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An aircraft tire durability study is underway to investigate the deformation and fracture behavior of cord-rubber composites. This study will identify the important parameters responsible for the structural failure of aircraft tires by the use of analytical and laboratory prediction methods. These methods will also identify the interaction between material property degradation and damage accumulation in cord-rubber composites. Preliminary results using coupon specimens of tire carcass have revealed that prolonged static and cyclic loading sequences produce extensive interply shear deformation at the free edges resulting in cord-matrix debonding followed by delamination type failure. These loading sequences represent the circumferential tension in the footprint region of aircraft tires. It was also determined experimentally that a fatigue endurance limit can be established for cord-rubber composites.

A multi-axial dynamic test instrument was designed to perform wear testing of actual aircraft tires as well as tread/carcass composite specimens under laboratory loading conditions which simulate the elements of take-off, landing and taxiing operations. The wear tester consists of a self-spinning abrading head, mounted on the actuator of a servo-hydraulic test system, which faces either (1) the tread surface of a composite specimen clamped by a horizontal stretch frame or (2) the tread region of actual inflated tires. The test concept has been partially proven in the case of tread/carcass composite specimens by building a proto-type test apparatus and operating it successfully. In the current test set-up, the specimen is subjected to static tension to simulate a circumferential load in the tire footprint and the tread surface is in periodic contact with an abrading head under a specific level of pressure.