Accumulation of time-dependent strain during dwell-fatigue experiments of iBN-Sylramic melt infiltrated SiC/SiC composites with and without holes

A 2 h tensile load cycle is repeated for specimens without holes and specimens with a central hole under the following conditions: (i) a stress ratio of 0.05, (ii) various stress levels, (iii) 815 °C and 1204 °C, (iv) different times up to 600 h and (v) different hole diameters. An increase in the accumulation of time-dependent strain with the increase in time and stress level is observed for specimens with and without holes. All specimens recovered part of their time-dependent strain at the minimum stress level.Residual strain to failure for specimens without holes showed a reduction with the increase in the amount of strain accumulated during the experiment. A curve fitting procedure of this experimental data, as well as data from archived literature, pointed at the possibility of the existence of a similar finite amount of strain to failure of all specimens tested at both temperatures.