1. Problematic study of wear

In frictional mechanical contact, the possible causes of wear are extremely varied. The different types of phenomena that can occur, separately or simultaneously, belong to two groups of factors:

• the effects of contact itself: mechanical, chemical and metallurgical interactions between the two bodies involved;

• the effects of the environment (atmosphere, lubricant, etc.): physico-chemical actions due to the composition of the environment, mechanical actions induced by the nature and cleanliness of this environment (the abrasive nature of a polluted environment, for example).

The study of friction-wear problems in mechanics calls on the concept of the tribological system (see