Automotive Science and Engineering

Experimental Study & Modeling of Surface Roughness in Turning of Hardened AISI 4340 Steel Using Coated Carbide Inserted

R. Das

Turning of hardened steels using a single point cutting tool has replaced the cylindrical grinding now as it offers attractive benefits in terms of lower equipment costs, shorter set up time, fewer process setups, higher material removal rate, better surface quality and elimination of cutting fluids compared to cylindrical grinding. In order to obtain desired surface quality by machining, proper machining parameters selection is essential. This can be achieved by improving quality and productivity in metal cutting industries. The present study is to investigate the effect of machining parameters such as cutting speed, feed and depth of cut on surface roughness during dry turning of hardened AISI 4340 steel with CVD (TiN+TiCN+Al2O3+ZrCN) multilayer coated carbide inserts. A full factorial design of experiment is selected for experimental planning and the analysis of variance (ANOVA) has been employed to analyze the significant machining parameters on surface roughness during turning. The results showed that feed (60.85%) is the most influencing parameter followed by cutting speed (24.6%) at 95% confidence level. And the two-level interactions of feed-cutting speed (F*V), depth of cut-feed (D*F) and depth of cutcutting speed (D*V) are found the significant effects on surface roughness in this turning process. Moreover, the relationship between the machining parameters and performance measure i.e. surface roughness has been modeled using multiple regression analysis.

Axial Crush of Metallic and Hybrid Energy Absorbing Thin-walled Tubes with Polygonal Cross-sections: Numerical Analysis

Yousefsani

Material properties and geometry are two important design parameters which their effects should be considered in a crashworthiness analysis. In this paper, the axial impact of metallic and hybrid energy absorbing thin-walled tubes with poly-gonal cross-section is simulated using LS-DYNA software. The combined effects of changing the geometry and material properties on the mass specific energy absorption (MSEA) as well as the mean and maximum crush forces are investigated. To compare the results, all metallic tubes have identical thickness, length, and circumference. The hybrid tubes are made of the same metallic tubes which are reinforced with special composite overlays. These materials are intentionally selected in such a way that the effects of yield strength and Young’s modulus can be separately investigated. The results show that, in contrast with the current belief, there are some metallic and hybrid tubes with non- circular cross-section shapes, which have better mass specific energy absorption capabilities than the circular ones during the impact.

A review of thermal barrier coating effects on diesel engine performance and components lifetime

Azadi

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.

Enhancing Rollover Threshold of an Elliptical Container Based on Binary-coded Genetic Algorithm

Shojaeefard

In this paper, a method based on binary-coded genetic algorithm is proposed to explore an optimization method, for obtaining an optimal elliptical tank. This optimization method enhances the rollover threshold of a tank vehicle, especially under partial filling conditions. Minimizing the overturning moment imposed on the vehicle due to c.g. height of the liquid load, lateral acceleration and cargo load shift are properly applied. In the process, the width and height of tanker are assumed as constant parameters. Additionally, considering the constant cross-sectional area, an optimum elliptical tanker of each filling condition is presented to provide more roll stability. Moreover, the magnitudes of lateral and vertical translation of the cargo within the proposed optimal cross section under a constant lateral acceleration field are compared with those of conventional elliptical tank to demonstrate the performance potentials of the optimal shapes. Comparing the vehicle rollover threshold of proposed optimal tank with that of currently used elliptical and circular tank reveals that the optimal tank is improved approximately 18% higher than conventional one.

A 3D Numerical Model to Investigate Mechanical, Thermal and Material Flow Characteristics in Friction Stir Welding of Copper Sheets

Pashazadeh

The objective of this study was to develop a numerical model for the prediction of temperature distribution, effective plastic strain distribution, and especially material flow in friction stir welding of copper plates. The DEFORM-3D software was used by incorporating a lagrangian incremental formulation. Threedimensional results of the material flow pattern which were extracted using the point tracking are in good agreement with the experiment. It was shown that the main part of material flow occurs near the top surface. Material near the top surface at the behind of tool stretches from retreating side towards advancing side which leads to non-symmetrical shape of the stir zone. The stir zone shape in FSW of copper alloys, which was predicted by simulation, does not lean completely towards any sides of welding line.

Stability of Three-Wheeled Vehicles with and without Control System

Saeedi

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.

The Impact of Nano-fluid Concentration Used as an Engine Coolant on the Warm-up Timing

Eftekhar

Running the industrial components at a proper temperature is always a big challenge for engineers. Internal combustion engines are among these components in which temperature plays a big role in their performance and emissions. With the development of new technology in the fields of ‘nano-materials’ and ‘nano-fluids’, it seems very promising to use this technology as a coolant in the internal combustion engines. In this study, a nano-fluid (Al2O3-Water/Ethylene Glycol (EG)) is used as an engine coolant along with an optimized heat exchanger to reduce the warm-up timing. The effect of nano-fluid concentration is considered here by using their corresponding governing equations, such as momentum and energy. The engine coolant thermal behavior calculation is carried out based on the lumped method. The obtained results indicated that using different percentage of nano-fluid mixtures (by volume), such as Al2O3- Water/EG as engine coolant enhances the heat transfer coefficient and reduces the warm-up timing which, in turn, results in reduced emissions and fuel consumption.