On the instrument to evaluate damage in steel belted radial truck tires

Towards improving a scanning instrument capable of detecting/evaluating ply cord fatigue damage, which is a likely cause of the zipper mode of failure in steel-reinforced radial truck tires, an air-coupled transducer was used to replace a contact ultrasonic rolling transducer without reducing the pr obability of defect detection. By reducing the number of moving parts in th e sensing unit, the instrument increased its robustness to better endure th e environment of a new tire or retreading facility for on-line inspection o f new or used tires. The instrument continues to be production oriented and capable of producing color-coded scans, thereby reducing the possibility o f damaged tires causing property damage or personnel injury when being serv iced. The results of two tires, one with seeded defects and other with fiel d fatigue damage are presented and discussed.