Study On The Thermal Coupling Response Of Viscoelastic Plates Under Non-Isothermal Conditions

Viscoelastic material(e.g.,asphalt,glass,ceramics,concrete skeleton,etc.)stands as a new class of damping material which has been widely applied in ocean and civil engineering due its excellent rheological properties.With the development of rapid heating technology(e.g.,ultrafast pulse laser)in manufacture and fabrication of viscoelastic materials,accurately describing the dynamic response of viscoelastic materials in the thermodynamic coupling environment has important guiding significance for the practical application of viscoelastic materials.In classical thermoviscoelastic theory,scholars believe that the effect of strain relaxation effect is small,and the effect of strain relaxation effect is usually ignored in constitutive relations.Based on the existing research results,scholars have conducted a series of interesting and valuable studies on the non-Fourier thermoviscoelastic problem.However,for the non-Fourier thermoviscoelastic theory established by introducing viscoelastic relaxation time,the strain relaxation effect is not considered.However,in unsteady heat transfer environments such as ultrafast heating,the strain relaxation effect has a significant impact on the dynamic response of components.In this paper,a new non-Fourier thermoviscoelastic theory(L-S type)is established by expanding the existing research and deriving constitutive equations including viscoelastic relaxation time and strain relaxation time based on thermodynamic laws.Based on newly established theory,the dynamic response of viscoelastic plates under the environment of thermodynamic coupling was studied,which including the following:(1)Through thermodynamic derivation,a non-Fourier thermoviscoelastic theory considering viscoelastic relaxation time and strain relaxation time was established,the dynamic response problem of semi-infinite viscoelastic plate with variable heat transfer coefficient under thermal shock was studied,and the analytical solutions of dimensionless temperature,dimensionless displacement and dimensionless stress were solved by normal mode analysis.The results show that the strain relaxation time has an obviously effect on the peak and response regions of dimensionless displacement and dimensionless stress.The heat transfer coefficient has a significant effect on dimensionless temperature,dimensionless displacement and dimensionless stress.(2)Based on the established non-Fourier thermoviscoelastic theory,the non-local theory and fractional order theory are introduced by considering the temporal microscale effect and the spatial microscale effect,the dynamic response problem of semi-infinite non-Fourier viscoelastic plate under thermal shock when placed in a uniform magnetic field is studied,and the analytical solution of the problem is solved by normal mode analysis.The results show that the non-local parameters have no effect on the dimensionless temperature,but the dimensionless displacement and dimensionless stress decrease when the non-local parameters increase.The strain fractional operator has no effect on heat transfer,but with the increase of the strain fractional operator,the dimensionless displacement and dimensionless stress response regions decrease.(3)The unified expressions of the problems studied in Chapter 3 under L-S-type theory(the theory established in this paper),G-L-type theory and G-N type theory are derived,the analytical solution under the unified expression is solved by using the normal mode analysis,and the distribution of dimensionless temperature,dimensionless displacement and dimensionless stress in the direction of heat wave propagation and thermal shock under different theories is discussed.The results show that the response of viscoelastic plates under L-S theory(the theory established in this paper)and G-L theory is basically the same,and the dimensionless temperature,dimensionless displacement and dimensionless stress under G-L theory are slightly greater than those of the previous two theories.