PSI - Issue 47

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Mikhail Bannikov et al. / Procedia Structural Integrity 47 (2023) 685–692 Author name / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 4 – Multifractal spectra plotted for the first cluster (blue) and for cluster 2 (red), shown in Figure 4.1b

4. Cluster and multifractal analysis of distributions of fluctuations of deformation fields To analyze the spatial distribution of strain fields, the Strain Master measuring system was used based on the digital image correlation method. This system enabled in situ recording of the mixing field on the sample surface under uniaxial quasi-static and cyclic loading conditions. The obtained distributions of fluctuations of deformation fields were recalculated into strain fields at various time points with a time step of 0.1 s. An algorithm was used to determine the point with the highest fluctuations for these deformation fields. Similar calculations were performed for experiments on woven composite samples with a concentrator. Figure 5 shows the deformation field of a composite with a concentrator with the most fluctuating point which position is close to hole (Fig. 5).

Fig. 5. – (a) Distribution of deformation fields at a time of 124.1 seconds. Spatial coordinates in pixels are deposited along the abscissa and ordinate axes.

The temporal and spatial dependence of ε ~ ∂ε / ∂ t and ε ~ ∂ε / ∂ x; ~ ∂ε / ∂ y are shown in Fig. 6. Multifractal dependence spectra(t) for composites under uniaxial quasi-static and cyclic loading conditions are shown in Fig. 7 a, b, respectively.