting compressor boost pressure ratio. Ultimately, an optimum point of limiting compressor boost pressure ratio is obtained then an increase in the values of BMEP and engine power for the same fuel consumption in range of waste gate opening is achieved

Evaluating the thermal effects and variations in temperature of rolling pneumatic tires, is a very important factor in safe performance of the vehicles. Normally, the transient thermal investigation of rolling tires is performed by tire test rigs. However, experimental analysis is a very time and cost consuming process and because of technical limitations, the tests cannot be carried out in most severe conditions. In this work, a validated finite element model is proposed for transient thermal investigation of rolling pneumatic tires. Compared with the experimental tests, the current study gives satisfactory results for temperature distribution of the tire.

This paper is the representation of the computational and experimental methods of a new injector nozzle for a sequential port injection CNG engine. The objective of this study was to review the previous research in the development of gaseous fuel injector for port injection CNG engine converted from diesel engine. Next, a simulation of the fuel flow of the new injector nozzle was made using FLUENT. The final objective was to investigate the performance characteristics of the CNG engine using the new injector nozzle. The investigation focused on engine performance based on variations in location of injector, number of holes in injectors and pressure. The results showed that the conversion of the diesel engine to a CNG engine reduced engine performance. The simulation of the fuel flow of the new injector nozzle increased the spray distribution, fuel-air mixing and fuel flow velocity. The fuel nozzle injector multi holes geometries development was to produce optimum fuel air mixing and increasing the volumetric efficiency of the engine that will promote a comparable engine performance and efficiency.