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Fatigue damage calculations are traditionally based on the time domain approach. Acceleration time history inputs are used to excite the system and the outputs are in a form of stress time history. This transient dynamic approach, as time history is intuitive to understand, provides straightforward and reasonable result. Nevertheless, a typical automotive proving ground test consists of 20 to 30 road events, it is not only computationally intensive but could be also a grueling process for an engineer to carry out as it requires several iterations for each event in the schedule before fatigue calculation. Alternatively, a frequency domain fatigue calculation is widely used. In this approach, both the dynamic loading and response are expressed in terms of Power Spectral Density (PSD) functions and the dynamic structure is treated as a linear transfer function. The transfer function is then multiplied with the event PSD to get the PSD of the stress.

This paper summarizes the Fast Fourier Transform (FFT) methodology, special equipment, set-up and testing that is recommended to properly characterize the surface of bearing journals that will not result in objectionable noise or vibration. Traditional surface profiles and finish callouts do not capture some of the key characteristics for addressing what is often the customer's greatest complaint, noise. Noise can vary based on the sensitivity of the vehicle but understanding how to accurately describe (design, test, and measure) a surface for a given vehicle can result in an optimized design and reduce process time during manufacturing. Furthermore, this paper will recommend techniques for determining the proper limits of the FFT callouts.

An ignition delay correlation was developed for a toluene reference fuel (TRF) blend that is representative of automotive gasoline fuels exhibiting two-stage ignition. Ignition delay times for the autoignition of a TRF 91 blend with an antiknock index of 91 were predicted through extensive chemical kinetic modeling in CHEMKIN for a constant volume reactor. The development of the correlation involved determining nonlinear least squares curve fits for these ignition delay predictions corresponding to different inlet pressures and temperatures, a number of fuel-air equivalence ratios, and a range of exhaust gas recirculation (EGR) rates. In addition to NO control, EGR is increasingly being utilized for managing combustion phasing in spark ignition (SI) engines to mitigate knock. Therefore, along with other operating parameters, the effects of EGR on autoignition have been incorporated in the correlation to address the need for predicting ignition delay in SI engines operating with EGR.

The double linear damage model developed by Manson and Halford helps to determine the knee point, which is the intersection between the two straight lines. The damage to the component is then calculated based on this knee point. The new approach mentioned in this paper helps to evaluate the damage on the component in a slightly different way. It uses the knee points as mentioned by Manson and Halford and decomposes the damage to the component for Phase I & Phase II. It then uses the equivalent damage approach and establishes the damage to the component. This will be explained with an example.

Comfort is more than ever one of the major factors of car performance. The seat, a central component of the vehicle interior, contributes heavily to this perception. The increasing partnership between car manufacturers and automotive system equipment manufacturers pushes Faurecia to propose not only standard components but also a complete seat, with its functional and safety criteria, as well as those including comfort. This last aspect is what we will treat here. We are going to show you how the Soft & Firm Seat, a technical innovation developed by Faurecia, improves seat tactile and contact comfort behavior perceived by customers. This innovation has been designed according to Faurecia comfort methodology, using subjective assessment, objective measurements and simulation. Its validation concerns tactile and contact comfort, interactions with other comfort aspects and consequently the improvement of overall comfort.

This study is the result of 2 years of work between the Renault safety department and the Faurecia R&D department. The paper is based on 5 different items aimed at developing improved occupant safety and controlling development of the safety components: - Definition of different crash configurations and the associated biomechanical criteria by the car manufacturer. - Definition of functional specifications (geometry and stiffness for each component) using global simulations. This is the starting point for discussions between the car manufacturer and the suppliers. Comparison of the specifications to the state of the art gives the first orientations for future developments. - An exchange of simulation data to allow overall simulations as early as possible by the supplier's simulation department: Each component can be represented by springs or contact interfaces in the different calculation programs.

Motor vehicle Occupant related indications such as morphology class and dynamic position are important information to be taken into account by future passive safety systems in order to increase protection of occupants. Since 1998, the National Highway Traffic Safety Administration has initiated the first step that will require introduction of occupant sensing means. Occupant information will have to be considered as prior in airbag deployment decision in the event of a frontal crash. A first rule that amends the occupant crash protection standard will require application of improvements in order to reduce risk of severe or fatal airbag induced injuries to occupants, particularly young children and small adults [3], [4]. This paper presents the Faurecia BioVolume sensing system which has been developed for the purpose of occupant monitoring.

Faurecia has developed a numerical tool which allows an automatic optimization of an exhaust line with respect to tailpipe harmonic noise. An optimizer pilots an in-house acoustic software in order to find the exhaust line configuration which fulfills the targets on the two first harmonics. The optimization method as well as the acoustic prediction tool are presented in this paper. Then, two examples of application of the methodology are detailed.

The Federal Motor Vehicle Safety Standards No 208 now includes directives rendering the morphological estimation of passengers mandatory for Advanced Air Bag systems. The Dynamic Automatic Suppression System, which is part of the advanced air bag system uses both the morphological and positional information about the passenger to allow or prevent air bag deployment. Various solutions have been proposed to obtain these information by using for instance capacitive sensors. The response of this kind of sensors depends drastically on their distance from the passenger. This paper presents a method, now implemented in the BIOVOLUME technology developed by Faurecia in partnership with Hitachi computer products, to render those sensors independent from this distance.

A Thermal Enhancer™ has been developed. Primarily, this device functions to increase exhaust gas temperatures to ensure appropriate catalytic heating as an enabler for diesel particulate filter regeneration and nitrogen oxide reduction technologies such as Selective Catalytic Reduction. In addition, this system also gives capability for hydrocarbon dosing as an efficient means for full active regeneration of a diesel particulate filter. An overview of this system and its functional applications will be given. Focus will be directed toward the design and test methodology that was adopted to develop a combustor. Results obtained from steady-state, stationary and transient engine dynamometer tests will illustrate the performance benefits and emissions control capabilities of this system.

Traditionally, fatigue calculations are based on the time domain approach. Acceleration time history inputs are used to excite the system. Through the element stress time history output and rainflow cycle count algorithm, fatigue damage can be calculated through the Palmgren-Miner cumulative damage rule. Nevertheless, it can be a daunting process for CAE analysts as it requires iteration for each individual event in the schedule before calculating the fatigue life. The alternative approach is frequency domain fatigue calculation. In this approach, both the dynamic loading and response are expressed in terms of Power Spectral Density (PSD) functions and the dynamic structure is treated as a linear transfer function. The stress PSD is then obtained by multiplying the transfer function with the PSD load. The objective of this paper is to present a CAE based virtual shaker table procedure for an automotive exhaust component and subjecting it to PSD for fatigue life prediction.

Advanced High-Strength Steels (AHSS) have become an essential part of the lightweighting strategy for automotive body structures. The ability to fully realize the benefits of AHSS depends upon the ability to aggressively form, trim, and pierce these steels into challenging parts. Tooling wear has been a roadblock to stamping these materials. Traditional die materials and designs have shown significant problems with accelerated wear, galling and die pickup, and premature wear and breakage of pierce punches. [1] This paper identifies and discusses the tribological factors that contribute to the successful stamping of AHSS. This includes minimizing tool wear and galling/die pick-up; identifying the most effective pierce clearance (wear vs. burr height) when piercing AHSS; and determining optimal die material and coating performance for tooling stamping AHSS.

Scuffing is one of the major problems that influence the life cycle and reliability of several auto components, including engine cylinder kits, flywheels, camshafts, crankshafts, and gears. Ferrous casting materials, such as gray cast iron, ductile cast iron and austempered ductile cast iron (ADI) are widely applied in these components due to their self-lubricating characteristics. The purpose of this research is to determine the scuffing behavior of these three types of cast iron materials and compare them with 1050 steel. Rotational ball-on-disc tests were conducted with white mineral oil as the lubricant under variable sliding speeds and loads. The results indicate that the scuffing initiation is due to either crack propagation or plastic deformation. It is found that ADI exhibits the highest scuffing resistance among these materials.

The development process of a water pump impeller used on a sport utility vehicle engine is described. A review of the design process is presented in this paper including the computer-aided flow analysis together with testing procedures. By computer modeling, one can estimate the coolant flow characteristics of a given impeller blade shape for providing increased cooling performance and improved efficiency on the engine. It also provides directions for the improved design. The test data are used specifically to confirm the analysis results.

In an effort to improve the dent resistance of exterior body panels at reduced steel thicknesses, some automobile manufacturers have pursued the application of bake hardenable steels. Unfortunately, bake hardenable steels have only been available as cold rolled or with electro-zinc or electro zinc/iron coatings. This situation has been a deterrent for those automobile manufacturers that prefer the use of hot dip galvanneal coatings. Recently, the interest in hot dip galvanneal bake hardenable steels has led to the investigation and development of this more advanced steel grade. This paper presents the results of a stamping trial and dent testing on three exposed hot dip galvannealed materials; i) Regular Ultra Low Carbon (ULC), ii) Rephosphorized ULC, and iii) Rephosphorized Bake Hardenable ULC steel.

Exhaust systems are a necessary solution to reduce combustion engine noise originating from flow fluctuations released at each firing cycle. However, exhaust systems also generate a back pressure detrimental for the engine efficiency. This back pressure must be controlled to guarantee optimal operating conditions for the engine. To satisfy both optimal operating conditions and optimal noise levels, the internal design of exhaust systems has become complex, often leading to the emergence of undesired noise generated by turbulent flow circulating inside a muffler. Associated details needed for the manufacturing process, such as brackets for the connection between parts, can interact with the flow, generating additional flow noise or whistles. To minimize the risks of undesirable noise, multiple exhaust designs must be assessed early to prevent the late detection of issues, when design and manufacturing process are frozen. However, designing via an experimental approach is challenging.

Today, some vehicles include a regenerative-braking system such as the electrical motor-generator that converts the vehicle's kinetic energy into electrical energy to recharge one or more vehicle batteries. The idea is to use air flow to produce additional electrical energy in response to deceleration of the vehicle. With the Wind Power Generator System (WPGS) as a green system, a vehicle can produce extra energy, reduce gasoline usage, and reduce air pollution.