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1. pfm-cracks: A parallel-adaptive framework for phase-field fracture propagation

   https://doi.org/10.1016/j.simpa.2020.100045  

   Heister, Timo; Wick, Thomas (November 2020, Software Impacts)

   null (Ed.)
2. A phase‐field model for hydraulic fracture nucleation and propagation in porous media

   https://doi.org/10.1002/nag.3612  

   Fei, Fan; Costa, Andre; Dolbow, John E.; Settgast, Randolph R.; Cusini, Matteo (August 2023, International Journal for Numerical and Analytical Methods in Geomechanics)

   Abstract Many geo‐engineering applications, for example, enhanced geothermal systems, rely on hydraulic fracturing to enhance the permeability of natural formations and allow for sufficient fluid circulation. Over the past few decades, the phase‐field method has grown in popularity as a valid approach to modeling hydraulic fracturing because of the ease of handling complex fracture propagation geometries. However, existing phase‐field methods cannot appropriately capture nucleation of hydraulic fractures because their formulations are solely energy‐based and do not explicitly take into account the strength of the material. Thus, in this work, we propose a novel phase‐field formulation for hydraulic fracturing with the main goal of modeling fracture nucleation in porous media, for example, rocks. Built on the variational formulation of previous phase‐field methods, the proposed model incorporates the material strength envelope for hydraulic fracture nucleation through two important steps: (i) an external driving force term, included in the damage evolution equation, that accounts for the material strength; (ii) a properly designed damage function that defines the fluid pressure contribution on the crack driving force. The comparison of numerical results for two‐dimensional test cases with existing analytical solutions demonstrates that the proposed phase‐field model can accurately model both nucleation and propagation of hydraulic fractures. Additionally, we present the simulation of hydraulic fracturing in a three‐dimensional domain with various stress conditions to demonstrate the applicability of the method to realistic scenarios. 

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3. SIMULATION OF DUCTILE FRACTURE PROPAGATION IN STRUCTURAL STEEL SUBJECTED TO ULTRA-LOW CYCLE FATIGUE

   Pericoli, V.S.; Lao, X; Terashima, M; Ziccarelli, A; Deierlein, G; Kanvinde, A.M. (January 2018, Eleventh U.S. National Conference on Earthquake Engineering)

   While considerable progress has been made in simulating the overall seismic response of steel structures using nonlinear response history (dynamic) analysis, techniques to simulate fracture propagation under large scale inelastic cyclic loading are not as well developed. This is despite the fact that fracture is often a critical limit state that can precipitate structural failure and collapse. To address this, a new ductile damage-based cohesive zone model is presented. The proposed model is an extension of the established continuum-based local or micromechanical ductile fracture models for evaluating ultra-low cycle fatigue in structural steels. This model is implemented in the finite element program WARP3D, and evaluated against tests of notched bars that fail by ductile crack propagation. The preliminary results indicate that the model is an effective tool for predicting ductile fracture initiation and propagation in structural steels subjected to monotonic and cyclic large scale inelastic loading. Implications of this for characterizing the post-fracture response of structural steel components are discussed, along with limitations of the research. 

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4. Modeling interactions of natural and two-phase fluid-filled fracture propagation in porous media

   https://doi.org/10.1007/s10596-020-09975-0  

   Lee, Sanghyun; Wheeler, Mary F. (April 2021, Computational Geosciences)

   null (Ed.)
5. Simulation of Ductile Fracture Propagation in Structural Steel Subjected to Ultra-Low Cycle Fatigue

   Pericoli, VS; Lao, X; Terashima, M; Ziccarelli, A; Deierlein, G; Kanvinde, AM (January 2018, Eleventh U.S. National Conference on Earthquake Engineering)

   While considerable progress has been made in simulating the overall seismic response of steel structures using nonlinear response history (dynamic) analysis, techniques to simulate fracture propagation under large scale inelastic cyclic loading are not as well developed. This is despite the fact that fracture is often a critical limit state that can precipitate structural failure and collapse. To address this, a new ductile damage-based cohesive zone model is presented. The proposed model is an extension of the established continuum-based local or micromechanical ductile fracture models for evaluating ultra-low cycle fatigue in structural steels. This model is implemented in the finite element program WARP3D, and evaluated against tests of notched bars that fail by ductile crack propagation. The preliminary results indicate that the model is an effective tool for predicting ductile fracture initiation and propagation in structural steels subjected to monotonic and cyclic large scale inelastic loading. Implications of this for characterizing the post-fracture response of structural steel components are discussed, along with limitations of the research. 

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