On mechanics and material length scales of failure in heterogeneous interfaces using a finite strain high performance solver

Abstract

Three-dimensional simulations capable of resolving the large range of spatial scales, from the failure-zone thickness up to the size of the representative unit cell, in damage mechanics problems of particle reinforced adhesives are presented. We show that resolving this wide range of scales in complex three-dimensional heterogeneous morphologies is essential in order to apprehend fracture characteristics, such as strength, fracture toughness and shape of the softening profile. Moreover, we show that computations that resolve essential physical length scales capture the particle size-effect in fracture toughness, for example. In the vein of imagebased computational materials science, we construct statistically optimal unit cells containing hundreds to thousands of particles. We show that these statistically representative unit cells are capable of capturing the first-and second-order probability functions of a given data-source with better accuracy than traditional inclusion packing techniques. In order to accomplish these large computations, we use a parallel multiscale cohesive formulation and extend it to finite strains including damage mechanics. The high-performance parallel computational framework is executed on up to 1024 processing cores. A mesh convergence and a representative unit cell study are performed. Quantifying the complex damage patterns in simulations consisting of tens of millions of computational cells and millions of highly nonlinear equations requires data-mining the parallel simulations, and we propose two damage metrics to quantify the damage patterns. A detailed study of volume fraction and filler size on the macroscopic traction-separation response of heterogeneous adhesives is presented.

An inverse micro-mechanical analysis toward the stochastic homogenization of nonlinear random composites

“…We however note that the developed multiscale approach looses objectivity when the homogenized stress-strain relationship reaches strain softening onset. Beyond that point, the homogenized behavior should be formulated in terms of other quantities for which size objectivity can be recovered, such as fracture toughness or traction-displacement jump softening response [89,90,91,92]. With a view to the development of a stochastic multiscale process, which can be used to carry out a complete structural analysis including the degradation and failure of composite structures, the localization stages should thus be up-scaled using other indicator such as fracture toughness, which also exhibits uncertainties [71,93].…”

Sharp volumetric billboard based characterization and modeling of complex 3D Ni/Al high energy ball milled composites

“…As an illustration of the SVB method, we simulate the mechanical response of HEBM Ni/Al composites utilizing the parallel generalized finite element code, PGFem3D, with crystal plasticity constitutive equations [70,71,72]. In our work, two sets of simulations are performed.…”

Large-scale simulations of quasi-brittle microcracking in realistic highly heterogeneous microstructures obtained from micro CT imaging

“…all pores, gravels, sand grains, initial microcracks... present, for instance, in a concrete sample, is nowadays still out of reach. In [17,16], Mosby and Matouš developed hierarchically parallel solvers based on multi-scale simulations on extreme scales in terms of both physical length scales and computed capabilities resources, and show the ability to efficiently compute the failure of heterogeneous samples from sub-micrometer to centimeter scales in damage mechanics problems of particle-reinforced adhesives. In [24], another multiscale framework using large-scale simulations at the microstructural level has been proposed to study cracking in a ultra-high strength steel.…”

“…Such simulations can be either used within multiscale simulations such as in [17,16,24], or in combined experiments/simulations sub-volume techniques as described in [18] to accurately describe the damage due to microscale cracking.…”