Speed Analysis of Yawing Passenger Vehicles Following Tire Tread Detachment 2019-01-0418
This paper presents yaw testing of vehicles with tread removed from tires at various locations on the vehicle. A 2004 Chevrolet Malibu and a 2003 Ford Expedition were included in the test series. Speeds up to 60 mph were achieved. The vehicles were instrumented to record speed, steering angle, yaw angle, wheel speeds, and other parameters. The tire marks on the roadway were surveyed and photographed.
Critical speed analysis has long been used by Accident Reconstructionists for calculating speed at the beginning of a yaw. Traditionally, the method has been used to calculate the speed a vehicle with four intact tires. The critical speed model is extended to include the analysis of speed of vehicles following a tread detachment event. It was found that the critical speed formula produces results of acceptable and known accuracy provided the appropriate inputs are used for the given situation and several guidelines are observed. The inputs and guidelines for the use of the critical speed formula for the case of tread detachment are discussed.
Additional speed analysis of the same tests was conducted with the simulation package PC-Crash. Modifications were made to the TM-Easy tire model within PC-Crash to account for the removal of the tire tread. The physical evidence from each test was used to simulate the tests, and a range of speeds for each test were determined. The accuracy range of the PC-Crash simulations is reported.
Gray Beauchamp, David Pentecost, Daniel Koch, William Bortles