PSI - Issue 42
Dennis Domladovac et al. / Procedia Structural Integrity 42 (2022) 382–389 Domladovac et al. / Structural Integrity Procedia 00 (2019) 000–000
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cracktip at 0 mm no void.
cracktip at 0 mm width of void: 40 mm
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Fig. 5. DIC results of the specimen without void (left) and specimen with void (right).
u
without void
interferogram
demodulated shearogram
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voids width of 40 mm
interferogram
demodulated shearogram
Fig. 6. Shearography results of the specimen without void (top) and specimen with void (bottom).
In comparison, all three methods are capable to detect the gap. The shearography is the easiest method to detect the gap, when only the position and the knowledge about the irregularity is needed. For example, the method is best suited for non-destructive testing as integrated in a production chain. However, the experimental evaluation shows that it is more di ffi cult to obtain quantitative results here, which would be mandatory for determining the J-integral in fracture mechanical investigations. Based on this work, no continuous measurements can be performed with the shearography, because the deformation of the adherends were to large and rigid body rotation occurs during the test. Whereby the latter shows the greater influence. The DIC approach is best suited when a camera system is already used for the evaluation of other quantities such as the COD. But the e ff ort of numerical post processing, caused by the signal noise, is huge and not advisable for stand alone measuring. First and foremost, the comparatively huge noise is caused by the large measuring window and the associated low positional resolution of 0 . 1 mm. Usually, a smaller measuring window is chosen to acquire the deformation around the crack tip and not those of the whole specimen. In contrast to this, with the BFSM arbitrary
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