Preconditioning strategies for vectorial finite element linear systems arising from phase-field models for fracture mechanics

2021 ◽  
Vol 373 ◽  
pp. 113472
Author(s):  
M.A. Badri ◽  
G. Rastiello ◽  
E. Foerster
2019 ◽  
Vol 9 (12) ◽  
pp. 2436 ◽  
Author(s):  
Adrian Egger ◽  
Udit Pillai ◽  
Konstantinos Agathos ◽  
Emmanouil Kakouris ◽  
Eleni Chatzi ◽  
...  

Three alternative approaches, namely the extended/generalized finite element method (XFEM/GFEM), the scaled boundary finite element method (SBFEM) and phase field methods, are surveyed and compared in the context of linear elastic fracture mechanics (LEFM). The purpose of the study is to provide a critical literature review, emphasizing on the mathematical, conceptual and implementation particularities that lead to the specific advantages and disadvantages of each method, as well as to offer numerical examples that help illustrate these features.


2020 ◽  
Vol 235 ◽  
pp. 107133
Author(s):  
Khuong D. Nguyen ◽  
Charles E.Augarde ◽  
William M. Coombs ◽  
H. Nguyen-Xuan ◽  
M. Abdel-Wahab

Author(s):  
Philip K. Kristensen ◽  
Christian F. Niordson ◽  
Emilio Martínez-Pañeda

The phase field paradigm, in combination with a suitable variational structure, has opened a path for using Griffith’s energy balance to predict the fracture of solids. These so-called phase field fracture methods have gained significant popularity over the past decade, and are now part of commercial finite element packages and engineering fitness- for-service assessments. Crack paths can be predicted, in arbitrary geometries and dimensions, based on a global energy minimization—without the need for ad hoc criteria. In this work, we review the fundamentals of phase field fracture methods and examine their capabilities in delivering predictions in agreement with the classical fracture mechanics theory pioneered by Griffith. The two most widely used phase field fracture models are implemented in the context of the finite element method, and several paradigmatic boundary value problems are addressed to gain insight into their predictive abilities across all cracking stages; both the initiation of growth and stable crack propagation are investigated. In addition, we examine the effectiveness of phase field models with an internal material length scale in capturing size effects and the transition flaw size concept. Our results show that phase field fracture methods satisfactorily approximate classical fracture mechanics predictions and can also reconcile stress and toughness criteria for fracture. The accuracy of the approximation is however dependent on modelling and constitutive choices; we provide a rationale for these differences and identify suitable approaches for delivering phase field fracture predictions that are in good agreement with well-established fracture mechanics paradigms. This article is part of a discussion meeting issue ‘A cracking approach to inventing new tough materials: fracture stranger than friction’.


Author(s):  
Marcus Stiemer ◽  
André Große-Wöhrmann ◽  
Slawa Gladkov ◽  
Bob Svendsen ◽  
Robert Spatschek ◽  
...  

2021 ◽  
Vol 349 ◽  
pp. 02001
Author(s):  
Aris Tsakmakis ◽  
Michael Vormwald

Phase field models have been successfully applied in recent years to a variety of fracture mechanics problems, such as quasi-brittle materials, dynamic fracture mechanics, fatigue cracks in brittle materials, as well as ductile materials. The basic idea of the method is to introduce an additional term in the energy functional describing the state of material bodies. A new state variable is included in this term, the so-called phase field, and enables to determine the surface energy of the crack. This approach allows to model phenomena such as crack initiation, crack branching and buckling of cracks, as well as the modelling of the crack front in three-dimensional geometries, without further assumptions. There is yet no systematic investigation of the influence of strain hardening on crack development within the phase field method. Thus, the aim of the paper is to provide an analysis of the effect of kinematic and isotropic hardening on the evolution of the phase field variable.


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