A methodology to calibrate and to validate effective solid potentials of heterogeneous porous media from computed tomography scans and laboratory-measured nanoindentation data

Abstract

Built on the framework of effective interaction potentials using lattice element method, a methodology to calibrate and to validate the elasticity of solid constituents in heterogeneous porous media from experimentally measured nanoindentation moduli and imported scans from advanced imaging techniques is presented. Applied to computed tomography (CT) scans of two organic-rich shales, spatial variations of effective interaction potentials prove instrumental in capturing the effective elastic behavior of highly heterogeneous materials via the first two cumulants of experimentally measured distributions of nanoindentation moduli. After calibration and validation steps while implicitly accounting for mesoscale texture effects via CT scans, Biot poroelastic coefficients are simulated. Analysis of stress percolation suggests contrasting pathways for load transmission, a reflection of microtextural differences in the studied cases. This methodology to calibrate elastic energy content of real materials from advanced imaging techniques and experimental measurements paves the way to study other phenomena such as wave propagation and fracture while providing a platform to fine-tune effective behavior of materials given advancements in additive manufacturing and machine learning algorithms.

Micromechanical testing and modelling of blast furnace slag cement pastes

“…Since nanoindentation actually measures the mechanical properties of the interaction volume around the indent (estimated as 3-5 h max , h max being the maximum indentation depth [47]), this allows for adjusting the interaction volume to correspond to the voxel size of X-ray CT (as described in detail in our previous work [35]). A similar approach has been proposed by others for correlating the nanomechanical measurements and chemical composition determined by WDS (wavelength dispersive spectroscopy) [48,49] and recently extended to nanoindentation [50]. Since the resolution of the Xray CT was set to 2 lm 3 , the E moduli for each indent were calculated in the range between 400 and 660 nm indentation depth.…”

Experimental study of shear failure and crack propagation in water‐bearing coal samples

“…14 Shear failure is a common failure form in engineering. [22][23][24][25] Previous studies have investigated how macroscopic features, microscopic composition, and structure affect the shear behavior of rocks under compression. 15 Acoustic emission (AE) technology has been used to nondestructively detect cracks and assess damage 16,17 and may be used to divide the crack development process in brittle materials into five stages: crack closure, elastic deformation, stable crack development, unstable crack development, and the postpeak stage.…”

“…21 In addition, high-resolution three-dimensional (3D) X-ray microscopy (3D-XRM) or computed tomography of rock offers another route to study the internal pore and crack distribution in rock materials and solid waste. [22][23][24][25] Previous studies have investigated how macroscopic features, microscopic composition, and structure affect the shear behavior of rocks under compression. 26 However, few studies have investigated the mechanical properties and crack propagation of coal samples with different water content and under compression shear.…”