Understanding the tensile strength of ceramics in the presence of small critical flaws

International audienceThe effect of small critical flaws on the strength of polycrystalline ceramic materials is analyzed with the help of an initiation criterion combining both a stress and an energy conditions. If the size of the defect is smaller than the characteristic material length, numerical predictions reveal that the defect (either sharp or blunt) has no effect on the strength. This result is in a good agreement with experimental results obtained from the strength measurements of ceramic materials with controlled flaws. Combining two fracture tests after introducing flaws with controlled sizes enables to identify the fracture parameters of the ceramic material