PSI - Issue 28

F.W. Panella et al. / Procedia Structural Integrity 28 (2020) 1709–1718 Author name / Structural Integrity Procedia 00 (2019) 000–000

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removing CFRP parts from test machine. CFRP sample tests under bending experimental static tests are performed in combination with macroscopic digital image correlation analysis within a region of interest (ROI), customized for a material sample undergoing deformation in specific zones, employing image processing techniques (Dattoma et al. (2019), Galietti et al. (2015)). During static test, a series of images (with a resolution of 4000 × 6000 pixels) are taken at sample’s center using a Nikon High-resolution camera with macro camera lens, as in Fig. 6a. Basically, images are taken throughout test and used as inputs to DIC code. An open source software can be modified for user requirements. Ncorr is used for 2D digital image correlation implemented in Matlab Software, whose capabilities and reliability has been verified in other works. a b

Fig. 5. Phased Array ultrasonic setup for (a) CFRP beam and (c) wrinkle samples.

3. Results and discussion 3.1. DIC static results

Authors conduct displacement/strain measurements on CFRP static tests using DIC technique; a frame rate of five images per second is chosen, employing the actuator speed of 0.5 mm/min. The noise and erroneous DIC parameters could arise during surface preparation and optical arrangement, therefore the authors evaluated capabilities of selected DIC codes comparing displacement results of Matlab Ncorr and GOM softwares through a determination of local ROI (Dattoma et al. (2019)). a b

Fig. 6. (a) Experimental DIC setup and (b) ε xx [mm/mm] and ε xy [mm/mm] strain plot of static bending test.