Purpose.

The standard defines the performance tests to obtain the torsional fatigue life and ultimate strength of metallic shafts, shells, hubs, or shaft assemblies. Torsional fatigue life is tested where the strains are predominately elastic, both upon initial torque input and throughout the test, to determine effect of variations in material, geometry, and manufacturing processes or to select or compare shafts, shells, hubs, or shaft assemblies under conditions of repeated direct stress. Ultimate strength is tested to determine the yield torque, ultimate torque, and ultimate failure mode.

This standard does not specifically include the effect of randomly varying torque, i.e., duty cycle, including occasional high torque, overlayed on fatigue torque. In addition, it is not a method of determining customer reliability and is not intended to verify daily production quality. For production quality verification, single torque input methodology can be used that exceeds normal vehicle usage torque or frequencies to return timely results.