Calibration of COD Gauge and Determination of Crack Profile for Prediction of Through the Thickness Fatigue Crack Growth in Pipes Using Exponential Function

In present investigation the calibration of COD gauge and study of crack profile for part-through cracked pipes subjected to four-point bending has been done. The results show that crack profile is semi-elliptical in nature for lower crack depth and is flattened with the increase in crack depth. The linear relationship is obtained between crack depth and COD gauge. The COD calibration curve is used to study fatigue crack propagation by exponential function. The material of the pipes under investigation was TP316L grade stainless steel. The specimens were subjected to four-point bend fatigue load in air and at room temperature. The predicted results were compared with experimental crack growth data. It has been observed that the results obtained using exponential function is in good agreement with experimental data.