A viscoelastic model for the dynamic response of soils to periodical surface water disturbance

2006 ◽  
Vol 30 (12) ◽  
pp. 1201-1212 ◽  
Author(s):  
P. C. Hsieh
Keyword(s):  
Surface Water ◽  
Dynamic Response ◽  
Viscoelastic Model

scholarly journals Dynamic response of surface water-groundwater exchange to currents, tides, and waves in a shallow estuary

2013 ◽  
Vol 118 (4) ◽  
pp. 1749-1758 ◽  
Author(s):  
Audrey H. Sawyer ◽  
Fengyan Shi ◽  
James T. Kirby ◽  
Holly A. Michael
Keyword(s):  
Surface Water ◽  
Dynamic Response ◽  
Shallow Estuary ◽  
Groundwater Exchange

Sternal Force-Displacement Relationship During Cardiopulmonary Resuscitation

1993 ◽  
Vol 115 (2) ◽  
pp. 195-201 ◽  
Author(s):  
K. G. Gruben ◽  
A. D. Guerci ◽  
H. R. Halperin ◽  
A. S. Popel ◽  
J. E. Tsitlik
Keyword(s):  
Cyclic Loading ◽  
Cardiopulmonary Resuscitation ◽  
Dynamic Response ◽  
Elastic Properties ◽  
Clinical Data ◽  
Viscoelastic Model ◽  
Damping Properties ◽  
Cpr Training ◽  
Force Displacement

A viscoelastic model is presented to describe the dynamic response of the human chest to cyclic loading during manual cardiopulmonary resuscitation (CPR). Sternal force and displacement were measured during 16 clinical resuscitation attempts and during compressions on five CPR training manikins. The model was developed to describe the clinical data and consists of the parallel combination of a spring and dashpot. The human chests’ elastic and damping properties were both augmented with increasing displacement. The manikins’ elastic properties were stiffer and both elastic and damping properties were less dependent on displacement than the humans’.

scholarly journals Tropical Cyclone–Induced Upper-Ocean Mixing and Climate: Application to Equable Climates

2008 ◽  
Vol 21 (4) ◽  
pp. 638-654 ◽  
Author(s):  
Robert L. Korty ◽  
Kerry A. Emanuel ◽  
Jeffery R. Scott
Keyword(s):  
Carbon Dioxide ◽  
Heat Flux ◽  
Surface Water ◽  
Tropical Cyclone ◽  
Dynamic Response ◽  
Tropical Cyclones ◽  
Climate Changes ◽  
Tropical Oceans ◽  
Warm Surface Water ◽  
Upper Ocean Mixing

Abstract Tropical cyclones instigate an isolated blast of vigorous mixing in the upper tropical oceans, stirring warm surface water with cooler water in the thermocline. Previous work suggests that the frequency, intensity, and lifetime of these storms may be functions of the climate state, implying that transient tropical mixing could have been stronger during warmer equable climates with higher concentrations of carbon dioxide. Stronger mixing of the tropical oceans can force the oceans’ meridional heat flux to increase, cooling tropical latitudes while warming higher ones. This response differs significantly from previous modeling studies of equable climates that used static mixing; coupling mixing to climate changes the dynamic response. A parameterization of mixing from tropical cyclones is developed, and including it leads to a cooling of tropical oceans and a warming of subtropical waters compared with control cases with fixed mixing. The mixing penetration depth regulates the magnitude of the response.

Three-dimensional pulse response of curved composite sandwich panel with compressible core using non-linear higher-order theory

2020 ◽  
pp. 109963622098008
Author(s):  
Seyed Ali Ahmadi ◽  
Mohammad Hadi Pashaei ◽  
Ramazan-Ali Jafari-Talookolaei
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Sandwich Panel ◽  
Viscoelastic Model ◽  
Three Dimensional ◽  
Higher Order ◽  
Computer Hardware ◽  
Computational Time ◽  
Damping Factor ◽  
Non Linear

In this paper, the dynamic response of cylindrical sandwich panels with compressible core is obtained using the extended non-linear higher-order sandwich panel theory. It is assumed that the sandwich panel has simply supported boundary at all edges and is consisted of orthotropic face sheets and viscoelastic core layer. To describe the mechanical properties of the viscoelastic foam core, the Kelvin-Voigt linear viscoelastic model was applied. Three-dimensional linear equations of motions were used to describe the sandwich panel deformations. The effects of various parameters including the panel span, core and facing thickness, the viscous damping factor, pulse duration, and maximum pressure on the dynamic response of the sandwich cylindrical panel are studied. The results obtained from present method are compared with finite element solutions and those reported in the literature, and consequently, agreement among the results could be observed. The results shown that applied viscoelastic model has a signification effect on the panel response and reduces the magnitude of vibrations. The presented programming code (DQ) needs less computational time and computer hardware capacity and is faster than finite element solution.

Evaluation of Nonlinear Damping Properties of Magnetorheological Gels Under Shear Loading

2013 ◽  
Author(s):  
Yotsugi Shibuya ◽  
Hiroshi Nasuno ◽  
Hirohisa Sakurai ◽  
Katsuaki Sunakoda
Keyword(s):  
Magnetic Field ◽  
Dynamic Response ◽  
Hysteresis Loop ◽  
Viscoelastic Model ◽  
Shear Loading ◽  
Material System ◽  
Damping Properties ◽  
Stress Strain ◽  
Nonlinear Viscoelastic ◽  
Nonlinear Viscoelastic Model

Rheological properties of magnetorheological gels can be changed reversibly by applied magnetic fields. Magnetorheological gels with different material system are characterized the dynamic response of the material by shearing test in magnetic field. Nonlinear behavior is observed in the dynamic response of the material. To understand mechanism of the behavior, dynamic properties of magnetorheological gels are evaluated by experiment and nonlinear viscoelastic model. Magnetorheological gels used in this study consist of three types of paramagnetic particles and a cyclic-poly-siloxane gel matrix. Three material systems of magnetic particles are chosen: Fe-Si-Ni, Si-Fe and Fe-Si-B-Cr types. Shear testing is conducted in magnetic field 0mT, 105mT and 211mT. The stress-strain response under shear deformation is characterized by non-ellipsoidal hysteresis loop due to nonlinearity of the response. To identify the nonlinear properties, analysis in frequency domain is applied to identify the dynamic response of the material. Nonlinear viscoelastic model with high order components is made and phenomenon of the non-ellipsoidal hysteresis loop in the stress-strain relation and damping properties are illustrated.

Dynamic Response of Fractionally Damped Viscoelastic Plates Subjected to a Moving Point Load

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Rajendra Kumar Praharaj ◽  
Nabanita Datta ◽  
Mohammed Rabius Sunny
Keyword(s):  
Dynamic Response ◽  
Fractional Derivative ◽  
Dynamic Behavior ◽  
Moving Load ◽  
Viscoelastic Model ◽  
Point Load ◽  
Dynamic Amplification Factor ◽  
Modal Summation ◽  
Liouville Fractional Derivative ◽  
Dynamic Amplification

Abstract The dynamic response of fractionally damped viscoelastic plates subjected to a moving point load is investigated. In order to capture the viscoelastic dynamic behavior more accurately, the material is modeled using the fractionally damped Kelvin–Voigt model (rather than the integer-type viscoelastic model). The Riemann–Liouville fractional derivative of order 0 < α ≤ 1 is applied. Galerkin's method and Newton–Raphson technique are used to evaluate the natural frequencies and corresponding damping coefficients. The structure is subject to a moving point load, traveling at different speeds. The modal summation technique is applied to generate the dynamic response of the plate. The influence of the order of the fractional derivative on the free and transient vibrations is studied for different velocities of the moving load. The results are compared with those using the classical integer-type Kelvin–Voigt viscoelastic model. The results show that an increase in the order of the fractional derivative causes a significant decrease in the maximum dynamic amplification factor, especially in the “dynamic zone” of the normalized sweep time. The dynamic behavior of the plate is verified with ansys.

Experimental Investigation on the Dynamic Response of Density-Stratified Fluid in a Submarine Trench

2009 ◽  
Author(s):  
Hwung-Hweng Hwung ◽  
Wen-Yang Hsu ◽  
Chi-Min Liu ◽  
Ray-Yeng Yang
Keyword(s):  
Image Processing ◽  
Experimental Investigation ◽  
Surface Water ◽  
Dynamic Response ◽  
Internal Wave ◽  
Internal Waves ◽  
Processing Technique ◽  
Image Processing Technique ◽  
Wave Flume ◽  
Incident Waves

The dynamic response of the generated internal wave as surface water propagating over a submarine trench is investigated in a wave flume. The image processing technique is used to observe the response of density-stratified interface. Two typical distinct phenomena of internal waves were caught in the experiments, which are standing internal waves usually occurred as the incident waves range from 0.6∼0.8 times the length of trench, and the traveling internal waves usually occurred outside this range.

Dynamic response of the isolated passive rat diaphragm strip

1992 ◽  
Vol 73 (6) ◽  
pp. 2681-2692 ◽  
Author(s):  
D. Navajas ◽  
S. Mijailovich ◽  
G. M. Glass ◽  
D. Stamenovic ◽  
J. J. Fredberg
Keyword(s):  
Dynamic Response ◽  
Plastic Material ◽  
Viscoelastic Model ◽  
Nonlinear Behavior ◽  
Step Response ◽  
Stress Adaptation ◽  
Amplitude Dependence ◽  
Rat Diaphragm ◽  
Stress Strain ◽  
Linear Viscoelastic

To further our understanding of the mechanisms underlying chest wall mechanics, we investigated the dynamic response of the isolated passive rat diaphragm strip. Stress adaptation of the tissue was measured from 0.05 to 60 s after subjecting the strips to strain steps of normalized strain amplitudes from 0.005 to 0.04. The tissue resistance (R), elastance (E), and hysteresivity (eta) were measured in the same range of amplitudes by sinusoidally straining the strip at frequencies from 0.03125 to 10 Hz. The stress (T) depended exponentially on the strain (epsilon) and relaxed and recovered linearly with the logarithm of time. E increased linearly with the logarithm of frequency and decreased with increasing amplitude. R fell hyperbolically with frequency and showed an amplitude dependence similar to that of E. To interpret the strong nonlinear behavior, we extended the viscoelastic model of Hildebrandt (J. Appl. Physiol. 28: 365–372, 1970) to include an exponential stress-strain relationship. Accordingly, the step response was described by T - Tr = Tr(e alpha delta epsilon - 1)(1 - gamma log t), where delta epsilon is the strain amplitude, Tr is the initial operating stress, alpha is a measure of the stress-strain nonlinearity, and gamma is the rate of stress adaptation. The oscillatory response of the model was computed by applying Fung's quasi-linear viscoelastic theory. This quasi-linear viscoelastic model fitted the step and oscillatory data fairly well but only if alpha depended negatively on delta epsilon, as might be expected in a plastic material.

Application of a Simple Cold Stub to the Direct Observation of Frozen Hydrated Sand

1973 ◽  
Vol 31 ◽  
pp. 212-213
Author(s):  
John M. Wehrung ◽  
Richard J. Harniman
Keyword(s):  
United States ◽  
Surface Water ◽  
Direct Observation ◽  
Controlled Study ◽  
Clay Particles ◽  
Organic Debris ◽  
Rock Formations ◽  
Water Tables ◽  
Permeable Rock ◽  
Natural Means

Water tables in aquifer regions of the southwest United States are dropping off at a rate which is greater than can be replaced by natural means. It is estimated that by 1985 wells will run dry in this region unless adequate artificial recharging can be accomplished. Recharging with surface water is limited by the plugging of permeable rock formations underground by clay particles and organic debris.A controlled study was initiated in which sand grains were used as the rock formation and water with known clay concentrations as the recharge media. The plugging mechanism was investigated by direct observation in the SEM of frozen hydrated sand samples from selected depths.

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