scope:

In the following, various types of failure that occur in plastic products as a result of tribology induced stress will be described along with the corresponding failure characteristics, the causes of failure and the failure mechanisms. According to the GfTArbeitsblatt 7 (German Society for Tribology Working Paper 7) this is defined as the wear on the surface of a solid body as a result of contact and relative movement of a counterbody in solid, liquid or gas form. A characteristic of tribological stress is that mechanical stress triggers secondary thermal, tribochemical and physical reactions between the elements involved in the tribological system. Hence, it is a separate type of stress that exists in addition to purely mechanical, thermal or chemical stress, on that is concentrated on the surface of materials and that dissipates towards the core of the material.

The types of defects described for sliding and rolling stress (hydrodynamic, elastohydrodynamic, mixed friction, solid body friction/technically dry) and for oscillating stress (fretting wear) usually occurs in classic machine elements, i.e. in "closed systems". Wear in "open systems" includes abrasive sliding wear as well as wear caused by erosion and solid particle erosion.

This guideline applies to defects that are caused by the effects of the wear mechanisms adhesion, abrasion, surface fatigue and tribochemical reactions. They can occur individually or simultaneously.

The chemical stress encountered in a tribological system, e.g. through lubricants, will not be taken into consideration here. For a description of these effects, see the guideline VDI 3822 Part 2.1.7.