Visualization and measurement of load transmission in granular assemblies using mechanoluminescent-coated particles
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Glass beads were coated with a mixture of mechanoluminescent (ML) paint and epoxy resin in order to visualize particle-level force distribution through an analog granular material. SEM observation and X-ray CT scanning was used to verify that the application of the ML coating on the glass beads was uniform. Load tests were conducted on single columns of coated glass particles to equate luminance to diametrical forces transmitted through the particles and particle contacts. The relationship between loading (force) rate during elastic loading of the coated particles and luminance was determined using a column of beads placed in an axial loading device. Coated glass particles were placed in a transparent plane strain container and subjected to biaxial loading to visualize the load transmission through the analog granular material placed in a regular packing. The anisotropy of chains of load transmission during loading was detectable using this test arrangement. The sum of contact forces at the top container boundary deduced from particle luminance is shown to be in agreement with applied boundary loads. This novel technique holds promise as an alternative approach to visualize and measure load transmission through idealized 2D assemblies of granular material.
KeywordsGranular material Force chains Mechanoluminescence
The authors would like to thank Dr. Tsunemi Monma, President of Technopaudalton Co., Ltd., for his assistance with the particle coating method used in this study. The authors also thank Mr. Kenji Mori of Sakai Chemical Industry Co., Ltd. for assisting with the calibration methodology. Finally, the authors are grateful to the Japan Society for the Promotion of Science for financial support through the Grants-in-Aid for Young Scientists (B) 17K14725 program and for a research Grant from the Kajima Foundation.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
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