24-10-2012, 02:24 PM
Power Law Versus Exponential Form of Slow Crack Growth of Advanced Structural Ceramics: Dynamic Fatigue
ABSTRACT
The life prediction analysis based on an exponential crack velocity formulation was examined using a variety of
experimental data on glass and advanced structural ceramics in constant stress-rate (‘dynamic fatigue’) and preload testing at
ambient and elevated temperatures. The data fit to the strength versus In (stress rate) relation was found to be very reasonable
for most of the materials. It was also found that preloading technique was equally applicable for the case of slow crack growth
(SCG) parameter n \g 30. The major limitation in the exponential crack velocity formulation, however, was that an inert
strength of a material must be known priori to evaluate the important SCG parameter n, a significant drawback as compared
to the conventional power-law crack velocity formulation.
ABSTRACT
The life prediction analysis based on an exponential crack velocity formulation was examined using a variety of
experimental data on glass and advanced structural ceramics in constant stress-rate (‘dynamic fatigue’) and preload testing at
ambient and elevated temperatures. The data fit to the strength versus In (stress rate) relation was found to be very reasonable
for most of the materials. It was also found that preloading technique was equally applicable for the case of slow crack growth
(SCG) parameter n \g 30. The major limitation in the exponential crack velocity formulation, however, was that an inert
strength of a material must be known priori to evaluate the important SCG parameter n, a significant drawback as compared
to the conventional power-law crack velocity formulation.