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

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.