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The effect of minimum stress on the fatigue life has been assessed for an angle-plied nylon cord-reinforced elastomer composite which represents the bias aircraft tire carcass. The S-N curves were established under constant minimum stress rather than constant R-ratio. ...In this manner, all data points in each S-N curve could be associated with the same level of creep stress. Composite laminate specimens exhibited a normal failure sequence of fiber-matrix debonding developing into the delamination under cyclic tension. ...A trend of longer fatigue life of the composite was clearly observed at a given stress amplitude with a higher level of minimum stress.

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.

The question of how the static strength of angle-plied nylon cord-reinforced rubber composites simulating aircraft tire carcass is affected by damage accumulation or materials degradation was examined in this study. ...Acoustic emission (AE) activities were monitored to assess the extent of damage and to explore a possibility of indirect monitoring of residual strength of composites. Total cumulative values of AE hits, counts, and energy, which were defined at the final point of gross failure in static tension, were proportional to the residual strength independently of the frequency used in previous fatigue loading. ...The observation indicates that, subjected to static tensile loading, initially stronger or less fatigue-damaged composite specimens can sustain more damage and therefore produce greater amounts of AE activities up to failure.

The intrinsic wear behavior of tire tread materials bonded to carcass plies was examined under static footprint load and static axial pretension. Relying on a specially designed test apparatus, the abrasion action was induced with constantly changing directions and cyclic change of sliding speed. A series of wear tests was performed for parametric studies. The morphology of resulting wear surfaces was examined to understand wear mechanisms. The wear process of tire tread materials consisted of a mechanical mode of abrasion when sliding speed was below a critical level. For this range of sliding speed, the extent of tread wear was found to be simply dependent on the cumulative number of abrading head revolution which reflects the total sliding distance. The relationship between the amount of wear and cumulative number of abrading head revolution deviated from linearity when the rotational frequency of abrading head reached a critical level.