{"title":"用数字图像相关法测量粗晶粒变形","authors":"C. Silvani, J. Réthoré, S. Nicaise","doi":"10.1111/str.12378","DOIUrl":null,"url":null,"abstract":"This work presents results from oedometric compression of coarse granular material. Coarse granular media exhibit significant deformations making it complicated to predict the settlement of structures. In this paper, a measurement technique was developed for the analysis of two‐dimensional (2‐D) images of a deforming coarse granular medium to investigate its deformation. This was achieved by realising grain‐based image correlation to measure the grain transformation in gravel with the use of a digital image correlation technique. The 2‐D displacement fields enable us to explore the behaviour of granular media at different scales: microscopic, mesoscopic and macroscopic scales. The mesoscopic scale is defined from branches that connect the centres of three neighbouring grains, using a Delaunay triangulation to account for an equivalent continuum media. Whereas the consistency of the macroscopic strain and the average mesoscopic strain is assessed, it is shown that a deviation from the normalised microscopic vertical displacement is an indicator of the heterogeneity of the mesoscopic strain field. The proposed mesoscopic analysis allows us to investigate these heterogeneities. Another important result is that even if the amplitude of the microscopic strain is small (approximately 100 times smaller) compared with the other strain measures, it confirms that the grains are not rigid and that their ultimate strain can be estimated using the proposed approach.","PeriodicalId":51176,"journal":{"name":"Strain","volume":null,"pages":null},"PeriodicalIF":1.8000,"publicationDate":"2021-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1111/str.12378","citationCount":"2","resultStr":"{\"title\":\"Measuring coarse grain deformation by digital image correlation\",\"authors\":\"C. Silvani, J. Réthoré, S. Nicaise\",\"doi\":\"10.1111/str.12378\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"This work presents results from oedometric compression of coarse granular material. Coarse granular media exhibit significant deformations making it complicated to predict the settlement of structures. In this paper, a measurement technique was developed for the analysis of two‐dimensional (2‐D) images of a deforming coarse granular medium to investigate its deformation. This was achieved by realising grain‐based image correlation to measure the grain transformation in gravel with the use of a digital image correlation technique. The 2‐D displacement fields enable us to explore the behaviour of granular media at different scales: microscopic, mesoscopic and macroscopic scales. The mesoscopic scale is defined from branches that connect the centres of three neighbouring grains, using a Delaunay triangulation to account for an equivalent continuum media. Whereas the consistency of the macroscopic strain and the average mesoscopic strain is assessed, it is shown that a deviation from the normalised microscopic vertical displacement is an indicator of the heterogeneity of the mesoscopic strain field. The proposed mesoscopic analysis allows us to investigate these heterogeneities. Another important result is that even if the amplitude of the microscopic strain is small (approximately 100 times smaller) compared with the other strain measures, it confirms that the grains are not rigid and that their ultimate strain can be estimated using the proposed approach.\",\"PeriodicalId\":51176,\"journal\":{\"name\":\"Strain\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.8000,\"publicationDate\":\"2021-01-13\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1111/str.12378\",\"citationCount\":\"2\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Strain\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://doi.org/10.1111/str.12378\",\"RegionNum\":3,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q2\",\"JCRName\":\"MATERIALS SCIENCE, CHARACTERIZATION & TESTING\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Strain","FirstCategoryId":"88","ListUrlMain":"https://doi.org/10.1111/str.12378","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"MATERIALS SCIENCE, CHARACTERIZATION & TESTING","Score":null,"Total":0}
Measuring coarse grain deformation by digital image correlation
This work presents results from oedometric compression of coarse granular material. Coarse granular media exhibit significant deformations making it complicated to predict the settlement of structures. In this paper, a measurement technique was developed for the analysis of two‐dimensional (2‐D) images of a deforming coarse granular medium to investigate its deformation. This was achieved by realising grain‐based image correlation to measure the grain transformation in gravel with the use of a digital image correlation technique. The 2‐D displacement fields enable us to explore the behaviour of granular media at different scales: microscopic, mesoscopic and macroscopic scales. The mesoscopic scale is defined from branches that connect the centres of three neighbouring grains, using a Delaunay triangulation to account for an equivalent continuum media. Whereas the consistency of the macroscopic strain and the average mesoscopic strain is assessed, it is shown that a deviation from the normalised microscopic vertical displacement is an indicator of the heterogeneity of the mesoscopic strain field. The proposed mesoscopic analysis allows us to investigate these heterogeneities. Another important result is that even if the amplitude of the microscopic strain is small (approximately 100 times smaller) compared with the other strain measures, it confirms that the grains are not rigid and that their ultimate strain can be estimated using the proposed approach.
期刊介绍:
Strain is an international journal that contains contributions from leading-edge research on the measurement of the mechanical behaviour of structures and systems. Strain only accepts contributions with sufficient novelty in the design, implementation, and/or validation of experimental methodologies to characterize materials, structures, and systems; i.e. contributions that are limited to the application of established methodologies are outside of the scope of the journal. The journal includes papers from all engineering disciplines that deal with material behaviour and degradation under load, structural design and measurement techniques. Although the thrust of the journal is experimental, numerical simulations and validation are included in the coverage.
Strain welcomes papers that deal with novel work in the following areas:
experimental techniques
non-destructive evaluation techniques
numerical analysis, simulation and validation
residual stress measurement techniques
design of composite structures and components
impact behaviour of materials and structures
signal and image processing
transducer and sensor design
structural health monitoring
biomechanics
extreme environment
micro- and nano-scale testing method.