Ceramics Division Characterization of Fracture Origins

$characterization of fracture$

Origin Location

The second attribute of a fracture origin is its location.

The location of an origin should be characterized in a qualitative fashion as:

Volume - located (in the bulk)
Surface - located
Edge - located (if an edge exists)
Near-surface - located

Note that, as the following figure illustrates, it is possible that an inherently volume-distributed flaw such as a pore may be found in any of these locations within a particular specimen:

in the volume (bulk), at the surface, near the surface, or at an edge.

Origins shall be considered surface-located if the origin is in direct contact with an external specimen or component surface. If there are two or more different types of surface (e.g. a rectangular flexure specimen that has tensile and side surfaces) these surfaces may be differentiated.

Origins which are located at the juncture of two external surfaces (the chamfer or corner of a test specimen or component) shall be considered edge-located.

The word "surface" may also apply to the exterior of a test specimen cut from a bulk ceramic or component, or alternatively, the original surface of the component in the as-fired state. Terms such as "original-surface," "as-processed surface," or "machined tensile surface" may be appropriate.

$volume-distributed fracture origin$

In some instances, it also may be convenient to define a "near- surface located" category.

The following figure provides guidance on one possible criterion for a near surface (NS) characterization.

near surface characterization

Origins may be characterized as near-surface (NS) depending upon whether they are within the distances illustrated. The origin size is the diameter for equiaxed origins, and is the length of the major and minor axes for elongated origins. Size measurements are approximate only.

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Date created: 08 February 2001
Last updated: 08 February 2001

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