PSI - Issue 23

Hynek Lauschmann et al. / Procedia Structural Integrity 23 (2019) 107–112 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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a b Fig. 2: a) Example of a field of 3D reconstruction, b) corresponding image of fracture surface, composed of sharp locations in images of the original set. Specimen A1, the mean macroscopic crack growth rate v = 0.039  m/cycle.

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7 8 Fig. 3: Example of a field of 3D reconstruction and sections of its 8-level decomposition.

Selection of features. Individual sections were characterized by 1662 parameters of roughness and morphometry and their statistical characteristics according to the chap. 2. Within the sequence of locations of 3D reconstructions, odd ones were taken for training, while even ones for testing. In this study, we tested the possibility of estimating crack growth rate on the basis of single features, namely their courses in 8 sections of the decomposition. Therefore, classification procedure has been applied 1662 times for all single features. Functions 2 ( ), ( ) and ( ) i i y x f x s x , i = 1,...,8 (see chap. 2) were found on the basis of training data as polynomial regressions of degree 3, 4 and 1, respectively. For examples see Fig. 4.