Effects of the cohesive law on ductile crack propagation simulation by using cohesive zone models

2014 ◽  
Vol 126 ◽  
pp. 1-11 ◽  
Author(s):  
Huang Yuan ◽  
Xiao Li
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Ductile Crack ◽  
Cohesive Law ◽  
Cohesive Zone Models

Numerical Simulation of Dynamic Ductile Fracture Propagation Using Cohesive Zone Modeling

2008 ◽  
Author(s):  
Do-Jun Shim ◽  
Gery Wilkowski ◽  
David Rudland ◽  
Brian Rothwell ◽  
James Merritt
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Crack Growth ◽  
Growth Model ◽  
Cohesive Zone ◽  
Zone Model ◽  
Pipe Material ◽  
Ductile Crack ◽  
Ductile Crack Growth ◽  
Crack Growth Model

This paper presents the development of a dynamic ductile crack growth model to simulate an axially running crack in a pipe by finite element analyses. The model was developed using the finite element (FE) program ABAQUS/Explicit. To simulate the ductile crack propagation, a cohesive zone model was employed. Moreover, the interaction between the gas decompression and the structural deformation was simulated by using an approximate three-dimensional pressure decay relationship from experimental results. The dynamic ductile crack growth model was employed to simulate 152.4 mm (6-inch) diameter pipe tests, where the measured fracture speed was used to calibrate the cohesive model parameters. From the simulation, the CTOA values were calculated during the dynamic ductile crack propagation. In order to validate the calculated CTOA value, drop-weight tear test (DWTT) experiments were conducted for the pipe material, where the CTOA was measured with high-speed video during the impact test. The calculated and measured CTOA values showed reasonable agreement. Finally, the developed model was employed to investigate the effect of pipe diameter on fracture speed for small-diameter pipes.

Modelling Ductile Tearing From Diffuse Plasticity to Crack Propagation

2010 ◽  
Author(s):  
A. Simatos ◽  
S. Marie ◽  
A. Combescure ◽  
F. Cazes
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Continuum Mechanics ◽  
Cohesive Zone ◽  
Continuum Model ◽  
Mechanical Energy ◽  
Stress Triaxiality ◽  
Cohesive Law ◽  
Ductile Tearing ◽  
Mechanics Model

Continuum models for ductile fracture accurately model onset of ductile tearing thanks to their stress triaxiality dependent formulations. Nevertheless, these models are subject to localization and convergence problems that hinder large crack propagation prediction. This paper presents a method to switch from a continuum mechanics model to a cohesive zone maintaining the mechanical energy. This is obtained thanks to a careful identification of the cohesive law whose computation is based on two points: The thermodynamical definition of the cohesive model and the assumption that, for a given problem, the plastic work during localization must be the same if modelled with a regularized continuum model or with introduction of an equivalent cohesive zone. The cohesive discontinuity is introduced in the framework of the eXtended Finite Element Method developed in CAST3M Finite Element code. This strategy permits to use the continuum model as long as it is the most appropriate and to introduce cohesive zone segments without energy loss. Moreover it solves numerical difficulties associated with the local vision of fracture. The performance of the proposed solution is illustrated on the Rousselier model for which a consistent cohesive law is identified. Results of fracture tests prediction on a CT specimen are compared with those obtained with the conventional Rousselier continuum mechanics formulation.

Modelling large crack propagation: from gradient damage to cohesive zone models

2012 ◽  
Vol 178 (1-2) ◽  
pp. 85-95 ◽  
Author(s):  
Eric Lorentz ◽  
Sam Cuvilliez ◽  
Kyrylo Kazymyrenko
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Models ◽  
Large Crack
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