EN 13234:2006

Foreword
1 Scope
2 Normative references
3 Principle
4 Significance and use
5 Terms, definitions and symbols
6 Apparatus
   6.1 Test machine
   6.2 Load train
   6.3 Data recording system
   6.4 Micrometers
   6.5 Ligament size measuring device
7 Specimens
   7.1 Un-notched test specimens
   7.2 Notched test specimens
   7.3 Notches
8 Test specimen preparation
   8.1 Machining and preparation
   8.2 Number of test specimens
9 Test procedure
   9.1 Test on reference specimen
   9.2 Test on notched specimen
10 Calculation of results
   10.1 Test specimen origin
   10.2 Tensile strength of un-notched specimen
   10.3 Tensile strength of the notched specimen
   10.4 Plotting of notch sensitivity diagram
   10.5 Calculation of equivalent fracture toughness for the
        different classes of behaviour
11 Test report
Bibliography

This European Standard describes a method for the classification of ceramic matrix composite (CMC) materials with respect to their sensitivity to crack propagation using tensile tests on notched specimens with different notch depths. Two classes of ceramic matrix composite materials can be distinguished: materials whose strength is sensitive to the presence of notches and materials whose strength is not affected. For sensitive materials, this European Standard defines a method for determining equivalent fracture toughness.

The parameter, Keq, is defined as the fracture toughness of a homogeneous material which presents the same sensitivity to crack propagation as the ceramic matrix composite material which is being considered. The definition of the Keq parameter offers the possibility to compare ceramic matrix composite materials with other materials with respect to sensitivity to crack propagation.

For notch insensitive materials, the concept of Keq does not apply.

This European Standard applies to all ceramic matrix composites with a continuous fibre reinforcement, unidirectional (1 D), bidirectional (2 D), and tridirectional (x D, where 2 < x ≤ 3), loaded along one principal axis of reinforcement.