Laser-Based Transient Surface Acceleration of Thermoelastic Layers

1999 ◽  
Author(s):  
Cetin Cetinkaya ◽  
Chen Li ◽  
Cunli Wu
Keyword(s):  
Wave Propagation ◽  
Transfer Matrix ◽  
Integral Transforms ◽  
Surface Cleaning ◽  
Current Work ◽  
Second Sound ◽  
Sound Effect ◽  
Matrix Formulation ◽  
Thermoelastic Wave ◽  
Second Sound Effect

Abstract The effectiveness of traditional surface cleaning methods, such as ultrasonically induced fluid flow, vibrational methods, centrifugal techniques, is limited to particles that require surface acceleration lower than 107m/s2. For sub-micron particles, a higher level surface acceleration is needed. In the current work, based on the generalized dynamic theory of thermoelasticity, a transfer matrix formulation including the second sound effect is developed for a layer. The transfer matrix for axisysmmetric wave propagation in the thermoelastic layer is obtained by adopting integral transforms. The second sound effect is included to eliminate the immediate arrival of thermal waves. A transfer function formulation for calculating the accelerations is developed for transient analysis. In the current work, only the surface acceleration due to transient thermoelastic wave propagation is under investigation.

Propagation and Localization of Longitudinal Thermoelastic Waves in Layered Structures

2000 ◽  
Vol 122 (3) ◽  
pp. 263-271 ◽  
Author(s):  
Cetin Cetinkaya ◽  
Chen Li
Keyword(s):  
Propagation Constant ◽  
Attenuation Factor ◽  
Layered Structures ◽  
Dynamical Theory ◽  
Transfer Model ◽  
Second Sound ◽  
Sound Effect ◽  
Matrix Formulation ◽  
Thermoelastic Waves ◽  
Second Sound Effect

Based on the generalized dynamical theory of thermoelasticity, a transfer matrix formulation including the second sound effect is developed for longitudinal wave component propagation in a thermoelastic layer. The second sound effect is included to eliminate the thermal wave travelling with infinite velocity as predicted by the diffusion heat transfer model. Using this formulation and the periodic systems framework, the attenuation and propagation properties of one-dimensional thermoelastic waves in both continuum and layered structures are studied. Strong localization of thermal waves predicted by the analysis in the transformed domain is demonstrated in the time-spacial domain by an FFT-based transient analysis. Also, a perturbation analysis for identifying leading terms in thermal attenuation is performed, and the role of the thermal elastic coupling term in attenuation is determined. The attenuation factor, defined as the real part of the propagation constant, is obtained in thermoelastic solids. The reflection and transmission coefficients between half-spaces are also calculated to evaluate the potential practical use of the approach in thermal-based nondestructive testing. [S0739-3717(00)00403-7]

Localization of One-Dimensional Thermoelastic Waves in Layered Structures

1999 ◽  
Author(s):  
Cetin Cetinkaya ◽  
Chen Li
Keyword(s):  
Layered Structures ◽  
Dynamical Theory ◽  
Sound Effect ◽  
Matrix Formulation ◽  
Thermoelastic Wave ◽  
One Dimensional ◽  
Transmission Coefficients ◽  
Propagation Properties ◽  
Systems Framework

Abstract Including the second sound effect, a transfer matrix formulation based on the generalized dynamical theory of thermoelasticity is developed for longitudinal wave component propagation in a thermoelastic layer. The attenuation and propagation properties of one-dimensional thermoelastic wave in both continuum and layered structures are studied using this formulation and the periodic systems framework. Localization of thermal waves is demonstrated in the time-spacial domain by an FFT-based transient analysis. A perturbation analysis tor identifying leading terms in thermal attenuation is performed, and the role of the thermal elastic coupling term in attenuation is determined. The reflection and transmission coefficients between half-spaces are calculated to evaluate the potential practical use of the approach in laser-based nondestructive testing.

A continuum approach to the second-sound effect

1975 ◽  
Vol 5 (3-4) ◽  
pp. 237-248 ◽  
Author(s):  
R. J. Atkin ◽  
N. Fox ◽  
M. W. Vasey
Keyword(s):  
Second Sound ◽  
Continuum Approach ◽  
Sound Effect ◽  
Second Sound Effect

Transfer Matrix Formulation With Optical Penetration for Axisymmetric Thermoelastic Wave Propagation in Films

2001 ◽  
Author(s):  
Chen Li ◽  
Jiadao Lin ◽  
Cetin Cetinkaya
Keyword(s):  
Wave Propagation ◽  
Light Intensity ◽  
Transfer Matrix ◽  
Modulation Frequency ◽  
Intensity Modulation ◽  
Wave Number ◽  
Radial Coordinate ◽  
Thermoelastic Wave ◽  
Radial Wave ◽  
Forcing Term

Abstract Using Laplace and Hankel integral transforms in time and the radial coordinate, a fully-coupled thermoelastic formulation based on the equation of motion and heat equation is developed to study the effects of axial optical penetration on axisymmetric wave propagation in thermoelastic layers and/or layered structures. It is demonstrated that the optical penetration has no effect on the entries of the sextic transfer matrix, however it introduces an equivalent forcing term for all state variables for both surfaces of a thermoelastic layer as opposed to the surface heating case in which the heating effect is localized in the heating volume (the thermal skin). The thickness of thermal skin depends on the light intensity modulation frequency while the optical penetration typically depends only on the wavelength of the light. This additional forcing vector is a function of the light intensity modulation frequency, the radial wave number, penetration decay rate, as well as thermoelastic material properties. Complexities in wavefields due to the nature of the forcing term are demonstrated and discussed. A thin copper layer with hypothetical penetration properties is considered for the demonstration of the current formulation.

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