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The action of load on the component is crucial to evaluate the performance of durability. Another factor that affects fatigue life is the boundary conditions of the test specimen being tested by introducing unrealistic loads on the component of interest. The physical test is widely conducted in the laboratory. The fixture provides additional constraints on the test specimen as well as reaction forces to balance the test system [1]. The characteristics of the fixture involved in the test is important to analyze and assess the test results [2]. The impact of the reaction force of the fixture on the spindle-coupled axle road simulation test is presented in this article. A simplified 7-DoF (degrees of freedom) model is introduced to demonstrate the dynamic behavior of the vehicle. The influence on the internal load by the fixture has been analyzed. Followed by a more detailed MBS (multibodysystem) model to give a thorough understanding of the phenomenon.

This study concerns experimental and theoretical analysis of early stages of the flame kernel development and subsequent stages of combustion and peak pressure in a spark-ignition engine. The simultaneous measurement of engine operating conditions, pressure traces and sequences of combustion images have been made in a single cylinder four stroke engine, in particular, at part load and under lean burn conditions. The early stages of the combustion have been analyzed using a new image analysis methods. These techniques can measure the total kernel growth, the thermal expansion part, the local translational velocity of the centroid, stretching of the flame kernel surface and its roughness as well as the flame contact area with the electrodes. In addition, the fraction of the flame surface area supporting propagation has been determined from the directional variation of flame propagation between successive image frames.

The response of a gasketed, bolted joint to an external load is understood to be effected by all components involved in the joint. The analysis involves the equilibrium of the gasket compressive force with the bolt tension force and the forces external to the bolted joint. Geometric compatibility is maintained when the change in the stretch of the bolt caused by an external force is equal to the change in compressed thickness of the gasket. When the flanges are treated as nondeformable, the classical joint diagram analysis indicates that externally applied loads, which unload the gasket, increase bolt tension. In this paper, the effect of flexible flanges is included in the analysis of simple gasketed bolted flanges. The results show that bolt tension response can deviate significantly from the rigid flange behavior. In certain situations where flanges have a relatively high level of flexibility, external joint forces that unload the gasket also unload the bolt.

Leakage rate tests were performed on two types of type 304 stainless steel gaskets. One type had asbestos fillers and the other had graphite fillers. The gaskets were tested at roughnesses of 125, 250, 500, and 1000 micro inches, AARH. Regression analysis was performed on the test data to obtain comparison curves for the effect of flange surface on each type of gasket.

This paper studies the influence of the discharge chamber geometrical parameters on the steady-state characteristics behavior of a conical seat valve having compensating profile. More in details, starting from the analysis of the experimental behavior of an actual valve showing inefficient characteristic curves, the metering openings leading to the transition from under to over compensation are individuated. Then, a 3D CFD steady-state, incompressible and isothermal analysis is involved, mainly to evidence the valve discharge coefficient and flow-forces variations with operating conditions. After, two alternative valve configurations, presenting a low pressure region designed to optimize the flow-forces compensation, are characterized through the 3D CFD analysis.

Increasing the number of cold-start engine cycles which could be run in any one day would greatly improve the productivity of an engine test facility. However with the introduction of forced cooling procedures there is the inherent risk that test-to-test repeatability will be affected. Therefore an investigation into the effects caused by forced cooling on fuel consumption and the temperature distribution through the engine and fluids is essential. Testing was completed on a 2.4 litre diesel engine running a cold NEDC. The test facility utilises a basic ventilation system, which draws in external ambient air, which is forced past the engine and then drawn out of the cell. This can be supplemented with the use of a spot cooling fan. The forced cool down resulted in a much quicker cool down which was further reduced with spot cooling, in the region of 25% reduction.

Forging simulations with a 1522 steel microalloyed by additions of 0.25% Mo, 0.13% V and 0.01% Ti were performed on a laboratory thermomechanical processing simulator. The forging conditions included a strain rate of 22s-1, 50% strain, and temperatures in the range from 1200°C to 950°C. The true stress was found to increase with decreasing deformation temperature for all values of instantaneous true strain. The maximum flow stress increased two-fold as deformation temperature decreased from 1200°C to 950°C, and the recrystallized austenite grain size decreased by a factor of two for this same decrease in temperature. Microstructures evolve from bainitic/ferritic at a cooling rate of 1.4°C/s, to fully martensitic at 16.8°C/s, independent of deformation temperature. Room temperature hardnesses depended primarily on cooling rate and were essentially independent of deformation temperature.

In the aircraft industry, hydroforming is widely used to form parts using aluminum alloys in tempered condition T-XXXX. Success of this process depends on accurate springback prediction. The magnitude of springback and its variation is high in aluminum alloys in tempered condition T-XXXX. Process and material variability causes variation in springback. Wide range of pressures and press types in hydroforming process attribute to process variability. Forming pressures can be varied to control springback. This study looks at the effect of forming pressure on springback in hydroforming of aluminum alloy 2024-T3 and 2524-T3 in two most popular industrial hydropresses. The study forms the basis for developing a new model for springback prediction in the future.

The thickness changes and work hardening arising during the forming process are generally ignored in crash analysis. This paper quantifies the effect of the forming process on crash response of a typical car of stamped steel construction using an analytical study. Forming results for fourteen panels of a medium-sized car were calculated using a one-step stamping analysis code. These were imported into the crash model, and crash results compared with and without the forming effects. The time taken to generate the forming data by a variety of methods is quantified, and the trade-off between the time taken and accuracy is examined. An efficient method of importing the forming data into the crash model is presented.

This paper describes the use of forming simulation output data from a hydroformed frame siderail as initial material properties for crash simulation of the component. The hydroforming simulation model is described and correlated to test measurements. Methods developed to transfer data between forming and crashworthiness analyses are presented and the limitations of the existing systems identified. The frame siderail was subjected to a representative crash load; LS-DYNA was used for both forming and crash simulations. The effect of thickness, work hardening and residual stresses on the crashworthiness results is quantified; crash response is seen to be significantly affected when the effects of forming are included.

This paper presents an investigation of the effect of fouling by considering a tube and plate fin geometry for which performance characteristics are well defined. By matching a particular heat exchanger to a given fan it can be shown that the air-side heat transfer coefficient increases as the air-side passages become progressively blocked, reaching a maximum close to the fully blocked condition. For moderate fouling this increase largely compensates for the change in mean temperature difference brought about by the variation in air flow rate, giving an overall performance very close to that for the clean condition.

The effect of frame flexibility on the stability of constant speed, straight line motions of a motorcycle is studied by reference to linearized differential equations governing the behavior of a system of five rigid bodies, two of which are connected to each other with a hinge, a spring, and a damper, and are intended to represent a flexible frame, while the rest represent the front fork and the wheels of the vehicle. Although the configuration of the system is characterized by seven generalized coordinates, it is shown that the stability information of interest can be deduced from four first-order differential equations.

Various studies have shown that the level of wind noise experienced inside cars on the road in unsteady conditions can be substantially different from that measured in wind tunnel tests conducted using a low turbulence facility. In this paper a simple geometric body representing the cabin of a passenger car has been used to investigate the effects of free stream turbulence, (FST), on the A-pillar vortex flowfield and the side glass pressure distribution. Beneath the A-pillar vortex, both mean and dynamic pressures are increased by FST. The unsteady pressure can be associated with wind noise and the flow visualization shows the peak unsteadiness is related to the separation of the secondary vortex.

This paper presents a method for studying the effect of frequency requirements on the optimum design of automotive structures. Performing such studies can lead to better designs, by helping the designer understand the nature of the design space and the effect of the frequency requirements on the optimum design. To demonstrate the methodology and the effect of the frequency requirements a case study for the optimum design of an automotive structure is considered.

A detailed transient analysis simulation program developed has been used to study the effect of friction modelling on the prediction of turbocharged diesel engine operating under transient conditions. Friction modelling during the transient event is simulated using one of the following methods: a) the mean fmep (friction mean effective pressure) approach with friction torque remaining constant during the cycle, b) the method proposed by Rezeka and Henein where friction torque is explicitly modelled at each degree crank angle, and c) a simplified method which combines the simplicity of the mean fmep approach with the in-cycle variations of the explicit one. It is revealed, as shown in a series of detailed diagrams for various load changes, that the mean fmep approach underestimates engine speed droop up to 12% for the transient cases considered, whereas the simplified method gives results which come very close to the results of the explicit one based on the Rezeka-Henein model.

Friction reduction in lubricated components through engine oil formulations has been investigated in the present work. Three different DI packages in combination with one friction modifier were blended in SAE 5 W-20 and SAE 0 W-16 viscosity grades. The friction performance of these oils was compared with GF-5 SAE 5 W-20 oil. A motored cranktrain assembly has been used to evaluate these, in which friction mean effective pressure (FMEP) as a function of engine speeds at different lubricant temperatures is measured. Results show that the choice of DI package plays a significant role in friction reduction. Results obtained from the mini-traction machine (MTM2) provide detailed information on traction coefficient in boundary, mixed and elastohydrodynamic (EHD) lubrication regimes. It has been shown that the results from the cranktrain rig are fairly consistent with those found in MTM2 tests for all the lubricants tested.

Engine oil plays an important role in improving fuel economy of vehicles by reducing frictional losses in an engine. Our previous investigation explored the friction reduction potential of next generation engine oils by looking into the effects of friction modifiers and dispersant Inhibitor packages when engine oil was fresh. However, engine oil starts aging the moment engine start firing because of high temperature and interactions with combustion gases. Therefore, it is more relevant to investigate friction characteristics of aged oils. In this investigation, oils were aged for 5000 miles in taxi cab application.

The effect of friction modifiers on the low-speed frictional properties of automatic transmission fluids (ATFs) was investigated by scanning force microscopy (SFM). A clutch lining material was covered by a droplet of test ATF, and a steel tip was scanned over the sample. The scanning speeds were varied from 0.13 to 8.56 mm /sec, and the frictional force was deduced from the torsion of the SFM cantilever. A reduction in dynamic friction due to the addition of the friction modifier was clearly observed over the entire speed range. This indicates that the boundary lubrication mechanism is dominant under this condition, and therefore surface-active friction modifiers can effectively improve the frictional characteristics. The friction reduction was more pronounced at lower sliding speeds. Thus addition of friction modifiers produced a more positive slope in the μ-ν (friction vs. sliding speed) plots, and would contribute to make wet clutch systems less susceptible to shudder vibrations.

The design of suspension affects the vehicle dynamics such as ride comfort and handling stability. Nonlinear characteristics and friction are important characteristics of suspension system, and the influence on vehicle dynamic performance cannot be ignored. Based on the seven-degree-of-freedom vehicle vibration nonlinear model with friction, the vibration response process of the vehicle and the influence of suspension friction on vehicle ride comfort and suspension action process were studied. The results show that friction will significantly affects the simulation of ride comfort and coincide with the function of the shock absorber. The suspension shock absorbers of vehicles were optimized with and without suspension friction. The results showed that the suspension tended to choose softer shock absorbers when there was friction. However, both of the two optimizations are able to improve the ride comfort of vehicles, and the simulation results were similar.

Wind tunnel measurements on a rectangular vehicle-like shape and on two detailed, scale-model trucks have been employed to define the front and rear edge geometries that minimize aerodynamic drag. Optimum configurations are identified with sufficient detail for commercial vehicle design purposes. Comparisons of the model-scale measurements with limited measurements on a full-scale straight truck in a large wind tunnel support the interpretation of these test results.