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Technical Paper

A development of diesel oxidation catalyst and the evaluation of its performance characteristic

The new concept oxidation for diesel engine has been developed. It has been designed to use under circumstances of the "dry condition" of exhausted emission, which indicates low soluble organics and high dry soot concentration under high exhaust gas temperature. For the reliability and performance of catalysts in dry condition, several design concepts were established. First of all, extremely low sulfate formation on catalyst at high temperature conditions, and an improved soluble organic burning characteristics was required. A minimization of deposition of the particulate component, especially sulfate, was obtained from the adjustment of washcoat loading and material property. Six different types of catalysts have been prepared and tested in a laboratory. Diesel vehicle test showed the possibility that soluble organic could be removed mostly with minimal sulfate formation.
Technical Paper

An Application of Acoustic Metamaterial for Reducing Noise Transfer through Car Body Panels

This paper presents the design of an additional structure based on acoustic metamaterial (AMM) for the reduction of vibro-acoustic transfer function of a car body panel. As vehicles are lighter and those engine forces are bigger recently, it has become more difficult to reduce the vibration and noise transfer through body panels by using just conventional NVH countermeasures. In this research, a new approach based on AMM is tried to reduce the vibration and noise transfer of a firewall panel. First, a unit cell structure based on the locally resonant metamaterial is devised and the unit cell’s design variables are studied to increase the wave attenuation in the stop band of a dispersion curve, where the Floquet-Bloch theorem is used to estimate the dispersion curve of a two-dimensional periodic structure. Also, the vibration transfer and the vibro-acoustic transfer are predicted in a FE model of meta-plate which is composed of a periodic system of the devised unit cell.
Technical Paper

Characterization of High Temperature Properties in Al Matrix Composite Fabricated by the Low Pressure Squeeze Infiltration Process

Al matrix composites containing alumina (Al2O3) fibers are fabricated by the low pressure (25MPa) squeeze infiltration process which is suitable for the low cost mass production. Mechanical properties at room temperature as well as elevated temperatures (250°C, 350°C) are improved due to the presence of reinforcements. Upto 350°C, composites maintain a reasonable strength, which is much better than strength of the conventional Al alloy. Composites have equivalent wear rates to those of Ni - resist cast iron. Wear behavior is changed with the sliding speed. At low sliding speed, wear proceeds by the excessive failure of matrix and fiber, whilst, at higher sliding speed, matrix fracture near fiber plays a major role in wear. Wear resistance of 125°C is inferior to that of room temperature due to the reduction of mechanical properties followed by matrix softening and poor bonding.
Technical Paper

Development of Valvetrain System to Improve Knock Characteristics for Gasoline Engine Fuel Economy

It is difficult to reach higher compression ratios of the gasoline engine even though higher compression ratios improve thermal efficiency. One of the barriers is large torque drop led by knocking. Extensive researches to suppress knocking of the gasoline engine have been conducted. It is focused on lowering the temperature of fuel mixture in combustion chamber at compression top dead center (TDC). This paper covers the new valvetrain system to decrease the temperature of exhaust valve bottom (combustion) side. Hollow head and stem sodium filled valve (HHSV) have shown more heat transfer from combustion chamber to valve seat insert and valve guide, and higher thermal conductivity valve seat insert (HVSI) and valve guide (HVG) help to decrease valve temperature lower by higher heat transfer.
Journal Article

Development of Virtual Road Wheel Input Forces for Belgian Ground

Numerical durability analysis is the only approach that can be used to assess the durability of vehicles in early stages of development. In these stages, where there are no physical prototypes available, the road wheel forces (or spindle forces) for durability testing on Belgian PG (Proving Ground) must be predicted by VPG (Virtual Proving Ground) or derived from the measured forces of predecessor vehicles. In addition, the tuning parts and geometry are not fixed at these stages. This results in the variation of spindle forces during the development stages. Therefore, it is not reasonable to choose the forces predicted at a specific tuning condition as standard forces. It is more reasonable to determine the standard forces stochastically using the DB of the measured forces of predecessor vehicles. The spindle forces measured or predicted on Belgian PG are typically stationary random.
Technical Paper

Effects of Composite Sandwich Endplates on the Cold Start Characteristics of PEMFC

End-plates are highly stiff plates that hold together the components composing a fuel cell stack, i.e. Membrane Electrode Assemblies (MEAs), Gas Distribution Layers (GDLs) and bipolar plates, offering sufficient contact pressure between them. The proper contact pressure is required not only to improve energy efficiency of a stack by decreasing ohmic loss but also to prevent leakage of fluids such as hydrogen, air, or coolant. When a fuel cell starts in cold environment, heat generated in a fuel cell stack as a result of electrochemical reactions should not be used much to increase the temperature of endplates but to melt ice inside the stack to prevent ice-blocking and to increase the temperature near the three-phase-boundary on MEAs. However, to satisfy the high stiffness required, massive metallic endplates have been used despite their inferior thermal characteristics: high thermal conductivity and large thermal inertia.
Technical Paper

Fatigue Failure and Reinforcing Method of Spot Welded Area at the Stage of Vehicle Development

Vehicle body structures are formed by thousands of spot welds, and fatigue failure of vehicle structures occur near the spot welds after driving a long way at a durability test road. It is necessary to know accurately the reason of the fatigue failure of the spot weld in the developing stage in order to reinforce it. Many investigations have been done regarding the strength of spot welded joints, contributing to understand its fatigue strength. In the developing process, a fatigue failed spot welded area can be repaired by CO2 welding or another method to continue the test. To know the effect of reinforcing these welds, several methods of welding were analyzed and compared to spot welding. With the results of this test, the appropriate repair method can be used instead of spot welding during the development of a new car and the best design guide can be given for the strength.
Technical Paper

Low-pressure molding compound hood panel for a passenger car

Low-pressure molding compound (LPMC) is a new kind of composite material which can be used for automotive body panels. LPMC has similar mechanical properties compared to conventional sheet molding compound (SMC) but excellent moldability due to the different thickening system. In this paper, we prepared LPMC hood prototype for a passenger car using a low-cost tooling. Inner panel and outer panel were made of general-density- and low-density-grade LPMC, respectively, in order to maximize weight reduction maintaining surface quality. Physical properties containing tensile strength, flexural modulus, notched Izod impact strength of those samples were investigated. In addition, CAE simulation was also done for strength analysis of the hood assembly.
Technical Paper

Mechanical Properties and Fatigue Crack Propagation Behavior of Hybrid Metal Matrix Composites

The objective of this study is to investigate mechanical properties and fatigue crack propagation behavior in hybrid metal matrix composites by squeeze infiltration method (15% Al2O3 + SiCw/6061Al). The mechanical properties of Al2O3+SiCw/Al composites including tensile strength, yield strength, Young's modulus, were improved compared with those of unreinforced alloy and Al203/Al composites. The hybrid composites were more ductile than Al2O3/Al composites. Fatigue crack propagation rates of both Al2O3/Al and Al2O3+SiCw/Al composites showed a similar behavior in region II. Their propagation rates were higher in entire ▵K region compared with that of 6061 Al alloy. From the crack path morphology, fatigue cracks propagated linearly and smoothly in 6061 Al alloy. However, in the metal matrix composites cracks tend to avoid the reinforcements promoting crack deflection. It was observed that crack deflection enhanced crack closure due to wedging phenomenon.
Technical Paper

Optimization of Slot Disc Shape for Improving Brake Fade Performance

Due to improvements in vehicle powertrain performance, friction material fade performance is becoming an important topic. For this reason, needs for studies to improve thermal characteristics of the brake system is increasing. Methods for improving the fade characteristics have several ways to improve the thermal characteristic of friction materials and increase disc capacity. However, increasing disc capacity(size) have some risk of weight and cost rise, and friction factor improvements in friction material tend to cause other problems, such as increasing squeal wire brush noise and increasing metal pick up on disc surface. Therefore, a slot disc study is needed to overcome the problems discussed previously. Currently, there is few research history for slot disc related to fade and metal pickup improvements.
Technical Paper

Selecting the Spot Welding Condition of Multi-Layer Vehicle Structure

An automobile's structure is generally connected by spot welding the sheets together. Sometimes more than three layers of sheets can be used in a certain location for spot welding due to the limits of design conditions. Static strength and the fatigue life characteristics can be changed according to the welding conditions, which depend on the material, the thickness, and the number of sheets. Setting the appropriate conditions of multi-layer spot welding can be determined by analyzing static strength and fatigue life. For converting multi-layer spot welding to that of twofold layer with equal strength, the converting method can be suggested from static and fatigue test results. The increasing rate of static strength is larger than that of fatigue life, so it is reasonable to use fatigue life for limit condition.
Technical Paper

Study on the Long-Term Aging-Resistance of Anti-Vibration Rubber in the Vehicle

Anti-vibration rubbers in vehicle play an important role in restricting vibration generated from engine and road. But, degradation occurs when rubber is exposed for a long time to heat, light, ozone and etc. These make the rubber hard and lose its initial properties. The rubber change makes N.V.H performance of vehicle the worse, and gives the discomfort to the passengers. To reduce the change of rubber properties, sulfur-donor and heat stable cross-linking co-agent vulcanization system have been introduced in the developed natural rubber compounds of the anti-vibration rubber parts. These lead to a reduction of degradation of material properties, maintenance of the initial properties and increase of the fatigue life.
Technical Paper

The Design and Development of the Hyundai Alpha Engine

Main design features and some of the development work carried out on the first new engines to be produced in-house by Hyundai Motor Co. are described. The Alpha family of multi-valve, four cylinder engines comprises 1.3 and 1.5L naturally aspirated units and a 1.5L turbocharged version. Modern features are incorporated in the engines in order to provide higher performance and good fuel economy with excellent durability at reasonable cost. Hyundai Motor Co. (HMC) was established in 1967 and, in the following year, commenced production of passenger cars for the domestic market, using CKD components supplied by Ford of Europe. In 1974 the Pony saloon car entered production; this used mainly locally produced components but most of the major items, including the power train - engine and gearbox - were manufactured under the license from Mitsubishi Motors.
Technical Paper

The Effect of Tempering on Mechanical and Fatigue Properties in Gas-Carburized Cr-Mo Gear Steel

The effects of tempering on carburized Cr-Mo gear steel were investigated through mechanical and fatigue tests. Specimens were carburized at 900°C for 180 minutes, and then oil quenched at 150°C for 10 minutes of holding time and cooled to room temperature. The subsequent tempering process was performed to 160°C for 90 minutes. Surface hardness and residual compressive stress were decreased by tempering treatment, whereas tensile strength, yield strength and impact energy were increased. Bending fatigue endurance limits for both tempered and untempered specimens were same as 779MPa. The strength of roller contact fatigue is also not greatly influenced by tempering treatment. Thermal distortion for carburized transfer driven gear before and after tempering exhibited a similar distribution. Microstructural changes during tempering were also discussed.
Technical Paper

The Wettability of Silicon Carbide by Liquid Pure Aluminum and Aluminum Alloys

There have been strong moves in recent years to introduce the metal matrix composites concept into higher volume applications, notably the automotive field where large volume production and lower material costs are required. The wettability between reinforcing materials and base material is one of important factors for the strength of composites and its manufacture. The main objective of this paper is to establish a basic understanding of wetting phenomena in SiC/liquid aluminum and aluminum alloy systems. In the present paper, results from the sessile drop method are reported for the effects on the wetting angle, θ, of free silicon in the silicon carbide substrate and of alloying additions of silicon, copper or magnesium to the aluminum drop for the temperature range 700-900 or 1400°C in the titanium-gettered vacuum (1.3 x 10-2 / 1.3 x 10-3 Pa).