Quantitative visualisation of the continuous whole-field stress evolution in complex pore structures using photoelastic testing and 3D printing methods

Abstract

Providing a quantitative description of the whole-field stress evolution in complex structures subjected to continuous loading processes using traditional photoelastic approaches is a significant challenge because of the difficulties with fabricating complex structures, identifying the stress distribution and evolution, and unwrapping isochromatic phase maps. To overcome the challenges, we proposed a novel method to quantify the continuous whole-field stress evolution in a complex porous structure that was fabricated with 3D printing technology. The stress fringes were identified by analysing a series of continuous frames extracted from a video recording of the fringe changes and determining the valleys of the light intensity change curve over the entire loading process. The experimental data were compared with the numerical results of the complex model with identical pore geometries, physical properties, and loading conditions to evaluate the accuracy and effectiveness of the method. In principle, the applicability of the reported method for identifying and unwrapping the continuous whole-field stress is not affected by the complexity of a structure.

Quantification of Hidden Whole‐Field Stress Inside Porous Geomaterials Via Three‐Dimensional Printing and Photoelastic Testing Methods

“…In the slice plane, the high‐concentration SPSDs usually appear at the four opposite edges, and their magnitude is influenced by the shape of the pores and the stress conditions. This is similar to the principal stress difference distribution around the irregular pores in the plane model when subjected to uniaxial compressive load (Ju, Ren, et al, ). However, the reconstructed 3‐D SPSD distribution around this pore indicates that some approximate 3‐D annular zones with higher stress were formed around the pore.…”

The Effect of a Liquid Phase on Force Distribution During Deformation in a Granular System

“…Discs of two different diameters are distributed randomly to inhibit perfect packing, and therefore locking, during deformation which occurs in single‐size granular systems (Kennedy, 2006). Using discs also minimizes shape effects that would lead to uneven stress distributions (e.g., Ju et al, 2018). Even though grain shape and orientation, as well as the distribution of the phases, are important parameters that can determine how a two‐phase system deforms (Handy, 1990; Jordan, 1987; Montesi, 2013), they are currently not accounted for in our experiments.…”