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High reinforcement content metal matrix composites are produced by the infiltration of molten Al alloys into preforms of ceramic particles using the PRIMEX™ pressureless metal infiltration process. These composites possess low density, very high specific stiffness, high fatigue strength, and good corrosion resistance, making them excellent candidates for automotive brake caliper applications. Most current production brake calipers are fabricated from ductile iron. Ductile iron provides good stiffness and fatigue strength, requirements for the application, but also possesses high density and poor corrosion resistance. The introduction of preform infiltrated metal matrix composites into brake caliper applications, however, has been slow due to the complex geometry. Low cost, high volume preform fabrication techniques suited to the production of full fist caliper preforms that can be subsequently infiltrated with molten Al alloy do not currently exist.

A semi-empirical model predicting the final rotor surface temperature under thermal steady state as a function material properties (thermal conductivity, specific heat, density), rotor thickness and test parameters (inertial load, cooling air speed) was constructed. The key observation that led to the construction of this model was that the initial rotor surface temperature during a stop varied linearly with the net temperature rise of the rotor surface during that stop of a fade sequence. The final rotor temperature under thermal steady state, Tfss (also referred to as maximum steady state temperature or MSST), is given by: Excellent agreement between the predicted and observed values Tfss of was found. This model was used to predict performance changes as a result of material modifications and can serve as an excellent tool for rotor material optimization.

Crashworthiness is a measure of a vehicle's structural integrity during mechanical impact and of its ability to absorb energy and provide occupant protection in crash situations. Finite element modeling has been successfully used to simulate collision events; the present work uses these techniques to simulate the side impact of a mid-size car in order to investigate the crash characteristics of a 45 km/hr impact. Five different analyses were conducted on orthogonal and oblique impacts under varying conditions. The numerical results from the first analysis were compared with published experimental crash results, showing favorable comparisons for this numerical model prediction.

Recently, a metal support catalyst has been successfully developed and its use has been gradually increasing because of its advantages over the conventional ceramic support. The material properties required of an automotive catalytic converter are expected to increase in severity with intensifying environmental regulations on a worldwide level. This study examined the material properties required of an Fe-Cr-Al alloy foil for a metal support having increased heat resistance. First, the effect of rare earth metals against high temperature oxidation resistance of the Fe-Cr-Al alloy foil is examined and the developed alloy is proposed. Second, the durability of the metal support is discussed. Third, the accelerated creep elongation caused by the growth of an oxide film when catalyst related material is loaded, is described and the influence on the performance of the metal support is discussed.

The A 390 (18% silicon, 1% copper Aluminum alloy) and a new designed friction material which could have a potential use in brake application have been studied on a pad-on-disk tribometer, where the pad was made of the friction material and the disk out of the hypereutectic alloy. An experimental study has allowed to optimize the formulation of the pad and the heat treatment of the disk material in order to get the best wear-properties (low wear, stable friction coefficient). Analysis have been used to understand the wear mechanisms, i.e. microstructural evolution and degradation of the material.

Effective slack associated with seat belt systems for rollover protection is studied for the purpose of improving or anticipating improvements to a motor vehicle rollover protection system. A test method and test devices were constructed to study and develop objective understandings of the effects of motor vehicle seat and seat belt characteristics on effective slack. The test devices and test method were proved in two separate motor vehicles with differing seat belt systems. Results demonstrated that effective slack as a conceptual equivalent to a seat belt webbing length could be repeatable and objectively determined for the systems tested. Determining a seat belt system's effective slack is useful for the purpose of comparing experimental restraints and experimental restraint testing to motor vehicle restraint design and performance.

Disk brake rotors require reduced unsprung weight and improved cooling ability for improved fade performance. Automotive brake rotors made from aluminum metal matrix composites (MMC) were evaluated by dynamometer and vehicle tests for the required improvement. The friction and wear performance and the thermal response during fade stops were compared with those of commercially produced gray cast iron (GCI) rotors. It was proved that MMC is a very effective material to replace GCI for brake rotor application, as it reduces unsprung weight and decreases maximum operation temperature of the brake system.

The addition of nickel-coated graphite to silicon carbide particulate reinforced aluminium alloys imparts unique properties to the new composite GrA-Ni™; the graphite makes it useful in high wear applications where it behaves analogously to flake graphite in grey cast iron. Graphite improves scuffing resistance and significantly increases the critical load at which the transition from mild wear to severe wear occurs. The graphitic silicon carbide MMC has better machinability and can be machined at higher metal removal rates than other existing SiC reinforced composites. Fatigue life was determined to be similar to A356-15% SiC composite.

The Simulation Model of Automobile Collisions (SMAC) computer program, developed in the early 1970's, includes a complex collision algorithm for monitoring, detecting and modeling the collision interactions of motor vehicles. A detailed review of some aspects of the logic, rationale and, in particular, limitations of the original SMAC collision algorithm is presented. This paper presents refinements in the definition of the collision interface, the definition of collision type, the vehicle proximity and collision detection logic, and the form of supplementary impulsive constraints on relative motions. The effects of the modifications of the SMAC algorithm on reconstruction results are presented in the form of direct comparisons of results obtained with the original and modified algorithms.

The trajectory solution procedures of the original CRASH program included both the SPIN routine and an exploratory trajectory simulation option to approximate and refine the linear and angular velocities at separation. The resulting separation speeds were then used to determine the impact speeds by means of application of the principle of conservation of linear momentum. This paper presents a detailed review of the logic, rationale and limitations of the trajectory solution procedures of the original CRASH program and discusses a number of refinements including: incorporation of the principle of conservation of angular momentum, approximations of the effects of changes during collision in the positions and orientations of the two vehicles and of the effects of external forces and moments that act on the two-body system during the collision, and adaptations of optimization techniques for error reduction and convergence in iterative solutions.

This paper examines the dynamic displacement-crushing force and dynamic displacement-absorbed energy behaviour of eight cars in full width barrier, 45% overlap rigid barrier and 30° angled barrier tests at 56, 50 and 56 kph respectively. This study shows the frontal crush behaviour of these cars can be divided into three regions or zones of constant force, these zones being associated with crushing of the front structure as far as the engine, the engine and rear front structure and the occupant compartment. The highest average crushing force is associated with crushing of the engine and rear front structure with lower average crushing forces required for the extreme front of the car and for the occupant compartment. It is hypothesised that the energy absorbed-dynamic displacement behaviour in the full width barrier test represents the energy absorbed-mean displacement for all other crush configurations.

When the vacuum-powered brake booster in a passenger vehicle becomes disabled, the brake force gain of the system is reduced significantly, and the brake pedal force required to lock the tires increases beyond the ability of some adults. In such cases, the maximum braking deceleration acheived by those individuals will be something less than the upper boundary as defined by available traction. This paper's goal is to review the design of vacuum boosters, the literature concerning human ability to depress a brake pedal, and FMVSS 105 requirements which must be met by vehicle manufacturers, and to present performance data with and without the booster operational for four passenger vehicles. Furthermore, the application of this information to accident investigations involving disabled boosters will be discussed.

In order to reduce the cost of engine cooling systems in particular the turbo Diesel engines with charge air coolers, we want to understand the relationship between oil sump temperatures and engine coolant temperatures and their impact on one another. Several cars have been tested in the climatic wind tunnel. The following are the cooling specifications: hill climbing with 12% grade with or without a trailer at a 20°C ambient max. speed at 35°C ambient. The main results of these studies were: a great variation of oil sump temperature versus coolant temperature a small variation of coolant temperature versus oil sump temperature a very small variation of heat flux in the oil, in the coolant and the output of engine versus oil sump and coolant temperature.

Test results have been obtained on the thermal performance of aqueous mixtures of propylene-glycol and ethylene-glycol for conditions simulating automotive engine operation. For the present study, thermal performance is defined as the test section surface temperature for a given set of operating conditions. In addition to testing over a wide range of surface heat fluxes up to 2.3 MW/m2, data were also obtained at different mixture concentrations. For all cases considered, both coolant mixtures provided similar results.

On highway and proving ground vehicle tests were conducted in the Southwestern United States to compare the performance of propylene glycol and ethylene glycol based coolants. A cross-section of vehicles encompassing pickup trucks, large and small cars, a minivan and a sport utility vehicle from various manufacturers were included in the program. Test protocols were completed with vehicles ballasted to curb weight with a four passenger load, with and without maximum recommended weight trailers. On highway driving schedules were run simultaneously with each vehicle pair. Two sets of tests were completed with each pair; once with ethylene glycol/water coolant and once with propylene glycol/water coolant. This was done in an AB/BA test sequence to reduce the impact of different ambient conditions between test. Ambient temperatures during the testing ranged from 35°C to 50°C.

There are many collisions in which the “standard” analysis methods are not sufficient to complete an analysis. Many times the points of rest for the vehicles are not documented or the vehicles were “driven” to the points of rest. There are also cases in which one of the vehicles is repaired prior to being documented. In these cases, there is a method that can be used to establish the approximated speed change of the vehicles. This method involves using the crush profile of one of the vehicles and balancing the opposing forces across the crush profile to determine an equivalent crush depth on the undocumented vehicle. Using this “balanced forces” method requires a detailed crush profile of one of the vehicles and good stiffness data for both vehicles. The method is not as accurate as standard methods because of the unknowns, but does yield reasonable results for the speed change severity for the vehicles involved.

The market needs for quieter and more compact engine cooling modules have led Valeo to develop a complete simulation based design (SBD) for its future fan technology. Its purpose is not only to improve the performances of the existing range, but also to reduce the design times significantly, and therefore to cut down the development costs. The current SBD involves using state-of-the-art CFD as a backbone. From an initial guess for a given design point based on a ducted flow approach, 2D blade cascade Navier-Stokes computations are performed to improve and optimize the initial profile. 3D Navier-Stokes computations are then performed to get the final stacking that will match the objective performances. All computations presented here have been achieved with TASCflow by ASC.

Central to the problem of heat exchangers design is the prediction of pressure drop and heat transfer in the exchanger passages. In order to make such predictions for non-Newtonian fluids, it is necessary to know the relation between the viscous properties of the fluid and the wall shear rate. This is done by assuming a constitutive equation which relates the local apparent viscosity of the fluid to the local shear rate. An often used constitutive equation because of its simplicity is the power law equation which however is only valid for particular fluids over a limited wall shear rate (or duct Reynolds number) range. This study concerns the limits of applicability of the power law equation. The method involves a considerations of a more general equation which has power law and Newtonian behavior as asymptotes. The more general equation contains an operating and property parameter whose values specify the operating shear rate range and thus the appropriate viscous properties.

The numerical optimization techniques coupled with a three-dimensional Navier-Stokes solver have been developed to design an automotive cooling fan. The conjugate gradient method is used to look for the search direction and the golden section method is used for the one dimensional search. Concerning the constraints, exterior penalty functions are employed. In the applications of this numerical optimization technique to the design of an automotive cooling fan, using the object functions defined as an increase in the pressure coefficients and a ratio of production rate of turbulent kinetic energy to the pressure head, the final shapes are obtained after sixth and seventh changes of shape function, respectively.

Instruments and analytical techniques are described for in-vehicle monitoring of amounts of air (void fraction) in engine coolant systems and for evaluating the performance of degas reservoirs. This method, based on electrical conductivity measurements of flowing air / coolant mixture, provides measurement, acquisition and display of coolant system temperature, pressure, flow rate, instantaneous void fraction and rate of air removal by degas bottle. Embedded temperature compensation equations are used for essentially real time display of the void fraction.