The aim of this paper is to propose a continuous-discontinuous computational homogenization-localization framework to upscale microscale localization toward the onset and propagation of a cohesive discontinuity at the macroscale. The major novelty of this contribution is the development of a fully coupled micromacro solution strategy, where the solution procedure for the macroscopic domain is based on the extended finite element method. The proposed approach departs from classical computational homogenization, which allows to derive the effective stress-strain response before the onset of localization. Upon strain localization, the microscale is characterized by a strain localization band where damage grows and by two adjacent unloading bulk regions at each side of the localization zone. The microscale localization band is lumped into a macroscopic cohesive crack, accommodated through discontinuity enriched macroscale kinematics. The governing response of the continuum with a discontinuity is obtained numerically based on proper scale transition relations in terms of the traction-separation law and the stress-strain description of the continuous surrounding material at both sides of the discontinuity. The potential of the method is demonstrated with a numerical example, which illustrates the onset and propagation of a macroscale cohesive crack emerging from microstructural damage within the underlying microstructure.
Dedicated to the memory of Professor Ted BelytschkoAs one of the world leaders in computational mechanics, Ted Belytschko greatly influenced the scientific community. Many of his contributions to the field were groundbreaking, thereby initiating novel routes which inspired many researchers, young and old. Moreover, Ted Belytschko always showed a great interest in the work of others. Among the various subjects, he had a great interest for multi-scale approaches addressing damage and fracture. Based on his outspoken interest for our work on this topic, this paper presents our latest developments in computational homogenizationlocalization to an X-FEM enriched macroscale continuum. He was one of the founding fathers of X-FEM, and this paper is therefore our scientific contribution to pay tribute to the memory of professor Ted Belytschko.an intrinsic limitation of the classical embedded discontinuity technique emerges: the displacement field enrichment is performed at the element level only, which does not allow to describe a compatible displacement field across element boundaries. The assumptions made on the strain field are relaxed in [38], where the macrostructural kinematics allows for the description of a discontinuous displacement field together with a non-uniform deformation field across the discontinuity. Consistent scale transitions are formulated to couple the discontinuous macroscale fields to the continuous kinematics at the microstructural level. The effective microscale response is recovered consisting of the effective stress tensors at each side of the discontinuity (while preserving tract...