Ductile fracture of high strength steels with morphological anisotropy, Part II: Nonlocal micromechanics-based modeling. (1st May 2021)

• Record Type: Journal Article
• Authors: Leclerc, Julien; Marteleur, Matthieu; Colla, Marie-Stéphane; Pardoen, Thomas; Noels, Ludovic; Nguyen, Van-Dung
• Is Part Of: Engineering fracture mechanics. Volume 248(2021)
• Publication Date: 2021-05-01
• Subjects: Ductile fracture -- Gurson -- Thomason -- Cohesive band model; Fracture mechanics -- Periodicals; Rupture, Mécanique de la -- Périodiques; Fracture mechanics; Periodicals; 620.112605
• DOI: 10.1016/j.engfracmech.2021.107716
• Languages: English
• ISSNs: 0013-7944

Abstract

Abstract: The ductile fracture behavior of a high strength steel is addressed in this two-part study using a micromechanics-based approach. The objective of Part II is to propose, identify, and validate a numerical model of ductile fracture based on the Gurson–Tvergaard–Needleman model. This model is enhanced by the Nahshon–Hutchinson shear modification in combination with a generalization of the Thomason coalescence criterion within a fully nonlocal form and relying on a damage-to-crack transition technique. The material model involves parameters of different natures either related to the micro-mechanics of porous materials or to semi-empirical formalisms. The void nucleation model and elastoplastic behavior have been developed and identified in Part I. The other parameters are identified in this part using inverse modeling based on both the numerical results of void cell simulations and the experimental measurements. The model is shown to adequately predict the effect of stress triaxiality and Lode parameter on the fracture strain as well as the fracture anisotropy. While the cup-cone and slant fracture paths in the round bars and in the plane strain specimens, respectively, cannot be captured using the pure continuum approach, the damage-to-crack transition framework reproduces these experimental observations. Highlights: A coupled nonlocal Gurson-coalescence model is framed in a crack transition framework. The model parameters are identified using mainly micromechanical argumentations. Void cell simulations are exploited by postulating the dissipation equivalence. The characteristic lengths are taken from microstructure characterization. The numerical framework is experimentally validated for several stress states.