Delayed fracture behavior of alumina was investigated by four-point bending tests which were conducted under both static and cyclic loads to produce stress-life curves. Experimental results were analyzed by two statistical time-dependent models involving the merging of the concepts of statistical variations in strength and subcritical crack growth leading to delayed fracture. The first model considers only the growth of a single major crack to a critical size while the second considers both the flaw statistics and crack growth of multiple cracks in a nonuniform stress field. Both models gave a good description of the strength-probability-lifetime relationship for the static data. They also predicted the same cyclic lifetime distribution from experimental static data. These predictions conform well to the experimental cyclic data implying that no true cyclic fatigue effect exists for this particular alumina. Results from cyclic tests with various frequencies provide further support for this conclusion because the total failure time in cyclic loading is independent of frequency.
|Number of pages||11|
|Journal||Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Engineers, Series C/Chung-Kuo Chi Hsueh Kung Ch'eng Hsuebo Pao|
|State||Published - Apr 1996|