17 results on '"He, Tianhu"'
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2. Investigation on the electromagneto-thermoelastic coupling behaviors of a rotating hollow cylinder with memory-dependent derivative.
- Author
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Xie, Pengfei and He, Tianhu
- Subjects
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THERMOELASTICITY , *THERMAL stresses , *STRAINS & stresses (Mechanics) , *RADIAL stresses , *MAGNETIC flux density , *THERMAL shock , *THERMOPHYSICAL properties - Abstract
Compared with the fractional order generalized themoelastic theory, the generalized thermoelastic theory based on the memory-dependent derivative has following significant advantages: First, the generalized thermoelastic theory with memory-dependent derivative has more specific physical meanings and can excellently describe that the present state of a system is dependent on its past states; Second, the memory-dependent derivative is based on the integer order calculus, which is more convenient to operate than fractional order model; Particularly, for different kernel functions, the time-dealy factor has different choice to adapt to different specific problems, which makes it greatly possible to describe the real thermoelastic response of medium. In present work, the transient response of an infinite rotating hollow cylindrical conductor with variable material properties subjected to a thermal shock at its inner surface is investigated based on the generalized thermoelastic theory with memory-dependent derivative. The hollow cylinder is placed in an external magnetic field with constant intensity, whose outer surface is traction free. The governing equations are formulated and then solved by using Laplace transform and its numerical inversion. The distributions of the dimensionless temperature, displacement, induced electric field, induced magnetic field, hoop stress as well as radial stress in the cylinder are obtained and illustrated graphically. The obtained results show that the kernel function, the time-delay factor and the temperature-dependent material properties influence the distributions of the considered variables more or less, while, the angular velocity significantly influence the variations of the dimensionless displacement, hoop stress and radial stress. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
3. A modified fractional-order thermo-viscoelastic model and its application in thermal-induced nonlocal response analysis of a microscale plate.
- Author
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Tian, Lingchen, Peng, Wei, and He, Tianhu
- Subjects
THERMAL shock ,ELASTIC deformation ,HEAT transfer ,VISCOELASTIC materials ,PROBLEM solving ,MANUFACTURING processes - Abstract
The relaxation process of viscoelastic materials has the memory-dependent effect, while integer-order thermo-viscoelastic models may be challenged to predict precise thermal–mechanical behaviors in solving transient problems of viscoelastic materials in a heat transfer environment. It is found that the fractional-order viscoelastic models fit well with the experimental data from creep and relaxation tests. Additionally, the size-dependent effect on elastic deformation is becoming an issue of great importance recently due to the development of small-scale devices. To capture the memory-dependent and size-dependent effects, the present work aims to formulate a modified fractional-order thermo-viscoelastic model at small-scale for the first time by simultaneously incorporating the effects of the unified definition of the fractional-order parameter, the unified definition of the fractional-order strain parameter and the nonlocal parameter based on the generalized thermo-viscoelastic theory. Then the dynamic response of a viscoelastic microplate under a thermal shock is studied by using the modified fractional-order thermo-viscoelastic model. The corresponding governing equations are formulated and solved by the Laplace transform and its numerical inversion. In conclusion, the influences of the fractional-order parameters, the fractional-order strain parameters and the nonlocal parameters on the variations of the considered quantities are presented and discussed in detail. The obtained results show that these parameters significantly influence the variations of all the considered quantities. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Effect of Temperature-Dependent Properties on Thermoelastic Problems with Thermal Relaxations
- Author
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He, Tianhu and Shi, Shuanhu
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- 2014
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5. Structural dynamic responses of layer-by-layer viscoelastic sandwich nanocomposites subjected to time-varying symmetric thermal shock loadings based on nonlocal thermo-viscoelasticity theory.
- Author
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Guo, Huili, Yaning, Lu, Li, Chenlin, and He, Tianhu
- Subjects
THERMAL shock ,NANOCOMPOSITE materials ,LAPLACE transformation ,THERMAL stresses ,VIBRATION isolation ,VISCOELASTICITY ,ELASTIC waves - Abstract
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]
- Published
- 2022
- Full Text
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6. Analytical study of transient thermo-mechanical responses in a fractional order generalized thermoelastic diffusion spherical shell with variable thermal conductivity and diffusivity.
- Author
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Li, Chenlin, Tian, Xiaogeng, and He, Tianhu
- Subjects
THERMAL shock ,THERMAL diffusivity ,FOURIER transforms ,THERMOELASTICITY ,FEMTOSECOND lasers ,PHYSICAL constants ,THERMAL conductivity ,MICROMACHINING - Abstract
With the great development of micro-electromechanical devices and wide application of subpicosecond/femtosecond ultrafast laser technology in micro-machining of micro-electromechanical devices, the investigations of interactions between thermodiffusion and deformation become significantly important. To accurate modeling the thermo-elasto-diffusive coupling, a new time fractional-order (i.e. memory-dependent derivative) based model of generalized thermoelastic diffusion for a perfect thermally and isotropic conducting medium which is assumed to have variable thermal conductivity and diffusivity is given in this work. This model is applied to investigate transient responses of a spherical shell subjected to instantaneous thermal and chemical shock loadings at external surface, whilst it is assumed that a permeating substance is in contact with the rigid surface at its internal surface. The solutions in the Laplace transform domain are obtained by using Kirchhoff and Laplace transform techniques and then the numerical inversion process based on fast Fourier transformation is carried out to derive the transient solutions in the time domain. Numerical computations for all the physical quantities considered are implemented and represented graphically. The results show that the variable thermal conductivity and diffusivity as well as memory-dependent parameters have the varying degrees of influences on the structural transient thermo-elasto-diffusive responses. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
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7. Nonlocal thermoelastic analysis of a functionally graded material microbeam.
- Author
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Peng, Wei, Chen, Like, and He, Tianhu
- Subjects
THERMOELASTICITY ,FUNCTIONALLY gradient materials ,THERMAL shock ,HEAT conduction ,MECHANICAL models ,THERMAL resistance ,HEAT transfer - Abstract
In extreme heat transfer environments, functionally graded materials (FGMs) have aroused great concern due to the excellent thermal shock resistance. With the development of micro-scale devices, the size-dependent effect has become an important issue. However, the classical continuum mechanical model fails on the micro-scale due to the influence of the size-dependent effect. Meanwhile, for thermoelastic behaviors limited to small-scale problems, Fourier's heat conduction law cannot explain the thermal wave effect. In order to capture the size-dependent effect and the thermal wave effect, the nonlocal generalized thermoelastic theory for the formulation of an FGM microbeam is adopted in the present work. For numerical validation, the transient responses for a simply supported FGM microbeam heated by the ramp-type heating are considered. The governing equations are formulated and solved by employing the Laplace transform techniques. In the numerical results, the effects of the ramp-heating time parameter, the nonlocal parameter, and the power-law index on the considered physical quantities are presented and discussed in detail. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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8. Transient responses of sandwich structure based on the generalized thermoelastic diffusion theory with memory-dependent derivative.
- Author
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He, Tianhu and Li, Yan
- Subjects
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THERMOELASTICITY , *DIFFUSION , *THERMAL shock , *KERNEL functions , *STRESS concentration , *CHEMICAL potential , *SANDWICH construction (Materials) - Abstract
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]
- Published
- 2020
- Full Text
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9. Dynamic analysis to the fractional order thermoelastic diffusion problem of an infinite body with a spherical cavity and variable material properties.
- Author
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Peng, Wei, Ma, Yongbin, Li, Chenlin, and He, Tianhu
- Subjects
THERMOELASTICITY ,MECHANICAL properties of condensed matter ,THERMAL shock ,RADIAL stresses ,DIFFUSION ,MASS transfer - Abstract
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]
- Published
- 2020
- Full Text
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10. The generalized electromagnetic-thermoelastic coupling problem of hollow cylindrical conductor based on the memory-dependent derivative.
- Author
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He, Tianhu, Ma, Jintao, and Li, Yan
- Subjects
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THERMOELASTICITY , *THERMAL shock , *RADIAL stresses , *KERNEL functions , *HEAT conduction , *MAGNETIC fields - Abstract
In present work, the transient responses of a hollow cylindrical conductor based on the generalized thermoelastic theory with memory-dependent derivative are investigated. The conductor with temperature-dependent mechanical properties is subjected to a thermal shock on its internal surface. The hollow cylindrical conductor is placed in a magnetic field along the axial direction of the cylinder. The effects of memory-dependent derivative and temperature-dependent properties influenced by the variable material property factors on the heat conduction and structural responses are emphatically discussed. 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 distributions of the non-dimensional induced electric field, induced magnetic field, hoop stress, radial stress, temperature and displacement at different values of time delay factors, kernel functions and variable material property factors are obtained and illustrated graphically. Finally, some conclusions are summed up, based upon which guidelines may be provided in the design of a hollow cylindrical conductor working in a thermo-mechanical coupling environment. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
11. Transient response analysis of a spherical shell embedded in an infinite thermoelastic medium based on a memory-dependent generalized thermoelasticity.
- Author
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He, Tianhu, Zhang, Pei, Xu, Chi, and Li, Yan
- Subjects
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THERMAL resistance , *INTERFACIAL resistance , *THERMOELASTICITY , *TRANSIENT analysis , *THERMAL shock , *KERNEL functions , *PHYSICAL constants - Abstract
In the context of a memory-dependent generalized thermoelasticity, the thermal-induced transient response in an infinite elastic body containing a spherical shell is investigated. A thermal shock is applied on the inner surface of the spherical shell. The infinite body and the spherical shell are assumed to be isotropic but two dissimilar materials. By using an analytical technique based on the Laplace transform along with its numerical inversion, the governing equations of the problem are solved and the non-dimensional physical quantities in the two materials, i.e., temperature, displacement and stress, are obtained and illustrated graphically respectively. In simulation, the accuracy of memory-dependent derivative (MDD) is verified by degrading the present model into L-S model to compare the results obtained from the cases with interfacial thermal resistance and without interfacial thermal resistance. In addition, the effects of the different kernel functions as well as the ratios of the two materials, including the ratios of the density, the thermal-conductivity and the time-delay, on the distributions of the considered variables are obtained and demonstrated graphically respectively. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
12. Generalized thermoviscoelastic analysis with fractional order strain in a thick viscoelastic plate of infinite extent.
- Author
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Li, Chenlin, Guo, Huili, Tian, Xiaogeng, and He, Tianhu
- Subjects
VISCOELASTIC materials ,THERMAL shock ,LAPLACE transformation ,PULSED lasers ,HEAT flux ,GUMS & resins - Abstract
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]
- Published
- 2019
- Full Text
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13. A generalized thermoelastic diffusion problem with memory-dependent derivative.
- Author
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Li, Yan and He, Tianhu
- Subjects
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THERMOELASTICITY , *DIFFUSION , *KERNEL functions , *THERMAL shock , *CHEMICAL potential , *HEAT conduction - Abstract
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]
- Published
- 2019
- Full Text
- View/download PDF
14. Two-dimensional electromagneto-thermoelastic coupled problem under fractional order theory of thermoelasticity.
- Author
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Ma, Yongbin, Liu, Zequan, and He, Tianhu
- Subjects
THERMOELASTICITY ,COUPLED problems (Complex systems) ,THERMAL shock ,FRACTIONAL differential equations ,EQUATIONS - Abstract
The dynamic response of a two-dimensional generalized thermal shock problem is investigated in the context of the fractional order theory of thermoelasticity proposed by Sherief et al. To demonstrate the solution process, a thermoelastic half-space subjected to a thermal shock on its bounding surface is considered in detail. The governing equations for the problem are formulated and then solved by normal mode analysis. The distributions of the considered nondimensional temperature, displacement, and stress are obtained and illustrated graphically. The effect of fractional order parameter on the variations of the considered variables is investigated, and the results show that the fractional order parameter has significant influence on the variations of the considered variables. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
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15. Fractional-order rate-dependent thermoelastic diffusion theory based on new definitions of fractional derivatives with non-singular kernels and the associated structural transient dynamic responses analysis of sandwich-like composite laminates.
- Author
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Li, Chenlin, Liu, Jiaheng, and He, Tianhu
- Subjects
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LAMINATED materials , *THERMOELASTICITY , *ACTIVE noise & vibration control , *LAPLACE transformation , *THERMAL shock , *HEAT conduction , *MANUFACTURING processes - Abstract
• Rate-dependent thermoelastic diffusion theory based on new fractional derivatives with non-singular kernel s is developed. • New constitutive and governing equations are derived with the aids of extended thermodynamics. • Structural transient responses of the sandwich-like composite laminates with idealized interfacial conditions are investigated. • Newly introduced fractional derivatives and material constants ratios remarkably affect the dynamic responses and wave propagations. • Harmful higher levels of stress, thermal and diffusion isolation abilities are improved to some extent. Nowadays, the ultrafast heating technologies (e.g., laser-aided material processing, etc.) have been extensively applied in the manufacturing and micro-machining of microelectronic and semiconductor devices (e.g., field-effect transistor, etc.). In recent years, there have been a large number of literatures contributed on constitutive modeling and transient dynamic responses analysis of the coupled thermoelastic diffusion to provide a comprehensive understanding on multi-field coupling behavior on this topic and avoid the unwanted vibration response in intelligent active vibration control. Although the rate-dependent thermoelastic diffusion theories have been historically proposed, the memory-dependence characteristics of strain relaxation as well as heat conduction and mass diffusion are still not considered in ultrafast heating condition. To compensate for such deficiency, a fractional-order rate-dependent thermoelastic diffusion theory is established in this work by introducing the new fractional derivatives with non-singular kernels (i.e., the Atangana-Baleanu and the Tempered-Caputo definitions) into the strain rate dependent constitutive equation as well as classical Fourier heat conduction and Fick mass diffusion laws. With the aids of the extended thermodynamic principles, the new constitutive and governing equations are obtained. The proposed theory is applied to investigate the structural dynamic responses of sandwich-like composite laminates subjected to axisymmetric transient thermal and chemical shock loadings by using Laplace transformation approach. The influences of the different fractional derivatives and material constants ratios on wave propagations and structural dynamic responses are evaluated and discussed. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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16. A direct finite element method study of generalized thermoelastic problems
- Author
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Tian, Xiaogeng, Shen, Yapeng, Chen, Changqing, and He, Tianhu
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FINITE element method , *THERMOELASTICITY , *ELASTICITY , *THERMAL conductivity - Abstract
Abstract: By using the principle of virtual work, the finite element equations corresponding to the generalized thermoelasticity with two relaxation times (i.e., the G–L theory) are derived. In order to improve the accuracy of integral transform method, especially in two/three-dimension, the equations are solved directly in time-domain. As numerical examples, the developed method is used to investigate the generalized thermoelastic behavior of a slim strip and a semi-infinite plate subject to thermal shock loading. The results demonstrate that the developed method can faithfully predict the deformation of the structure and most importantly the delicate second sound effect of heat conduction in both one and two-dimensional solids whilst it is usually difficult to model, especially in two-dimensional, by using the transform method. This method can also be used to study generalized piezothermoelastic and magnetothermoelastic problems. [Copyright &y& Elsevier]
- Published
- 2006
- Full Text
- View/download PDF
17. Investigation on the transient response of a porous half-space with strain and thermal relaxations.
- Author
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He, Shuangquan, Peng, Wei, Ma, Yongbin, and He, Tianhu
- Subjects
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THERMAL strain , *THERMOELASTICITY , *THERMAL shock , *MECHANICAL shock , *POROUS materials , *THERMODYNAMIC laws - Abstract
In present paper, a linear thermoelastic theory for porous materials is established by extending the existing theory, in which the strain relaxation and the thermal relaxation are included. Based on the thermodynamic laws, the constitutive relations are derived, and then the corresponding constitutive equations are obtained by specifying the generalized free energy. Further, by combining the existing theory, the non-Fourier's heat conduction law and the obtained constitutive equations, the linear thermoelastic theory for porous materials is formulated. To apply the established theory, the transient response of a half-space with voids is considered. The half-space with voids is subjected to a thermal shock and a mechanical shock simultaneously on its bounding surface. The problem is solved by means of Laplace transform and its numerical inversion. The distributions of the non-dimensional temperature, displacement, stress as well as the volume fraction field are obtained and illustrated graphically. In calculation, the effects of the thermal relaxation factor, the strain relaxation factor and the magnitude of the mechanical shock on the considered variables are examined and discussed in detail. • A new linear thermoelastic theory for porous materials is established by extending the existing theory. • The main novelty of this new theory lies in that both the strain relaxation and the thermal relaxation are included. • This new theory is formulated by means of thermodynamic laws and work-energy relation. • The application of this new theory to the thermoelastic dynamic response of a half-space with voids is presented. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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