InterPore2025

Pore Structure Evolution During Indentation of a Granular Ensemble

21 May 2025, 14:20

15m

Oral Presentation (MS10) Advances in imaging porous media: techniques, software and case studies MS10

Speaker

Bhupendra Chand (Indian Institute of Science Bengaluru)

Description

Indentation is a commonly encountered boundary value problem in infrastructure, petroleum and manufacturing. It is often utilised as a common way to approach the problem of drilling which is typically decoupled into one of indentation and cutting process. The interrupted indentation tests are generally used to study the deformation at multiple length scales and these are the basic markers for what is identified as a shallow indentation vs. a deep indentation problem. The physics of indentation is well defined at the ensemble scale and partially at micro-scale using PIV and other image analysis tools, however evolution of pore structure remains unexplored. The understanding of evolving pore structure during the indentation process can address crucial issues related to the mechanical, physical and transport properties of the granular materials, bridging a significant knowledge gap across various fields of engineering.
This study investigates the evolution of pore structures around an indenter in a granular ensemble composed of uniformly sized glass ballotini particles. Interrupted indentation tests were conducted using a displacement-controlled loading setup, and high-resolution X-ray computed tomography (X-ray CT) scans were acquired after each incremental displacement. The reconstructed images were segmented using a robust Morse-gram software, enabling detailed analysis of particle and pore behaviour.
Mechanics of the indentation is addressed through two complementary approaches. The first involved segmenting individual particles to extract their kinematic responses. The second focused on segmenting the pore structure to examine different regions within the granular ensemble and track changes in pore characteristics. This dual approach provides a comprehensive understanding of the interplay between particle displacements and pore evolution. Riley et al. (2023) used LOVAMAP to study granular packing and we adopted a similar methodology to analyse the evolving pore structure during indentation. The results highlight the critical role of pore evolution in understanding boundary value problems such as indentation, offering new perspectives on granular material behaviour under localised loading.