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30th Annual Meeting & Conference on Tire Science & Technology Akron/Fairlawn Hilton Hotel: Akron, OH, USA
Tuesday, September 13, 2011: 8:50 AM
Akron/Summit Ballroom (Akron/Fairlawn Hilton Hotel)
Tire marks play a central role in the reconstruction of traffic accidents, as they can provide valuable information about the vehicle’s trajectory, initial speeds or the steering and braking input of the driver. How the latest changes in vehicle and tire technology influence the applicability of these methods has not yet been completely ascertained. Changes in tire mark characteristics of modern vehicles due to chassis control systems or new types of tires can be observed. The research project described in this paper focuses on the analysis of tire marks under controlled conditions using a mono-wheel setup to permit a selective variation of different driving dynamic parameters without mutual influence. The long-term goal is to find a model for the development of tire marks which allows predicting the influence of specific driving dynamic parameters on the occurrence of tire marks. This model may be applied in accident reconstruction tools. A literature review has been performed to find evidence for the development of tire marks and to identify relevant parameters for their occurrence. Currently no explicit mathematical model showing the influence of tire forces or slip on the occurrence of tire marks is available. Many authors describe the development process mainly related to frictional heating of the pavement and tire tread wear. Based on these assumptions, a mathematical formula has been developed which allows the calculation of the dissipated friction energy within the contact patch as a function of the tire forces, the longitudinal slip and the side slip angle. The main hypothesis deduced from this formula is that the strength of a tire mark depends on the amount of this friction energy independent of the varying parameter. To verify this hypothesis, experiments have been conducted with variation of wheel load, longitudinal slip, side slip angle and tire type. First results indicate a correlation between tire mark characteristics and dissipated friction energy. Nevertheless, modifications of the description model and additional tests with respect to different tire/road combinations and the influence of environmental factors are necessary. Further improvements of the tire mark analysis methodology focus on the refinement of methods to detect and quantify the visibility of tire marks.
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