Fatigue Crack Growth of Circular Pipes and Modeling of Single-Edge-Notched Tension (SENT) Specimen

Abstract

Pipe installations usually experience high amplitude Seismic Vibrations. These vibrations may initiate a new cracks or it may extend the severity of the exiting cracks. The monitoring of crack growth and propagation becomes essential if the installation of pipes carry a hazardous fluid. The compliance technique is one of the most commonly used methods to measure the crack growth in small size specimen used to monitor crack. Compact tension (CT), three point bend bar (TPBB) etc. are generally preferred for laboratory tests. Correlations are available for CT, TPBB and some other geometry of small laboratory specimens. However, for pipes and elbows no such correlations are available. Fatigue crack growth tests were carried out on a test specimen in Instron 8502 machine and the necessary data and graphs were analyzed. Fracture toughness analysis is done with the help of Scanning Electron Microscope (SEM).
The fatigue crack growth in a body is Exponential in nature. In the second part of this project a modified gamma model has been proposed to predict the crack growth in a Single Edge Notched Tension (SENT) Specimen. The values of the different parameters were obtained and the analysis was done after coding different programs in C++ and MATLAB software. The final result obtained was found to be coherent with the experimental findings.