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Squeak and rattle (SAR) noise audible inside a passenger car causes the product quality perceived by the customer to deteriorate. The consequences are high warranty costs and a loss in brand reputation for the vehicle manufacturer in the long run. Therefore, SAR noise must be prevented. This research shows the application and experimental validation of a novel method to predict SAR noise on an actual vehicle interior component. The novel method is based on non-linear theories in the frequency domain. It uses the harmonic balance method in combination with the alternating frequency/time domain method to solve the governing dynamic equations. The simulation approach is part of a process for SAR noise prediction in vehicle interior development presented herein. In the first step, a state-of-the-art linear frequency-domain simulation estimates an empirical risk index for SAR noise emission. Critical spots prone to SAR noise generation are located and ranked.

Despite increasingly stringent crash requirements, the body structures of future mainstream production cars need to get lighter. Carbon fiber reinforced polymer (CFRP) composites with a density 1/5th of steel and very high specific energy absorption represent a material technology where substantial mass can be saved when compared to traditional steel applications. BMW have addressed the demanding challenges of producing several hundred composite Body-in-White (BIW) assemblies a day and are committed to significant adoption of composites in future vehicle platforms, as demonstrated in the upcoming i3 and i8 models. A next step to further integrate composites into passenger cars is for primary structural members, which also perform critical roles in passive safety by absorbing large amounts of energy during a crash event.

Comfort and well-being have always been connected with a flawless interior acoustic, free of any background noise or BSR, (buzz, squeak and rattle). BSR noises dominate the interior acoustic and represent one of the main sources for discomfort often causing considerable warranty costs. Traditionally BSR issues have been identified and rectified through extensive hardware testing, which by its nature intensifies toward the end of the car development process. In the following paper the integration of a virtual BSR validation technique in a modern development process by the use of appropriate CAE methods is presented. The goal is to shift, in compliance with the front loading concept, the development activities into the early phase. The approach is illustrated through the example of an instrument panel, from the early concept draft for single components to an assessment of the complete assembly.

This paper presents the results of CFD study on sunroof buffeting suppression using a dividing bar. The role of a dividing bar in side window buffeting case was illustrated in a previous study [8]. For the baseline model of the selected vehicle in this study, a very high level of sunroof buffeting, 133dB, has been found. The CFD simulation shows that the buffeting noise can be significantly reduced if a dividing bar is installed at the sunroof. A further optimization study on the dividing bar demonstrates that the peak buffeting level can be reduced to 123dB for the selected vehicle if the dividing bar is installed at its optimal location, 65% of the total length from the front edge of the sunroof. The peak buffeting level can be further reduced to 100dB if the dividing bar takes its optimal width 80mm, 15% of the total length of the sunroof for this vehicle, while staying at its optimal location.

This paper presents the results of optimization study for sunroof buffeting reduction using CFD technology. For an early prototype vehicle as a baseline model in this study a high level of sunroof buffeting 133dB has been found. The CFD simulation shows that the buffeting noise can be reduced by installing a wind deflector at its optimal angle 40 degrees from the upward vertical line. Further optimization study demonstrates that the buffeting peak SPL can be reduced to 97dB if the sunroof glass moves to its optimal position, 50% of the total length of the sunroof from the front edge. For any other vehicles, the optimization procedure is the same to get the optimal parameters. On the other hand, however, this optimization study is only based on fluid dynamics principle without considering manufacturability, styling, cost, etc. Further work is needed to utilize the results in the production design.

The average weight of a car has increased significantly in recent years due to higher crash requirements and demands in standard equipment. Therefore, BMW has decided to use aluminium for the body front end of the new BMW 5-series. During the paint process, the 6XXX-alloys currently adopted for the body front end exhibit a considerable increase in yield strength in the E-coat dryer. The increase of strength, the so-called paint bake response of 6XXX-alloys, needs to be fully exploited to meet the increasing demand of future passive safety concepts.

Advanced design of modern engine cooling and vehicle HVAC components involves sophisticated simulation. In particular, front end air flow models must be able to cover the complete range of conditions from idle to high road speeds involving multiple fans of varying types both powered and unpowered. This paper presents a model for electric radiator cooling fans which covers the complete range of powered and unpowered (freewheel) operation. The model applies equally well to mechanical drive fans.

Researchers at the National Renewable Energy Laboratory conducted outdoor vehicle thermal soak tests in Golden, Colorado, in September 2002. The same environmental conditions and vehicle were then tested indoors in two DaimlerChrysler test cells, one with metal halide lamps and one with infrared lamps. Results show that the vehicle's shaded interior temperatures correlated well with the outdoor data, while temperatures in the direct sun did not. The large lamp array situated over the vehicle caused the roof to be significantly hotter indoors. Yet, inside the vehicle, the instrument panel was cooler due to the geometry of the lamp array and the spectral difference between the lamps and sun. Results indicate that solar lamps effectively heat the cabin interior in indoor vehicle soak tests for climate control evaluation and SCO3 emissions tests. However, such lamps do not effectively assess vehicle skin temperatures and glazing temperatures.

The need for low pass filters stems from a need to eliminate high frequency noise from raw data (the output of the data acquisition system). As an example, consider the frame of a vehicle used in a crash test. The frame will exhibit high frequency vibrations, which do not affect the vehicles movement in space. The use of filters has since been expanded to include such things as the calculation of potential injury. Phaseless filters are now required for all FMVSS-208 injury calculations (see references). A single filter formula can not allow all test facilities to comply with the J211 CFC corridors. Even the SAE J211 recommended Butterworth filter may not comply with the J211 requirements. A new, universal, filtering system is required to harmonize the data processing at all testing facilities. The use of Fourier series for filtering provides a very powerful, yet overlooked, solution to today's filtering problems.

An early development vehicle experienced an unusually high rate of windshield breakage. Most breaks were identified as due to impact, but the severity of impact was low. It was reasoned that the windshield should possess a greater level of robustness to impact. Many theories were put forth to explain the breakage data. It was universally agreed that the unusual breakage rate could be due to only one condition, but its source was indefinite. The condition present must be tensile stress. One of three situations were considered regarding its source: 1) the tensile stress was present in the glass after manufacture due to improper annealing; 2) the installation of the windshield into the vehicle body put the glass into stress; 3) some combination of the other two sources. A gray-field polariscope was used to measure the stresses of the windshield from both the manufacturing process as well as the installation in the vehicle.

The automobile industry is seeing an increased need for the application of plastics and their derivatives in various forms such as fiber reinforced plastics, in the design and manufacture of various automotive structural components, to reduce weight, cost and improve fuel efficiency. A lot of effort is being directed at the development of structural plastics, to meet specific automotive requirements such as stiffness, safety, strength, durability and environmental standards and recyclability. This paper presents the concept of reinforcing large injection molded fiber reinforced body panels with structural uni-directional fibers (carbon, graphite, kevlar or fiber glass) wound in tension around the body panels by filament winding technique. Structural uni-directional fibers in tension wound around the fiber reinforced plastic inner body panels would place these body panels under compression.