Modeling of phase interfaces during pre-critical crack growth in concrete

Simulating the Poisson effect in lattice models of elastic continua

“…Download full-size image The needs to remedy inadequacies in representing the Poisson effect are even greater when using irregular lattices [3]. The large amount of scatter, which is due to irregular geometry of the lattice, cannot be removed by calibration of the spring coefficients.…”

“…Lattice models are another means for studying elasticity and breakdown of a variety of materials and structures [17], [33], [22], [15]. Global representation of Young's modulus and Poisson's ratio can be obtained by adjusting longitudinal and transverse dimensions, or stiffnesses, of the lattice beam elements [8], [3], [36]. Whereas such models simulate the Poisson ratio in a global sense, inaccuracies are present at the elemental level, which can be viewed as an artificial form of heterogeneity that is not present in most models constructed from continuum elements.…”

Report on THMC Modeling of the Near Field Evolution of a Generic Clay Repository: Model Validation and Demonstration

“…Such Voronoi scaling also serves energy-conserving, grid-size insensitive representations of tensile fracture. Details regarding the RBSN are given elsewhere (Bolander and Saito, 1998;Asahina et al, 2011). The stress tensor at the Voronoi cell nodes can be calculated by considering the equilibrium conditions of the spring force.…”

Poro-Micromechanics of Materials with Complex Morphologies—A Review, and Recent Results for Concrete, Bone, and Paper

“…While this situation has motivated extensive activity in the field of classical computational mechanics, e.g. based on Rigid Body Spring Networks (Asahina et al 2011), we have recently derived a fully analytical form of the stress fields throughout the ITZs, by combining the known (homogeneous) stress state inside the aggregates with traction and displacement continuity conditions for the aggregate-to-paste interface, and with the elastic law characterizing the ITZ material itself (Königsberger et al 2014a(Königsberger et al , 2014b. These fields, in combination with higher-order downscaling to the hydrate gel level, recently allowed us to successfully upscale one single, "universal" data pair of cohesion and internal friction values determined from nanoindentation of hydrates (Sarris and Constantinides 2013), up to the strength evolutions of various cement pastes and mortars at different hydration degrees.…”