ANALYTICAL SOLUTIONS OF POLYMERIC GEL STRUCTURES UNDER BUCKLING AND WRINKLE

2011 ◽  
Vol 03 (02) ◽  
pp. 235-257 ◽  
Author(s):  
Z. S. LIU ◽  
S. SWADDIWUDHIPONG ◽  
F. S. CUI ◽  
W. HONG ◽  
Z. SUO ◽  
...  
Keyword(s):  
Thin Film ◽  
Analytical Solutions ◽  
Critical Stress ◽  
Chemical Potential ◽  
Slenderness Ratio ◽  
Experimental Studies ◽  
Structure Design ◽  
Inhomogeneous Field ◽  
Gel Structure ◽  
Polymeric Gel

One of the unique properties of polymeric gel is that the volume and shape of gel can dramatically change even at mild variation of external stimuli. Though a variety of instability patterns of slender and thin film gel structures due to swelling have been observed in various experimental studies, many are not well understood. This paper presents the analytical solutions of swelling-induced instability of various slender and thin film gel structures. We have adopted the well developed constitutive relation of inhomogeneous field theory of a polymeric network in equilibrium with a solvent and mechanical load or constraint with the incremental modulus concept for slender beam and thin film gel structures. The formulas of buckling and wrinkle conditions and critical stress values are derived for slender beam and thin film gel structures under swelling-induced instability using nonlinear buckling theories of beam and thin film structures. For slender beam structure, we construct the stability diagram with the distinct stable and unstable zones. The critical slenderness ratio and corresponding critical stresses are provided for different dimensionless material parameters. For thin film gel structures, we consider the thin film gel on an elastic foundation with different stiffness. The analytical solutions of critical stress and corresponding wrinkle wavelength, as well as buckling condition (or critical chemical potential) are given. These analytical solutions will provide a guideline for gel structure design used in polymeric gels MEMS and NEMS structures such as sensors and actuators. More importantly, the work provides a theoretical foundation of gel structure buckling and wrinkle, instability phenomena are different from normal engineering or material buckling.

ИССЛЕДОВАНИЕ МАГНИТОРЕЗИСТИВНЫХ НАНОСТРУКТУР С МАГНИТОСТРИКЦИОННЫМ ЭФФЕКТОМ ДЛЯ УСТРОЙСТВ МАГНИТНОЙ СТРЕЙНТРОНИКИ

2020 ◽  
Vol 96 (3s) ◽  
pp. 420-423
Author(s):  
Д.А. Жуков ◽  
В.В. Амеличев ◽  
Д.В. Костюк ◽  
А.И. Крикунов ◽  
Д.В. Васильев ◽  
...  
Keyword(s):  
Thin Film ◽  
Experimental Studies ◽  
Silicon Substrates ◽  
Multilayer Nanostructures ◽  
Magnetoresistive Effect ◽  
Anisotropic Magnetoresistive Effect

Представлены результаты экспериментальных исследований магнитострикционных и магниторезистивных свойств тонкопленочных многослойных наноструктур Ta/FeNiCo/CoFe/Ta и Ta/FeNiCo/CoFeВ/Ta на окисленных кремниевых подложках диаметром 100 мм. Экспериментально установлена зависимость величины анизотропного магниторезистивного эффекта от величины механических деформаций в экспериментальных образцах наноструктур. The paper presents the results of experimental studies of the magnetostriction and magnetoresistive properties of thin-film multilayer nanostructures Ta/FeNiCo/CoFe/Ta and Ta/FeNiCo/CoFeB/Ta on oxidized silicon substrates with a diameter of 100 mm. The dependence of the magnitude of the anisotropic magnetoresistive effect on the magnitude of mechanical strains in experimental samples of nanostructures has been experimentally established.

Reactive Phase Formation in Thin Films: Evolution of Grain Structure

1995 ◽  
Vol 403 ◽  
Author(s):  
K. Barmak ◽  
C. Michaelsent ◽  
J. Rickman ◽  
M. Dahmstt
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Phase Formation ◽  
Experimental Studies ◽  
Grain Structure ◽  
Structure Evolution ◽  
Future Research ◽  
Polycrystalline Materials ◽  
Product Phase ◽  
Nucleation Kinetics

AbstractIt is a well known fact that the properties and performance of polycrystalline materials, including polycrystalline thin films, are strongly affected by the grain structure. Therefore, in treating reactive phase formation in these films, it is (or it will inevitably be) necessary to quantify the grain structure of reactant and product phases and its evolution during the course of the reaction. Theoretical models and the conventional view of thin film reactions, however, have been largely extensions, to small and finite dimensions, of theories and descriptions developed for bulk diffusion couples. These models and descriptions primarily focus on the growth stage and to a much lesser extent on the nucleation stage. Consequently, these models and descriptions are not able to treat the development of product phase grain structure. Recent calorimetric investigations of several thin film systems demonstrate the importance of nucleation kinetics (and hence nucleation barriers) in product phase formation and provide quantitative measures of the thermodynamics and kinetics of formation of the product phases, thereby allowing some degree of comparison with reaction models. Furthermore, microstructural investigations of thin-film reactions demonstrate the non-planarity of the growth front and highlight the role of reactant-phase grain boundaries. In this paper, a summary of these experimental studies and recent theoretical treatments, which combine nucleation and growth in an integrated manner, is presented, with particular emphasis on the Nb/Al system. These experiments and models lead to a new view of reactive phase formation and grain structure evolution as one in which the latter is an integral part of the former. Based on this view, directions for future research are discussed.

EXPERIMENTAL STUDIES OF THE INFLUENCE OF THIN-FILM COATINGS ON THE RESISTANCE OF THE TOOL

2020 ◽  
Vol 5 ◽  
pp. 55-60
Author(s):  
G.V. BARSUKOV ◽  
A.V. KIRICHEK ◽  
K.F. SELEMENEV ◽  
E.M. SELEMENEVA
Keyword(s):  
Thin Film ◽  
Experimental Studies ◽  
Cutting Fluids ◽  
Adhesive Interaction ◽  
Film Coatings ◽  
Thin Film Coatings ◽  
Rigid Contact

The article deals with the problems of increasing the efficiency of centrifugal processing with a rigid contact. It is shown that when materials with different properties interact, it is energetically "advantageous" to have a discontinuous contact between interacting elements of the surfaces of the tool and the part. It has been established that epilating the working surfaces of the tool significantly changes the nature of the resistance to adhesive interaction, the effectiveness of which is significantly increased when using cutting fluids (lubricating and cooling technological media).

Characterizing the Effective Bandwidth of Tri-Stable Energy Harvesters

2016 ◽  
Author(s):  
Meghashyam Panyam ◽  
Mohammed F. Daqaq
Keyword(s):  
Magnetic Field ◽  
Analytical Solutions ◽  
Energy Harvester ◽  
Multiple Scales ◽  
Method Of Multiple Scales ◽  
Experimental Studies ◽  
Effective Bandwidth ◽  
Frequency Bandwidth ◽  
Effective Frequency ◽  
Energy Harvesters

This paper aims to investigate the response and characterize the effective frequency bandwidth of tri-stable vibratory energy harvesters. To achieve this goal, the method of multiple scales is utilized to construct analytical solutions describing the amplitude and stability of the intra- and inter-well dynamics of the harvester. Using these solutions, critical bifurcations in the parameter’s space are identified and used to define an effective frequency bandwidth of the harvester. A piezoelectric tri-stable energy harvester consisting of a uni-morph cantilever beam is considered. Stiffness nonlinearities are introduced into the harvesters design by applying a static magnetic field near the tip of the beam. Experimental studies performed on the harvester are presented to validate some of the theoretical findings.

SERS of a-C Thin Film on Ag, Au, Ag0.52-Au0.48 Alloy Nanoparticle Arrays with Normal Particles Size Distribution Formed by Vacuum Thermal Evaporation

2018 ◽  
Vol 386 ◽  
pp. 250-255 ◽  
Author(s):  
Sergey Dubkov ◽  
Alexey Trifonov ◽  
Yuri Shaman ◽  
Evgeny Kitsyuk ◽  
Andrey Savitskiy ◽  
...  
Keyword(s):  
Thin Film ◽  
Particle Size ◽  
Raman Scattering ◽  
Size Distribution ◽  
Thermal Evaporation ◽  
Experimental Studies ◽  
Alloy Nanoparticles ◽  
Nanoparticle Arrays ◽  
Vacuum Thermal Evaporation ◽  
Particles Size Distribution

This paper presents the results of experimental studies of arrays of Ag0.52Au0.48 alloy nanoparticles. Arrays were formed by vacuum-thermal evaporation on an unheated substrate and subsequent low-temperature vacuum annealing. The TEM images of the obtained nanoparticle arrays and corresponding histograms of particle size distribution are shown. The transmission spectra of these arrays showing the displacement of the plasma frequency as a function of the mean particle size are obtained. Spectra of Raman scattering from a thin film of amorphous carbon in presence of AgAu particles are obtained, and a comparative analysis of Raman scattering amplification factors for pure Ag, pure Au and Ag0.52Au0.48 alloy nanoparticles is presented.

A Piezoelectric Droplet Generating Device for Experiment in Successive Droplets Impacting Onto Solid Surface

2018 ◽  
Author(s):  
Jianxin Li ◽  
Huang Zhang ◽  
Yuzheng Li ◽  
Qianfeng Liu ◽  
Hanliang Bo
Keyword(s):  
Solid Surface ◽  
High Speed ◽  
Experimental Studies ◽  
Structure Design ◽  
Nozzle Diameter ◽  
Signal Frequency ◽  
Duty Ratio ◽  
Droplet Generator ◽  
Uniform Size ◽  
Drop On Demand

The outcomes of successive droplets impacting onto solid surface of the steam separator in a nuclear power system’s steam generator has a strong effect on the separating efficiency. Due to amounts of influencing factors, experimental research is an important method to study the phenomena of droplet-wall collision. However, because it is hard to generator continuous droplets with controllable uniform size and frequency, experimental studies about successive droplets impacting on solid surface are relative limited. In this study, a novel drop-on-demand (DOD) droplet generator is designed and fabricated based on piezoelectric ceramics, in which successive droplets with a uniform diameter can be generated. Firstly, the structure design of the DOD droplet generator, the setup of the control system and working principle are described in detail in this paper. Then the droplet generating performance of the device under different signal frequency fs, signal amplitude U, duty ratio Dr, and nozzle diameter Dn are investigated experimentally using a high-speed camera at 4000 fps. Finally, the influence of the signal frequency fs, voltage U, duty ratio Dr and nozzle diameter Dn on the diameter of droplet Dd is discussed. A test of successive droplets generated by the device impacting on an aluminum plate is conducted.

scholarly journals Numerical and experimental studies on a novel magneto-rheological fluid brake based on fluid–solid coupling

2019 ◽  
Vol 103 (1) ◽  
pp. 003685041987900 ◽  
Author(s):  
Shujun Li ◽  
Wenjun Meng ◽  
Yao Wang
Keyword(s):  
Heat Dissipation ◽  
Coupling Effect ◽  
Experimental Studies ◽  
Test System ◽  
Structure Design ◽  
Brake Disc ◽  
Braking Torque ◽  
Braking Process ◽  
Magneto Rheological ◽  
The Impact

The previous work of the authors indicated that the fluid–solid coupling effect of the magneto-rheological fluid and the brake disc is a necessary focus during braking process. In this study, a novel design of magneto-rheological fluid brake was proposed and studied theoretically and numerically, aiming to solve the prominent problem of heat dissipation, especially in the case of single emergency braking. First, based on the modified Bingham model, a parameter defined as the apparent equivalent viscosity was utilized to represent the relationship of magnetic field, flow field, and temperature field. The braking torque and the formula for calculating the impact factor of fluid–solid coupling employed for characterizing the associations among the thermal field and the stress field were established based on fluid–solid coupling. With a detailed explanation of simulation method, the distribution disciplinarian’s numerical simulation of each field was analyzed using COMSOL software. To validate the accuracy of the established model on the designed magneto-rheological fluid brake, the prototype was also manufactured, and results achieved experimentally which were measured on inertia test system of brake, for braking torque, motion parameters, and surface temperature in braking process, were compared with simulations. Simulation results manifested that the designed magneto-rheological fluid brake’s magnetic circuit structure is feasible based on magnetic induction intensity distribution. Finally, it has been shown that the simulations appear to be basically consistent with the experimental results, and the heat dissipation of the designed magneto-rheological fluid brake is partially improved. These results might contribute to the structure design, optimization, and improvement of magneto-rheological fluid products, extending the previous work on fluid–solid coupling analyses.

Dynamics and Morphological Outcomes in Thin-Film Spherical Crystallization of Glycine from Microfluidic Emulsions: Experimental Studies and Modeling

2014 ◽  
Vol 14 (7) ◽  
pp. 3485-3492 ◽  
Author(s):  
Arpad I. Toldy ◽  
Lu Zheng ◽  
Abu Zayed Md. Badruddoza ◽  
T. Alan Hatton ◽  
Saif A. Khan
Keyword(s):  
Thin Film ◽  
Experimental Studies ◽  
Spherical Crystallization

Grain Boundary Diffusion Controlled Precipitation as a Model For thin Film Reactions

1993 ◽  
Vol 311 ◽  
Author(s):  
K. Barmak ◽  
K.K. Coffey
Keyword(s):  
Thin Film ◽  
Driving Force ◽  
Boundary Diffusion ◽  
Chemical Potential ◽  
Driving Forces ◽  
Transport Model ◽  
Interface Reaction ◽  
Grain Structure ◽  
Phase Selection ◽  
Reaction Barriers

ABSTRACTIn order to arrive at a model for nucleation in the reaction of polycrystalline thin films, we have made use of a transport model that combines atom transport across interface reaction barriers with transport along grain boundaries. Through this transport model, the boundary chemical potential, μIi, and a characteristic length Li for each specie are defined. Li and the ratio of grain size to Li determine the spatial variation and the time evolution of the boundary chemical potential respectively. Nucleation of the product phase is modeled as a process whose driving force is determined by these position dependent (and time dependent) boundary chemical potentials. Thus thin film reactions become similar to precipitation from bulk homogeneous supersaturated solid solutions. Numerical calculations, however, show that boundary diffusion results in low “effective” driving forces for nucleation which can lead to heterogeneous nucleation of even the first phase. The model provides a new approach to phase selection by re-evaluation of the driving force and considers the effect of product and reactant grain structure to be fundamental to the reaction process.

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