Figure 5

Representation of the different loading phases. A hysteresis-loop like loading cycle as displayed by the testing software (top), represented translational motion of the base-plate (a) and rotation of the cylindrical counter-body (b). Two phases of motion are represented, which contain elements of pure rolling and pure gliding, as well as a small transition phase of rolling with slip (middle) occurs. Because of the oscillating nature of the movement, these three different kinematic modes are superimposed. Three types of loading zones on the base-plate are hereby created: rolling and gliding, rolling with slip and rolling, and a pure rolling zone. Due to the symmetry of the system, a total of five distinct loading zones can be observed on the base-plate: A) Rolling and Gliding, B) Rolling with slip and Rolling, C) Rolling and Rolling, D) Rolling with slip and Rolling, E) Rolling and Gliding. In the scanning electron micrograph of a ceramic base-plate after 3 million cycles (bottom) the wear marks resulting from the different types of motion are visible. In the area of rolling and gliding (A and E), it is possible to identify grooves and scratches which demonstrate zones of high wear.