Morphology of Voltage-Triggered Ordered Wrinkles of a Dielectric Elastomer Sheet

2017 ◽  
Vol 84 (11) ◽  
Author(s):  
Guoyong Mao ◽  
Lei Wu ◽  
Xueya Liang ◽  
Shaoxing Qu
Keyword(s):  
High Voltage ◽  
Optical Sensor ◽  
Material Science ◽  
Dielectric Elastomer ◽  
Theoretical Studies ◽  
Science And Engineering ◽  
Future Design ◽  
Experimental And Theoretical Studies ◽  
Theory And Experiment ◽  
Good Agreement

Wrinkles widely existing in sheets and membranes have attracted a lot of attention in the fields of material science and engineering applications. In this paper, we present a new method to generate ordered (striplike) and steady wrinkles of a constrained dielectric elastomer (DE) sheet coated with soft electrodes on both sides subjected to high voltage. When the voltage reaches a certain value, wrinkles will nucleate and grow. We conduct both experimental and theoretical studies to investigate the wavelength and amplitude of the wrinkle. The results show a good agreement between theory and experiment. Moreover, the amplitude and wavelength of ordered wrinkles can be tuned by varying the prestretch and geometry of the DE sheet, as well as the applying voltage. This study can help future design of DE transducers such as diffraction grating and optical sensor.

Formation of solitons in transitional boundary layers: theory and experiment

1993 ◽  
Vol 251 ◽  
pp. 273-297 ◽  
Author(s):  
Y. S. Kachanov ◽  
O. S. Ryzhov ◽  
F. T. Smith
Keyword(s):  
Experimental Data ◽  
Boundary Layer ◽  
Asymptotic Theory ◽  
Subsequent Development ◽  
Boundary Layer Transition ◽  
Theoretical Studies ◽  
Layer Transition ◽  
Experimental And Theoretical Studies ◽  
Theory And Experiment ◽  
Good Agreement

This work brings together experimental and theoretical studies of nonlinear stages aimed at the K-regime in boundary-layer transition, and some combined theoretical and experimental results are discussed. It is shown that the initial stages in the formation of so-called spikes, observed in many experiments, may be described very well by the asymptotic theory. These flashes-spikes are shown to be (in certain regimes) possible solitons of the boundary layer and governed by the integral-differential Benjamin-Ono equation. Properties of the spike-solitons, obtained both theoretically and experimentally in the quasi-planar stages of their development, are presented. Features of the disturbance behaviour connected with the subsequent development of three-dimensionality are also discussed, as are the effects of viscosity and shorter lengthscales. The main conclusion of the work concerns the hypothesis of the possible soliton nature of the flashes-spikes (within limits), which seems reliably corroborated by the good agreement found between the theory and the experimental data.

Weak Extinction Limits of Turbulent Heterogeneous Fuel/Air Mixtures

1980 ◽  
Vol 102 (2) ◽  
pp. 416-421 ◽  
Author(s):  
D. R. Ballal ◽  
A. H. Lefebvre
Keyword(s):  
Liquid Fuel ◽  
Drop Size ◽  
Air Pressure ◽  
Theoretical Studies ◽  
Turbulence Level ◽  
Test Program ◽  
Stabilized Flames ◽  
Experimental Values ◽  
Experimental And Theoretical Studies ◽  
Good Agreement

Experimental and theoretical studies are made of the factors governing the weak extinction limits of stabilized flames supplied with flowing mixtures of liquid fuel drops and air. The test program includes wide variations in inlet air pressure, velocity and turbulence level, and also covers wide ranges of fuel volatility and mean drop size. The influence of flameholder size and blockage is also examined. An equation is derived for predicting weak extinction limits which shows good agreement with the corresponding experimental values.

scholarly journals Weak Extinction Limits of Turbulent Heterogeneous Fuel/Air Mixtures

1979 ◽  
Author(s):  
D. R. Ballal ◽  
A. H. Lefebvre
Keyword(s):  
Liquid Fuel ◽  
Drop Size ◽  
Air Pressure ◽  
Theoretical Studies ◽  
Turbulence Level ◽  
Test Program ◽  
Stabilized Flames ◽  
Experimental Values ◽  
Experimental And Theoretical Studies ◽  
Good Agreement

Experimental and theoretical studies are made of the factors governing the weak extinction limits of stabilized flames supplied with flowing mixtures of liquid fuel drops and air. The test program includes wide variations in inlet air pressure, velocity and turbulence level, and also covers wide ranges of fuel volatility and mean drop size. The influence of flameholder size and blockage is also examined. An equation is derived for predicting weak extinction limits which shows good agreement with the corresponding experimental values.

Flame Blowoff Studies Using Large-Scale Flameholders

1982 ◽  
Vol 104 (4) ◽  
pp. 853-857 ◽  
Author(s):  
K. V. L. Rao ◽  
A. H. Lefebvre
Keyword(s):  
Experimental Data ◽  
Large Scale ◽  
Water Injection ◽  
Injection Technique ◽  
Theoretical Studies ◽  
Effective Pressure ◽  
Test Program ◽  
Combustible Mixtures ◽  
Experimental And Theoretical Studies ◽  
Good Agreement

Experimental and theoretical studies are made of the factors governing the blowoff velocities of stabilized flames supplied with flowing gaseous combustible mixtures. The test program includes wide variations in effective pressure, obtained using the water injection technique, and also covers wide ranges of velocity, flameholder size, and flameholder blockage. An equation is derived for predicting blowoff velocities which shows good agreement with the experimental data.

scholarly journals Simulation and experimental studies on the evolution of a laser spark in air

1992 ◽  
Vol 10 (4) ◽  
pp. 707-713 ◽  
Author(s):  
X. C. Zeng ◽  
D. P. Singh ◽  
V. Palleschi ◽  
A. Salvetti ◽  
M. De Rosa ◽  
...  
Keyword(s):  
Shock Waves ◽  
Experimental Studies ◽  
Numerical Code ◽  
Radiation Hydrodynamics ◽  
Theoretical Studies ◽  
Air Plasma ◽  
Hot Plasma ◽  
Laser Spark ◽  
Experimental And Theoretical Studies ◽  
Good Agreement

Experimental and theoretical studies on the evolution of shock waves in air plasma induced by laser spark have been carried out. The systematic study of the shock wave has been performed experimentally and 1-D numerical code of radiation hydrodynamics (1-DRHC) has been used to simulate the later stage of laser spark in air. The numerical results on the propagation of shock waves and the expansion of hot plasma are presented and subsequent results on the first divergent and convergent shock waves are found to be in good agreement with the experimental data.

The Stabilizing Effect of Pre-Equilibria: A Trifluoromethyl Complex as CF2 Reservoir in Catalytic Olefin Difluorocarbenation

2020 ◽  
Author(s):  
Thomas Louis-Goff ◽  
Huu Vinh Trinh ◽  
Eileen Chen ◽  
Arnold L. Rheingold ◽  
Christian Ehm ◽  
...  
Keyword(s):  
High Selectivity ◽  
Side Reactions ◽  
Theoretical Studies ◽  
Attractive Feature ◽  
Catalyst Recovery ◽  
Wide Range ◽  
Stabilizing Effect ◽  
Experimental And Theoretical Studies

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF<sub>3</sub> as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF<sub>2</sub> in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF<sub>2</sub>-recombination side-reactions.

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