Visualization of particle micro-rotations and strain (force) chain in granular materials using three-dimensional electronic speckle pattern interferometry

Abstract

Photoelasticity can be used for visualization to quantify the internal stresses within particles in a granular material. However, most granular materials are opaque in the visible spectrum or not optically-sensitive materials. It is critical limitation to the research is put on few choice of testing material. In this paper, three-dimensional electronic speckle pattern interferometry(3D ESPI) is developed and proven to give new insights on the spatial repartition of minute rotation and deformations in granular materials. By use of numerical differential method, the strain chain can be further evaluated and visualized in granular particles. The detail of the test system and how to determine the particles rotation and deformation is introduced and a few measurements have been performed and demonstrate the implementation of the method.