Crack initiation and propagation in ductile fracture: Path dependence and one parameter characterization?

1986 ◽  
Vol 30 (3) ◽  
pp. R49-R52 ◽  
Author(s):  
Anthony G. Atkins ◽  
Yiu-Wing Mai
Keyword(s):  
Crack Initiation ◽  
Ductile Fracture ◽  
Path Dependence ◽  
Fracture Path ◽  
Crack Initiation And Propagation ◽  
Initiation And Propagation

scholarly journals Bayesian inversion for unified ductile phase-field fracture

2021 ◽  
Vol 68 (4) ◽  
pp. 943-980 ◽  
Author(s):  
Nima Noii ◽  
Amirreza Khodadadian ◽  
Jacinto Ulloa ◽  
Fadi Aldakheel ◽  
Thomas Wick ◽  
...  
Keyword(s):  
Crack Initiation ◽  
Ductile Fracture ◽  
Phase Field ◽  
Ductile Failure ◽  
Bayesian Inversion ◽  
Crack Initiation And Propagation ◽  
Posterior Density ◽  
Ductile Phase ◽  
Material Parameters ◽  
Initiation And Propagation

AbstractThe prediction of crack initiation and propagation in ductile failure processes are challenging tasks for the design and fabrication of metallic materials and structures on a large scale. Numerical aspects of ductile failure dictate a sub-optimal calibration of plasticity- and fracture-related parameters for a large number of material properties. These parameters enter the system of partial differential equations as a forward model. Thus, an accurate estimation of the material parameters enables the precise determination of the material response in different stages, particularly for the post-yielding regime, where crack initiation and propagation take place. In this work, we develop a Bayesian inversion framework for ductile fracture to provide accurate knowledge regarding the effective mechanical parameters. To this end, synthetic and experimental observations are used to estimate the posterior density of the unknowns. To model the ductile failure behavior of solid materials, we rely on the phase-field approach to fracture, for which we present a unified formulation that allows recovering different models on a variational basis. In the variational framework, incremental minimization principles for a class of gradient-type dissipative materials are used to derive the governing equations. The overall formulation is revisited and extended to the case of anisotropic ductile fracture. Three different models are subsequently recovered by certain choices of parameters and constitutive functions, which are later assessed through Bayesian inversion techniques. A step-wise Bayesian inversion method is proposed to determine the posterior density of the material unknowns for a ductile phase-field fracture process. To estimate the posterior density function of ductile material parameters, three common Markov chain Monte Carlo (MCMC) techniques are employed: (i) the Metropolis–Hastings algorithm, (ii) delayed-rejection adaptive Metropolis, and (iii) ensemble Kalman filter combined with MCMC. To examine the computational efficiency of the MCMC methods, we employ the $$\hat{R}{-}convergence$$ R ^ - c o n v e r g e n c e tool. The resulting framework is algorithmically described in detail and substantiated with numerical examples.

On the Influence of Strain-Path in Multiaxial Fatigue Failure

1987 ◽  
Vol 109 (2) ◽  
pp. 107-113 ◽  
Author(s):  
Han C. Wu ◽  
C. C. Yang
Keyword(s):  
Crack Initiation ◽  
Strain Path ◽  
Path Dependence ◽  
Fatigue Tests ◽  
Multiaxial Fatigue ◽  
Crack Initiation And Propagation ◽  
Torsional Fatigue ◽  
Initiation And Propagation ◽  
Strain Paths ◽  
Tubular Specimens

A set of strain-controlled experiments has been performed on tubular specimens of annealed stainless steel. The strain-paths are designed to highlight the characteristics of path-dependence in the axial-torsional fatigue tests. Fatigue life, directions of crack initiation, and propagation are the subjects of interest in this investigation. They have been observed to be strongly influenced by the strain-path. For all the specimens tested, crack initiation was in the tensile mode.

Sign in / Sign up

Export Citation Format

Share Document