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An understanding of the flow around a tire in contact with the ground is important when designing fuel-efficient tires as the aerodynamic drag accounts for about one third of an entire vehicle's rolling loss. Recently, non-pneumatic tires (NPTs) have drawn attention mainly due to their low rolling resistance associated with the use of low viscoelastic materials in their construction. However, an NPT's fuel efficiency should be re-evaluated in terms of aerodynamic drag: discrete flexible spokes in an NPT may cause more aerodynamic drag, resulting in greater rolling resistance. In this study, the aerodynamic flow around a non-pneumatic tire in contact with the ground is investigated for i) stationary and ii) rotating cases using the steady state Reynolds-Averaged Navier-Stokes (RANS) method. A sensitivity analysis was carried out with a varying mesh density. The flow into cavity by the discrete spoke geometry of the NPT does not significantly affect the overall aerodynamic drag.

In the development of an FAW SUV, one of the goals is to achieve a state of the art drag level. In order to achieve such an aggressive target, feedback from aerodynamics has to be included in the early stage of the design decision process. The aerodynamic performance evaluation and improvement is mostly based on CFD simulation in combination with some wind tunnel testing for verification of the simulation results. As a first step in this process, a fully detailed simulation model is built. The styling surface is combined with engine room and underbody detailed geometry from a similar size existing vehicle. From a detailed analysis of the flow field potential areas for improvement are identified and five design parameters for modifying overall shape features of the upper body are derived. In a second step, a response surface method involving design of experiments and adaptive sampling techniques are applied for characterizing the effects of the design changes.

Historically vehicle aerodynamic development has focused on testing under idealised conditions; maintaining measurement repeatability and precision in the assessment of design changes. However, the on-road environment is far from ideal: natural wind is unsteady, roadside obstacles provide additional flow disturbance, as does the presence of other vehicles. On-road measurements indicate that turbulence with amplitudes up to 10% of vehicle speed and dominant length scales spanning typical vehicle sizes (1-10 m) occurs frequently. These non-uniform flow conditions may change vehicle aerodynamic behaviour by interfering with separated turbulent flow structures and increasing local turbulence levels. Incremental improvements made to drag and lift during vehicle development may also be affected by this non-ideal flow environment. On-road measurements show that the shape of the observed turbulence spectrum can be generalised, enabling the definition of representative wind conditions.

Zirconium dioxide (ZrO2) doped with Yttria exhibits superplastic behaviour, corrosion resistance and excellent ion conducting properties [1] at moderate temperatures and thus it can be used as an electroceramic to measure the pH of high temperature water used in fuel cells. Several fabrication processes are available for preparation of zirconia ceramics. This research focused on the study of using Spark Plasma Sintering (SPS) process to prepare Yttria Stabilized Zirconia (YSZ) ceramic. 8 mol% YSZ was subjected to varying SPS sintering conditions. Samples were sintered by changing the heating cycle, dwell time, sintering pressure and cooling cycle. Subsequently, these parameters were related to the densification characteristics of the as-sintered YSZ. The results of specific gravity measurements and microstructure evaluation suggest that stepped heating followed by a slow cooling results in YSZ with highest relative density (99.9%).

In the present paper we introduce a monolithic CFD approach to simulate the cooling-down characteristics of disk brakes. To ensure a strong coupling between fluid and solid domain the overall transient thermal problem is solved within a single flow solver during the complete cooling-down process. We employ a fully implicit second order solution procedure. The experimental configuration consists of an inertia dynamometer including a generic 17 inch vented front disk with caliper, dust shield, bearing and knuckle. The validation is carried out for three different air flow velocities, with and without dust shield. The temperature is monitored via two thermocouples embedded into outer and inner rotor cheeks. In order to quantify the cooling-down characteristics, regression analysis are conducted on the temperature curves. The obtained cooling coefficient serves as comparison between measurement and computation.

Understanding the creep and bolt load retention (BLR) behavior of promising Mg-Al alloys are crucial to developing elevated temperature resistance alloys. This is especially true for elevated temperature automotive applications with a prevalence of bolted joints. In this study, creep and fastener clamp load response of Mg-Al alloy AS41 was investigated and compared to that of Mg4Al and AS41 micro-alloyed with 0.15 % Ca. A compliance-creep approach was used to model the response of these Mg-Al alloys at bolted joints. The equation prediction of the BLR response and experimental results are in good agreement. AS41+0.15 Ca shows improved creep and BLR properties up to 175°C. A correlation between the microstructures, creep and BLR results reveal that the formation of a ternary CaMgSi phase is responsible for the improved elevated temperature behavior.

A new nitriding technology and material technology have been developed to increase the strength of microalloyed gears. The developed nitriding technology makes it possible to freely select the phase composition of the nitride compound layer by controlling the treatment atmosphere. The treatment environment is controlled to exclude sources of supply of [C], and H2 is applied as the carrier gas. This has made it possible to control the forward reaction that decomposes NH3, helping to enable the stable precipitation of γ′-phase, which offers excellent peeling resistance. A material optimized for the new nitriding technology was also developed. The new material is a low-carbon alloy steel that makes it possible to minimize the difference in hardness between the compound layer and the substrate directly below it, and is resistant to decline in internal hardness due to aging precipitation in the temperature range used in the nitriding treatment.

In this research, a new wire material made using surface-reforming heat treatment was developed in order to enhance the corrosion fatigue resistance of suspension springs. The aim of surface reforming is to improve hydrogen embrittlement characteristics through grain refinement and to improve crack propagation resistance by partial softening of hardness. The grain refinement method used an α'→γ reversed transformation by rapid short-term heating in repeated induction heating and quenching (R-IHQ) to refine the crystal grain size of SAE 9254 steel spring wire to 4 μm or less. In order to simultaneously improve the fatigue crack propagation characteristics, the possibility of reducing the hardness immediately below the spring surface layer was also examined. By applying contour hardening in the second IHQ cycle, a heat affected zone (HAZ) is obtained immediately below the surface.

Polyvinyl butyral (PVB) film and SentryGlas® Plus (SGP) film have been widely used in automotive windshield and architecture curtain serving as protective interlayer materials. Viscoelasticity is the unique property of such film materials, which can contribute to improving impact resistance and energy absorbing characteristics of laminated glass. In this study, the uniaxial tensile creep and stress relaxation tests are conducted to investigate the viscoelasticity of PVB and SGP films used in laminated glass. Firstly, tensile creep and stress relaxation tests of PVB film (0.76mm) and SGP film with three thickness (0.89mm, 1.14mm and 1.52mm) are conducted using Instron universal testing machine to obtain creep and stress relaxation curves. Afterwards, both viscoelastic models (Burgers model, Maxwell-Weichert model) and empirical equations (Findley power law, Kohlrausch equation) are applied to simulate the creep and stress relaxation results.

A pre-treatment technique for improving coating adhesion on stainless steel has been developed. This method dramatically enhances the adhesion between the stainless steel and the coating by pre-treating the stainless steel with a known nickel strike plating for a short period of time. Furthermore, when this process was applied to stainless fuel filler pipes to improve corrosion resistance, layout restrictions and chipping covers became unnecessary, costs were reduced, and vehicle weight was lowered.

Honda developed a technology to quantify automotive steel corrosion from the rust reduction current detected by a proprietary developed sensor. The values calculated based on Faraday's law did not match the actual measured values for the mass loss of iron due to the added resistance of rust formed between electrodes on the sensor. It was determined that the resistance of rust depends on the environment, and this issue was resolved by setting the correction values for that influence. As a result of this research it was found that the values calculated from the sensor measurements matched those from the mass loss of test specimen on a vehicle. Honda is utilizing this newly developed technology for corrosion research and field data collection.

The ratio of two forces acting respectively perpendicular and normal to a contact surface of two bodies, the coefficient of friction, is widely used in engineering and science depicting the friction resistance of materials sliding over one another. Ruled by the so-called Amontons-Coulomb friction laws (independence from the load, the contact area and the sliding speed), this dimensionless quantity appears to be convenient for engineering and relatively easy to determine. Nevertheless, the use of tabulated friction coefficients becomes somewhat an issue to predict friction behavior of mechanical systems. The system dependence of friction is sometimes ignored, leading to misapplication. Moreover, the fundamental origins of sliding resistance are not as clear and care should be taken when attributing a fundamental significance to the friction coefficient. This paper aims to clarify findings on friction Charles Augustin Coulomb did and that have been used for hundred of years.

In this paper an effective technology of virtual thermal test of disc brake with several advanced analytic techniques was presented. With the virtual thermal test process, thermal performance of brake system could be easily evaluated without any possibility of great errors that used to happen in the past. In addition to the classical result of CFD, this virtual thermal test produced several valuable applications such as thermal deformation of rotor, optimization of thermal performance and estimation of braking distance.

Vehicle manufacturers among others are putting great emphasis on improving fuel economy (FE) of light-duty vehicles in the U.S. market, with significant FE gains being realized in recent years. The U.S. Environmental Protection Agency (EPA) data indicates that the aggregate FE of vehicles produced for the U.S. market has improved by over 20% from model year (MY) 2005 to 2013. This steep climb in FE includes changes in vehicle choice, improvements in engine and transmission technology, and reducing aerodynamic drag, rolling resistance, and parasitic losses. The powertrain related improvements focus on optimizing in-use efficiency of the transmission and engine as a system, and may make use of what is termed downsizing and/or downspeeding. This study quantifies recent improvements in powertrain efficiency, viewed separately from other vehicle alterations and attributes (noting that most vehicle changes are not completely independent).

Copper-free non-asbestos-organic (NAO) brake pads have been developed to satisfy the copper content regulations in North America. Copper-free NAO brake pads are required to have a stable friction coefficient owing to the electrification of the control systems, as well as to exhibit improved wear resistance to reduce brake dust emissions. Our previous study indicated that the transfer film formed on the rotor surface affects both the friction coefficient stability and amount of wear. In this study, we investigated how different types of inorganic fillers affect the transfer film formation and its composition in a wear test controlled by temperature. It was confirmed that the main component of the transfer film was iron oxide derived from the rotor. Furthermore, the contained components changed according to the appearance of the rotor surface after each wear test.

Recreational vehicles have a lot of potential consumers in China, especially the type C recreational vehicle is popular among consumers due to its advantages, prompting an increase in the production and sales volumes. The type C vehicle usually has a higher air drag than the common commercial vehicles due to its unique appearance. It can be reduced by optimizing the structural parameters, thus the energy consumed by the vehicle can be decreased. The external flow field of a recreational vehicle is analyzed by establishing its computational fluid dynamic (CFD) model. The characteristic of the RV’s external flow field is identified based on the simulation result. The approximation models of the vehicle roof parameters and air drag and vehicle volume are established by the response surface method (RSM). The vehicle roof parameters are optimized by multi-objective particle swarm optimization (MO-PSO).

Currently the Automotive industry demands highly competitive product to survive in the global tough competition. The engine cooling system plays a vital role in meeting the stringent emission norms and improving the vehicle fuel economy apart from maintaining the operating temperature of engine. The airflow through vehicle subsystems like the grille, bumper, the heat exchangers, the fan and shroud and engine bay are called as front-end flow. Front end flow is crucial factor in engine cooling system as well as in determining the aerodynamic drag of vehicle. The airflow through the engine compartment is determined by the front-end vehicle geometry, the CRFM and CAC package, the engine back restriction and the engine compartment geometry including the inlet and outlet sections. This paper discusses the 1D modelling method for front-end airflow rate prediction and thermal performance by 1D method. The underbody components are stacked using heat stack and simulated in pressure mode.

Passenger and light-duty vehicles have a high, and steadily increasing, greenhouse gas emissions footprint. Industry and regulators put effort into new, efficient propulsion configurations to reduce carbon dioxide (CO2) emissions from the transport sector. Energy savings are highly impacted not only by the driving style and needs of the driver, but also by the energy mix used during a trip, making the vehicle efficiency benchmarking increasingly complex. A potential way to curb the vehicle energy demand is by minimising the losses due to factors opposing the forward movement, such as vehicle inertia, tyre deformation, drivetrain, and vehicle air-drag. These losses are included in the vehicle road loads. In the present study, we derive representative road load values by employing open access vehicle information and combining physical and statistical methods. These values are then compared to the ones declared by the manufacturer, which are derived by physical coast down tests.

Road Load parameters (rolling resistance and aerodynamic drag) of a vehicle have strong impact on overall Vehicle Emissions and Fuel Economy. The road load coefficients are simulated on chassis dynamometer to carryout emission and fuel economy measurement and are hence required to be found beforehand. A realistic measure of road load parameters can be obtained by conducting a coastdown test. Coastdown test results are hugely impacted by various environmental parameters like ambient temperature, atmospheric pressure, wind speed etc. Though performed in standard boundary conditions, results of multiple tests performed on a vehicle vary from one another due to variations in the mentioned environmental parameters over and above standard test to test variation. This paper aims at studying the variation in test results due to ambient temperature as one of the parameters responsible.

Fuel cell technology can play a major role in reducing transportation-related emissions, especially in heavy-duty, long-haul applications. Consequent transfer of technology from air supply systems for combustion engines to cathode air paths serves as an enabler for necessary system cost reduction. To achieve the required system lifetime, the supply of clean air is essential. Gases like NOx, SO2 and NH3 poison the catalyst, leading to increased stack degradation rates. Effective removal with functionalized activated carbons enhances the catalyst´s lifetime. Research on real-life concentrations of these contaminants under different driving patterns and road profiles enables knowledge-based design of cathode air filter elements. To prevent flooding of components like air filter, humidifier, or stack, water separators are integrated at different position inside the system.