A new device for fretting fatigue testing

Fretting fatigue damage occurs in contacting parts when they are subjected to fluctuating loads and sliding movements at the same time. Fretting fatigue can reduce the fatigue life of materials by half or even more. Fretting fatigue tests are usually performed using universal hydraulic testing devices. The contact pressure is produced by a fixture, typically designed and manufactured by researchers. In this investigation, a new device is introduced in which the fluctuating loading is supplied by a variable crank system (VCSD). The device called VCSD for abbreviation is basically a position control machine in which displacements can be imposed with an accuracy of 0.01 mm. The axial and contact loads are measured by load cells. The friction load is also measured by using foil strain gauges using a Wheatstone bridge configuration. The functionality of the device is examined by making a comparison between fretting fatigue lives of a number of Al7075-T6 specimens tested on a universal testing machine and VCSD. The results show a very close agreement between the functionality of the two testing rigs. The main advantages of VCSD are its higher frequency with respect to universal devices, simplicity, and cheapness. It can be developed further for high and low temperature tests in future.