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Tire noise is caused due to the complex interactions between the rotating tire and the road surface at the tire/road interface. It is usually caused due to a combination of individual noise generation mechanisms, which can either be structural or air-borne. The influence of each of these noise generation mechanism may vary, depending on various conditions such as tire design, road surface and operating conditions. Due to the many variables that affect the noise generation mechanisms in tires, it is usually a very complex task to isolate and categorize those that are present in the overall tire/road noise spectrum. Various approaches are used to categorize noise generation mechanisms in tires. In this paper, a statistical model based on the assumption that the tire noise acoustic pressure at a specific frequency band is related to the vehicle speed, is used, in order to study tire noise at different speeds.

Flexible polyurethane foam is the main cushioning element used in car seats. Optimization of an occupied seat's static and dynamic behavior requires models of foam that are accurate over a wide range of excitation and pre-compression conditions. In this research, a method is described to estimate the parameters of a global model of the foam behavior from data gathered in a series of impulse tests at different settling points. The estimated model is capable of describing the responses gathered from all the impulse tests using a unique set of parameters. The global model structure includes a nonlinear elastic term and a hereditary viscoelastic term. The model can be used to predict the settling point for each mass used and, by expanding the model about that settling point, local linear models of the response to impulsive excitation can be derived. From this analysis the relationship between the local linear model parameters and the global model parameters is defined.

Vehicle occupants are exposed to low frequency vibrations which can adversely affect the ride comfort. Exposure to vibrations can also lead to problems ranging from fatigue and lower back pain to more serious issues like injuries to the spine. The transmission of vibration to seated occupants can be controlled by appropriately designing car seats, which requires a deep understanding of the seat-occupant system behavior. A seat-occupant system is composed of two main components: the seat and the occupant. A key element in the seat, which is a challenge to model, is the flexible polyurethane foam in the seat cushion, which is a nonlinear and viscoelastic material exhibiting behavior on multiple time-scales. The multi-body occupant model is also geometrically nonlinear. The combined model also incorporates profiles of the seat and the occupant, and includes relatively simple friction models at the occupant and seat interfaces.