scholarly journals Wave propagation in periodic buckled beams. Part I: Analytical models and numerical simulations

Wave Motion ◽  
2016 ◽  
Vol 66 ◽  
pp. 190-209 ◽  
Author(s):  
Florian Maurin ◽  
Alessandro Spadoni
Keyword(s):  
Wave Propagation ◽  
Numerical Simulations ◽  
Analytical Models ◽  
Buckled Beams

The effects of geometric offsets on the dynamic responses of a Scott—Russell amplifying mechanism with flexible hinges

2009 ◽  
Vol 223 (10) ◽  
pp. 2413-2423 ◽  
Author(s):  
C-M Chen ◽  
R-F Fung
Keyword(s):  
Numerical Simulations ◽  
Analytical Model ◽  
Dynamic Responses ◽  
Analytical Models ◽  
Dynamic Equations ◽  
Magnification Factor ◽  
Flexure Hinges ◽  
Magnification Factors ◽  
Straight Line ◽  
Deviation Factor

The dynamic equations of a micro-positioning Scott—Russell (SR) mechanism associated with two flexible hinges and an offset are developed to calculate output responses. Both rigid and flexible hinges are considered to explore the results. The main features in the kinematics of the SR mechanism are its displacement amplification and straight-line motion, which are widely needed in practical industries. The manufacturing inaccuracy of the SR mechanism definitely causes geometric offsets of flexure hinges, and affects displacement amplification and straight-line output motion. Analytical models based on kinematics and Hamilton's principle are derived to explore the variation of linearity ratio, magnification factor, and deviation factor due to various offsets and link lengths. From numerical simulations for the SR mechanism with various offsets of flexible hinges in the conditions of different link lengths, it is found that offsets of flexure hinges obviously affect the amplifying factor and linearity ratio, and appear to dominate the changes of magnification factors. Moreover, an analytical model is also used to predict magnification factors due to various offsets. Finally, some conclusions concerning the effects of offset on the performance of the SR mechanism are drawn.

Modeling of Acoustic Wave Propagation HAMR Media

2005 ◽  
Author(s):  
Wei Peng ◽  
Yiao-Tee Hsia ◽  
Julius Hohlfeld
Keyword(s):  
Wave Propagation ◽  
Acoustic Wave ◽  
Elastic Waves ◽  
Wave Pattern ◽  
Analytical Models ◽  
Acoustic Wave Propagation ◽  
Pump Probe ◽  
Change Measurement ◽  
Complex Wave ◽  
Acoustic Fluid

In multi-layered solids, an acoustic wave is partially reflected and partially transmitted at boundaries, which renders a too complex wave pattern to be predicted with analytical models. A Finite Element Method (FEM) based numerical model is developed to predict the acoustic wave propagation in multi-layered solids, where an ANSYS acoustic fluid element is adopted to solve this problem. The model is applied to study the pump-probe transient reflectivity measurements on Heat Assisted Magnetic Recording (HAMR) media, where the thermo-elastic waves are isolated and then subtracted from the composite reflectivity change measurement. As a result, the reflectivity change caused by the thermal decay is separated from the thermo-elastic waves, allowing a more accurate prediction and measurement of the thermal properties of HAMR media.

Approximate analytical models for cylindrical shear wave propagation in viscoelastic media

2013 ◽  
Vol 134 (5) ◽  
pp. 4011-4011
Author(s):  
Yiqun Yang ◽  
Matthew W. Urban ◽  
Bob Qiang ◽  
Robert J. McGough
Keyword(s):  
Wave Propagation ◽  
Shear Wave ◽  
Analytical Models ◽  
Viscoelastic Media

scholarly journals Magnetically driven jets and winds from weakly magnetized accretion discs

2019 ◽  
Vol 490 (3) ◽  
pp. 3112-3133 ◽  
Author(s):  
J Jacquemin-Ide ◽  
J Ferreira ◽  
G Lesur
Keyword(s):  
Numerical Simulations ◽  
Energy Content ◽  
Initial Energy ◽  
Accretion Discs ◽  
Analytical Models ◽  
Magnetorotational Instability ◽  
New Class ◽  
Analytical Criterion ◽  
First Time

Abstract Semi-analytical models of disc outflows have successfully described magnetically driven, self-confined super-Alfvénic jets from near-Keplerian accretion discs. These jet-emitting discs (JEDs) are possible for high levels of disc magnetization μ defined as μ = 2/β, where beta is the usual plasma parameter. In near-equipartition JEDs, accretion is supersonic and jets carry away most of the disc angular momentum. However, these solutions prove difficult to compare with cutting-edge numerical simulations, for the reason that numerical simulations show wind-like outflows but in the domain of small magnetization. In this work, we present for the first time self-similar isothermal solutions for accretion–ejection structures at small magnetization levels. We elucidate the role of magnetorotational instability-like (MRI) structures in the acceleration processes that drive this new class of solutions. The disc magnetization μ is the main control parameter: Massive outflows driven by the pressure of the toroidal magnetic field are obtained up to μ ∼ 10−2, while more tenuous centrifugally driven outflows are obtained at larger μ values. The generalized parameter space and the astrophysical consequences are discussed. We believe that these new solutions could be a stepping stone in understanding the way astrophysical discs drive either winds or jets. Defining jets as self-confined outflows and winds as uncollimated outflows, we propose a simple analytical criterion based on the initial energy content of the outflow, to discriminate jets from winds. We show that jet solution is achieved at all magnetization levels, while winds could be obtained only in weakly magnetized discs that feature heating.

Study on Numerical Simulation of Explosion in Soil Based on Fluid-Solid Coupling Arithmetic

2014 ◽  
Vol 580-583 ◽  
pp. 2916-2919
Author(s):  
Juan Song ◽  
Shu Cai Li
Keyword(s):  
Numerical Simulation ◽  
Wave Propagation ◽  
Dynamic Response ◽  
Numerical Simulations ◽  
Soil Medium ◽  
Coupling Process ◽  
Contact Algorithm ◽  
Modeling Simulation ◽  
Propagation Law ◽  
Simulation Results

Numerical simulations play a significant role in explosion in a mass of soil due to an underground explosive. Common methods available in hydrocode for fluid-solid coupling process are contact algorithm, Lagrange algorithm, and Arbitrary Lagrange-Euler (ALE) algorithm. A numerical simulation of explosion process with concentrated charge in a mass of soil was carried out by using three methods in this paper. The dynamic response of soil medium, the formation and development law of explosion cavity and the explosion wave propagation law in soil were simulated. Merits and drawbacks of three different methods are analyzed in the aspect of modeling, simulation results and computing cost.

scholarly journals Precession-driven flows in non-axisymmetric ellipsoids

2013 ◽  
Vol 737 ◽  
pp. 412-439 ◽  
Author(s):  
J. Noir ◽  
D. Cébron
Keyword(s):  
Theoretical Model ◽  
Numerical Simulations ◽  
Celestial Body ◽  
Excellent Agreement ◽  
Analytical Models ◽  
Forced Flow ◽  
Spheroidal Geometry ◽  
Strong Contrast ◽  
Do So

AbstractWe study the flow forced by precession in rigid non-axisymmetric ellipsoidal containers. To do so, we revisit the inviscid and viscous analytical models that have been previously developed for the spheroidal geometry by, respectively, Poincaré (Bull. Astronomique, vol. XXVIII, 1910, pp. 1–36) and Busse (J. Fluid Mech., vol. 33, 1968, pp. 739–751), and we report the first numerical simulations of flows in such a geometry. In strong contrast with axisymmetric spheroids, where the forced flow is systematically stationary in the precessing frame, we show that the forced flow is unsteady and periodic. Comparisons of the numerical simulations with the proposed theoretical model show excellent agreement for both axisymmetric and non-axisymmetric containers. Finally, since the studied configuration corresponds to a tidally locked celestial body such as the Earth’s Moon, we use our model to investigate the challenging but planetary-relevant limit of very small Ekman numbers and the particular case of our Moon.

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