Topic
Digital image correlation
About: Digital image correlation is a research topic. Over the lifetime, 7842 publications have been published within this topic receiving 132166 citations.
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TL;DR: In this article, the authors proposed an all-strain based MMC (eMMC) model under plane stress condition, predicting the fracture strain dependent on strain ratio or Φ angle, instead of stress triaxiality and Lode angle parameter.
86 citations
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85 citations
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TL;DR: In this article, a case study of a SiC/SiC composite comprising 2-D woven fiber is presented, where the results of mechanical tests on aluminum alloy specimens in various geometric configurations are provided for selecting DIC test parameters to maximize the extent of correlation and to minimize errors in displacements and strains.
Abstract: Digital image correlation (DIC) is assessed as a tool for measuring strains with high spatial resolution in woven-fiber ceramic matrix composites. Using results of mechanical tests on aluminum alloy specimens in various geometric configurations, guidelines are provided for selecting DIC test parameters to maximize the extent of correlation and to minimize errors in displacements and strains. The latter error is shown to be exacerbated by the presence of strain gradients. In a case study, the resulting guidelines are applied to the measurement of strain fields in a SiC/SiC composite comprising 2-D woven fiber. Sub-fiber tow resolution of strain and low strain error are achieved. The fiber weave architecture is seen to exert a significant influence over strain heterogeneity within the composite. Moreover, strain concentrations at tow crossovers lead to the formation of macroscopic cracks in adjacent longitudinal tows. Such cracks initially grow stably, subject to increasing app lied stress, but ultimately lead to composite rupture. Once cracking is evident, the composite response is couched in terms of displacements, since the computed strains lack physical meaning in the vicinity of cracks. DIC is used to identify the locations of these cracks (via displacement discontinuities) and to measure the crack opening displacement profiles as a function of applied stress.
85 citations
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TL;DR: A typical shrinkage strain field obtained on a specimen surface was highly non-uniform, even at positions of constant distance from the irradiation surface, indicating possible heterogeneity in material composition and shrinkage behavior in the composite.
85 citations
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TL;DR: In this paper, the role of fissure angle and heat treatment temperature on the mechanical properties and deformation failure behavior of brittle granite was investigated using uniaxial compression tests.
Abstract: To investigate the role of fissure angle and heat treatment temperature on the mechanical properties and deformation failure behavior, uniaxial compression tests were carried out on granite specimens containing a single fissure. Using stress–strain curves, the peak strength, peak strain, and elastic modulus of the one-fissured granite specimens were analyzed in detail. The mechanical parameters are closely related to the fissure angle and the high temperature. As the fissure angle increases from 0° to 90°, the peak strength and elastic modulus first decrease and then increase, while the peak strain increases slowly. However, the peak strength and elastic modulus first increase and then decrease, while the peak strain first decreases and then increases with increasing treatment temperature. During the experiments, the crack evolution process and acoustic emission (AE) counts were obtained using real-time photography and the AE monitoring technique. In the granite specimens containing a pre-existing fissure, large AE counts are clearly observed before the peak strength, which indicates crack initiation and propagation. The accumulated AE count first increases slowly, but is followed by a sharp increase, with increasing deformation. The AE events in the one-fissured specimen also depend on the heat treatment temperature. As the temperature increases, the rate of increase of the accumulated AE count curve is reduced. Finally, using a digital image correlation method, the full fields of surface deformation were obtained for the entire testing process. In addition, the local strain around the pre-existing fissure was measured using strain gauges. The full strain field and local strain concentration are discussed to describe the fracture mechanism of brittle granite.
85 citations