Digital-Image-Correlation Technique versus Infinitely Small Element Technique for Crack Analysis of Pipe with Crevice

Conduits of water pipelines are subjected to huge internal pressure for conveying water. Cracks induced by water pollution, material defects and seismic excitation may be forming on a conduit to cause damage. This phenomenon generating stress concentration threatens the safety of a conduit. Thus, techniques to monitor the strain variation of a cracked member are essential. Based on the assumption of linear elastic material, the application of the infinitely small element analysis in a crack problem for numerical simulation was validated. Herein, this research reveals that Digital Image Correlation, DIC, technique is a new manner of surveying the practical strain distribution of a member. By the cracked cylindrical pipe test, the DIC method is used to observe the strain variation in the micro-region surrounding the crack tip. Additionally, to utilize the skills of meshing digital image into subimages increases the precision of analyzing a crack problem via the DIC method. According to the experiment in this research, the capacity of DIC method for capturing a crack progress is validated.