Fatigue behaviour of mullite studied by the indentation flexure method

A systematic study has been performed of the use of the Indentation Flexure Fatigue (IFF) method to study crack growth in mullite at room temperature and high temperature (1300 degreesC). The results obtained for a mullite ha ve been compared with previous data generated on the same material, but usi ng the more direct compact tension method. The material produces transgranu lar crack growth and consequently does not show R-curve behaviour, which co nsiderably simplifies the comparison of the data generated by both methods. The IFF method can significantly overestimate the crack tip stress intensi ty factor because of the way in which the residual stress intensity produce d by the indentation is estimated. The experimental details that influence the test results were investigated. (C) 2000 Elsevier Science Ltd. All righ ts reserved.