Dynamic surface acoustic response to a thermal expansion source on an anisotropic half space

2013 ◽  
Vol 133 (5) ◽  
pp. 2634-2640 ◽  
Author(s):  
Peng Zhao ◽  
Ji-Cheng Zhao ◽  
Richard Weaver
Keyword(s):  
Thermal Expansion ◽  
Half Space ◽  
Acoustic Response ◽  
Dynamic Surface

The Effect of a Thin Layer Surface Inhomogeneity on Dynamic Surface Response

1978 ◽  
Vol 45 (1) ◽  
pp. 95-99 ◽  
Author(s):  
L. M. Brock
Keyword(s):  
Thin Layer ◽  
Half Space ◽  
Critical Parameter ◽  
Rigid Bodies ◽  
Layer Surface ◽  
Noticeable Effect ◽  
Dynamic Surface ◽  
Surface Inhomogeneity ◽  
Interface Waves ◽  
Surface Response

A thin layer surface inhomogeneity consisting of small, evenly distributed rigid bodies is perfectly bonded to an elastic half space. Constant normal and shear line loads are applied to the layer and the dynamic surface response is calculated by Laplace transform techniques. The product of the layer thickness and the rigid body/half-space mass densities proves to be a critical parameter in determining the response. It is found that the layer has a noticeable effect on the half-space surface response in relation to the free-surface behavior. In particular, while no standard surface-interface waves exist, evidence for small values of the critical parameter indicates the presence of pseudo-Rayleigh waves similar to those found in fluid-solid interface analyses.

scholarly journals The influence of closed brine pockets and permeable brine channels on the thermo-elastic properties of saline ice

2017 ◽  
Vol 375 (2086) ◽  
pp. 20150351 ◽  
Author(s):  
Aleksey Marchenko ◽  
Ben Lishman
Keyword(s):  
Experimental Data ◽  
Thermal Expansion ◽  
Half Space ◽  
Elastic Properties ◽  
Elastic Waves ◽  
Elastic Behaviour ◽  
Model Solutions ◽  
Data Support ◽  
University College London ◽  
The University

A model of the thermo-elastic behaviour of saline ice is formulated, and model solutions describing thermo-elastic waves (TEW) propagating into a half-space of the ice are investigated. The model is based on a proposal that saline ice is a matrix, which encompasses both closed brine pockets and permeable channels filled with brine. Experiments on the thermal expansion of saline ice samples, and on TEW in saline ice, have been performed in the cold laboratories of the University Centre in Svalbard and in University College London. The experimental data are compared with theoretical conclusions. The experimental data support our hypothesis that the brine in saline ice is divided between closed pockets and open, permeable channels. This article is part of the themed issue ‘Microdynamics of ice’.

scholarly journals A note on dynamic surface displacements in an elastic half-space

1973 ◽  
Vol 17 (1-2) ◽  
pp. 145-152 ◽  
Author(s):  
O. F. Afandi ◽  
R. A. Scott
Keyword(s):  
Half Space ◽  
Elastic Half Space ◽  
Dynamic Surface ◽  
Surface Displacements

scholarly journals Structural Monitoring of Underground Structures in Multi-Layer Media by Dynamic Methods

Sensors ◽  
2020 ◽  
Vol 20 (18) ◽  
pp. 5241 ◽  
Author(s):  
Alexandr Lyapin ◽  
Alexey Beskopylny ◽  
Besarion Meskhi
Keyword(s):  
Half Space ◽  
Dynamic Load ◽  
Fourier Transforms ◽  
Sensor System ◽  
Structural Monitoring ◽  
Dynamic Features ◽  
Surface Source ◽  
Stress Strain ◽  
Dynamic Surface ◽  
Actual Problem

The actual problem of structural monitoring and modeling of dynamic response from buried building is considered in the framework of arbitrary dynamic load. The results can be used for designing underground transport constructions, crossings, buried reservoirs and foundations. In existing methods, the system of sensors that register the response to a dynamic action does not allow for effective interpretation of the signal without understanding the dynamic features and resonance phenomena. The analytical and numerical solution of the problem of the dynamics of a buried object in a layered medium is considered. A multilayer half-space is a set of rigidly interconnected layers characterized by elastic properties. At a distance, an arbitrary dynamic load acts on the half-space, which causes oscillations in the embedded structure, and the sensor system registers the response. The problem of assessing the dynamic stress-strain state (DSSS) is solved using Fourier transforms with the principle of limiting absorption. As an example, the behavior of an embedded massive structure of an underground pedestrian crossing under the influence of a dynamic surface source on a multilayer medium is considered, as well as instrumental support of the sensor system. The solution in the form of stress, strain and displacement fields is obtained and compared with the experimental data. The frequency-dependent characteristics of the system are determined and the possibility of determining the DSSS by a shock pulse is shown.

Refraction of P- and S-Wave at the Interface of Micropolar Elasticity and Thermoelasticity with Voids

2018 ◽  
Vol 06 (03n04) ◽  
pp. 1850005
Author(s):  
R. Lianngenga ◽  
J. Lalvohbika ◽  
Lalawmpuia
Keyword(s):  
Thermal Expansion ◽  
Half Space ◽  
Plane Waves ◽  
Linear Thermal Expansion ◽  
Elastic Half Space ◽  
Micropolar Elasticity ◽  
S Wave ◽  
Incident Plane ◽  
Energy Ratios ◽  
Refracted Waves

The problem of incident plane waves at the interface of micropolar thermoelastic half-space with voids and micropolar elastic half-space with voids has been attempted. The amplitude and energy ratios of various reflected and refracted waves for the incident [Formula: see text]- and [Formula: see text]-waves are obtained with the help of appropriate boundary conditions at the interface. The effect of linear thermal expansion and microinertia on the amplitude and energy ratios due to the incident [Formula: see text]- and [Formula: see text]-waves are discussed. Numerically and analytically, these amplitude and energy ratios are computed to show the effect of linear thermal expansion and microinertia. It is observed that the effect of linear thermal expansion is less for incident [Formula: see text]-wave and the effect of microinertia is less for incident [Formula: see text]-wave.

Light-driven dynamic surface wrinkles for adaptive visible camouflage

2021 ◽  
Vol 118 (48) ◽  
pp. e2114345118
Author(s):  
Tianjiao Ma ◽  
Jing Bai ◽  
Tiantian Li ◽  
Shuai Chen ◽  
Xiaodong Ma ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Dynamic Characteristics ◽  
Optical Signal ◽  
Photothermal Effect ◽  
Dynamic Surface ◽  
Scattering Of Light ◽  
On Demand ◽  
The Military ◽  
Demand Control

Camouflage is widespread in nature, engineering, and the military. Dynamic surface wrinkles enable a material the on-demand control of the reflected optical signal and may provide an alternative to achieve adaptive camouflage. Here, we demonstrate a feasible strategy for adaptive visible camouflage based on light-driven dynamic surface wrinkles using a bilayer system comprising an anthracene-containing copolymer (PAN) and pigment-containing poly (dimethylsiloxane) (pigment-PDMS). In this system, the photothermal effect–induced thermal expansion of pigment-PDMS could eliminate the wrinkles. The multiwavelength light–driven dynamic surface wrinkles could tune the scattering of light and the visibility of the PAN film interference color. Consequently, the color captured by the observer could switch between the exposure state that is distinguished from the background and the camouflage state that is similar to the surroundings. The bilayer wrinkling system toward adaptive visible camouflage is simple to configure, easy to operate, versatile, and exhibits in situ dynamic characteristics without any external sensors and extra stimuli.

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