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Defects or cracks of the component, a corrosive presence or a covering detach are damages which can appear during the component utilization in all those fields where metallic alloys employment is requested.
In order to better understand the cracks read the following definitions:
> cracks extension: an increase in crack size. See also crack length, effective crack size, original crack size, and physical crack size;
> cracks length (depth) In fatigue and stress-corrosion cracking, the physical crack size used to determine the crack growth rate and the stress-intensity factor. For a compact type specimen, crack length is measured from the line connecting the bearing points of load application. For a center-crack tension specimen, crack length is measured from the perpendicular bisector of the central crack. See also crack site;
> cracks mouth opening dispiacement (CMOD). See crack opening displacement;
> cracks opening displacement (COD). On a K, specimen, the opening displacement of the notch surfaces at the notch and in the direction perpendicular to the plane of the notch and the crack. The displacement at the tip is called the Crack tip opening displacement (CTOD); at the mouth, it is called the crack mouth opening displacement (CMOD);
> cracks plane orientation: an identification of the plane and direction of a fracture in relation to product geometry. This identification is designated by a hyphenated code, the first letter(s) representing the direction normal to the crack plane and the second letter(s) designating the expected direction of crack propagation;
> cracks size: a lineal measure of a principal planar dimension of a crack. This measure is commonly used in the calculation of quantities descriptive of the stress and displacement fields. In practice, the value of crack size is obtained from procedures for measurement of physical crack size, original crack size, or effective crack size, as appropriate to the situation under consideration. See also crack length (depth);
> crack tip opening displacement (CTOD). See crack opening displacement;
> crack-tip plane strain. A stress-strain field near a crack tip that approaches piane strain to the degree required by an empirical criterion. |
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