Experimental Study on Tire Contact Patch Characteristics for Vehicle Handling with Enhanced Optical Measuring System

Understanding the behavior of the contact patch can help to identify various parameters like pressure distribution, contact patch dimension, and tire forces, which play a crucial role in vehicle handling performance. In current work, the Stereo-Digital Image Correlation (DIC) application in measuring the contact patch dimension in the static and dynamic condition of standing or rolling tire is developed. Under the static measurement of a standing tire, Stereo DIC is used to plot the three-dimensional (3D) view of the contact patch aiming to extract contact patch dimension information. Under the dynamic condition of a rolling tire, tire carcass deflection in the radial direction can help to obtain contact patch dimensions using curvature information as presented. Also, a novel method to measure the contact patch dimension is proposed. The technique uses a white strip pasted onto the drum of the tire test rig available. A pair of action cameras is applied on the tire test rig to capture videos of tire rolling behavior over the drum. Captured videos are then processed in MATLAB to track the position of the white strip pasted on the drum using color intensity information. Based on the video images, the contact patch length (CPL) is calculated in combination with a scale factor. The lateral deformation of a tire plays a vital role in lateral force and moment generation, and it is essential to understand the relationship between deformation and force. The study also shows how the contact patch displacement is measured and integrated to calculate the forces generated by the tire. Stereo-DIC is applied to measure displacement distribution. Separate testing is performed of a rubber sample from the tire tread area to evaluate tire tread material property, which is then used in combination with strain to calculate forces. Test rig measurements have confirmed the estimated tire forces.