CNT Thin Film Network Failure due to Concentrated Current Loadings

2011 ◽  
Author(s):  
David A. Jack
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Response ◽  
Three Dimensional ◽  
Element Model ◽  
Scale Model ◽  
Lightning Strike ◽  
Similar System ◽  
Network Failure ◽  
Multi Scale

Polymer composite carbon nanotube (CNT) thin films have been hypothesized as a possible material for lightning strike protection for next generation aircraft structures. This study employs the author’s previously presented three-dimensional physics-based coupled thermal and electrical multi-scale model which constructs the non-deterministic nanostructure variations for a CNT thin film, and returns the bulk thermal and electrical response due to high electrical loadings. The key results of the present study are the presentation of a possible failure mechanism for CNT thin films under increasing electrical loadings. This paper discusses the nanoscale breakdown of the network conductivity using a quasi-static loading, and uses the nanoscale results in a macroscopic finite element model which couples resistive heating with thermal breakdown. The results are in reasonable agreement with those found in the literature for a similar system.

Numerical analysis of punch shear failure and stress characteristics of three-dimensional braided composite with different braiding angles

2019 ◽  
Vol 28 (9) ◽  
pp. 1418-1437
Author(s):  
Yuanyuan Li ◽  
Zhijuan Pan ◽  
Bohong Gu ◽  
Baozhong Sun
Keyword(s):  
Shear Failure ◽  
Shear Bands ◽  
Three Dimensional ◽  
Element Model ◽  
Scale Model ◽  
Strain Rates ◽  
Braided Composites ◽  
Braided Composite ◽  
Multi Scale ◽  
Braided Structure

This paper presents a multi-scale finite element model to calculate the stress field and analyze the punch shear failure of three-dimensional braided composite at high strain rates. The multi-scale model was established based on real braided structure taking the surface and corner braiding yarns into consideration. Constitutive material modeling and failure criterions were introduced into the model. Three braiding angles of 25°, 35°, and 45° were applied to reveal the relations between failure states and braided structure. The results showed that the punch shear failure states and stress distribution were greatly dependent on the strain rates and braiding angles. Nonuniform stress propagation resulted in shear bands and different formation paths were observed on the composite with different braiding angles. The ultimate failure of braided composite was determined by comprehensive action of compressive and tensile stress. In addition, the progressive damage of typical braiding yarns in different conditions was obtained from the modeling simulation. The three-dimensional braided composites with different braiding angles showed unique failure morphology. It was closely determined by the complex braided structures.

Three-dimensional Reconstruction of Microscopic Image Based on Multi-ST Algorithm

2020 ◽  
Vol 64 (2) ◽  
pp. 20506-1-20506-7
Author(s):  
Min Zhu ◽  
Rongfu Zhang ◽  
Pei Ma ◽  
Xuedian Zhang ◽  
Qi Guo
Keyword(s):  
3D Reconstruction ◽  
Three Dimensional ◽  
Scale Model ◽  
Microscopic Image ◽  
Multi Scale ◽  
Gaussian Pyramid ◽  
Cost Aggregation ◽  
Dimensional Reconstruction ◽  
Image Pairs ◽  
Accurate Matching

Abstract Three-dimensional (3D) reconstruction is extensively used in microscopic applications. Reducing excessive error points and achieving accurate matching of weak texture regions have been the classical challenges for 3D microscopic vision. A Multi-ST algorithm was proposed to improve matching accuracy. The process is performed in two main stages: scaled microscopic images and regularized cost aggregation. First, microscopic image pairs with different scales were extracted according to the Gaussian pyramid criterion. Second, a novel cost aggregation approach based on the regularized multi-scale model was implemented into all scales to obtain the final cost. To evaluate the performances of the proposed Multi-ST algorithm and compare different algorithms, seven groups of images from the Middlebury dataset and four groups of experimental images obtained by a binocular microscopic system were analyzed. Disparity maps and reconstruction maps generated by the proposed approach contained more information and fewer outliers or artifacts. Furthermore, 3D reconstruction of the plug gauges using the Multi-ST algorithm showed that the error was less than 0.025 mm.

scholarly journals Tip-Based Nanomachining on Thin Films: A Mini Review

2021 ◽  
Author(s):  
Shunyu Chang ◽  
Yanquan Geng ◽  
Yongda Yan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Data Storage ◽  
Three Dimensional ◽  
Maintenance Cost ◽  
Two Dimensional ◽  
Force Microscopy ◽  
Atomic Force ◽  
Current State ◽  
Two Dimensional Materials

AbstractAs one of the most widely used nanofabrication methods, the atomic force microscopy (AFM) tip-based nanomachining technique offers important advantages, including nanoscale manipulation accuracy, low maintenance cost, and flexible experimental operation. This technique has been applied to one-, two-, and even three-dimensional nanomachining patterns on thin films made of polymers, metals, and two-dimensional materials. These structures are widely used in the fields of nanooptics, nanoelectronics, data storage, super lubrication, and so forth. Moreover, they are believed to have a wide application in other fields, and their possible industrialization may be realized in the future. In this work, the current state of the research into the use of the AFM tip-based nanomachining method in thin-film machining is presented. First, the state of the structures machined on thin films is reviewed according to the type of thin-film materials (i.e., polymers, metals, and two-dimensional materials). Second, the related applications of tip-based nanomachining to film machining are presented. Finally, the current situation of this area and its potential development direction are discussed. This review is expected to enrich the understanding of the research status of the use of the tip-based nanomachining method in thin-film machining and ultimately broaden its application.

Parametric Study of Nanostructure Variations on the Macroscopic Thermal and Electrical Behavior of Neat CNT Thin Film Networks

2011 ◽  
Author(s):  
Nikhil A. Ashtekar ◽  
David A. Jack
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Electrical Conductivity ◽  
Sensitivity Analysis ◽  
Carbon Nanotube ◽  
Probability Distribution ◽  
Electrical Response ◽  
Electrical Behavior ◽  
Commercial Applications ◽  
Nanotube Chirality

Carbon nanotube thin films are considered by many researchers as a material for the future in many electrical and thermal applications, but a lack of systematic physics-based modeling approaches to quantify the bulk thermal and electrical response due to nanostructure variations makes employing these thin films difficult for commercial applications. In this work we employ the previously presented 3D physics-based computational model for characterizing the bulk thermal and electrical response of a neat carbon nanotube thin film network involving stochastic distributions of length, diameter, chirality, orientation and values of intercontact resistivity obtained from the literature. The model is employed to test the sensitivity of bulk thermal and electrical conductivity on stochastic variations in the nanostructure parameters. We examine the sensitivity of the thin film networks to the experimentally obtained Weibull probability distribution for length and diameter. Additionally, we present a study to quantify the macroscopic conductivity dependence on the nanotube chirality ratio. Through these studies we present an approach that is very generic and can be used for the sensitivity analysis due to variations within the nanostructure.

Simulation of 3D Films Deposited by Glancing Angle Deposition Using 3D-Films

2000 ◽  
Vol 616 ◽  
Author(s):  
T. Smy ◽  
D. Vick ◽  
M. J. Brett ◽  
S. K. Dew ◽  
A. T. Wu ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Three Dimensional ◽  
Thin Film Deposition ◽  
Glancing Angle Deposition ◽  
Film Deposition ◽  
Porous Thin Films ◽  
Glancing Angle ◽  
Memory Resources ◽  
Angle Deposition

AbstractA new fully three dimensional (3D) ballistic deposition simulator 3D-FILMS has been developed for the modeling of thin film deposition and structure. The simulator may be implemented using the memory resources available to workstations. In order to illustrate the capabilities of 3D-FILMS, we apply it to the growth of engineered porous thin films produced by the technique of GLancing Angle Deposition (GLAD).

scholarly journals Three-dimensional multi-scale model of deformable platelets adhesion to vessel wall in blood flow

2014 ◽  
Vol 372 (2021) ◽  
pp. 20130380 ◽  
Author(s):  
Ziheng Wu ◽  
Zhiliang Xu ◽  
Oleg Kim ◽  
Mark Alber
Keyword(s):  
Blood Flow ◽  
Blood Vessel ◽  
Vessel Wall ◽  
Platelet Adhesion ◽  
Three Dimensional ◽  
Clot Formation ◽  
Scale Model ◽  
Injury Site ◽  
Platelet Receptors ◽  
Multi Scale

When a blood vessel ruptures or gets inflamed, the human body responds by rapidly forming a clot to restrict the loss of blood. Platelets aggregation at the injury site of the blood vessel occurring via platelet–platelet adhesion, tethering and rolling on the injured endothelium is a critical initial step in blood clot formation. A novel three-dimensional multi-scale model is introduced and used in this paper to simulate receptor-mediated adhesion of deformable platelets at the site of vascular injury under different shear rates of blood flow. The novelty of the model is based on a new approach of coupling submodels at three biological scales crucial for the early clot formation: novel hybrid cell membrane submodel to represent physiological elastic properties of a platelet, stochastic receptor–ligand binding submodel to describe cell adhesion kinetics and lattice Boltzmann submodel for simulating blood flow. The model implementation on the GPU cluster significantly improved simulation performance. Predictive model simulations revealed that platelet deformation, interactions between platelets in the vicinity of the vessel wall as well as the number of functional GPIb α platelet receptors played significant roles in platelet adhesion to the injury site. Variation of the number of functional GPIb α platelet receptors as well as changes of platelet stiffness can represent effects of specific drugs reducing or enhancing platelet activity. Therefore, predictive simulations can improve the search for new drug targets and help to make treatment of thrombosis patient-specific.

Ultra high-yield one-step synthesis of conductive and superhydrophobic three-dimensional mats of carbon nanofibers via full catalysis of unconstrained thin films

2014 ◽  
Vol 2 (36) ◽  
pp. 15118-15123 ◽  
Author(s):  
Efrat Shawat ◽  
Ilana Perelshtein ◽  
Andrew Westover ◽  
Cary L. Pint ◽  
Gilbert D. Nessim
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Carbon Nanofibers ◽  
Three Dimensional ◽  
High Yield ◽  
One Step

We directly synthesized large conductive and superhydrophobic 3D mats of entangled carbon nanofibers (CNFs). The mechanism is based on thin film delamination and bi-directional catalytic CNF growth.

Transformations in Thin Solid Layers: The Reversible Polymerization-Depolymerization of 2,6-Di-n-propyl- 1,3,5,7-tetraoxa-2,6-dibora-4,8-octalindiones at Low Temperatures

1985 ◽  
Vol 40 (2) ◽  
pp. 222-228 ◽  
Author(s):  
Mohamed Yalpani ◽  
E. Klotzbücher
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Title Compound ◽  
Low Temperatures ◽  
Three Dimensional ◽  
Visible Spectroscopy ◽  
Varying Thickness ◽  
Spontaneous Formation ◽  
Uv Visible ◽  
Lattice Energies

The course of Aggregation of molecules of the title compound (1b) through different, spectroscopically discernible and chemically identifiable forms of associations could be followed by matrix isolation and thin film infrared and UV-visible spectroscopy. It was found that molecules of 1b in thin films form clusters which at low temperatures interact weakly, probably through the carbonyl oxygens of one and the boron atoms of the neighbouring molecules. On warming to 260 K this association gradually takes the form of more defined chelate bonds, probably with ordered three-dimensional intermolecular structures. Above this temperature spontaneous formation of crystallites of the previously reported ʻhotʼ and ʻcoldʼ modifications was observed. Studies with films of varying thickness indicate an interdependence of crystallite size and lattice energies.

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