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Stress Analysis in Thin Films and Multilayers Materials

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Thin Films and Interfaces".

Deadline for manuscript submissions: closed (31 December 2021) | Viewed by 6444

Special Issue Editor


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Guest Editor
Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland
Interests: stress analysis in thin films; oxide thin films; XRD
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Thin films and multilayers typically present high and strongly non-uniform internal stress. Stress-induced degradation of functional thin films and coating systems poses a persistent problem in materials science and technology. The performance, reliability, and durability of material components in micro/opto-electronics applications can be dramatically affected by excessive residual stress levels (compressive or tensile). The study of stress in thin films has congregated many efforts, both from experimental and fundamental points of view, to get a better understanding on how to deal with it and, particularly, how to tailor stresses during deposition and post processing. This Special Issue is devoted to all scientific and analytical aspects related to:

  • stress evaluation methods and measurement techniques (including in-situ advanced experiments)
  • stress investigation, tailoring and analysis in thin films and multilayers: influence of the growth parameters on the stress formation
  • role of interface reactivity and phase transformation on stress

Dr. Claudia Cancellieri
Guest Editor

Manuscript Submission Information

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Keywords

  • stress analysis
  • thin films
  • multilayers
  • interfacial stress

Published Papers (3 papers)

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Research

17 pages, 1929 KiB  
Article
Rheological Relaxation of OSB Beams Reinforced with CFRP Composites
by Tomasz Socha, Krzysztof Kula, Arkadiusz Denisiewicz, Grzegorz Lesiuk and Wojciech Błażejewski
Materials 2021, 14(24), 7527; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14247527 - 08 Dec 2021
Cited by 7 | Viewed by 1954
Abstract
An experimental and analytical approach to the relaxation problem of wood-based materials—OSB (Oriented Strand Boards—pressed wood-based composite panels) beams, including beams with CFRP (Carbon fiber reinforced polymer) tape composite reinforcement, is presented. It is a relevant engineering and scientific problem due to the [...] Read more.
An experimental and analytical approach to the relaxation problem of wood-based materials—OSB (Oriented Strand Boards—pressed wood-based composite panels) beams, including beams with CFRP (Carbon fiber reinforced polymer) tape composite reinforcement, is presented. It is a relevant engineering and scientific problem due to the fact that wood and wood-based materials, as well as composite reinforcements, are widely used in building constructions. Their rheological properties are very important and complicated to estimate. A 10 day long relaxation test of thick OSB beams without reinforcement and with CFRP tape was performed. A four-point bending test with five different bending levels was performed, during which the reduction of the loading force was measured. A five-parameter rheological model was used to describe the rheology of the beams. The equations of this model were calculated with the use of Laplace transform, whereas the values of the parameters were calculated based on the experimental relaxation curves. A high correlation between experimental and theoretical results was obtained. A beam reinforced with CFRP tape was treated as a system with a viscoelastic element (OSB) and an elastic element (CFRP), joined together without the possibility of slipping. The equations of the mathematical model were calculated based on the assumptions of the linear theory of viscoelasticity and the convolution integral. A good correlation between experimental and theoretical results was obtained. A significant redistribution of stresses was observed during the relaxation of the reinforced beam. The reinforced beams show a higher stiffness of approximately 63% and carry proportionally higher loads than unreinforced beams at the same deflection values. Full article
(This article belongs to the Special Issue Stress Analysis in Thin Films and Multilayers Materials)
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15 pages, 20974 KiB  
Article
Flexural Pseudo-Ductility Effect in Hybrid GFRP/CFRP Bars under Static Loading Conditions
by Szymon Duda, Grzegorz Lesiuk, Paweł Zielonka, Paweł Stabla, Marek Lubecki and Grzegorz Ziółkowski
Materials 2021, 14(19), 5608; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14195608 - 27 Sep 2021
Cited by 5 | Viewed by 1561
Abstract
The problem with composite rebars in the civil engineering industry is often described as the material’s brittleness while overloaded. To overcome this drawback, researchers pay attention to the pseudo-ductility effect. The paper presents four-point bending tests of pure unidirectional (UD) rods with additional [...] Read more.
The problem with composite rebars in the civil engineering industry is often described as the material’s brittleness while overloaded. To overcome this drawback, researchers pay attention to the pseudo-ductility effect. The paper presents four-point bending tests of pure unidirectional (UD) rods with additional composite layers obtained by filament winding and hand braiding techniques. Two types of core materials, glass FRP (fibre reinforced polymer) and carbon FRP, were used. Regarding the overwrapping material, the filament winding technique utilized carbon and glass roving reinforcement in the epoxy matrix, while in the case of hand braiding, the carbon fibre sleeve was applied with the epoxy matrix. Microstructural analysis using scanning electron microscopy (SEM) and computed tomography (CT) was performed to reveal the structural differences between the two proposed methods. Mechanical test results showed good material behaviour exhibiting the pseudo-ductility effect after the point of maximum force. The two applied overwrapping techniques had different influences on the pseudo-ductility effect. Microstructural investigation revealed differences between the groups of specimens that partially explain their different characters during mechanical testing. Full article
(This article belongs to the Special Issue Stress Analysis in Thin Films and Multilayers Materials)
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7 pages, 8136 KiB  
Article
Parasitic Current Induced by Gate Overlap in Thin-Film Transistors
by Hyeon-Jun Lee, Katsumi Abe, June-Seo Kim, Won Seok Yun and Myoung-Jae Lee
Materials 2021, 14(9), 2299; https://0-doi-org.brum.beds.ac.uk/10.3390/ma14092299 - 29 Apr 2021
Viewed by 2285
Abstract
As novel applications of oxide semiconductors are realized, various structural devices and integrated circuits are being proposed, and the gate-overlay defect phenomenon is becoming more diverse in its effects. Herein, the electrical properties of the transistor that depend on the geometry between the [...] Read more.
As novel applications of oxide semiconductors are realized, various structural devices and integrated circuits are being proposed, and the gate-overlay defect phenomenon is becoming more diverse in its effects. Herein, the electrical properties of the transistor that depend on the geometry between the gate and the semiconductor layer are analyzed, and the specific phenomena associated with the degree of overlap are reproduced. In the semiconductor layer, where the gate electrode is not overlapped, it is experimentally shown that a dual current is generated, and the results of 3D simulations confirm that the magnitude of the current increases as the parasitic current moves away from the gate electrode. The generation and path of the parasitic current are then represented visually through laser-enhanced 2D transport measurements; consequently, the flow of the dual current in the transistor is verified to be induced by the electrical potential imbalance in the semiconductor active layer, where the gate electrodes do not overlap. Full article
(This article belongs to the Special Issue Stress Analysis in Thin Films and Multilayers Materials)
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