Belt edge détérioration in radial steel

Traditional test methods, such as road wheel endurance testing, high speed road wheel testing, low-inflation road wheel testing, resistance to bead unseating, plunger testing, model compound rheology analysis, short term field testing, etc., are utilized to study and rank expected tire performance in the field. These tests perform a crucial role in ranking tires However, these tests do not necessarily have the capability to rank tires based on their resistance to belt edge separation in the belt coat compounds generally in use in radial steel belted tires. We present the recent evolution of tire material property testing and its applicability to rank tire aging resistance. An illustrative example will be presented to study the effect of temperature, time, tire cavity oxygen partial pressure and antioxidant level on model compounds oven-aged in tire cavities Additionally the aged tires are analyzed using new road wheel test techniques. The mechanism of belt. edge deterioration and crack growth development along the edge of radial steel belted tires will be presented using the techniques of "Circumferential Cuts" and "Stepped Shearography" to illustrate its usefulness to evaluate the effect of time, temperature and partial pressure of oxygen as a predictive tool. Understanding the chemistry changes that occur in a tire over many years is an important factor in devising new tests to evaluate expected field product performance tests. This paper will present these new testing techniques developed by Akron Rubber Development Laboratory Inc. to rank tires based on the aging factors contributing to the belt edge deterioration in radial steel belted tires. This predictive methodology of rubber product change monitoring is a practical guide for ranking tires, benchmarking tire designs and material changes, and other natural rubber applications where product performance and life are affected by crack growth development due to thermo-oxidative aging mechanisms.