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Created page with "{{Language_sel|LANG=ger|ARTIKEL=Kerb}} {{PSM_Infobox}} <span style="font-size:1.2em;font-weight:bold;">Notch</span> __FORCETOC__ ==Definition== The distinction between the fracture mechanics terms notch and crack is often somewhat blurred in the literature. Notches and cracks differ in that the inner boundary surfaces of a crack are in contact in the unloaded state, whereas they are not in the case of a notch. From a mathematical point of view..."

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{{Language_sel|LANG=ger|ARTIKEL=Kerb}}
{{PSM_Infobox}}
<span style="font-size:1.2em;font-weight:bold;">Notch</span>
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==Definition==

The distinction between the [[Fracture Mechanics | fracture mechanics]] terms notch and crack is often somewhat blurred in the literature.

Notches and cracks differ in that the inner boundary surfaces of a crack are in contact in the unloaded state, whereas they are not in the case of a notch. From a mathematical point of view, a crack is a discontinuity surface limited by the crack contour for displacements in the undeformed body. In mathematical modelling, a cut across the largest surface expansion results in a line for the crack and an ellipse for the notch. This means that a crack has an infinitely large curvature at its ends, whereas a notch has a finite curvature at each point of the ellipse. In the direction of its largest surface extension, an internal crack is also assumed to be elliptical, while a surface crack is assumed to be semi-elliptical.

==Geometry in the notch base==

Both cracks and notches are characterised by discontinuities in which surfaces come very close to each other over large areas and which have a linear boundary (crack edge, crack front, notch base) with a very small radius of curvature at least at one point (see: [[Notch Geometry|notch geometry]]). The surfaces of notches and cracks are very large compared to the volumes they enclose. As cracks grow, the volume hardly changes, while the crack surfaces continue to increase.

==Influence on the [[Material Value | characteristic value]] level==

In materials testing, notches of various geometries are specifically introduced into test specimens (see: [[Notch Geometry|notch geometry]]) in order to investigate their effect, e.g. on the toughness parameters.

Less common are side notches, which are used specifically in fracture mechanics to obtain flat crack fronts. (see: [[ICIT – Types of Impact Load–Deflection Diagrams|ICIT – Types of impact load–deflection diagrams]]).

==See also==

*[[Notch Geometry | Notch geometry]]
*[[Notch Sensitivity | Notch sensitivity]]
*[[Instrumented Charpy Impact Test|Instrumented Charpy impact test (ICIT)]]
*[[ICIT – Types of Impact Load–Deflection Diagrams | ICIT–Types of impact load–deflection diagrams]]

'''References'''

* Morgner, W.: Wechselwirkungen zwischen ZfP und Bruchmechanik oder „Alles über den Riss“. In: Berichtsband 65 „ZfP und Bruchmechanik“. DGZfP Berlin (1998), (ISBN 3-931381-26-9)
* [[Blumenauer, Horst|Blumenauer, H.]], Pusch, G.: Technische Bruchmechanik. Deutscher Verlag für Grundstoffindustrie, Leipzig Stuttgart (1987) 2. Auflage (siehe [[AMK-Büchersammlung | AMK-Library]] under E 29-2)
*Anderson, T. L.: Fracture Mechanics. Fundamentals and Applications. 2nd Ed., CRC Press, Boca Raton (1995) 2nd. Edition (ISBN 978-0849342608; see AMK-Library under E 8-1); https://doi.org/10.1201/9781315370293
* Sähn, S., Göldner, H.: Bruch- und Beurteilungskriterien in der Festigkeitslehre. Fachbuchverlag, Leipzig Köln (1993), (ISBN 3-343-00854-0; see[[AMK-Büchersammlung | AMK-Library]] under E 26)

[[Category:Fracture Mechanics]]

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