Opening-mode fractures of a brittle coating bonded to an elasto-plastic substrate

Chen, F.L.; He, Xiujuan; Prieto-Muñoz, Pablo A.; Yin, Huiming

doi:10.1016/j.ijplas.2014.10.007

Cited by 30 publications

(17 citation statements)

References 57 publications

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“…In addition, BC and substrate are considered as perfectly elastic materials. Experimental investigations 8,15,16 and analytical solutions [46][47][48] reveal that the channel cracks appear at initial stages of the loading when the substrate deforms elastically or there is no considerable plastic deformation in the substrate. Therefore, this assumption can be accurate enough to simulate damage initiation and propagation (although, considering elasto-plastic behavior adopts more to the reality of the problem).…”

Section: Dem Modelmentioning

confidence: 99%

Investigation on the effective parameters of through-the-width crack propagation in ceramic coatings due to substrate tension using discrete element method

Ghasemi

Falahatgar

2019

Proceedings of the Institution of Mechanical Engineers, Part L:

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This paper aims to simulate surface cracking and interfacial delamination in ceramic coatings due to their application in different industries. For this purpose, one of the most widely used ceramics, yttrium-stabilized zirconia, which is used as a thermal insulator for superalloy substrate is considered as a case study. Discrete element method was used, due to its great ability to capture the damages at the microscale, to investigate the effect of crack spacing and coating thickness on crack initiation and propagation. Discrete element method solver code is provided by the authors. To investigate damages, a unit cell of the structure between two successive surface cracks was considered. The length of the unit cell represents the crack density in the structure. In addition, for each unit cell length, three coating thicknesses were considered. The results of the current study were compared and validated with those experiments and numerical simulation results presented in the open literature. Good agreement was found. Finally, the effect of interface roughness on stress distribution and damage initiation was examined.

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Section: Dem Modelmentioning

confidence: 99%

Investigation on the effective parameters of through-the-width crack propagation in ceramic coatings due to substrate tension using discrete element method

Ghasemi

Falahatgar

2019

Proceedings of the Institution of Mechanical Engineers, Part L:

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“…Finite element analyses of thermal barrier coatings have been presented by (Sait et al, 2020;Zhu et al, 2015). Chen et al, (2015) calculated the fracture energy release rate for brittle elastic coatings on ductile elasto-plastic substrates. The case of thin elastic films delaminating from cylindrical substrates has been investigated (Hutchinson, 2001), and the effect of subsequent ridge cracking has been studied (Faulhaber et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

A mechanistic analysis of delamination of elastic coatings from the surface of plastically deformed stents

Máirtín

Concannon

Parry

et al. 2021

International Journal of Solids and Structures

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Several medical papers have reported delamination of the coating from the stent-substrate following intravascular deployment leading to adverse outcomes for patients. However, the mechanisms of delamination of such polymer coatings from the surface of a stent due to large deformations during device deployment has not been studied. In this paper, a novel and indepth investigation of the mechanisms and parameters that govern stent-coating delamination is performed, using a cohesive zone formulation to simulation the evolution of traction at the stent-coating interface. The study firstly analyses the behaviour of elastic coatings on idealised elastic stent substrates. Simulations reveal that the mode mixity of delamination is strongly dependent on the level of stent deployment at initiation. In general, peak normal tractions exceed peak shear tractions at low levels of stent deployment whereas the reverse trend is computed at high levels of stent deployment. Interface tractions increase with both increasing stent thickness and coating thickness suggesting that thinner stents and thinner coatings should be utilised for the delivery of antiproliferative drugs in order to reduce the risk of coating delamination. Next, the influence of stent plasticity on interface tractions and coating delamination is investigated. Even at low levels of deployment, plastic yielding occurs in the stent hinge region and the patterns of normal and shear tractions are found to be significantly more complex than those computed for elastic stents, with both tensile and compressive regions of normal traction occurring in the stent arch. At a high level of stent deployment shear tractions at the stent-coating interface are computed to increase with decreasing strain hardening modulus. The findings of this paper provide a new insight into the stress-state at the stentcoating interface as a function of the stent design parameters and large deformation elasticity and plasticity during deployment, allowing for a more reliable assessment of the limits relating to safe implantation of coated stents.

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“…Typically, a substrate-coating system is composed of a relatively brittle coating layer and a ductile substrate. Under externally applied load, common failure mechanisms such as cracking and delamination in the coating layer have often been observed (Chen et al., 2015). These negatively affect the performance of the system and decrease its protection efficacy.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the large plastic deformations that develop in ductile substrates have to be accounted for in order to achieve better predictions and interpretations of the structural response and failure mechanisms of the coating/substrate system. To fulfill this purpose, an elastoplastic fracture model has been developed recently to study the opening-mode fracture in coating layered structures undergoing large-scale yielding (Chen et al., 2015).…”

Section: Introductionmentioning

confidence: 99%

“…It has been observed that no slip or debonding occurs between the substrate and the coating layer. Therefore, it is reasonable to assume that the thin film is fully bonded to the substrate (Chen et al., 2015). Once the opening-mode crack initiates in the coating layer, it will propagate toward the interface between the coating layer and the substrate.…”

Section: Introductionmentioning

confidence: 99%

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Opening-mode micro-cracking in brittle coatings on ductile wires/rods

Chen

Yin

2016

International Journal of Damage Mechanics

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A simplified two-dimensional model is presented to simulate periodically distributed micro-cracking in a thin coating fully bonded to an elastoplastic aluminum wire/rod. The alumina coating which is generated by anodic oxidation is treated as an elastic material, while the ductile aluminum wire substrate is characterized by a bi-linear elastoplastic hardening model. An elastoplastic shear lag model is applied to transfer the shearing stress from the substrate layer to the thin coating. When the coated structure is subjected to different applied load, the system will undergo different stress levels and exhibit different cracking stages. Accordingly, explicit solutions corresponding to different loading stages are presented based on a generalized axisymmetric formulation. Finite element simulation is employed to verify the present elastic solution when the applied load is relatively small and the whole system is in the elastic state. Experimental characterization is conducted to validate the present elastoplastic solution when the substrate or interlayer undergoes large deformation. A versatile high-fidelity optical microscope is utilized to check the micro structure of the coating and continuously monitor the fracture development in the coating layer, through which valuable detailed micro-cracking information, such as critical applied load corresponding to crack initiation, crack pattern and crack spacing, is obtained. It shows that the presented fracture model is able to accurately capture the stress and strain distribution in the coated structure and predict the fracture initiation, infilling, and saturation in the thin coating layer.

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Opening-mode fractures of a brittle coating bonded to an elasto-plastic substrate

Cited by 30 publications

References 57 publications

Investigation on the effective parameters of through-the-width crack propagation in ceramic coatings due to substrate tension using discrete element method

Investigation on the effective parameters of through-the-width crack propagation in ceramic coatings due to substrate tension using discrete element method

A mechanistic analysis of delamination of elastic coatings from the surface of plastically deformed stents

Opening-mode micro-cracking in brittle coatings on ductile wires/rods

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