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Creep groan is a low frequency noise generated by the stick-slip phenomenon that occurs when moderate brake pressure is applied between the surfaces of the brake disc and brake pad in a low-speed vehicle. It generally occurs when a vehicle is starting to move from a complete static condition or as it slowly comes to a stop when driving. Transfer path analysis (TPA) is a technique than not only provides a methodical approach to trace the flow of vibro-acoustic energy but also allows users to analyze structure-borne noise contributions. Thus, TPA is extensively used to scrutinize creep groan. The primary purpose of this paper is to empirically identify and evaluate the influences of the environmental conditions, chassis system, and brake material on creep groan using the TPA technique. Once the route that contributes the most vibro-acoustic energy from the source to the receiver is identified through TPA, a mass is added on that specific path to observe the changes in creep groan.

A Brake By Wire (BBW) system is generally composed of electro-mechanical calipers at each wheel, a pedal simulator and a central controller. The brake demand is processed by the pedal and the central controller commands the brake distribution for each brake actuator. The highly responsive and independent brake actuators lead to enhanced controllability which should result in not only better basic braking performance, but also improvements in various active braking functions such as integrated chassis control, driver assistance systems, or cooperative regenerative braking. Although the BBW system has the potential for numerous advantages and innovations in braking, it has yet to be successfully introduced in series production mainly due to safety and cost concerns. Recent studies have been made to investigate the functional safety aspects and additional mechanical backup measures in this regard.

Recently, the automotive industry has become more interested in knee injury, particularly in the application and development of knee airbag modules in vehicles to achieve a good rating during EuroNCAP and IIHS tests. Also, EuroNCAP and IIHS press the automotive industry to equip vehicles with knee airbag modules for occupant safety improvement in barrier tests. (1) Therefore, an invisible knee airbag module has been independently developed through design, simulation, static deployment tests and dynamic knee impact tests. A knee airbag module development process has been established and test results that were obtained from the development process are presented. Also, some design considerations for invisible knee airbag module development are discussed in this paper. A knee airbag module, which has been changed to match the IP lower panel shape and packaging specific vehicle environment, will be developed and produced in the near future.

A three-dimensional numerical method for the prediction of transient temperature of various brake components including brake fluid reached during the ALPINE braking mode in a ventilated disc brake assembly is presented in this paper. The ALPINE braking mode is the representative mountain descent simulation mode. For this precise analytical prediction of each brake component temperature during a repeated braking and heat soaking, a specified disc brake system is modeled including the brake disc, pad assembly consist of lining and back plate, piston and caliper body. Through this three-dimensional numerical method, a correlativity of the brake assembly geometry and the brake fluid temperature could be expected. Analytical results are compared with measured data with a good correlation. The effects of the various system parameters on the brake fluid temperature are also investigated with a three-dimensional computation.

Under driving condition, vehicles undergo various kinds of load, which consequently induces the fracture of automotive suspension system component. Not only to prevent these fractures but also to cut down cost and weight, it is important to predict load conditions and stresses at an early design stage. This paper covers the abuse condition that means extreme load condition such as pothole and curb strike. In this simulation, the limit behavior of car is considered, including non-linearity and large displacement of suspension system, and the method for simulating these events is described as an exemplary application using ADAMS.

Curtain airbag simulations become more and more complex in order to get the best correlation between the numerical simulation and the (hardware) experiment possible. Detailed airbag folding and gas flow simulations already have been introduced as the solution to model the real deploying condition as close as possible. But these advanced methods do also have disadvantages like requiring extensive computing time and detailed input information (for example the gas mixture). This paper presents a new methodology for curtain airbag modeling using the uniform pressure method combined with an analysis using the gas flow approach. It is taken into account that a curtain airbag is often inflated by gas distributed over the airbag by vent holes in the diffuser tube. To obtain the outflow characteristics (mass flow rates and temperatures) of each hole in the diffuser tube, new features of MADYMO R6.1 were used.

The integrated correlation methodology is applied to the correlation of the airbag body block test and the component tests of sub systems consisting of the steering control system. By using the optimization technique for the occupant simulation model involving two-dimensional curves as the input, the optimal scale factors of the input F-D curves are found in order to minimize the sum of deviations between simulation and test results. In addition, the optimal one-dimensional unknown inputs that can't be obtained by component tests are found. It is found that the optimization technique used in this study is very suitable for the correlation of the occupant simulation model that has 2-dimensional test input data, and it is able to shorten the entire correlation time and ensure the reliability of the correlation result. This correlation methodology can be applied to the sled test and the barrier test for validating the occupant analysis model.

The tear seam of invisible passenger side airbag door is made on the back of an instrument panel by laser scoring method and it is not shown outside. One of the requirements for the invisible passenger side airbag door is that the airbag module should deploy with no fragmentation at hot, room and cold temperature conditions. In this paper, a section model was developed by detail inspection of tearing phenomena at the laser-scored region. To validate the model, the finite elements of continuous and dot type laser-scored tear seam were built and analyzed in room and cold temperature conditions. Finally, a three-dimensional equivalent shell model was developed and it was proved that the section model and the equivalent shell model could represent well the tearing phenomena of the airbag door. It is expected that the tearing pattern prediction models developed in this study can be used to design the types of laser scoring and the airbag door with the minimum of real deployment tests.

In this study, an integrated process was constructed to perform DOE analysis and find out effects of factors related to the driver airbag shape in NCAP frontal crash. A finite element driver airbag was modeled using BAGGEN, one of the MADYMO ver.5.4.1 utilities. The airbag modeling process was integrated with a driver NCAP frontal occupant crash model. An additional translation process was also integrated to the processes for the XML-based crash model that was modeled using MADYMO ver.6.1. iSIGHT was employed to the whole integration process parsing and the entire processes from driver airbag modeling to Design of Experiment (DOE) were performed automatically exchanging files between MADYMO server and iSIGHT server. From DOE analyses, improved results were achieved compared to the base design specification and factors that dominantly affect passive safety performance were found out.

Numerical simulations are performed to investigate whistle noise originated from air ventilation ducts in automotive heating, ventilating, and air conditioning (HVAC) system. Whistle noise is caused by periodic vortex shedding from damper tip when damper blocks nearly all of the air passage. In this study, this whistle noise is reproduced using CFD and acoustic analogy. The effects of different damper geometry and different gap width between damper and duct wall are investigated through 2D simulation. Also spanwise and temporal variations of flow/aeroacoustic quantities over the damper are investigated through 3D simulation, too. In this study, unsteady Reynolds averaged Navier-Stokes equations (RANS) are solved with a turbulence model and Ffowcs-Williams and Hawkings equation is used to calculate aeroacoustic pressure.

In current inflatable curtain airbag development process, the curtain airbag performance is developed sequentially for the airbag coverage, FMVSS 226, FMVSS 214 and NCAP. Because the FMVSS 226 for the ejection mitigation and the NCAP side impact test require the opposite characteristics in terms of the dynamic stiffness of the inflatable curtain airbag, the sequential development process cannot avoid the iteration for dynamic stiffness optimization. Airbag internal pressure characteristics are can be used to evaluate the airbag performance in early stage of the development process, but they cannot predict dynamic energy absorption capability. In order to meet the opposite requirements for both FMVSS 226 and NCAP side impact test, a test and CAE simulation method for the inflatable curtain airbag was developed.