scholarly journals A Unified Abaqus Implementation of the Phase Field Fracture Method Using Only a User Material Subroutine

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 1913
Author(s):  
Yousef Navidtehrani ◽  
Covadonga Betegón ◽  
Emilio Martínez-Pañeda
Keyword(s):  
Phase Field ◽  
Crack Nucleation ◽  
Crack Density ◽  
Contact Problems ◽  
Element Mesh ◽  
Robust Implementation ◽  
Current Implementation ◽  
User Material Subroutine ◽  
Complex Crack ◽  
Monolithic Solution

We present a simple and robust implementation of the phase field fracture method in Abaqus. Unlike previous works, only a user material (UMAT) subroutine is used. This is achieved by exploiting the analogy between the phase field balance equation and heat transfer, which avoids the need for a user element mesh and enables taking advantage of Abaqus’ in-built features. A unified theoretical framework and its implementation are presented, suitable for any arbitrary choice of crack density function and fracture driving force. Specifically, the framework is exemplified with the so-called AT1, AT2 and phase field-cohesive zone models (PF-CZM). Both staggered and monolithic solution schemes are handled. We demonstrate the potential and robustness of this new implementation by addressing several paradigmatic 2D and 3D boundary value problems. The numerical examples show how the current implementation can be used to reproduce numerical and experimental results from the literature, and efficiently capture advanced features such as complex crack trajectories, crack nucleation from arbitrary sites and contact problems. The code developed is made freely available.

scholarly journals A mesoscale numerical approach to predict damage behavior in concrete basing on phase field method

2021 ◽  
Author(s):  
Nguyen Hoang Quan ◽  
Tran Bao Viet ◽  
Nguyen Thanh Tung
Keyword(s):  
Phase Field ◽  
Crack Nucleation ◽  
Crack Density ◽  
Numerical Procedure ◽  
Simulation Method ◽  
Numerical Approach ◽  
Field Method ◽  
Phase Field Method ◽  
Generation Process ◽  
Damage And Fracture

In this paper, we develop a numerical approach to simulate the 2D complex damage and fracture process of quasi-brittle concrete materials. Based on the phase field theory for the case of elastic isotropic multicomponent materials and the generation process based upon Monte Carlo’s simulation method, we construct a numerical  procedure to solve complex damage thermodynamic problems. The diffusive phase field variable obtained from this calculation can be used to represent the crack nucleation and propagation within 2D complex mesostructure. Some factors that affect the numerical result (type of crack density function and type of split decomposition of strain energy) are accounted to make the predictions more accurate for the case of concrete material. Some new numerical examples are provided to show the usefulness of the approach. 

scholarly journals Phase-field fracture modelling of crack nucleation and propagation in porous rock

2020 ◽  
Vol 224 (1) ◽  
pp. 31-46 ◽  
Author(s):  
Alex Spetz ◽  
Ralf Denzer ◽  
Erika Tudisco ◽  
Ola Dahlblom
Keyword(s):  
Numerical Model ◽  
Phase Field ◽  
Crack Nucleation ◽  
Phase Field Model ◽  
Experimental Tests ◽  
Shear Cracks ◽  
Rock Samples ◽  
Fine Grained ◽  
Propagation Pattern ◽  
Complex Crack

AbstractIn this work, we suggest a modified phase-field model for simulating the evolution of mixed mode fractures and compressive driven fractures in porous artificial rocks and Neapolitan Fine Grained Tuff. The numerical model has been calibrated using experimental observations of rock samples with a single saw cut under uniaxial plane strain compression. For the purpose of validation, results from the numerical model are compared to Meuwissen samples with different angles of rock bridge inclination subjected to uni-axial compression. The simulated results are compared to experimental data, both qualitatively and quantitatively. It is shown that the proposed model is able to capture the emergence of shear cracks between the notches observed in the Neapolitan Fine Grained Tuff samples as well as the propagation pattern of cracks driven by compressive stresses observed in the artificial rock samples. Additionally, the typical types of complex crack patterns observed in experimental tests are successfully reproduced, as well as the critical loads.

A Strategy for Fine Mesh Resolution in Contact Mechanics

2021 ◽  
Author(s):  
Gaurav Chauda ◽  
Daniel J. Segalman
Keyword(s):  
Degrees Of Freedom ◽  
Contact Problems ◽  
Boundary Integral ◽  
System Of Equations ◽  
Element Mesh ◽  
Contact Patch ◽  
Linear System Of Equations ◽  
Fine Mesh ◽  
Stiffness Matrices ◽  
Analytic Expressions

Abstract To obtain detail in elastic, frictional contact problems involving contact many — at least tens, and more suitably hundreds [1] — of nodes are necessary over the contact patch. Generally, this fine discretization results in intractable numbers of system equations that must be solved, but this problem is greatly mitigated when the elasticity of the contacting bodies is represented by elastic compliance matrices rather than stiffness matrices. An examination of the classical analytic expressions for the contact of disks — an example of smooth contact — shows that for most standard engineering metals, such as brass, steel, or titanium, the pressures that would cause more than one degree of arc of contact would push the materials past the elastic limit. The discretization necessary to capture the interface tractions would be on the order of at least tens of nodes. With the resulting boundary integral formulation would involve several hundreds of nodes over the disk, and the corresponding finite element mesh would have tens of thousands. The resulting linear system of equations must be solved at each load step and the numerical problem becomes extremely difficult or intractable. A compliance method of facilitating extremely fine contact patch resolution can be achieved by exploiting Fourier analysis and the Michell solution. The advantages of this compliance method are that only degrees of freedom on the surface are introduced and those not in the region of contact are eliminated from the system of equations to be solved.

A polyconvex phase-field approach to fracture with application to finite-deformation contact problems

PAMM ◽  
2017 ◽  
Vol 17 (1) ◽  
pp. 297-298
Author(s):  
Marlon Franke ◽  
Maik Dittmann ◽  
Christian Hesch ◽  
Peter Betsch
Keyword(s):  
Phase Field ◽  
Finite Deformation ◽  
Contact Problems ◽  
Field Approach

Surface Rolling Effect on Effective Short Fatigue Cracks Density for Railway LZ50 Axle Steel

2010 ◽  
Vol 118-120 ◽  
pp. 75-79 ◽  
Author(s):  
Bing Yang ◽  
Yong Xiang Zhao
Keyword(s):  
Surface Layer ◽  
Fatigue Life ◽  
Crack Nucleation ◽  
Fatigue Cracks ◽  
Crack Density ◽  
Short Crack ◽  
The Other ◽  
Replica Technique ◽  
Rolling Technology ◽  
Compressive Residual Stresses

Surface rolling effect on effective short fatigue cracks density, which reflect the affecting capacity on the initiation firstly and then growth of the dominant short crack result finally in specimen failure, is experimentally studied by a replica technique. Two groups of smooth hourglass shaped specimens of LZ50 axle steel with/without rolled surfaces were tested. The crack density of surface rolled specimens was much lower than that of the other group. This indicates surface rolling technology having the effect of hardening surface layer material to introduce compressive residual stresses. The effect appears to restrain the short crack nucleation and propagation and then, to extend the fatigue life.

scholarly journals Fatigue phase-field damage modeling of rubber using viscous dissipation: Crack nucleation and propagation

2020 ◽  
Vol 142 ◽  
pp. 103282 ◽  
Author(s):  
Pascal J. Loew ◽  
Bernhard Peters ◽  
Lars A.A. Beex
Keyword(s):  
Viscous Dissipation ◽  
Phase Field ◽  
Crack Nucleation ◽  
Damage Modeling

scholarly journals Phase-field approach to fracture for finite-deformation contact problems

PAMM ◽  
2016 ◽  
Vol 16 (1) ◽  
pp. 123-124 ◽  
Author(s):  
Marlon Franke ◽  
Christian Hesch ◽  
Maik Dittmann
Keyword(s):  
Phase Field ◽  
Finite Deformation ◽  
Contact Problems ◽  
Field Approach
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