Augmented Cohesive Elements for Efficient Delamination Analyses of Composite Laminates

In this paper, a new type of cohesive element that employs multiple subdomain integration (MSDI) for improved cohesive stress integration accuracy of bonded plate/shell elements has been formulated. Within each subdomain, stress integration is compatible with existing schemes such as Gaussian integration (GI), Newton–Cotes integration, or the mixed Gaussian and subdomain integration (mixed GI&SDI). The numerical accuracy, efficiency, and robustness of this element when employing three integration methods for MSD cohesive stress integration have been evaluated and compared through a benchmark mode-I fracture problem of bonded double-cantilever plates. The MSDI offers at least 50% improvement of numerical accuracy as compared to the best integration method in literature and has the best numerical robustness. This significant improvement pushes the structural mesh size restriction from limiting size of 1/3–1/5 cohesive zone length to 1.5–2 times the cohesive zone length. The formulation is very easy to be implemented into any finite element programs including commercial packages. Furthermore, this formulation enables the use of dual-mesh for delamination analyses of bonded structural shells/plates, which is of practical importance because it greatly reduces the burden of mesh generation for complicated composite structures. It has also been demonstrated that using high-order shell/plate elements can improve the numerical accuracy in general because the nonlinear deformation profile permitted by this type of elements can better describe the nonlinear deformation in the crack-tip element (partially bonded elements).

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Prediction on Initiation of Hydrogen-Induced Delayed Cracking in High-Strength Steel Based on Cohesive Zone Modeling

Volume 6B: Materials and Fabrication ◽

10.1115/pvp2014-28964 ◽

2014 ◽

Author(s):

Yanfei Wang ◽

Jianming Gong ◽

Luyang Geng ◽

Yong Jiang

Keyword(s):

Stress Analysis ◽

Hydrogen Concentration ◽

High Strength Steel ◽

Cohesive Zone ◽

High Strength ◽

Cohesive Zone Modeling ◽

Cohesive Elements ◽

Cohesive Stress ◽

Delayed Cracking ◽

Zone Modeling

This study presents prediction on initiation of hydrogen-induced delayed cracking (HIDC) in hydrogen pre-charged high-strength steel notched bars under a constant load based on hydrogen influenced cohesive zone modeling (CZM). The prediction is implemented by using a three-step sequential coupling finite element procedure including elastic-plastic stress analysis, stress-assisted hydrogen diffusion analysis and cohesive stress analysis with cohesive elements embedded along the potential crack path. Hydrogen influenced linear traction separation law is applied to the cohesive elements. The predicted initiation time of HIDC gives a good agreement with the experimental fracture time reported in a literature. The prediction reproduces the experimental trend that the critical hydrogen concentration for crack initiation is independent of the initial hydrogen concentration, while decreases with increasing load or stress concentration factor of the notch. CZM has a potential to predict HIDC of high-strength steel.

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Reduction of the volume redundancy in combined embedded elements/cohesive zone modelling – Comments on the paper: Liu Q, Gorbatikh L, Lomov SV. A combined use of embedded and cohesive elements to model damage development in fibrous composites, Composite Structures, 2019, 223:110921 (doi 10.1016/j.compstruct.2019.110921)

Composite Structures ◽

10.1016/j.compstruct.2019.111273 ◽

2019 ◽

Vol 226 ◽

pp. 111273

Author(s):

Fangzhou Lu ◽

Qiang Liu ◽

Pavel Druzhinin ◽

Dirk Vandepitte ◽

Guangming Zhou ◽

...

Keyword(s):

Cohesive Zone ◽

Composite Structures ◽

Fibrous Composites ◽

Cohesive Elements ◽

Damage Development ◽

Cohesive Zone Modelling ◽

Combined Use

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Improved cohesive stress integration schemes for cohesive zone elements

Engineering Fracture Mechanics ◽

10.1016/j.engfracmech.2013.04.009 ◽

2013 ◽

Vol 107 ◽

pp. 14-28 ◽

Cited By ~ 20

Author(s):

B.C. Do ◽

W. Liu ◽

Q.D. Yang ◽

X.Y. Su

Keyword(s):

Cohesive Zone ◽

Cohesive Stress ◽

Integration Schemes ◽

Stress Integration ◽

Cohesive Zone Elements

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The effect of delamination on ring specimen failure in the split-disk test with cohesive zone modelling – Comments on the paper: Zhao Y, Druzhinin P, Ivens J, Vandepitte D, Lomov SV. Split-disk test with 3D Digital Image Correlation strain measurement for filament wound composites, Composite Structures, 2021, 263:113686 (doi 10.1016/j.compstruct.2021.113686)

Composite Structures ◽

10.1016/j.compstruct.2021.114617 ◽

2021 ◽

pp. 114617

Author(s):

Yinglun Zhao ◽

Dirk Vandepitte ◽

Stepan V. Lomov

Keyword(s):

Digital Image Correlation ◽

Cohesive Zone ◽

Strain Measurement ◽

Composite Structures ◽

Image Correlation ◽

Ring Specimen ◽

3D Digital Image Correlation ◽

Filament Wound ◽

Cohesive Zone Modelling ◽

Disk Test

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EXPERIMENTAL FINDING OF FRACTURE TOUGHNESS CHARACTERISTICS AND THEORETICAL MODELING OF CRACK PROPAGATION PROCESSES IN CARBON FIBER SAMPLES UNDER CONDITIONS OF ADDITIVE PRODUCTION

Periódico Tchê Química ◽

10.52571/ptq.v16.n33.2019.340_periodico33_pgs_325_336.pdf ◽

2019 ◽

Vol 16 (33) ◽

pp. 325-336

Author(s):

V. N. DOBRYANSKIY ◽

L. N. RABINSKIY ◽

O. V. TUSHAVINA

Keyword(s):

Fracture Toughness ◽

Carbon Fiber ◽

Crack Resistance ◽

Tensile Properties ◽

Practical Importance ◽

Effect Of Temperature ◽

Zone Model ◽

Cohesive Elements ◽

Damage Development ◽

Mechanical Tensile

The relevance of the problem stated in this article is that the development of aerospace technology increased the demand for good quality materials. An important issue is ensuring durability in conditions of longterm loads and in conditions of damage development. One of the criteria that ensure the toughness of the material is crack resistance. The aim of the work is to study the interlayer crack resistance (fracture toughness) under loading under conditions of separation and transverse shear, interlayer strength, as well as the effect of temperature on interlayer strength, mechanical tensile properties. A comparison of the values of interlayer crack resistance GIС (separation) and GIIС (shear) and of mechanical tensile properties and interlayer strength of carbon fiber samples is made. The main methods for studying this problem were the short-beam method, the DCB method, the ENF method. The results of the experimental data were compared with modeling the processes of the appearance and development of cracks in the finite element complexes ABAQUS and Ansys based on the VVCT models, cohesive elements. Deviations from the experiment were found and conclusions were drawn that the point of application of the load had to be shifted from the edge of the sample, which will reduce the initial separation and increase the stiffness of the sample. Due to the fact that the cohesion zone model is very sensitive to input parameters, it is necessary to know many parameters and take into account a large number of factors. The practical importance of this work is to show how to use the VCCT model to obtain the critical load of the germination of the first crack. The research technique can be used for further experiments, including simulation further stratification with low inaccuracy.

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Critical value of the generalized stress intensity factor for a crack perpendicular to an interface

Proceedings of The Royal Society A Mathematical Physical and Engineering Sciences ◽

10.1098/rspa.2015.0571 ◽

2015 ◽

Vol 471 (2183) ◽

pp. 20150571 ◽

Cited By ~ 6

Author(s):

George G. Adams

Keyword(s):

Stress Intensity Factor ◽

Stress Intensity ◽

Intensity Factor ◽

Cohesive Zone ◽

Cohesive Zone Model ◽

Crack Tip ◽

Critical Value ◽

Zone Model ◽

Cohesive Stress ◽

Generalized Stress Intensity Factor

When a crack tip impinges upon a bi-material interface, the order of the stress singularity will be equal to, less than or greater than one-half. The generalized stress intensity factors have already been determined for some such configurations, including when a finite-length crack is perpendicular to the interface. However, for these non-square-root singular stresses, the determination of the conditions for crack growth are not well established. In this investigation, the critical value of the generalized stress intensity factor for tensile loading is related to the work of adhesion by using a cohesive zone model in an asymptotic analysis of the separation near the crack tip. It is found that the critical value of the generalized stress intensity factor depends upon the maximum stress of the cohesive zone model, as well as on the Dundurs parameters ( α and β ). As expected this dependence on the cohesive stress vanishes as the material contrast is reduced, in which case the order of the singularity approaches one-half.

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Study on 3D Edge Crack Extension Simulation in Cold Rolling with the Cohesive Zone Model

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.853.101 ◽

2016 ◽

Vol 853 ◽

pp. 101-105

Author(s):

Da Qian Zan ◽

Quan Sun ◽

Hong Liang Pan ◽

Jian Jun Chen ◽

Zheng Dong Wang

Keyword(s):

Cold Rolling ◽

Cohesive Energy ◽

Cohesive Zone ◽

Edge Crack ◽

Crack Extension ◽

Cohesive Zone Model ◽

Rolling Process ◽

Zone Model ◽

Hybrid Technique ◽

Cohesive Stress

In the cold rolling process, the edge crack extension can cause the strip rupture completely due to the micro manufacturing defects in the edge. It can greatly impact on the production efficiency and cause the huge economic loss. Thus predicting the edge crack extension behavior becomes important to cold rolling industry. In this paper, a 3D extended finite element method (XFEM) based on the cohesive zone model (CZM) was used to study the edge crack extension under the non-reversing two-high mill cold rolling experiment condition. A bi-linear traction-separation law was utilized which is primarily given by the CZM parameters including the cohesive stress, T0 and the cohesive energy, Γ0. The cohesive stress was determined by hybrid technique of the thin-plate tension test and FEM simulation. The cohesive energy was obtained by the In-Situ SEM three points bending experiment. Different reductions were the mainly analysis factor which can study the extent of the edge crack extension by presetting the edge notch. By comparing the experimental and simulation results, they agreed well with each other. It illustrated that the CZM can provide accurate predictions for the edge crack extension in the cold rolling process. Parametric analysis was carried out and showed that the extent of the crack extension increases with the increasing of the reduction ratio.

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Investigating Some Technical Issues on Cohesive Zone Modeling of Fracture

Journal of Engineering Materials and Technology ◽

10.1115/1.4007605 ◽

2012 ◽

Vol 135 (1) ◽

Cited By ~ 13

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.

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Modelling the Effect of Microstructural Randomness on the Fracture of Composite Laminates with Stochastic Cohesive Zone Elements

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.417-418.13 ◽

2009 ◽

Vol 417-418 ◽

pp. 13-16

Author(s):

Zahid R. Khokhar ◽

Ian A. Ashcroft ◽

Vadim V. Silberschmidt

Keyword(s):

Cohesive Zone ◽

Composite Laminates ◽

Composite Structures ◽

Laminated Composite ◽

Specific Strength ◽

Laminated Composite Structures ◽

Structural Applications ◽

Fibre Reinforced Polymer ◽

Strength And Stiffness ◽

Cohesive Zone Elements

Fibre reinforced polymer composites (FRPCs) are being increasingly used in structural applications where high specific strength and stiffness are required. The performance of FRPCs is affected by multi-mechanism damage evolution under loading which in turn is affected by microstructural stochasticity in the material. This means that the fracture of a FRPC is a stochastic process. However, to date most analyses of these materials have treated them in a deterministic way. In this paper the effect of stochasticity in FRPCs is investigated through the application of cohesive zone elements in which random properties are introduced. These may be termed ‘stochastic cohesive zone elements’ and are used in this paper to investigate the effect of microstructural randomness on the fracture behaviour of cross-ply laminate specimens loaded in tension. It is seen from this investigation that microstructure can significantly affect the macroscopic response of FRPC’s, emphasizing the need to account for microstructural randomness in order to make accurate prediction of the performance of laminated composite structures.

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