DIN Standards Committee Materials Testing
DIN EN 14425-3
Advanced technical ceramics - Test methods for determination of fracture toughness of monolithic ceramics - Part 3: Chevron notched beam (CNB) method; German version EN 14425-3:2010
Hochleistungskeramik - Prüfverfahren zur Bestimmung der Bruchzähigkeit von monolithischer Keramik - Teil 3: Verfahren für Biegeproben mit Chevron-Kerb (CNB-Verfahren); Deutsche Fassung EN 14425-3:2010
Overview
This standard specifies a test method for fracture toughness determination according to the Chevron notched beam method in a four-point bending geometry. For the purposes of this standard, the term monolithic includes particle and whisker reinforced advanced technical ceramics which can be regarded as macroscopically homogeneous. The specified method does not apply to long-fibre reinforced ceramics. When test pieces are tested according to this method, a crack is generated during the test from a sharp tip resulting when the two coplanar notches are cut in the test piece. During the test, the crack front widens as the crack propagates from the tip, resulting in an increase in the force required to maintain growth. Countering this, the test piece becomes more compliant as the crack lengthens, and so the two effects result in a peak load being attained after some distance of propagation. The fracture toughness is determined from the peak force applied. The standard has been prepared by CEN/TC 184 "Advanced technical ceramics", the secretariat of which is held by the BSI (United Kingdom). The responsible German committee is Working Committee NA 062-02-91 AA "Hochleistungskeramik - Monolithische Werkstoffe" ("Advanced technical ceramics - Monolithic materials") at NMP.
