A cohesive zone finite element approach to model tensile cracks in thin film coatings

Nekkanty, Srikant; Walter, Michael G.; Shivpuri, Rajiv

doi:10.2140/jomms.2007.2.1231

Cited by 19 publications

(12 citation statements)

References 18 publications

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“…The value of λ̂is determined by the interfacial shear stress between the brittle coating and the more ductile substrate. This model has been previously used to evaluate the adhesion strength of several brittle inorganic [22][23] [29] and organic [30] hard coatings on relatively ductile substrates.…”

Section: Theorymentioning

confidence: 99%

Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

Ouyang

Kuo

et al. 2016

Acta Biomaterialia

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Conjugated polymers such as poly(3,4-ethylenedioxythiphene) (PEDOT) are of interest for a variety of applications including interfaces between electronic biomedical devices and living tissue. The mechanical properties, strength, and adhesion of these materials to solid substrates are all vital for long-term applications. We have been developing methods to quantify the mechanical properties of conjugated polymer thin films. In this study the stiffness, strength and the interfacial shear strength (adhesion) of electrochemically deposited PEDOT and PEDOT-co-1,3,5-tri[2-(3,4-ethylene dioxythienyl)]-benzene (EPh) were studied. The estimated Young’s modulus of the PEDOT films was 2.6 ± 1.4 GPa, and the strain to failure was around 2%. The tensile strength was measured to be 56 ± 27 MPa. The effective interfacial shear strength was estimated with a shear-lag model by measuring the crack spacing as a function of film thickness. For PEDOT on gold/palladium-coated hydrocarbon film substrates an interfacial shear strength of 0.7 ± 0.3 MPa was determined. The addition of 5 mole% of a tri-functional EDOT crosslinker (EPh) increased the tensile strength of the films to 283 ± 67 MPa, while the strain to failure remained about the same (2%). The effective interfacial shear strength was increased to 2.4 ± 0.6 MPa.

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Section: Theorymentioning

confidence: 99%

Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

Ouyang

Kuo

et al. 2016

Acta Biomaterialia

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“…Augmented FEM, Extended FEM). These methods have proven useful when carefully combined and calibrated with results of mixed-mode fracture experiments ( Bayesteh and Mohammadi, 2013;Kumar et al, 2015;Liu et al, 2014;Motamedi and Mohammadi, 2012;Pathak et al, 2013;Rabczuk et al, 2008 ), with applications ranging from interfacial fracture in polymer-matrix composites, deformation in welded joints ( Cavalli et al,20 04;20 05 ), and cracking in advanced multilayer systems ( Białas et al, 2005;Nekkanty et al, 2007 ). These approaches require external kinking and growth criteria to be supplied in advance.…”

Section: Review Of Related Simulationsmentioning

confidence: 99%

Conditions controlling kink crack nucleation out of, and delamination along, a mixed-mode interface crack

Pro

Sehr

Lim

et al. 2018

Journal of the Mechanics and Physics of Solids

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This paper analyzes the competition between kink nucleation and interface fracture for an interface crack (without a putative kink flaw) subject to mixed-mode loading. The simulations utilize a distributed cohesive zone approach that embeds cohesive elements throughout the entire mesh; dynamic crack path evolution occurs through a loss of cohesive traction associated with a critical separation between elements. The simulations identify mesh densities that lead to mesh-independent results for randomly oriented triangular meshes, and provide clear guidelines regarding parameters that recover toughness-controlled cracking (i.e. linear elastic fracture mechanics). The results demonstrate that, when the when the normalized bulk toughness is far from the transition between kinking and delamination, crack direction and critical loads are identical to those predicted by He and Hutchinson, who analyzed cracking from a putative flaw associated with the maximum energy release rate. Near the transition between fracture modes, kink nucleation depends on the relative size of the interface and bulk process zones, such that additional criteria are needed (beyond those postulated by He and Hutchinson). Regime maps are presented which indicate regions of kink nucleation versus delamination as a function of controlling cohesive parameters.

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“…The cohesive elements, combined with the FE, using a traction-separation relation in order to describe the interface as a continuum of coatings and the host, are defined in order to simulate the formation and propagation of cracks under indentation. Several traction laws have, to-date, been applied for this kind of analysis, either in a form of exponential relationship [90,91] or in a bilinear relationship [92][93][94] between the stress and the displacement. Figure 5.…”

Section: Formation and Propagation Of Cracks For Examplesmentioning

confidence: 99%

Numerical Modelling of Multilayered Coatings – Latest Developments and Applications

Yin

Feng

et al. 2014

Manufacturing Rev.

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-The remarkable mechanical properties of multilayered coatings, such as super-hardness, excellent resistance against cracking, low wear-rate and high thermal-stability, are due to their unique interfacial structures and deformation mechanisms at the nanometer scale. The multilayered coating process itself is a typical multi-scale phenomenon. The modelling of multilayered coatings has become an important topic in research recently, largely due to the recent progress that has been made in the numerical modelling of materials and structures at different length-scales as well as the improved effectiveness achieved in linking such progress in numerical modelling to enable multi-scale modelling. In this paper, numerical modelling for the analysis of multilayered coatings at individual lengthscales: Continuum, Molecular and Nano-scale, is reviewed, along with that at multi-scale modelling. Examples are presented showing numerical models obtained using: the Finite Element Method (FEM), Molecular Dynamics (MD), First-principles calculations and Multi-scale modelling, are presented. Their relative limitations are discussed and challenges to their future work highlighted.

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A cohesive zone finite element approach to model tensile cracks in thin film coatings

Cited by 19 publications

References 18 publications

Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

Stiffness, strength and adhesion characterization of electrochemically deposited conjugated polymer films

Conditions controlling kink crack nucleation out of, and delamination along, a mixed-mode interface crack

Numerical Modelling of Multilayered Coatings – Latest Developments and Applications

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