Development of Exponential Model to Find Fatigue Crack Growth and Residual Life for Constant Amplitude Loading

Abstract

Fatigue results in the nucleation of cracks in the structure. Over a period of time, the sizes of these cracks reach a critical dimension and this result into a catastrophic failure of the structure. Hence it is necessary to replace the structure before the crack reaches the critical value. Thus evaluation of fatigue crack growth rate and fatigue life is necessary for safety as well as from economic point of view. In this project, a modified exponential model has been developed to determine the fatigue crack growth rate and residual fatigue life of the structure. The modeling is based on the tests carried out on single edge notched tension (SENT) specimens in Instron 8502 machine, at constant amplitude loading conditions. To calculate the specific growth rate (m) in the exponential model,an expression has been derived using dimensional analysis. The values of different constants in the expression for specific crack growth rate have been obtained using the MATLAB software