PSI - Issue 28

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Najat Zekriti and al/ Structural Integrity Procedia 00 (2019) 000–000

Najat Zekriti et al. / Procedia Structural Integrity 28 (2020) 1745–1754

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Fig. 2. (a) Tensile test machine; (b) zoom on the machine clamping jaws; (c) dumbbell specimen of extruded ABS; (d) printed ABS

2.2. Method DIC has the potential to record images of deformed surfaces, permitting accurate analysis of the material under load stress. The distribution of deformations can then be determined by using the derivatives in the displacement field. This can be carried out by generating different methods such as points, grids, lines, etc. on the specimen surfaces. While the resolution of the camera, and quality of the speckle pattern on the specimen are the main factors for the qualities of the results. The distribution of deformations can then be determined by the application of the derivatives in the displacement field Berfield and al. (1996) To implement this method, the specimen surfaces must be prepared with a random spot pattern. The correlation concept is used to determine the deformations due to the deformation of the sample. Comparisons can be made, By observing the speckle of the image before and after loading. In the last few years, several improvements to the basic computational algorithms have been made and implemented. Helm and al.(1920) Pan (2012) Lu and Cary (2000) but Ncorr Open Source, based on the Matlab platform, is a potential tool for researchers who are interested in using displacement and stress measurement technology at an accessible cost compared to higher quality post-processing equipment and software Blaber and al. (2015) Ab Ghaniand al (2016). The experimental setup consists of:  Sufficient light source  A high resolution camera  A computer and frame grabbing circuit card to digitize the output Concept : the concept consist that the Digital camera takes a picture of the surface of the specimen • Image is downloaded from the camera to a frame grabbing circuit card The measurement of displacement/deformation using the DIC system requires the following consecutive stages: • Preparation of the surface of the analysed specimen (patterning) • Calibration of a device according to the required procedure (using the DIC system calibration) • Recording images of the examined object/material surface before and during its movement/deformation fig.3. • Image analysis (evaluation) using a specialised computer program (software)