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Nano-batteries have been widely used in electric vehicles, new energy, and aerospace engineering since their high energy density, low manufacturing cost, and long cycle life. In recent years, there have been many papers that contributed to investigate the diffusion-mechanical coupling problems under non-uniform molar concentration environments (e.g., rapid charging, etc.). Nevertheless, the memory dependence of strain relaxation and mass transfer has not been considered yet. This paper aims to construct a unified fractional-order non-Fick mechanical-diffusion coupling model by introducing the fractional derivatives of the Caputo (C), Caputo–Fabrizio (CF), Atangana–Baleanu (AB), and Tempered-Caputo (TC) types. The proposed theoretical model is applied to investigate structural transient dynamic responses of multilayered composite laminates with imperfect interfacial conditions by Laplace transformation approach. The influences of different fractional derivatives, imperfect interfacial conditions, and materials constants ratios on the wave propagations and dynamic mechanical-diffusion responses are evaluated and discussed in detail. [ABSTRACT FROM AUTHOR]

In order to obtain the transient thermoelastic diffusion responses of porous materials heated by the ultrashort pulse laser, the focus of this work is to establish a generalized thermoelastic diffusion theory considering strain, thermal and diffusion relaxation effect within the thermodynamic framework. Firstly, we derive the governing equations of the linear generalized thermoelastic diffusion theory of porous media in the context of the thermodynamic laws. Secondly, the copper material with voids occupying a half-space heated by the ultrashort pulse laser is investigated based on the built theory. The bounding plane is assumed to be traction free and impacted by a non-Gaussian laser beam. The exact solutions of the governing equations are obtained by Laplace transformation and the numerical inverse Laplace transformation. Finally, the effect of strain relaxation factor, thermal relaxation factor, fractional order parameter, and laser parameters on non-dimensional temperature, displacement, stress, volume fraction field, and chemical potential is studied and presented graphically. [ABSTRACT FROM AUTHOR]

Nano sandwich-like storage structure or device is commonly designed as diaphragm to extend nano-battery working life, or fabricated as nanocomposite anode materials to maximumly improve electrochemical performance in nano-battery systems. This work aims to investigate size-dependent dynamic mechanical-diffusion responses of multi-layered laminated sandwich-like nanocomposites subjected to shock loadings of molar concentration in the context of nonlocal diffusion-elasticity model by a semi-analytical technique via Laplace transformation. The results reveal that the diffusion isolation will be maximally improved and lager harmful chemical stresses can be reduced to some extent for proper materials nonlocal parameters and constants ratios of selected. [ABSTRACT FROM AUTHOR]

The layer-by-layer viscoelastic sandwich nanocomposites have been widely used as high-efficient shock absorbers in nano-engineering since its excellent performance in vibration isolation. Such structure often works in thermoelastic coupling condition, and a thorough and comprehensive investigation on its structural dynamic responses is imperatively needed to achieve the goal of improving heat isolation and avoiding unwanted vibration. In this work, an analytical study is conducted to investigate the structural dynamic responses of layer-by-layer viscoelastic sandwich nanocomposites based on nonlocal thermo-viscoelasticity theory. The two lateral bounding surfaces of the structure are subjected to the time-varying symmetric thermal shock loadings. It is assumed that thermal contact resistance and elastic wave impedance at the interface are zero with idealized adhesion. Governing equations of each homogeneous isotropic viscoelastic layer are derived and solved by a semi-analytical technique via Laplace transformation. The achieved results show that the heat isolation will be maximally improved and harmful thermal induced stress is lowered to some extent if properly selecting nonlocal parameters and material constants ratios. [ABSTRACT FROM AUTHOR]

Viscoelastic laminated sandwich composite structure has been used as a new class of high-efficient structural damping in the passive vibration control systems. This work aims to investigate transient thermo-viscoelastic responses of viscoelastic laminated sandwich composite structure. The effects of fractional order parameters and material constants ratio on the structural transient thermo-viscoelastic responses are evaluated and discussed. For each homogeneous isotropic layer, the governing equations are formulated and solved by Laplace transformation techniques. The results are expected to provide new insights on the vibration control and thermal management of viscoelastic laminated sandwich composite structure under extreme non-isothermal conditions. [ABSTRACT FROM AUTHOR]

Multi-cell storage devices (e.g. lithium-ion batteries (LIBs)) stand as one of the most important components which are widely used in battery energy storage technology for renewable energy power system, hybrid electric vehicles and portable electronic devices due to its high energy density and low manufacturing cost. In recent years, there has been an explosion of developing new and multifunctional nanomaterials with particular interest to electrode nanomaterials (nano-MnO2, nano-LiMn2O4, etc.). In such case, size-dependent mechanical-diffusion responses analysis of multilayered composite nanostructure under non-uniform concentration in-service environment will become significantly important. To address the problem, a multilayered composite nanoplates account for diffusion impedance and elastic wave impedance at the interface is considered in this research. Governing equations involving with size-dependent characteristic lengths and material constant ratio of each two adjacent layers are formulated, and then, a semi-analytical approach via the Laplace transformation is applied. Then, the obtained solutions are applied to bilayered composite nanoplates, and the influences of size effects and material constants ratio on structural responses are emphatically discussed to provide guidelines on and new insights into the optimal design and management of mechanical responses and vibration control of nano-sized multi-cell storage devices under non-uniform concentration environment, especially for the nano-coating. [ABSTRACT FROM AUTHOR]

Summary: Nanoscale piezoelectric energy‐harvesting from ambient vibration sources has great potential for practical applications in powering nanoelectronic and nano‐wireless sensors. Nowadays, the piezoelectric laminated sandwich smart nanocomposites have been extensively applied as nanogenerators, nano‐energy harvesters, and the other nano‐electromechanical devices. However, no works have thoroughly investigated the size‐dependent dynamic thermo‐electromechanical response of such structure that consider the perfect/non‐idealized interfacial conditions and piezoelectric material constants ratios. This article will address this problem based on the size‐dependent piezoelectric thermoelasticity theory by a semi‐analytical technique via the Laplace transformation. If the thermal/elastic nonlocal parameters or material constants ratios are properly selected, the results show that: (a) the electrical energy harvesting and heat isolation can be maximally improved; (b) the harmful thermal stresses will be lowered to some extent. This work not only provides a thorough and comprehensive understanding on response of piezoelectric laminated sandwich smart nanocomposites serving in non‐uniform thermal environment, but also offers basic guidelines for its thermal management and piezoelectric energy harvesting. [ABSTRACT FROM AUTHOR]

Due to the advantages of high-power density, short duration, and high machining accuracy, ultrashort laser pulses are widely used in the fields of ultra-precision machining and microelectronic manufacture. In the manuscript, the L-S generalized thermoelastic diffusion theory considering the memory-dependent effect and spatial nonlocal effect is established and the thermoelastic diffusion responses of a semi-infinite thin plate subjected to a non-Gaussian laser pulse and a chemical shock on its boundary are studied. The Laplace integral transformation and its numerical inversion are used to solve the problem. The variation of the temperature, chemical potential, displacement, stress, and concentration with different nonlocal parameters, time delay factors, and kernel functions are obtained. The results show that heat conduction has a significant effect on mass transfer, while mass transfer has little effect on heat conduction; nonlocal parameter has a significant influence on displacement and stress, but little effect on temperature, chemical potential, and concentration. The establishment of this theory and the solution of the corresponding problem are aimed at reasonably predicting the transient responses of heat conduction and mass transfer under the coupling effects of mechanics, heat, and diffusion. [ABSTRACT FROM AUTHOR]

Piezoelectric materials have become one of the most promising candidates for a new class of smart structures which are widely used as sensors and actuators in control systems due to their superior electromechanical performance and high‐efficiency in electro‐mechanical energy conversion. In recent years, although there are many papers of theoretical modeling of generalized piezoelectric thermoelasticity that considered the piezoelectric‐thermoelastic coupling of piezoelectric structures serving in the extreme fast heating environment (e.g. ultra‐fast laser), the strain relaxation effect has not been considered yet. This work aims to investigate the generalized piezoelectricity problem with strain rate with the aid of extended thermodynamic principles, and corresponding generalized variational theorem is also strictly formulated to provide a complete rationale for numerical method by using semi‐inverse method. For numerical evaluation, transient thermo‐electromechanical responses of a one‐dimensional semi‐infinite piezoelectric medium with one end subjecting to a sudden thermal loading are considered and solved by applying Laplace transformation methods. Then the transient responses of temperature, displacement, strain, stress and electric potential are obtained and illustrated graphically, and the influences of strain relaxation parameters on them are also analyzed and discussed. [ABSTRACT FROM AUTHOR]

Nowadays, the nanosandwich structure stands as one of the most promising candidates for nanodevices and nanocomposites (e.g., nanogenerator, nano-energy harvester) due to its superior mechanical properties. The size-dependent response analysis of nanosandwich structure under extreme in-service environment is of great importance for its fabrication and exploitation. This motivates us to study the transient responses of nanosandwich structure subjected to the symmetrical transient thermal and chemical potential shock loads, which are both imposed on its upper and lower bounding surfaces. It is further assumed that thermal contact resistance and diffusional contact impedance at the interface of each two adjacent layers are zero with ideal adhesion. For each isotropic homogeneous elastic layer, the governing equations are formulated in the context of size-dependent generalized thermoelastic diffusion theory and then are solved by using Laplace transformation techniques. The effects of elastic nonlocal parameter, fractional order parameters as well as material characteristic parameters on structural transient responses are also analyzed and discussed. The present study not only provides a comprehensive understanding of the size-dependent thermoelastic diffusion coupling of nanosandwich structure, but also offers basic guidelines for optimal design. [ABSTRACT FROM AUTHOR]

Viscoelastic materials (e.g. rubber, resin, concrete skeleton, etc.) serve as one of the most promising candidate for new multifunctional materials due to their excellent rheological properties, as they are widely used in biology, petroleum industry, chemical and civil engineering, and other areas. The interaction of high-heat-flux loads (e.g. ultrafast pulsed lasers) with viscoelastic materials is a hot topic of numerous theoretical and experimental studies. Nevertheless, classical and extended generalized thermoviscoelasticity models available in literatures cannot characterize the strain relaxation behavior for viscoelastic materials. In this work, the time-based fractional thermoviscoelasticity model is further extended with a new consideration of fractional order strain. The governing equations involving strain and thermal relaxation times as well as fractional order parameters of strain and heat flux are formulated and are also applied to investigate thermal shock problem of a transient heated thick viscoelastic plate of infinite extent. With the aids of Laplace transformation methods, the transient solutions are also obtained. Finally, the effects of fractional order parameters of strain and heat flux on the transient thermoviscoelastic responses are studied and discussed. [ABSTRACT FROM AUTHOR]

The transient thermo-piezoelectric response of a functionally graded piezoelectric rod subjected to a moving heat source is investigated in the context of fractional order theory of thermoelasticity proposed by Sherief. The material properties of the functionally graded piezoelectric rod are assumed to vary exponentially along the length, except for the thermal relaxation time and the specific heat, which are taken to be constant. To solve the governing equations of the problem, Laplace transform is applied, eliminating the time effect; the analytical solutions of the displacement, stress, temperature, and electric field in Laplace domain are obtained. Subsequently, the solutions of the considered variables in time domain are obtained by numerical Laplace inversion and illustrated graphically. In calculation, the effect of the fractional order parameter on the variations of the considered variables is presented. [ABSTRACT FROM PUBLISHER]

The dynamic response of a piezoelectric-thermoelastic rod made of piezoelectric ceramics (PZT-4) subjected to a moving heat source is dealt with in the context of the fractional order theory of thermoelasticity. The piezoelectric-thermoelastic governing equations for the problem are formulated and then solved by means of Laplace transform together with its numerical inversion. The distributions of the considered nondimensional temperature, displacement, stress, and electric potential are obtained and illustrated graphically. The effects of fractional order parameter and the velocity of heat source on the variations of the considered variables are investigated, and the results show that they have significant influence on the variations of the considered variables. The present investigation could be helpful for better understanding the multi-field coupling effect of mechanical, electric, and thermal fields in real piezoelectric ceramics structures, and provide some guidelines in the optimal design of actuators or sensors made of piezoelectric ceramics serving in a thermoelastic environment. [ABSTRACT FROM PUBLISHER]

Abstract: Based on the Lord and Shulman generalized thermo-elastic theory with one relaxation time, the dynamic thermal and elastic responses of a piezoelectric rod fixed at both ends and subjected to a moving heat source are investigated. The generalized piezoelectric–thermoelastic coupled governing equations for piezoelectric rod are formulated. By means of Laplace transformation and numerical Laplace inversion the governing equations are solved. Numerical calculation for stress, displacement and temperature within the rod is carried out and displayed graphically. The effect of moving heat source speed on temperature, stress and temperature is studied. It is found from the distributions that the temperature, thermally induced displacement and stress of the rod are found to decrease at large source speed. [Copyright &y& Elsevier]

The Stefan conditions are suitable for describing the solid-liquid phase change processes with moving interface. However, the existing literature only focuses on the Stefan problem of heat conduction and does not involve the thermo-mechanical coupling effects. In this work, the generalized thermoelastic Stefan problem with spatio-temporal nonlocal effect is investigated. The solid-liquid phase change of silicon with picosecond pulse laser machining is depicted by the Stefan interface conditions. We find the solutions making use of Laplace transformation and Laplace numerical inverse transformation. The temperature distribution at the moment of surface melting is seen as the initial state of the second phase. The distributions of transient thermoelastic responses under different laser intensities, pulse widths, fractional order parameters, spatial nonlocal parameters and time are obtained and expressed graphically. • The introduction of Stefan conditions into the nonlocal generalized thermoelasticity. • The solid-liquid interfaces moving with time due to laser processing are considered. • The temperature at the surface melting moment is taken as the initial condition. • The heat taken away by vaporization is considered in the boundary condition. • With laser intensity increasing/duration decreasing, the transient responses increase. [ABSTRACT FROM AUTHOR]

The absorption mechanisms of plasma plume (such as inverse bremsstrahlung, photo-ionization and Mie absorption) to ultrashort pulse laser have significantly influence on efficiency and quality of laser machining. This motivates us to establish the spatial nonlocal generalized thermoelastic model with plasma absorption mechanisms. Based on the new model, the porous sandwich composite material with perfectly bonded interface is researched. The two outer layers are made of copper and two boundaries are heated by the picosecond pulse laser. The middle layer's material properties are proportionate to those of the outer layers. By using the Laplace transformation and inverse Laplace transform, the governing equations that incorporate spatial nonlocal parameter, strain and thermal relaxation factors are solved. The transient responses, such as temperature, volume fraction field, etc., with different laser parameters, material characteristic parameter and absorption mechanisms of plasma plume are obtained and illustrated graphically. [ABSTRACT FROM AUTHOR]