@article {658,
	title = {A methodology to calibrate and to validate effective solid potentials of heterogeneous porous media from computed tomography scans and laboratory-measured nanoindentation data},
	journal = {Acta Geotechnica},
	volume = {13},
	year = {2018},
	month = {Jan-12-2018},
	pages = {1369 - 1394},
	abstract = {<p>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 .</p>
},
	issn = {1861-1125},
	doi = {10.1007/s11440-018-0687-9},
	url = {http://link.springer.com/10.1007/s11440-018-0687-9},
	author = {Monfared, Siavash and Hadrien Laubie and Farhang Radja{\"\i} and Hubler, Mija H. and Roland Jean-Marc Pellenq and Franz-Josef Ulm}
}
@article {319,
	title = {Size-Effect Law for Scratch Tests of Axisymmetric Shape},
	journal = {Journal of Engineering Mechanics},
	volume = {142},
	year = {2016},
	month = {Dec-2016},
	pages = {Article Number: 04016094 },
	abstract = {<p>This paper presents a theoretical and experimental framework for the application of size-effect analysis to microscratch testing as a means to quantify the fracture properties and internal friction of materials at the microscale. The energetic size-effect law (SEL) for microscratch tests is developed for a general monomeric probe shape in terms of an intrinsic size function. The fundamental idea of the proposed approach is to rescale the scratch response to that of the flat punch, a conjecture that allows one to compare the SEL for different probe geometries, and thus solve for the asymptotic fracture toughness and effective process zone length from scratch tests done on homogenous (acetal homopolymer resin and polycarbonate resin) and inhomogeneous materials (mica ceramic and gas shale). As a material of current interest for controlled fracture studies, two samples of gas shale cored from the Marcellus and Eagle Ford formations are tested and analyzed to quantify all material properties that may be derived from the scratch resistance; namely fracture parameters, asymptotic hardness, strength, cohesion, and internal friction.</p>
},
	issn = {0733-9399},
	doi = {10.1061/(ASCE)EM.1943-7889.0001159},
	author = {Hubler, Mija H. and Franz-Josef Ulm}
}
