Measurement of Contact Patch Pressure Behaviors in High-Speed Dynamic Conditions
Many of the challenging problems in tire dynamics are related to what happens inside the contact patch. Important tire performance attributes such as grip/friction, wear, and noise are all directly related to the contact patch. Calspan and its technology partner Tekscan have developed a novel sensor system that measures the contact patch pressure of the tire as it is rolling at high speed on a flat-belt tire test machine. The measurement results provide detailed insights into the dynamic contact patch pressure (DCPP) in a wide range of realistic and relevant operating conditions on a flat roadway surface. The contact patch behaviors of three tires of similar size and type, but from different manufacturers, were compared. The results highlight how differences in tire design decisions influence the contact patch behavior and in turn the overall tire performance. Additional applications of the DCPP data are presented and discussed.ABSTRACT
Flat-belt tire testing machine at Calspan’s Tire Research Facility, Buffalo, New York.
Schematic of sensor orientation and size, as installed on the flat-belt tire test machine.
Schematic of Tekscan pressure sensor design.
Individual slices are recorded as the sensor travels under the tire. The slices are then assembled to form the full contact patch pressure measurement.
Comparison of contact patch measurements by using three different measurement methods.
Photos of three tires used in the benchmarking study, showing similar tread designs.
Effect of vertical load on contact patch behavior for three tires at 250-kPa inflation pressure, 0° camber, and 22.2 m/s speed.
Effect of camber on contact patch behavior at 250-kPa inflation pressure, 6-kN vertical load, and 22.2 m/s speed.
Effect of slip angle/lateral force on contact patch behavior at 250-kPa inflation pressure, 6-kN vertical load, 0° camber, and 22.2 m/s speed.
Contact patch buckling during severe cornering (6-kN vertical load, −5° slip angle, 250-kPa inflation pressure, and 22.2 m/s speed). The location (blue circle) correlates well with the cooler area of the tread in the time synchronized thermal image (blue arrow).
Contact patch buckling during extreme cornering (9-kN vertical load, −5° slip angle, 250-kPa inflation pressure, and 22.2 m/s speed) for three different tires.
Contributor Notes