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With the rapid evolution of small‐scale devices, the effect of size dependence on elastic deformation becomes more and more obvious. Furthermore, the physical processes usually involve memory and inheritance for some anomalous diffusion that the constitutive relation does not obey the standard gradient rate. Owing to capturing the memory‐dependent effect and the size‐dependent effect, the existing thermoelastic diffusion theories cannot be applicable. To further refine the thermoelastic diffusion model for micro/nano structures, a refined nonlocal thermoelastic diffusion model is developed by combining the fractional‐order dual‐phase‐lag (DPL) heat conduction model and fractional‐order diffusion model in this paper. In addition, the Tempered‐Caputo (TC) definition is an extension of the Caputo definition without the fractional derivative of the singular kernel, which is adopted for the first time to reflect the memory‐dependent effects of heat conduction and stress–strain relationship. Then, this new model is applied to investigating the transient response of an elastic microplate subjected to a sinusoidal thermal loading. The corresponding governing equations are formulated and solved by the Laplace transform method and its numerical inversion. In calculation, the influences of the fractional‐order parameter, the tempered parameter and the nonlocal parameter on the variations of the considered quantities are presented and discussed in detail. It is expected to provide new insights into thermoelastic diffusion behaviors of structures at the micro/nanoscale. [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]

The present work is devoted to investigating the transient responses of a sandwich structure based on the generalized thermoelastic diffusion theory with memory-dependent derivative. Both the left and the right bounding surfaces are subjected to a thermal shock and a chemical potential shock simultaneously. It is assumed that the values of thermal contact resistance and diffusional contact impedance at the interface are zero with ideal adhesion. The coupled governing equations containing time delay factors and kernel functions, which can be chosen freely according to specific problems, are solved by the Laplace transform together with its numerical inversion. The influences of the material characteristic parameters at the interface on the structural responses are emphatically discussed, and the non-dimensional temperature, chemical potential, displacement, stress as well as concentration at different values of time delay factors and kernel functions are obtained and illustrated graphically. The results show that: the changes of the time delay factors, kernel functions, and material characteristic parameters have the varying degrees of influences on the considered variables. Based on the above conclusions, the sandwich structure working under the thermoelastic diffusion coupling condition can be designed reasonably. [ABSTRACT FROM AUTHOR]

Based on the generalized thermoelastic diffusion theory with fractional order derivative, the dynamic response of an infinite thermoelastic medium with a spherical cavity is investigated. The thermoelastic and diffusive properties of the medium are assumed to be temperature-dependent, and the medium is subjected to a thermal shock and a chemical potential shock at the inner surface of the spherical cavity simultaneously. The governing equations of the problem are formulated and then solved by Laplace transform together with its numerical inversion. The distributions of the non-dimensional temperature, displacement, radial stress, concentration and chemical potential are obtained and illustrated graphically. In calculation, the effects of the fractional order parameter and the temperature-dependent properties on the variations of the considered variables are presented and discussed in detail. The results show that the fractional order parameter and the temperature-dependent properties significantly influence the variations of all the considered variables. The present investigation may be valuable in heat and mass transfer, waste disposal or petroleum engineering, etc. [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]

Based on the generalized thermoelastic diffusion theory with memory-dependent derivative in both the generalized heat conduction law and the generalized diffusion law, the transient response is investigated of a half-space subjected to a thermal shock and a chemical potential shock on its bounding surface. The coupled governing equations containing time-delay factors and kernel functions, which can be chosen freely according to specific problems, are solved by the Laplace transform together with its numerical inversion. The non-dimensional temperature, chemical potential, displacement, stress, as well as concentration at different values of time, time-delay factors, and kernel functions are obtained and illustrated graphically. The results show that: all the considered variables have obvious changes with the passage of time; the thermal time-delay and kernel functions hardly influence the distributions of the non-dimensional chemical potential, modestly influence the distributions of the non-dimensional concentration, while appreciably influence the distributions of the non-dimensional temperature, displacement, and stress; the diffusion time-delay and kernel functions barely affect the distributions of the non-dimensional temperature, slightly affect the distributions of the non-dimensional concentration, while remarkably affect the distributions of the non-dimensional chemical potential, displacement and stress. [ABSTRACT FROM AUTHOR]

The dynamic response of a two-dimensional generalized thermoelastic diffusion problem for a half-space is investigated in the context of the generalized thermoelastic diffusion theory. The half-space is subjected to a thermal shock and a chemical potential shock on its bounding surface. The governing equations of this problem are formulated, and due to the complexity of the equations, a numerical method, i.e., hybrid Laplace transform-finite element method, is used to solve them. The non-dimensional temperature, displacement and chemical potential are obtained and illustrated graphically. The results show that the non-zero values of all the considered variables are only in a bounded region and vanish identically beyond this region, and the propagating speed of diffusive wave is larger than that of thermoelastic wave. [ABSTRACT FROM AUTHOR]

A two-dimensional generalized electromagnetothermoelastic problem for a half-space with diffusion is investigated in the present work. The problem is formulated in the context of the generalized thermoelastic diffusion theory. The half-space is initially placed in an external magnetic field with constant intensity, and its bounding surface in contact with a permeating substance is taken to be traction free and subjected to a time-dependent thermal load. The chemical potential is also assumed to be known function of time on the bounding surface. The half-space deforms because of the thermal load, and due to the application of magnetic field, there results in an induced magnetic field and an induced electric field in the half-space. The system of Maxwell's equations is given and the generalized electromagnetothermoelastic diffusive coupled governing equations are established. To solve the formulated equations, normal mode analysis is adopted and the exact expressions for the non-dimensional temperature, displacement, stress, induced magnetic field, induced electric field, and chemical potential and concentration are obtained and represented graphically. [ABSTRACT FROM AUTHOR]

The studies of the coupling of thermodiffusion and mechanical deformation in solids have aroused great interests with miniaturization of the micro/nano-electromechanical devices and wide application of ultrafast heating technologies. In such situation, it is commonly accompanied with high heat/diffusion flux and thermal/diffusion induced stress accordingly. So far, although there have been many developments and extensions of research and theorizing within the generalized thermoelastic diffusion problems, these theoretical formulations are only applicable when the strain rate is assumed to be relatively small, but this is questionable under ultrafast heating condition. The present work aims to investigate generalized thermoelastic diffusion problems with fractional order strain within the extended thermodynamic framework. For numerical evaluation, the analytical model of a sandwich structure with ideal interfacial conditions is investigated whilst its bounding surfaces are subjected to symmetrical transient heat and chemical potential shock loads. From numerical results, the effects of the fractional order parameters and material characteristic parameters of each layer on structural transient thermo-elasto-diffusive responses are also analyzed and discussed, which is expected to provide a comprehensive understanding on thermoelastic diffusive coupling and optimal design of sandwich structures under extreme fast heating condition. • Generalized thermoelastic diffusion theory with fractional strain is developed. • Transient thermoelastic diffusion responses of sandwich structure are studied. • Fractional order strain can characterize the strain relaxation feature. • Fractional order parameters have great effects on structural responses. [ABSTRACT FROM AUTHOR]