PSI - Issue 60

S.S. Satpute et al. / Procedia Structural Integrity 60 (2024) 525–534 S. S. Satpute et. al./ Structural Integrity Procedia 00 (2023) 000–000

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3. Crack Tip Images from Fracture Experiments 3.1. Specimen Preparation for Crack Tip Images

(b) Zoomed view of crack growth region near crack tips

(a) Test Setup

(c) Arrangement for camera positioning

Fig.3: Setup showing different cameras deployed for fracture experiment on a typical pipe specimen.

Both the crack tip regions of the pipe were painted with white color for better visibility of the crack tip during crack propagation during the fracture test. For grid making, a stencil with small holes of grid points at 5mm×5mm , as shown Fig. 2(a)) was prepared and that stencil was wrapped ahead of both crack tips. A marker ink pen along with a stencil wrapped around the pipe is used to create this pattern through the holes of the stencil paper. The stencil is removed after marking the dot pattern. The points at 10mm×10mm were encircled by the marker ink for better visibility as shown in the Fig. 2(b) . These are named as 2D world coordinates and named as 11, 12, 21, etc. Here the first and second number represents distance from crack tip in cm in x-coordinates and y-coordinates respectevily. The pitch in circumferential and axial directions was 5mm. The extent of meshing ahead of crack tip was 100mm in the circumferential direction at each crack tip and 60mm in axial direction on either side of each crack tip. Each node of the mesh was numbered such that it gives the location of each node w.r.t. crack tip at any stage as shown in Fig. 2(b).