scholarly journals Quantized wrinkles and fracture of stiff membranes on soft films

2022 ◽  
Author(s):  
Yancheng Meng ◽  
Henggao Xiang ◽  
Jianqiang Zhang ◽  
Zhili Hu ◽  
Jun Yin ◽  
...  
Keyword(s):  
Morphological Evolution ◽  
Scaling Law ◽  
Compressive Loading ◽  
Advanced Manufacturing ◽  
Large Area ◽  
Coating Materials ◽  
Post Buckling ◽  
Overall Bending

Abstract Stiff membranes on soft substrates may wrinkle and fold during compression1-11, but the strong post-buckling nonlinearity3,12 and the propensity of overall bending of these systems4,9,11 under large compression make the intriguing morphological evolution ill-controlled and less understood. Here, we present a simple peeling strategy that controllably makes stiff nanomembranes on soft microfilms wrinkled, then folded with a preset period, and ultimately fractured into regular ribbons. The fold and fracture periods exhibit a quantized, stepped dependence on the microfilm thickness, with the period doubled per step. The controlled wrinkle-to-fold-to-fractures transitions can be quantified by both computations and a scaling law, showing generality to different forms of compressive loading. This quantized wrinkle evolution deepens our understanding of complex behaviors of such natural and artificial systems as cerebral cortexes, skins, and coating materials, and opens a way to advanced manufacturing by fracturing large-area nanomembranes into uniformly shaped microflakes.

The Contact Problem at Delamination

1995 ◽  
Vol 62 (4) ◽  
pp. 989-996 ◽  
Author(s):  
A. E. Giannakopoulos ◽  
K.-F. Nilsson ◽  
G. Tsamasphyros
Keyword(s):  
Contact Problem ◽  
Plate Theory ◽  
Compressive Loading ◽  
Material Anisotropy ◽  
Intensity Factors ◽  
Finite Element Scheme ◽  
Contact Conditions ◽  
Delamination Buckling ◽  
Post Buckling ◽  
Delamination Front

The important phenomenon of delamination buckling is examined subjected to the condition of frictionless contact. Buckled delamination is examined in particular, because in-plane compressive loading is typical and detrimental. Two types of contact can be distinguished, local and global. The latter may occur everywhere in the plate while the local contact is limited to the crack front (negative KI stress intensity factors). Both local and global contact conditions were considered using a finite element scheme which employed nonlinear plate theory. The global contact problem is formulated as it appears in post-buckling of delamination. The case of simultaneous buckling and contact is also addressed in this paper. Two particularly interesting examples of thin film delaminations are presented. In the first, the contact at buckling is due to the material anisotropy. In this case the bucking load and the post-bucking analysis were very well supported by experiments. In the second example, contact at buckling arises because of a pin that holds down the delaminated layer at its center. The treated cases indicated that contact may significantly affect the fracture parameters along the delamination front, and is, therefore, important for delamination arrest.

Novel Dichroic Polarizing Materials and Approaches to Large-Area Processing

1998 ◽  
Vol 508 ◽  
Author(s):  
Yuri. A. Bobrov ◽  
Sean M. Casey ◽  
Leonid. Y. Ignatov ◽  
Pavel I. Lazarev ◽  
Daniel Phillips ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Liquid Crystals ◽  
Liquid Crystal Display ◽  
Substrate Surface ◽  
Continuous Production ◽  
Lyotropic Liquid Crystals ◽  
Large Area ◽  
Rigid Plastic ◽  
Coating Materials ◽  
Wide Range

AbstractWe have developed new polarizing coating materials and processes which enable the fabrication of polarizers for large-area liquid-crystal displays. The polarizing materials are novel discotic surfactants which self-assemble in aqueous solutions to provide a stable liquid-crystalline phase within a wide range of concentrations and temperatures. These lyotropic liquid crystals in an aqueous medium can be spread on a substrate surface by a variety of techniques including a knife-like doctor blade, a rolling cylinder, or a roll-to-roll method. Under the shearing force applied during deposition, the liquid crystals align on the substrate forming a dichroic polarizer. This alignment process allows continuous production of large-area polarizing films at low cost compared with the current technology that requires stretching of the films. Thin coatings can be applied to flexible plastic films, glass, or rigid plastic substrates. Direct coating of the polarizing material on glass eliminates several process steps in liquid-crystal display production since lamination of the polarizing film is no longer required. These new polarizing films have a high optical performance including a polarizing efficiency of above 98% and a dichroic ratio as high as 7.7.

Smart Structural Health Monitoring Validated on a Simple Plate under Compressive Loading

2013 ◽  
Vol 569-570 ◽  
pp. 1052-1059
Author(s):  
Christoph Viechtbauer ◽  
Kai Uwe Schröder ◽  
Martin Schagerl
Keyword(s):  
Structural Analysis ◽  
Structural Health Monitoring ◽  
Health Monitoring ◽  
Damage Identification ◽  
Compressive Loading ◽  
Structural Health ◽  
Deformation State ◽  
Post Buckling ◽  
Stress And Deformation ◽  
The Given

The subject of this research is the implementation of a Smart Structural Health Monitoring based on structural analysis and its validation on the plate under compressive loading. In the given context the structural analysis provides the most probable failure mode of the structure, e.g. buckling and the stress and deformation state at failure. With this information an algorithm analyses the onset of failure and infers from these analysis results the measurement values, which have to be monitored to identify the damage. By means of this, an appropriate sensor and the optimal sensor placement are chosen. As this pre-process supports the damage identification it is referred to as Smart Structural Health Monitoring (SSHM). The potential of SSHM to optimize the damage identification process is compared to a simple Structural Health Monitoring is demonstrated with a plate under compressive loading. In an experimental setup the plate is loaded up to buckling. After buckling the loading still increases up to failure of the plate caused by the deformations in the post buckling region. With a minimum of sensors and in combination with the analysis results of the SSHM the damage of the plate is detected, located and quantified.

scholarly journals Revisiting slope influence in turbulent bedload transport: consequences for vertical flow structure and transport rate scaling

2018 ◽  
Vol 839 ◽  
pp. 135-156 ◽  
Author(s):  
Raphael Maurin ◽  
Julien Chauchat ◽  
Philippe Frey
Keyword(s):  
Granular Flow ◽  
Morphological Evolution ◽  
Scaling Law ◽  
Bedload Transport ◽  
Transport Rate ◽  
Past Century ◽  
Granular Bed ◽  
Present Contribution ◽  
Wide Range ◽  
Gravity Driven

Gravity-driven turbulent bedload transport has been extensively studied over the past century in regard to its importance for Earth surface processes such as natural riverbed morphological evolution. In the present contribution, the influence of the longitudinal channel inclination angle on gravity-driven turbulent bedload transport is studied in an idealised framework considering steady and uniform flow conditions. From an analytical analysis based on the two-phase continuous equations, it is shown that: (i) the classical slope correction of the critical Shields number is based on an erroneous formulation of the buoyancy force, (ii) the influence of the slope is not restricted to the critical Shields number but affects the whole transport formula and (iii) pressure-driven and gravity-driven turbulent bedload transport are not equivalent from the slope influence standpoint. Analysing further the granular flow driving mechanisms, the longitudinal slope is shown to not only influence the fluid bed shear stress and the resistance of the granular bed, but also to affect the fluid flow inside the granular bed – responsible for the transition from bedload transport to debris flow. The relative influence of these coupled mechanisms allows us to understand the evolution of the vertical structure of the granular flow and to predict the transport rate scaling law as a function of a rescaled Shields number. The theoretical analysis is validated with coupled fluid–discrete element simulations of idealised gravity-driven turbulent bedload transport, performed over a wide range of Shields number values, density ratios and channel inclination angles. In particular, all the data are shown to collapse onto a master curve when considering the sediment transport rate as a function of the proposed rescaled Shields number.

Steel Plate Serviceability in Marine Structures

2002 ◽  
Author(s):  
Anto´nio F. Mateus ◽  
Joel A. Witz
Keyword(s):  
Compressive Loading ◽  
Maximum Load ◽  
Load Carrying Capacity ◽  
Element Analysis ◽  
Load Carrying ◽  
Extended Range ◽  
Post Buckling ◽  
New Criterion ◽  
Resultant Stress ◽  
Reduction Of Uncertainty

Plates are structural components that are able to provide support beyond compressive collapse, i.e. in the post-buckling regime. To date the criterion used to define plate failure under compressive loading is the plate maximum load carrying capacity which is identified as the peak of the associated load versus plate end-shortening curve. Recent advances in structural analysis techniques, such as nonlinear finite element analysis, have enabled the reduction of uncertainty that is embedded into the behaviour and strength prediction of new and in-service structures. Consequently, a new criterion for ultimate plate compressive strength is suggested and justified. This criterion is based on the unloaded edge resultant stress reaching yield. It is considered to be a suitable threshold of serviceability based on the relation between drop of strength versus the gain in plate end-shortening. In practical terms this means that a plate will be able to work in an extended range of end-shortenings.

Controlled deposition of large-area and highly-ordered thin films: effect of dip-coating-induced morphological evolution on resistive memory performance

2019 ◽  
Vol 7 (12) ◽  
pp. 3512-3521 ◽  
Author(s):  
Yang Li ◽  
Cheng Zhang ◽  
Zhuang Li ◽  
Peiyang Gu ◽  
Zilong Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Morphological Evolution ◽  
Memory Performance ◽  
Dip Coating ◽  
Resistive Memory ◽  
Large Area ◽  
Coating Technique ◽  
Patterned Films ◽  
Controlled Deposition ◽  
Dip Coating Technique

A scalable dip-coating technique is reported to precisely control nano-patterned films and resistive memory devices with a record reproducibility of 96%.

scholarly journals Buckling Behavior of Non-Retrofitted and FRP-Retrofitted Steel CHS T-Joints

2021 ◽  
Vol 11 (7) ◽  
pp. 3098
Author(s):  
Amin Yazdi ◽  
Maria Rashidi ◽  
Mohammad Alembagheri ◽  
Bijan Samali
Keyword(s):  
Compressive Loading ◽  
Local Buckling ◽  
Buckling Mode ◽  
T Joints ◽  
Hollow Section ◽  
Frp Composite ◽  
Buckling Behavior ◽  
Global Buckling ◽  
Post Buckling ◽  
Circular Hollow Section

This paper aims to investigate the buckling behavior of circular hollow section (CHS) T-joints in retrofitted and non-retrofitted states under axial brace compressive loading. For this purpose, two types of analysis are carried out. The first one is evaluating the critical buckling load in various tubular joints, and the other one is investigating the post-buckling behavior after each buckling mode. More than 180 CHS T-joints with various normalized geometric properties were numerically modeled in non-retrofitted state to compute their governing buckling mode, i.e., chord ovalization, brace local, or global buckling. Then three joints with different buckling modes were selected to be retrofitted by fiber-reinforced polymer (FRP) patches to illustrate the improving effect of the FRP wrapping on the post-buckling performance of the retrofitted joints. In addition, FRP composite failures were investigated. The results indicate that the FRP retrofitting is able to prevent the brace local buckling, and that matrix failure is the most common composite failure in the retrofitted joints.

A Fully Automated Porosity Measure for Thermal Barrier Coating Images

2018 ◽  
Vol 9 (4) ◽  
pp. 40-58
Author(s):  
Wei-Bang Chen ◽  
Benjamin N Standfield ◽  
Song Gao ◽  
Yongjin Lu ◽  
Xiaoliang Wang ◽  
...  
Keyword(s):  
Thermal Barrier Coating ◽  
Automated Image Analysis ◽  
Thermal Barrier ◽  
Advanced Manufacturing ◽  
Coating Materials ◽  
Surface Protection ◽  
Domain Experts ◽  
Barrier Coating ◽  
Local Thresholding ◽  
Coat Layer

Thermal barrier coating (TBC), a widely used advanced manufacturing technique in various industries, provides thermal insulation and surface protection to a substrate by spraying melted coating materials on to the surface of the substrate. This article is an extended version of a previously published work. To quantify microstructures in the TBC, the authors introduce a fully automated image analysis-based TBC porosity measure (TBCPM) framework which includes 1) top coat layer (TCL) detection module, and 2) microstructure recognition and porosity measure module. The first module is designed to automatically identify the TCL in a TBC image using a histogram-based approach. The second module recognizes the microstructures in the TCL using a local thresholding-based method. This article extends the previous work by introducing convolutional neural networks (CNNs) to enhance the performance of the second module. The experimental results show that the CNN-based methods outperform local thresholding-based methods, and results of the proposed porosity measure are comparable to that of the domain experts.

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