The Experts below are selected from a list of 1572 Experts worldwide ranked by ideXlab platform
Michal Zouhar - One of the best experts on this subject based on the ideXlab platform.
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estimation of the critical configuration of a crack arrested at the interface between two materials
2012Co-Authors: Martin Ševčík, Luboš Náhlík, Zdeněk Knésl, Pavel Hutař, Michal ZouharAbstract:Abstract Surface crack propagation in a thin soft protective layer on a massive Stiffer Substrate is analysed using generalised linear elastic fracture mechanics. The growth of the initial crack is considered in both forward and sideways directions and the influence of the interface between the protective layer and massive Substrate on the final crack configuration is investigated. It is shown that, depending on the elastic mismatch, the part of the crack front can be arrested at the interface protective layer/Substrate and the rest of the crack grows continuously sideways only. The effective value of a stress intensity factor is used in order to predict the conditions under which the crack will propagate through the interface into the second material. Corresponding calculations have been made by finite elements.
Jin Woo Park - One of the best experts on this subject based on the ideXlab platform.
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the effect of the surface physical properties of polymer Substrates on the adhesion and cracking of transparent conductive oxide tco coatings
2012Co-Authors: Seungho Lee, Chanwoo Yang, Jin Woo ParkAbstract:Abstract This work presents the effects of surface physical properties of compliant polymer Substrates on the properties of stiff oxide coatings. In this study, polyethylene terephthalate (PET) is selected as the Substrate and indium tin oxide (ITO), which is one of the most extensively used transparent conductive oxide (TCO) materials for electrodes in display applications, is sputter deposited on PET varying thickness ( h f ). Before deposition, PET surface profiles such as roughness and morphology are modified by Ar ion beam treatment. At a fixed beam power, treatment time is carefully controlled to vary only the physical profiles, excluding chemical states of the surfaces. PET and ITO surfaces and interfaces are analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. By fragmentation test, the adhesion and cracking of ITO are evaluated. Our investigation reveals that depositing atoms penetrate into the PET surface due to the low density of PET and the initial surface profiles of PET are not maintained during deposition due to its high compliance. When the effective surface area is highly increased by the ion beam treatment, the polymer surface becomes Stiffer since the number of penetrating atoms increases. The rough surface features on the Stiffer Substrate are less deformed during deposition; hence, interfacial interlocking that improves the adhesion becomes effective throughout the deposition.
Roger T Bonnecaze - One of the best experts on this subject based on the ideXlab platform.
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cohesive zone models to understand the interface mechanics of thin film transfer printing
2019Co-Authors: Shruti Jain, Kenneth M Liechti, Roger T BonnecazeAbstract:Competing fracture in the transfer of thin films from a relatively rigid host Substrate to a flexible polymer Substrate is studied using finite element simulations with cohesive zone models. Cohesive zone models for delamination based on traction-separation relations with a maximum stress criterion for damage initiation and mode-independent fracture energy for complete separation are explored to identify important parameters that affect transfer printing. Successful transfer of a thin film to a relatively compliant polymer Substrate from a Stiffer Substrate depends on relative crack lengths, interface strengths, and fracture energies. Interface selection occurs where the mode-mix at the crack tip is predominantly due to normal stresses, despite the interface toughness being mode-independent. The observations and the fracture maps developed here predict the interface selection directly with material properties of the interfaces, Substrates, and films.Competing fracture in the transfer of thin films from a relatively rigid host Substrate to a flexible polymer Substrate is studied using finite element simulations with cohesive zone models. Cohesive zone models for delamination based on traction-separation relations with a maximum stress criterion for damage initiation and mode-independent fracture energy for complete separation are explored to identify important parameters that affect transfer printing. Successful transfer of a thin film to a relatively compliant polymer Substrate from a Stiffer Substrate depends on relative crack lengths, interface strengths, and fracture energies. Interface selection occurs where the mode-mix at the crack tip is predominantly due to normal stresses, despite the interface toughness being mode-independent. The observations and the fracture maps developed here predict the interface selection directly with material properties of the interfaces, Substrates, and films.
Martin Ševčík - One of the best experts on this subject based on the ideXlab platform.
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estimation of the critical configuration of a crack arrested at the interface between two materials
2012Co-Authors: Martin Ševčík, Luboš Náhlík, Zdeněk Knésl, Pavel Hutař, Michal ZouharAbstract:Abstract Surface crack propagation in a thin soft protective layer on a massive Stiffer Substrate is analysed using generalised linear elastic fracture mechanics. The growth of the initial crack is considered in both forward and sideways directions and the influence of the interface between the protective layer and massive Substrate on the final crack configuration is investigated. It is shown that, depending on the elastic mismatch, the part of the crack front can be arrested at the interface protective layer/Substrate and the rest of the crack grows continuously sideways only. The effective value of a stress intensity factor is used in order to predict the conditions under which the crack will propagate through the interface into the second material. Corresponding calculations have been made by finite elements.
Seungho Lee - One of the best experts on this subject based on the ideXlab platform.
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the effect of the surface physical properties of polymer Substrates on the adhesion and cracking of transparent conductive oxide tco coatings
2012Co-Authors: Seungho Lee, Chanwoo Yang, Jin Woo ParkAbstract:Abstract This work presents the effects of surface physical properties of compliant polymer Substrates on the properties of stiff oxide coatings. In this study, polyethylene terephthalate (PET) is selected as the Substrate and indium tin oxide (ITO), which is one of the most extensively used transparent conductive oxide (TCO) materials for electrodes in display applications, is sputter deposited on PET varying thickness ( h f ). Before deposition, PET surface profiles such as roughness and morphology are modified by Ar ion beam treatment. At a fixed beam power, treatment time is carefully controlled to vary only the physical profiles, excluding chemical states of the surfaces. PET and ITO surfaces and interfaces are analyzed by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. By fragmentation test, the adhesion and cracking of ITO are evaluated. Our investigation reveals that depositing atoms penetrate into the PET surface due to the low density of PET and the initial surface profiles of PET are not maintained during deposition due to its high compliance. When the effective surface area is highly increased by the ion beam treatment, the polymer surface becomes Stiffer since the number of penetrating atoms increases. The rough surface features on the Stiffer Substrate are less deformed during deposition; hence, interfacial interlocking that improves the adhesion becomes effective throughout the deposition.