Component Failure

Sprachauswahl/Language selection

Dieser Artikel ist auch auf Deutsch verfügbar

A service provided by

Polymer Service GmbH Merseburg
Tel.: +49 3461 30889-50 E-Mail: info@psm-merseburg.de Web: https://www.psm-merseburg.de
Our further education offers: https://www.psm-merseburg.de/weiterbildung
PSM on Wikipedia: https://de.wikipedia.org/wiki/Polymer Service Merseburg

Component failure

Property and requirements profile

Component failure (see Figure) occurs when the material's property profile (physical, mechanical, thermal and chemical properties) does not match the component's requirement profile (see: fracture behaviour of plastic components).

	a)
	b)

Figure:

Brittle fracture of a polyamide (abbreviation: PA) pipe

Common causes of failure

Damage to plastic components usually occurs in the form of deformation, cracking, discolouration and fracture, with one of the most common causes of failure being brittle fracture – the catastrophic failure of the component. Brittle fracture is promoted by various influencing factors, which can occur either individually or in combination (see: brittle fracture promoting factors). These include the chemical composition and material morphology (see: microscopic structure), the component geometry and any imperfections and cracks that may be present, the type and speed of stress and the stress state that occurs (see: uniaxial and multiaxial stress state), as well as the temperature and the media surrounding the component.

Component design under mechanical stress

In the event of component failure due to mechanical stress, two causes of failure can be distinguished:

Component failure due to purely mechanical stress is relatively rare. If a component fails in use as a result of purely mechanical stress, this is an indication that the component has been subjected to stress exceeding the permissible load limit (overstressing) or that it has not been used for its intended purpose (misuse). The permissible load limit is determined by the component design.

Component failure occurs much more frequently as a result of mechanical stress, even though the mechanical load does not exceed the load intended by the component design (subcritical stress). In these cases, the mechanical stress itself is not the actual cause of the damage. The cause can be found in the component design, the manufacturing quality, the choice of materials or the effect of external influences that were not anticipated in the component design. In these cases, the mechanical stress and the resulting failure are therefore merely indicators of other causes of damage.

To reduce component failure, close coordination between material selection, design, processing and use of plastic components is required. The resulting factors that may influence the failure behaviour of the components must be identified, whereby mechanical stress is always involved but does not always have to be the cause of damage. Mechanical stress can therefore be the actual cause of damage or act as an indicator of another cause of damage (see also: failure analysis – basics and failure analysis plastic products, VDI-Guide 3822).

Property and requirements profile

Common causes of failure

Component design under mechanical stress

See also