Mathematical data processing according to digital image correlation method for polymer composites

Abstract

The paper analyses the numerical algorithms for experimental data processing using a contactless video system Vic-3D, designed for three-dimension analysis of displacement and strain fields, and digital image correlation method. The authors considered methodological issues of conducting an experiment using a video system. They suggested recommendations on the choice of parameters of calculation of correlation, the size of subset and step during the analysis of non-homogeneous displacement and strain fields in polymer composite materials through laminated fiberglass composite. The efficient parameters of mathematical data processing are identified according to digital image correlation method on the basis of building fields for one frame on the surface of laminated fiberglass reinforced plastic at various subset values and at fixed step value. The paper shows the impact of step value on the strain fields detail degree. The authors have identified the relation of the chosen parameters of experimental data processing using digital image correlation method with the scaled levels of consideration of composite materials strain processes. To evaluate the strains at various scale levels, the paper uses supplementary video system instruments: “virtual extensometer”, “rectangular area” and “line”. The authors obtained a longitudinal strain profile that allows evaluating the location of strain peak areas on the composite object surface.

Evaluation of the Sensitivity of Various Reinforcement Patterns for Structural Carbon Fibers to Open Holes during Tensile Tests

“…The value of increment ∆X depends on the size of the structural element of the material (δ) that was found from a photo made using the Carl Zeiss SteREO Discovery V12 stereomicroscope (Figure 2). Since the numerical image processing parameters have a significant influence on the results of movement fields and strains, the presentation of results obtained by the digital image correlation method must include the subset size (X), increment (∆X), number of points (N) for the area under study, size of the composite material structural element (δ), and pixel size (s) [28][29][30] (Table 1). It should be noted that the selection of the parameters of the correlation analysis was done taking into account the material's structural irregularity, which may affect the recording scale of the strains.…”

“…It should be noted that the selection of the parameters of the correlation analysis was done taking into account the material's structural irregularity, which may affect the recording scale of the strains. To change structural strains, a smaller increment must be set that takes into account the structure of the material [28][29][30].…”

Investigation of anisotropy effects in glass fibre reinforced polymer composites on tensile and shear properties using full field strain measurement and finite element multi-scale techniques

“…steps size and the size of subset) during the digital image correlation analysis of heterogeneous laminated fibre glass composite materials has a significant impact on the measurement of strain fields and displacements . 51 In order to obtain full field strain maps for each specimen, the gradient tensor of displacement/strain were calculated at each deformation stage. The final strain map for tensile test specimen which was derived as an approximation of the strain tensor was then presented in terms of the components of normal strains (i.e.…”

Mechanical behavior of fiber-glass plastic with hole pattern using digital image correlation and acoustic emission methods

“…In study [12], modeling of a composite (WFKC) with multiple holes was carried out and compared with the experiment. In non-staggered plates, the maximum stresses occur in the outermost holes [13][14][15]. In staggered hole arrangement, the fracture depends on the smallest cross-sectional area in the direction perpendicular to the plane axis.…”