Ductile fracture modeling based on a mesh objective element removal technology
Conference contribution, 2014

The phenomenological Johnson-Cook continuum and failure models constitute a simple ap- proach to the modelling of ductile fracture in metals. Even though the model is simple, it catches the material behavior at high speed/temperature with a relatively few material parameters. This is an obvious advantage, in addition to its widespread use in commercial softwares, which makes it so often used in many applications, and, in particular, machining simulations of metal cutting processes. Even though there are advantages with the model, a major drawback from our expe- rience1 is that the JC–material model exhibits a significant mesh size dependence in orthogonal machining simulations. In order to overcome this difficulty a mesh objective element removal technology is devised based on a smeared out type of dissipation concept to represent the fracture energy. The tech- nology is investigated for the ductile failure modeling of the pearlite phase in a cast iron mi- crostructure with the objective to obtain a mesh size independent computational tool. In order to obtain mesh objective element deletion, an element removal criterion is defined on the plastic strain energy prior to fracture state is considered as fracture energy. A fracture state is achieved in a gauss-point when the accumulated effective plastic strain equals the fracture strain, com- puted with the Johnson-Cook fracture model. Then a total scaled fracture dissipation energy is computed based on the current accumulated dissipation. The figures below show the model set up, a shear loaded plate, and the computed reaction force, where vertical displacements are pre- scribed, for different mesh sizes. Indeed, our experience is that the model exhibits a significant mesh size dependence without the proper scaling of the energy dissipation.

element removal technology

mesh size dependence

Johnson-Cook

ductile failure modeling

Author

SENAD RAZANICA

Chalmers, Applied Mechanics, Material and Computational Mechanics

Ragnar Larsson

Chalmers, Applied Mechanics, Material and Computational Mechanics

Lennart Josefson

Chalmers, Applied Mechanics, Material and Computational Mechanics

14th European Mechanics of Materials Conference - EMMC14, 27-29 Aug. 2014, Gothenburg, Sweden

1652-8549 (ISSN)

Subject Categories

Production Engineering, Human Work Science and Ergonomics

Driving Forces

Sustainable development

Areas of Advance

Production

Materials Science

Infrastructure

C3SE (Chalmers Centre for Computational Science and Engineering)

More information

Created

10/8/2017