Abstract

Three-dimensional digital imaging correlation (DIC) techniques are a viable method for measuring surface displacements and strains on tires. DIC provides the capability to measure the full-field noncontact tire surface deformation and strain state, which supports multiple objectives: validation of tire models based on finite element (FE) predictions, setting targets for improving FE predictions and providing insight into the tire deformation state under static and dynamic conditions. A method for verifying the accuracy of the DIC measurement process is presented whereby a thin, rectangular test sample of rubber material is subjected to a combination of strains and rigid body motions of known amounts. Once the measurement technique is proven accurate with a simple specimen, the focus shifts to the objectives explained above. Tire surface strains will be discussed for purposes of validating model predictions of sidewall and belt edge strains. Several types of specimen geometries will be reviewed and their effect on material properties will be presented. Also, the DIC technique can provide insight into complex physical problems that may otherwise be very difficult to measure. Some examples presented here include tire sidewall standing waves at high speeds and strains near tread lugs of agricultural tires. The DIC measurement method is an accurate, noncontacting full field technique for measuring in-plane surface displacements and strains of the magnitudes encountered in tire analysis. This technique serves many functions and has become a valuable tool for both tire testing and development.

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