scope:

This guideline applies only to defects that are directly caused by mechanical stress, i.e. excessive or abusive use of thermoplastic components. Any previously existing defects caused by other types of stress, or by faulty processing, design or materials or the choice of an unsuitable material, and which ultimately result in failure under a comparatively low level of mechanical stress, will be dealt with in one of the other, corresponding parts. In this conjunction, mechanical stress only serves as an indicator of other causes of failure.

In the section on "fractography", typical fracture surface characteristics will be presented, which in turn provide information about the fracture process, the source of the crack, and the direction of crack propagation or the cracking speed. These structures will be illustrated using fracture surfaces, for which the origin and previous history is known, as examples.