scholarly journals Modeling Brittle Fractures in Epoxy Nanocomposites Using Extended Finite Element and Cohesive Zone Surface Methods

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3387
Author(s):  
John J. S. Biswakarma ◽  
Dario A. Cruz ◽  
Erich D. Bain ◽  
Joseph M. Dennis ◽  
Jan W. Andzelm ◽  
...  
Keyword(s):  
Finite Element ◽  
Cohesive Zone ◽  
Diglycidyl Ether ◽  
Mode I ◽  
Fracture Parameter ◽  
Extended Finite Element ◽  
Epoxy Nanocomposites ◽  
Softening Function ◽  
Mode I Fracture ◽  
Linear Softening

Linear elastic fracture modeling coupled with empirical material tensile data result in good quantitative agreement with the experimental determination of mode I fracture for both brittle and toughened epoxy nanocomposites. The nanocomposites are comprised of diglycidyl ether of bisphenol A cured with Jeffamine D-230 and some were filled with core-shell rubber nanoparticles of varying concentrations. The quasi-static single-edge notched bending (SENB) test is modeled using both the surface-based cohesive zone (CZS) and extended finite element methods (XFEM) implemented in the Abaqus software. For each material considered, the critical load predicted by the simulated SENB test is used to calculate the mode I fracture toughness. Damage initiates in these models when nodes at the simulated crack tip attain the experimentally measured yield stress. Prediction of fracture processes using a generalized truncated linear traction–separation law (TSL) was significantly improved by considering the case of a linear softening function. There are no adjustable parameters in the XFEM model. The CZS model requires only optimization of the element displacement at the fracture parameter. Thus, these continuum methods describe these materials in mode I fracture with a minimum number of independent parameters.

scholarly journals Modeling Brittle Fracture in Epoxy Nanocomposites using Extended Finite Element and Cohesive Zone Surface Methods

2021 ◽  
Author(s):  
John J.S. Biswakarma ◽  
Dario A. Cruz ◽  
Erich D. Bain ◽  
Josepth M. Dennis ◽  
Jan W. Andzelm ◽  
...  
Keyword(s):  
Finite Element ◽  
Cohesive Zone ◽  
Fracture Initiation ◽  
Quantitative Agreement ◽  
Fracture Parameter ◽  
Extended Finite Element ◽  
Epoxy Nanocomposites ◽  
Softening Function ◽  
Minimum Number ◽  
Linear Softening

Linear elastic fracture modeling coupled with empirical material tension data result in good quantitative agreement with experimental measurements of fracture failure for both brittle and tough epoxy nanocomposites. The nanocomposites comprise diglycidyl ethers of bisphenol A cured with O,O’ bis (2-aminopropylpropylene glycol) (Jeffamine D230) and doped with rubber nanoparticles of varying concentrations. Toughness, critical load, and critical displacement in quasi-static single edge-notched three-point bending are predicted accurately using both surface-based cohesive zone (CZS) and extended finite element (XFEM) methods implemented in Abaqus software. Fracture initiation within a crack is taken at the yield stress from uniaxial tension data. Prediction of fracture processes using a generalized truncated linear traction-separation law was significantly improved by considering the case of a linear softening function. There are no adjustable parameters in the XFEM model. The CZS model requires only optimization of the element displacement at fracture parameter. Thus, these continuum methods describe these materials in mode I fracture with a minimum number of independent parameters.

Finite element modelling for mode-I fracture behaviour of CFRP

2018 ◽  
Author(s):  
H. C. Chetan ◽  
Subhaschandra Kattimani ◽  
S. M. Murigendrappa
Keyword(s):  
Finite Element ◽  
Finite Element Modelling ◽  
Fracture Behaviour ◽  
Mode I ◽  
Element Modelling ◽  
Mode I Fracture

Use of the Extended Finite Element Method in the Assessment of Delayed Hydride Cracking

2016 ◽  
Author(s):  
Martin Booth ◽  
Michael Martin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cohesive Zone ◽  
Zirconium Alloy ◽  
Extended Finite Element Method ◽  
Process Zone ◽  
Zirconium Hydride ◽  
Extended Finite Element ◽  
Delayed Hydride Cracking ◽  
Element Method

Zirconium alloys, as used in water-cooled nuclear reactors, are susceptible to a time-dependent failure mechanism known as Delayed Hydride Cracking, or DHC. Corrosion of zirconium alloy in the presence of water generates hydrogen that subsequently diffuses through the metallic structure in response to concentration, temperature and hydrostatic stress gradients. As such, regions of increased hydrogen concentration develop at stress concentrating features, leading to zirconium hydride precipitation. Regions containing zirconium hydride are brittle and prone to failure if plant transient loads are sufficient. This paper demonstrates the application of the Extended Finite Element Method, or XFEM, to the assessment of the DHC susceptibility of stress concentrating features, typical of those considered in the structural integrity assessment of heavy water pressure tube reactors. The method enables the calculation of a DHC threshold load. This paper builds on the process-zone approach that is currently used to provide the industry-standard DHC assessment of zirconium alloy pressure tubes and also recent developments that have extended the application of the process-zone approach to arbitrary geometries by the use of finite element cohesive-zone analysis. In the standard cohesive-zone approach, regions of cohesive elements are situated in discrete locations where the formation of zirconium hydride is anticipated. In contrast, the use of XFEM based cohesive formulations removes the requirement to define cohesive zones a priori, thereby allowing the assessment of geometries in which the location of hydride material is not known.

Cohesive zone model for mode-I fracture with viscoelastic-sensitivity

2019 ◽  
Vol 221 ◽  
pp. 106578 ◽  
Author(s):  
Hui-Ru Cui ◽  
Hai-Yang Li ◽  
Zhi-Bin Shen
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Mode I ◽  
Zone Model ◽  
Mode I Fracture

Predictions of fracture load, crack initiation angle, and trajectory for V-notched Brazilian disk specimens under mixed mode I/II loading with negative mode I contributions

2017 ◽  
Vol 27 (8) ◽  
pp. 1173-1191 ◽  
Author(s):  
Bahador Bahrami ◽  
Majid R Ayatollahi ◽  
AR Torabi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Crack Initiation ◽  
Extended Finite Element Method ◽  
Fracture Load ◽  
Shear Loading ◽  
Mode I ◽  
Extended Finite Element ◽  
Brazilian Disk ◽  
Crack Initiation Angle

In this paper, first the fracture load, the crack initiation angle and the crack trajectory are experimentally measured for the round-tip V-notched Brazilian disk specimen made of polymethyl-methacrylate under compressive-shear loading. Then, the fracture load and the crack initiation angle are predicted by using the extended finite element method on the basis of the linear cohesive crack criterion. The fracture trajectory of the round-tip V-notched Brazilian disk specimens is also estimated by means of the extended finite element method and the incremental methods. Both the experimental observations and the theoretical fracture models indicate that although the notch bisector line is under compressive-shear loading, one half of the notch border still sustains tensile stresses and fracture takes place from this half. A very good agreement is shown to exist between the theoretical predictions and the experimental results for various notch opening angles and different notch radii.

Cohesive Zone Modeling of Mode I Fracture in Adhesive Bonded Joints

2007 ◽  
pp. 13-16 ◽  
Author(s):  
Marco Alfano ◽  
Franco Furgiuele ◽  
A. Leonardi ◽  
Carmine Maletta ◽  
Glaucio H. Paulino
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Modeling ◽  
Mode I ◽  
Bonded Joints ◽  
Mode I Fracture ◽  
Zone Modeling ◽  
Adhesive Bonded Joints
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