Thermoelastic Waves Research Articles

Thermoelastic wave generation and its longitudinal wave propagation measurement by a microscopic optical interferometer

Laser ultrasonics is a noncontact measurement method that uses a laser-induced elastic wave source in combination with an optical surface displacement-tracking system. This study compared the performances of two optical interferometers with different characteristics when applied to measurement of pulsed thermoelastic waves. The surface displacement-tracking system was designed to measure the center of the microscopic view. A pulsed laser beam irradiated a black ink layer to generate the thermoelastic waves. The out-of-plane displacement on the axially opposite side was then measured using either a Michelson interferometer or a Sagnac interferometer. The objective lens of the system was of a type commonly used in biological observations. The Michelson interferometer estimated a maximum displacement of 0.43 nm and a maximum sound pressure of 24.7 kPa. The signal-to-noise ratios from 16 averages were 14.9 dB (Michelson interferometer) and 19.2 dB (Sagnac interferometer). Furthermore, this paper compares the performance of the numerically estimated Sagnac interferometer outputs calculated from the measured Michelson interferometer outputs with the experimentally obtained Sagnac interferometer outputs. The numerically estimated Sagnac interferometer’s output was shown to be identical to the experimentally acquired output. The Michelson interferometer requires a higher average operating frequency (i.e., it needs a longer data acquisition time), although this interferometer does offer superior displacement output linearity. This property enables calculation of the sound pressure from the displacement amplitude. These findings indicated that combination of the measurement points of the Sagnac interferometer with those of the sparsely distributed Michelson interferometer reduced the measurement time when compared with a single use of the Michelson interferometer while also maintaining the data acquisition quality.

A rotating magneto-photothermoelastic effect with moisture diffusivity of nonlocal semiconductor medium

This study focuses on investigating the deformation of a one-dimensional elastic nonlocal semiconductor medium. The aim is to understand how the magnetic field and moisture diffusivity affect this deformation. The research aims to analyze the connection between plasma and moisture diffusivity processes in a rotational field, as well as thermo-elastic waves. The study examines the transport process of photo-thermoelasticity while considering the influence of moisture diffusivity. To derive the governing equations of the photo-thermo-elastic medium, Laplace’s transformation technique is used. These equations encompass the carrier density, elastic waves, moisture transport, heat conduction, and constitutive relationships. The fundamental physical parameters in the Laplace domain, such as mechanical stresses, thermal conditions, and plasma boundary conditions, are calculated. Numerical techniques are employed to invert the Laplace transform and obtain complete time-domain solutions for the various physical domains under investigation. The analysis takes into account reference moisture, nonlocality, magnetic field and rotation field. The effects of applied forces on displacement, moisture concentration, carrier density, stress resulting from forces, and temperature distribution are considered through graphical analysis.

Generalized thermoelastic wave response in a hollow cylinder with temperature-dependent properties based on the memory-dependent derivative of the heat conduction model

High-temperature pipelines are susceptible to defects due to the long-term service in high-temperature environments. The guided wave technology is promising for online non-destructive testing. Before implementing it in engineering, it is essential to better understand guided wave characteristics, especially attenuation, which significantly decreases the test distance and the resolution. However, describing the large attenuation is challenging due to the strong thermoelastic coupling, resulting in limitations of available models. To address these limitations, this paper aims to introduce a memory-dependent generalized thermoelastic model for investigating guided waves propagating in a hollow cylinder with temperature-dependent material properties. The analytical solutions are obtained using the Legendre polynomial method. The influence of the memory-dependent effect, temperature variation, and boundary conditions are studied. Some interesting findings are revealed: (1) The time delay factor is more dominant when adjusting κ and n to accurately describe guided wave propagation at high temperatures. (2): The mode conversion is accompanied by the attenuation and group velocity jump when the adjacent flexural torsional and longitudinal modes intersect, which is advisable to avoid when choosing the excitation frequency. (3) The relationship between phase velocity and attenuation versus temperature for quasi-elastic modes is nonlinear, while that for thermal modes is approximately linear.

Thermoelastic wave scattering by a multi-layered object

In this work the scattering of time-harmonic thermoelastic waves by a multi-layered thermoelastic body is considered. The mathematical formulation of the scattering problem is presented in a unified four-dimensional form. Using the thermoelastic analogue of Betti's identity, the transmission conditions and asymptotic analysis in the dyadic fundamental solution of thermoelasticity, an integral representation of the scattered field as well as formulas of the thermoelastic far-field patterns containing the physical parameters of the scatterer's layers are constructed. Via the Rellich's Lemma for vector fields, the Helmholtz decomposition of thermoelastic waves and the Kupradze's radiation conditions, uniqueness of solution is proved. Setting the solution to be a linear combination of single- and double- layer thermoelastic potentials and using their jump relations, the scattering problem is transformed into a system of integral equations written in a matrix form. Using the regularity properties of the potentials and the Riesz-Fredholm's theory existence of solution is obtained.

Characterizing elastic wave reflection in a semiconducting isotropic diffusive medium with temperature rate-dependent nonlocal theory

In this paper, we explore the application of nonlocal theory to analyze the phenomenon of coupled thermoelastic wave reflection in a semiconducting diffusive medium, considering its temperature rate dependence. The governing equations are deconstructed using the Helmholtz vector rule, allowing us to delve into the behavior of the system. By calculating the dispersion relation in terms of propagation speed, we investigate four coupled longitudinal waves alongside an independent nondispersive transverse wave within the local medium. The cut-off frequencies for each wave are discussed, shedding light on their characteristics. Furthermore, we delve into the phenomenon of coupled longitudinal displacement waves at the medium’s boundary. Analytical derivations of amplitude ratios are presented, accompanied by graphical representations of their behavior, focusing on a semiconductor material such as copper. We examine the effects of physical parameters, including the nonlocal and diffusive parameters, on the obtained results. It is important to note that the existing literature primarily lacks consideration of diffusivity and plasma transportation. Lastly, we validate our findings by investigating the conservation of energy within the system.

Synchronization phenomena in thermoelastic waves connected in parallel

In this paper, the phenomenon of synchronization in nonlinearly coupled thermoelastic waves is investigated. The existence of a finite-dimensional smooth global attractor A α is proven in the natural energy space, where α is the coupling parameter. It is also proved that the coupled thermoelastic wave system can be reduced to a single thermoelastic wave when α tends to infinity. Subsequently, the upper-semicontinuity of their attractors is proven as α → ∞ . These results are ultimately employed to establish the synchronization phenomena for coupled thermoelastic waves. To the best of our knowledge, the synchronization of thermoelastic waves has not been considered before.

Influence of Hall Current on Thermoelastic Wave Behavior in Viscoelastic Fractional-Order Rotating Porous Solids

Influence of Hall Current on Thermoelastic Wave Behavior in Viscoelastic Fractional-Order Rotating Porous Solids

Effect of homogeneous generalized thermoelasticity on semiconductor layer under magnetic field on Green and Naghdi model without energy dissipation

This paper aims to explore the impact of viscosity and time on the spread of thermoelastic waves within a uniform and isotropic three-dimensional medium subject to a thermal load on its surface. This study utilizes the temperature-rate-dependent thermoelasticity based on the GN model, specifically applying the GN II model of generalized thermoelasticity, which does not account for energy dissipation. The normal mode analysis technique is employed to address the non-dimensional coupled field equations, yielding precise formulas for displacement, stress, temperature distribution, and strain. This issue is further illustrated by graphically depicting the field variables for a material similar to copper alongside the corresponding results. Comparative analyses of numerical data, with and without considering viscosity effects, suggest that the wave propagation speed will be limited.

Correction: Effect of Impedance Boundary on the Reflection of Plane Waves in Fraction-Order Thermoelasticity in an Initially Stressed Rotating Half-Space with a Magnetic Field

Correction: Effect of Impedance Boundary on the Reflection of Plane Waves in Fraction-Order Thermoelasticity in an Initially Stressed Rotating Half-Space with a Magnetic Field

One-dimensional thermo-elastic wave analysis for dynamic thermoelasticity coupled with dual-phase-lag heat conduction model

One-dimensional thermo-elastic wave analysis for dynamic thermoelasticity coupled with dual-phase-lag heat conduction model

Grain boundary effects on thermal shock responses of yttria-stabilized zirconia

The rapid temperature change or thermal shock is inevitable in many engineering applications of polycrystalline yttria-stabilized zirconia (YSZ). Nevertheless, the thermal shock response of YSZ especially its dependence on the grain boundary (GB) structure in YSZ remains almost unknown to date. In this study, the effect of the GB on thermal shock behaviors of YSZ ceramics was investigated by molecular dynamics (MD) simulations in conjunction with experimental characterizations. According to the distribution of misorientation angles of GBs experimentally extracted from our sintered YSZ samples, four most common GBs with a misorientation angle ranging from 35° to 63° were constructed in MD simulations through the annealing technique. The thermal shock simulations on the bi-crystalline YSZ with such GBs show a weakening effect of the GB on the thermo-elastic strain wave, which is found to be the most significant in the [100]/[111] GB and almost vanish in its [110]/[111] counterpart. Our simulations also reveal that the weakening effect of GB on the thermo-elastic strain wave is majorly attributed to the impedance mismatch between its two adjacent grains, although the grain-boundary thermal resistance observed also can weaken the temperature wave after crossing GBs. These findings provide valuable atomic insights into the thermomechanical behaviors of YSZ under thermal shock, which will guide the design of microstructures of YSZ for some special applications in solid oxide fuel cells and thermal barrier coatings.

Thermoelastic Waves Propagation through Semiconductor Nanostructure by a Ramp Heat Source

Thermoelastic Waves Propagation through Semiconductor Nanostructure by a Ramp Heat Source

Theory of continental drift – causes of the motion. Outline of the theory

The theory of mantle convection currents as the cause of lithospheric plate movements has several major problems, including the absence of an adequate energy source. As shown in our previous contribution, an unbiased interpretation of geochemical data does not support the assumptions of a significant amount of radionuclides in the lower mantle or even in the core. It is our assertion that solar radiation is the primary energy source in the lithosphere. This energy is converted into mechanical energy via thermoelastic waves, even in depths with minimal temperature fluctuations. This has been confirmed by various methods of continuous stress measurement. The periodic and quasiperiodic thermoelastic reversible deformations, such as the circadian and annual cycles (including tidal periods), can also cause irreversible deformations due to the ratcheting mechanism. The 2D model showed that the strength limit is exceeded in 0.3 % of all diurnal cycles during the year. As a consequence, continents tend to extend while the oceanic lithosphere is pushed and overthrusted between continents. The middle-ocean ridges, similar to continental rifts, are filled by ascending magma which is one example of the ratcheting mechanism. The final plate movements are determined by the distribution of major continents and the overall westward drift of the lithosphere, which is slower for deep-rooted plates like the Indian one. Large asteroid impacts are important triggers (and possibly significant energy sources) of discrete events, like the formation of hotspots and large igneous provinces.

Thermoelastic impact modeling for projectile–target–muzzle components during penetration start of motion

This paper presents the thermoelastic shock wave model components of projectile, target, and muzzle tube during the initial start of penetration. The penetration model is combined using pressure and temperature (e.g., mechanical and thermal shock) that act separately at the moment of penetration (a few microseconds) into a homogeneous or first-layer armor body. The armor’s shape and material will be investigated based on contact principal stress. The reciprocal influence between the penetrator and the armor in the aspect of the projectile nose shape will also be demonstrated. Moreover, the penetrator thermoelastic material’s durability will be examined, based on von Mises criterion. The examination for the initial elastic contact stress impact will be performed by using the explicit solution to temperature-displacement coupling equilibrium, based on commercial finite elements modeling. In addition, a modified impact contact stress model based on both mechanical and thermal energies was proposed and found to agree with the literature. Brief conceptual analysis of projectile–shield interactions was examined. Finally, shooting tube muzzle thermoelastic analysis was performed alongside a literature comparison, which was found to agree qualitatively and quantitatively. Muzzle tube material impact analysis was performed. Finally, it was concluded that muzzle tubes obey the rule that a shorter cylinder length tube develops higher muzzle tube principal stresses.

Non-classical theory of electro-thermo-elasticity incorporating local mass displacement and nonlocal heat conduction

A non-classical local gradient theory of nonferromagnetic thermoelastic dielectrics is presented, incorporating both the local mass-displacement process and the heat-flux gradient effect. The process of local mass displacement is related to the changes in material microstructure. The nonlocal heat conduction law is also addressed in the model. Thus, the generalized relationship between the higher-grade heat and entropy fluxes is adopted. The gradient-type constitutive relations and governing equations are derived using the fundamental principles of continuum mechanics, non-equilibrium thermodynamics, and electrodynamics. Due to the contribution of higher-grade flux, the nonlocal law of heat conduction is obtained. The constitutive relations for isotropic materials with the corresponding additional material constants are derived. To illustrate the local gradient theory and to show the electro-thermo-mechanical coupling effect in isotropic materials, a straightforward problem is analytically solved for a layered non-piezoelectric structure under non-uniform temperature distribution. The analytical results reveal that the thermal polarization effect can also be pronounced in isotropic materials. To illustrate the model considering the effect of nonlocal heat conduction, the propagation of spherical thermoelastic harmonic waves in a homogeneous and isotropic elastic medium with non-classical heat conduction law is studied.

Propagation and reflection of thermoelastic wave in a rotating nonlocal fractional order porous medium under Hall current influence

This investigation relates to the research on Hall current on propagation and reflection of elastic waves through non-local fractional-order thermoelastic rotating medium with voids. The system is split up into longitudinal and transverse components using the Helmholtz vector rule. It is observed that, through the frequency dispersion relation four coupled quasi-waves exist in the medium. The rotating solid modifies the nature of purely longitudinal and transverse waves toward the quasi-type waves. All the propagating waves are dispersive as they depend upon angular frequency. The quasi-longitudinal wave qP and quasi-transverse wave qSV faces cut-off frequencies. The nonlocal parameter affect all the waves except the quasi void wave. Analytically, the reflection coefficients of the wave are computed using suitable boundary conditions. MATLAB software is used to perform numerical computations for a chosen solid material. The amplitude ratios and the speed of propagation of the wave are plotted graphically for rotational frequency, nonlocal, fractional order, and Hall current parameter. The significant effect of the physical parameters on the computed results has been observed. The cut-off frequency of the waves is also presented graphically. The energy conservation law is proved in the form of energy ratios. The earlier findings in the literature are obtained as special case in the absence of rotation, Hall current parameter and porous voids.

Analysis of thermo-mechanical coupling characteristics of feed system of woodworking center based on fuzzy control algorithm

With the rapid development of science and technology, automatic control systems have been applied in more and more fields. At the same time, the requirements for the stability, accuracy, response speed, and self-regulation ability of the system are also increasing. In the wood processing industry, the heating system of factories is an important link to ensure normal production. Therefore, in order to further improve the production efficiency of the wood processing industry and enhance the stability and controllability of the heating system in wood processing production, this article takes into account the delay and coupling effects in the rapid heating process, and combines fuzzy control with temperature control to study and establish a woodworking thermal mechanical coupling model based on fuzzy control algorithm. The results show that compared with traditional PID control, fuzzy control has advantages such as short response time, small overshoot, high steady-state accuracy, fast steady-state recovery, and good dynamic and static performance. Under the condition of rapid heating, the existence of delay effect weakens the effect of Thermal shock, while the coupling effect not only affects the propagation of thermoelastic waves in the elastic body, but also weakens the weakening effect of delay effect on Thermal shock to a certain extent.

The Effect of Nonlocal Scale Value and Phase Lags on Thermoelastic Waves in a Multilayered LEMV/CFRP Composite Cylinder

In this study, the effect of nonlocal scale value and two phase lags on the free vibration of generalized thermoelastic multilayered LEMV (Linear Elastic Material with Voids)/CFRP (Carbon Fiber Reinforced Polymer) composite cylinder is studied using nonlocal form of linear theory of elasticity. The governing equation of motion is established in longitudinal axis and variable separation model is used to transform the governing equations into a system of differential equations. To investigate vibration analysis from frequency equations, the stress free boundary conditions are adopted at the inner, outer and interface boundaries. The graphical representation of the numerically calculated results for frequency shift, natural frequency, and thermoelastic damping is presented. A special care has been taken to inspect the effect of nonlocal parameter on the aforementioned quantities. The results suggest that the nonlocal scale and the phase lag parameters alter the vibration characteristics of composite cylinders significantly.

The Effect of Nonlocal Scale Value and Phase Lags on Thermoelastic Waves in a Multilayered LEMV/CFRP Composite Cylinder

The Effect of Nonlocal Scale Value and Phase Lags on Thermoelastic Waves in a Multilayered LEMV/CFRP Composite Cylinder

Propagation of plane waves in nonlocal semiconductor nanostructure thermoelastic solid with fractional derivative due to ramp-type heat source

In this paper, propagation of thermoelastic waves in semi-conducting nanostructure medium is studied. First, the governing equations are formulated with the help of coupled nonlocal elasticity theory, thermoelastic three-phase-lag model, and equation of motion. Heat equation with fractional order is incorporated to study thermal effects on the propagation of wave. The problem is solved using Fourier series and Laplace transform to obtain the exact expressions of physical fields. The distributions of the nondimensional carrier density and stresses are obtained and illustrated graphically. The effects of nonlocal parameter, fractional order parameter, and time parameter on these wave characteristics are concerned and discussed in detail. Some semiconductor materials as Silicon (Si) and Germanium (Ge) are used to make the numerical simulation and some comparisons in different thermal memories are made.