scholarly journals Investigating Some Technical Issues on Cohesive Zone Modeling of Fracture

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
John T. Wang
Keyword(s):  
Cohesive Zone ◽  
Process Zone ◽  
Cohesive Zone Modeling ◽  
Small Scale ◽  
Zone Length ◽  
Cohesive Model ◽  
Cohesive Models ◽  
Cohesive Laws ◽  
Technical Issues ◽  
Linear Softening

This study investigates some technical issues related to the use of cohesive zone models (CZMs) in modeling the fracture of materials with negligible plasticity outside the fracture process zone. These issues include: (1) why cohesive laws of different shapes can produce similar fracture predictions, (2) under what conditions CZM predictions have a high degree of agreement with linear elastic fracture mechanics (LEFM) analysis results, (3) when the shape of cohesive laws becomes important in the fracture predictions, and (4) why the opening profile along the cohesive zone length (CZL) needs to be accurately predicted. Two cohesive models were used in this study to address these technical issues. They are the linear softening cohesive model and the Dugdale perfectly plastic cohesive model. Each cohesive model uses five cohesive laws of different maximum tractions. All cohesive laws have the same cohesive work rate (CWR) defined by the area under the traction–separation curve. The effects of the maximum traction on the cohesive zone length and the critical remote applied stress are investigated for both models. The following conclusions from this study may provide some guidelines for the prediction of fracture using CZM. For a CZM to predict a fracture load similar to that obtained by an LEFM analysis, the cohesive zone length needs to be much smaller than the crack length, which reflects the small-scale yielding condition requirement for LEFM analysis to be valid. For large-scale cohesive zone cases, the predicted critical remote applied stresses depend on the shape of the cohesive models used and can significantly deviate from LEFM results. Furthermore, this study also reveals the importance of accurately predicting the cohesive zone profile for determining the critical remote applied load.

scholarly journals Selected Aspects of Cohesive Zone Modeling in Fracture Mechanics

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 302
Author(s):  
Wiktor Wciślik ◽  
Tadeusz Pała
Keyword(s):  
Cohesive Zone ◽  
Mixed Mode ◽  
Review Paper ◽  
Failure Process ◽  
Cohesive Zone Modeling ◽  
Mixed Mode Loading ◽  
Cohesive Models ◽  
Cohesive Modeling ◽  
Zone Modeling ◽  
Intensive Development

This review paper discusses the basic problems related to the use of cohesive models to simulate the initiation and development of failure in various types of engineering issues. The most commonly used cohesive zone models (CZMs) are described. Recent achievements in the field of cohesive modeling are characterized, with particular emphasis on the problem of mixed mode loading, the influence of the strain rate, the stress state triaxiality, and fatigue. A separate chapter of the work is devoted to the identification of cohesive parameters. Examples of the use of CZMs for the analysis of the fracture and failure process in various applications, both on the macro and microscopic scale, are given. The directions of CZMs development were indicated as well as the issues that are currently under particularly intensive development.

Simulation of Ductile Crack Propagation in Pipeline Steels Using Cohesive Zone Modeling

2012 ◽  
Author(s):  
Andrew Dunbar ◽  
Xin Wang ◽  
Bill (W. R. ) Tyson ◽  
Su Xu
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Infinite Plate ◽  
Cohesive Zone Modeling ◽  
Opening Angle ◽  
Small Scale ◽  
Propagation Characteristics ◽  
Ductile Crack ◽  
Drop Weight Tear Test ◽  
Zone Modeling

This paper presents recent results of numerical studies on stable crack extension of high toughness steels typical of those in modern gas pipelines using cohesive zone modeling. Two sets of materials are modeled. The first material set models a typical structural steel, with variable toughness described by four traction-separation (TS) laws. The second set models an X70 pipe steel, with three different TS laws. For each TS law, there are three defining parameters: the maximum cohesive strength, the final separation and the work of separation. The specimens analyzed include a crack in an infinite plate (small-scale yielding, SSY) and a standard drop-weight tear test (DWTT). Fracture propagation characteristics and values of crack-tip opening angle (CTOA) are obtained from these two types of specimens. It is shown that cohesive zone models can be successfully used to simulate ductile crack propagation and to numerically measure CTOAs. The ductile crack propagation characteristics and CTOAs obtained from SSY and DWTT specimens are compared for each set of steels. In addition, the CTOA results from numerical cohesive zone modeling of DWTT specimens of X70 steel are compared with those from laboratory tests.

scholarly journals Thermal Delamination Modelling and Evaluation of Aluminium–Glass Fibre-Reinforced Polymer Hybrid

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 492
Author(s):  
Zhen Pei Chow ◽  
Zaini Ahmad ◽  
King Jye Wong ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů
Keyword(s):  
Crack Front ◽  
Cohesive Zone ◽  
Experimental Tests ◽  
Mode I ◽  
Mode Ii ◽  
Cohesive Model ◽  
Reinforced Polymer ◽  
Glass Fibre Reinforced Polymer ◽  
Fibre Reinforced Polymer ◽  
Glass Fibre Reinforced

This paper aims to propose a temperature-dependent cohesive model to predict the delamination of dissimilar metal–composite material hybrid under Mode-I and Mode-II delamination. Commercial nonlinear finite element (FE) code LS-DYNA was used to simulate the material and cohesive model of hybrid aluminium–glass fibre-reinforced polymer (GFRP) laminate. For an accurate representation of the Mode-I and Mode-II delamination between aluminium and GFRP laminates, cohesive zone modelling with bilinear traction separation law was implemented. Cohesive zone properties at different temperatures were obtained by applying trends of experimental results from double cantilever beam and end notched flexural tests. Results from experimental tests were compared with simulation results at 30, 70 and 110 °C to verify the validity of the model. Mode-I and Mode-II FE models compared to experimental tests show a good correlation of 5.73% and 7.26% discrepancy, respectively. Crack front stress distribution at 30 °C is characterised by a smooth gradual decrease in Mode-I stress from the centre to the edge of the specimen. At 70 °C, the entire crack front reaches the maximum Mode-I stress with the exception of much lower stress build-up at the specimen’s edge. On the other hand, the Mode-II stress increases progressively from the centre to the edge at 30 °C. At 70 °C, uniform low stress is built up along the crack front with the exception of significantly higher stress concentrated only at the free edge. At 110 °C, the stress distribution for both modes transforms back to the similar profile, as observed in the 30 °C case.

scholarly journals Cohesive Zone Modeling for Predicting Interfacial Delamination in over mold Components

2021 ◽  
Vol 1128 (1) ◽  
pp. 012018
Author(s):  
M Sai Krishnan ◽  
S Jeyanthi ◽  
Pradeep Kumar Mani ◽  
K T Hareesh ◽  
M. C Lenin Babu
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Modeling ◽  
Interfacial Delamination ◽  
Zone Modeling

Elasto-Plastic Fracture Analysis of Finite-Width Cracked Stiffened Plate

2014 ◽  
Vol 496-500 ◽  
pp. 1052-1057 ◽  
Author(s):  
Jun Lin Deng ◽  
Ping Yang ◽  
Qin Dong ◽  
Xiang Yan
Keyword(s):  
Field Method ◽  
Uniaxial Tensile ◽  
Small Scale ◽  
Finite Width ◽  
Stiffened Plate ◽  
Line Field ◽  
Strain Fields ◽  
Zone Length ◽  
Crack Line ◽  
Crack Tips

Thispaper adopts the crack line-field method to analyze finite-width stiffenedplates with central through I-type crack under uniaxial tensile loading. Themethod completely abandons the small scale yield hypothesis. The plastic stressand strain fields at crack tips and the plastic-zone length can be accurately determinedby combining with equivalent shear stress of Westergaard stress function in theposition of stiffener. It can be seen from the illustrative example that theresults of the paper agree well with those by finite element method.

Analysis of Energy Balance When Using Cohesive Zone Models to Simulate Fracture Processes

2002 ◽  
Vol 124 (4) ◽  
pp. 440-450 ◽  
Author(s):  
C. Shet ◽  
N. Chandra
Keyword(s):  
Cohesive Energy ◽  
Cohesive Zone ◽  
Strain Energy ◽  
Fracture Process ◽  
Fracture Process Zone ◽  
Process Zone ◽  
Elastic Strain Energy ◽  
Inelastic Strain ◽  
External Work ◽  
Cohesive Zone Models

Cohesive Zone Models (CZMs) are being increasingly used to simulate fracture and fragmentation processes in metallic, polymeric, and ceramic materials and their composites. Instead of an infinitely sharp crack envisaged in fracture mechanics, CZM presupposes the presence of a fracture process zone where the energy is transferred from external work both in the forward and the wake regions of the propagating crack. In this paper, we examine how the external work flows as recoverable elastic strain energy, inelastic strain energy, and cohesive energy, the latter encompassing the work of fracture and other energy consuming mechanisms within the fracture process zone. It is clearly shown that the plastic energy in the material surrounding the crack is not accounted in the cohesive energy. Thus cohesive zone energy encompasses all the inelastic energy e.g., energy required for grainbridging, cavitation, internal sliding, surface energy but excludes any form of inelastic strain energy in the bounding material.

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