Relaxation Time Parameter Research Articles

Analysis of the MHD partially ionized GO-Ag/water and GO-Ag/kerosene oil hybrid nanofluids flow over a stretching surface with Cattaneo–Christov double diffusion model: A comparative study

This investigation explores the augmentation in thermal characteristics of the hybrid nanoliquid, which has pretty imperative uses in the industries like coolant of various electrical devices, and heat exchangers, etc. keeping in view these important applications, the three-dimensional magnetohydrodynamic flow of partially ionized hybrid nanofluids over a stretching sheet has been considered in this investigation. Two different liquids namely water and kerosene oil is used as base liquids in which the nanoparticles of silver and graphene oxide are mixed to form a hybrid nanofluids. Cattaneo-Christov heat and mass flux model is used in the flow model. An appropriate set of variables is exploited to convert the modeled equations into dimension-free form. The present problem is simulated with the help of homotopic analysis technique. The outcomes of this analysis show that the rising values of Hall current and ion-slip number are enhanced the primary velocities of the kerosene oil-based and water-based hybrid nanofluids, while the greater Hartmann number has declined the primary and secondary velocities of the hybrid nanofluids. On the other hand, the larger values of Hall current and stretching parameter of the sheet have increased the primary and secondary velocities of the hybrid nanofluids, while the opposite impacts are found for increasing ion-slip number and Hartmann number. The temperature profiles of the hybrid nanofluids are weakened for thermal relaxation time parameter, while increased for higher thermal Biot number. It is found that the water-based hybrid nanofluid is greatly influenced by the embedded parameters as compared to the kerosene oil-based hybrid nanofluid.

Numerical study of non-Fourier heat transfer in MHD Williamson liquid with hybrid nanoparticles

This article studies non-Fourier heat in Williamson fluid under the suspension of is modeled. The conservation laws are simplified and transformed into dimensionless forms using the transformation proposed on the basis of the similarity principle. No-slip theory is used in developing the boundary conditions. The finite element method (FEM) is used for simulation purposes to investigate key parameters. The thermal relaxation time parameter has a decreasing tendency on temperature as this parameter determines the ability of the fluid to restore the thermal changes to maintain thermal equilibrium. Joule heating phenomenon in hybrid nanofluid is stronger than the pure and mono nanofluid. Moreover, the dissipation of heat as a result of Joule heating may affect the thermal performance of fluid diversely. The heat transfer rate by hybrid nanofluid is greater than that by the pure and mono nanofluid. Therefore, dispersion of nanoparticles in the Williamson fluid is recommended for optimized heat transfer. Hybrid nanofluid exerts greater stress on the surface of a pipe than that exerted by the pure and mono nanofluid on the surface of a pipe.

Quantitative relaxometry using synthetic MRI could be better than T2-FLAIR mismatch sign for differentiation of IDH-mutant gliomas: a pilot study

This study aimed to determine whether quantitative relaxometry using synthetic magnetic resonance imaging (SyMRI) could differentiate between two diffuse glioma groups with isocitrate dehydrogenase (IDH)-mutant tumors, achieving an increased sensitivity compared to the qualitative T2-fluid-attenuated inversion recovery (FLAIR) mismatch sign. Between May 2019 and May 2020, thirteen patients with IDH-mutant diffuse gliomas, including seven with astrocytomas and six with oligodendrogliomas, were evaluated. Five neuroradiologists independently evaluated the presence of the qualitative T2-FLAIR mismatch sign. Interrater agreement on the presence of the T2-FLAIR mismatch sign was calculated using the Fleiss kappa coefficient. SyMRI parameters (T1 and T2 relaxation times and proton density) were measured in the gliomas and compared by the Mann–Whitney U test. Receiver operating characteristic curve analysis was used to evaluate the diagnostic performance. The sensitivity, specificity, and kappa coefficient were 57.1%, 100%, and 0.60, respectively, for the qualitative T2-FLAIR mismatch sign. The two types of diffuse gliomas could be differentiated using a cutoff value of 178 ms for the T2 relaxation time parameter with 100% sensitivity, specificity, accuracy, and positive and negative predictive values, with an area under the curve (AUC) of 1.00. Quantitative relaxometry using SyMRI could differentiate astrocytomas from oligodendrogliomas, achieving an increased sensitivity and objectivity compared to the qualitative T2-FLAIR mismatch sign.

MHD boundary layer flow of couple-stress fluid over a bidirectional moving surface with non-Fourier heat flux

This work is addressed to the study of MHD boundary layer couple-stress fluid flow considering the non-Fourier Cattaneo-Christov hyperbolic heat transfer model over a bidirectional movable surface. The group of continuous symmetry transformations is adopted to determine invariant solutions of governing equations for boundary layer fluid flow with heat transfer. Using Lie symmetry analysis, the governing equations having boundary conditions are converted into self-similar equations under a group of transformations only when initial prescribed velocity distributions are in linear form. The similar velocity and temperature profiles are obtained and the effects of the magnetic field and hyperbolic heat-flux are explored. The study revealed that the flow boundary layer thickness becomes thicker due to the increase of the couple-stress parameter, while the thermal boundary layer thickness becomes thinner for increasing relaxation time of heat-flux. The couple-stress parameter acts in the flow field in opposite style to the magnetic parameter. Also, for an increase in the couple-stress parameter and the thermal relaxation-time parameter, the higher wall heat transfer is exhibited.

Analysis of Non-Linear Radiation and Activation Energy Analysis on Hydromagnetic Reiner–Philippoff Fluid Flow with Cattaneo–Christov Double Diffusions

Using magnetohydrodynamics (MHD), the thermal energy and mass transport boundary layer flow parameters of Reiner–Philippoff fluid (non-Newtonian) are numerically investigated. In terms of energy and mass transfer, non-linear radiation, Cattaneo–Christov double diffusions, convective conditions at the surface, and the species reaction pertaining to activation energy are all addressed. The stated governing system of partial differential equations (PDEs) is drained into a non-linear differential system using appropriate similarity variables. Numerical solutions are found for the flow equations that have been determined. Two-dimensional charts are employed to demonstrate the flow field, temperature and species distributions, and rate of heat and mass transfers for the concerned parameters for both Newtonian and Reiner–Philippoff fluid examples. The stream line phenomenon is also mentioned in this paper. A table has also been utilized to illustrate the comparison with published results, which shows that the current numerical data are in good accord. The findings point to a new role for heat and mass transfer. According to the findings, increasing values of solutal and thermal relaxation time parameters diminish the associated mass and thermal energy layers. The current study has significant ramifications for chemical engineering systems.

Influences of Cattaneo-Christov Heat Flux, Joule Heating, Viscous Dissipation and Chemical Reaction on Hydromagnetic Pulsating Flow of Oldroyd-B Nanofluid in a Porous Channel

In this present study, Cattaneo-Christov heat flux on the hydromagnetic pulsatile flow of Oldroyd-B nanofluid through a porous channel with the presence of Brownian motion, thermal radiation, and thermophoresis effects are studied. The effects of dissipation of viscous and Ohmic heating are considered. The Buongiorno model is taken into account in this analysis. By using the perturbation method the governing partial differential equations (PDEs) are converted into the ordinary differential equations (ODEs) and solved numerically by employing the Runge-Kutta 4th-order scheme along with shooting approach. The influence of distinct parameters on velocity, temperature, nanoparticle concentration, heat and mass transfer rates are examined in detail. The results indicate that nanofluid velocity increases with higher frequency parameter, and while it falls with rising Hartmann number, and cross-flow Reynolds number. An increase in thermophoresis parameter, Eckert number, radiation parameter, Brownian motion parameter leads to a rise in temperature whereas temperature decreases for increasing Hartmann number and thermal relaxation time parameter. Moreover, the nanoparticle concentration enhances with an increasing thermophoresis parameter, thermal relaxation time parameter while it falls with the rising values of Lewis number, chemical reaction parameter and Brownian motion parameter.

Joule heating in squeezed flow of hybrid nanomaterial via FDM with Cattaneo–Christov (C–C) heat flux

PurposeThis study aims to explore the combined impacts of velocity and thermal slips on hybrid nanomaterial (GO+Ag+kerosene oil) bounded between two parallel infinite walls (plates). Both the walls are separated by a distance. The upper wall is subjected to squeezing with velocity, while the lower wall stretches with velocity. A uniform magnetic field acts normally to the flow. Moreover, heat transmission is analyzed in the presence of Joule heating. Heat transport characteristics are investigated by imposing the Cattaneo–Christov (C–C) heat flux model. The behavior of velocities, skin friction and temperature under sundry variables are examined graphically.Design/methodology/approachThe obtained partial differential equations (PDEs) related to the considered problem are nondimensionalized by choosing appropriated variables. These nondimensional PDEs are then solved by the numerical technique, finite difference method (FDM). For implementation of this method, the obtained nondimensional PDEs are converted into finite difference equations (FDEs) using forward difference (FD) toolkits.FindingsVelocity of the hybrid nanomaterial decreases with higher Hartman number and velocity slip parameter, while it increases with increase in Reynolds and squeezing numbers. Temperature of the hybrid nanomaterial increases for large Hartman number, Eckert number and squeezing parameter, while it is reduced by higher thermal slip parameter, thermal relaxation time parameter and nanoparticle volume fractions for graphene oxide (GO) and silver (Ag). Skin friction is controlled through higher Reynolds number, while it intensifies with nanoparticle volume fractions for GO and Ag.Originality/valueHere, the authors have investigated 2D flow of hybrid nanomaterial bounded between two parallel walls. The lower and upper walls are subjected to stretching and squeezing, respectively. The authors guarantee that all outcomes and numerical technique (FDM) results are original, neither submitted nor published in any journal before.

Noninvasive Assessment of APAP (N-acetyl-p-aminophenol)-Induced Hepatotoxicity Using Multiple MRI Parameters in an Experimental Rat Model.

Early detection and accurate assessment of N-acetyl-p-aminophenol (APAP)-induced hepatotoxicity can prevent further aggravation of liver injury and reduce the incidence of liver failure. To evaluate the potential of multiple MRI parameters for assessing APAP-induced hepatotoxicity in an experimental rat model. Prospective. Twenty-one APAP-treated rats and 12 control rats. A 3 T, T1 mapping, Gd-EOB-DTPA-enhanced MRI, and intravoxel incoherent motion (IVIM). The severity of histological changes was assessed by a liver pathologist. Rat livers were pathologically classified into three groups: normal (n= 12), mild necrosis (n= 13), and moderate necrosis (n= 8). T1 relaxation time (T1) and diffusion parameters were measured. The reduction rate of T1 (ΔT1%) at different time points, the maximum value of ΔT1%, time period to the maximum value of ΔT1%, and time period from ΔT1max (%) to 2/3 value of ΔT1max (%) (ΔT1-T2/3) were calculated. Transporters activities like organic anion-transporting polypeptide 1 (oatp1) and multidrug resistance-associated protein 2 (mrp2) were compared among different necrotic groups. ANOVA/Kruskal-Wallis. Pearson/Spearman correlation. P< 0.05 was considered statistical significance. T1 Precontrast and ΔT1-T2/3 were strongly correlated with the severity of necrosis (r= 0.9094; r= 0.7978, respectively) and showed significant differences between the two groups. The apparent diffusion coefficient (ADC) and tissue diffusivity (D) values were significantly lower in the moderate necrosis group than in the normal and mild necrosis groups. The oatp1 activity of the necrosis groups was significantly reduced compared to that of the normal group, but the differences between normal and mild (P= 0.21), normal and moderate group (P= 0.56) were not significant. Meanwhile, enlargement of bile canaliculi and sparse microvilli was observed in the necrotic groups. MRI parameters such as precontrast T1 and ΔT1-T2/3 had promising potential in assessing the severity of early-stage hepatotoxicity in an APAP overdose rat model. 1 TECHNICAL EFFICACY: Stage 1.

Bidirectional flow of MHD nanofluid with Hall current and Cattaneo-Christove heat flux toward the stretching surface.

Vacuum pump oil (VPO) is used as a lubricant in pumps of different machines. The rate of heat transport is a fundamental requirement of all phenomena. To enhance the rate of heat transmission and reduce the amount of energy consumed as a result of high temperatures. For this reason, the vacuum pump oil (VPO) is taken as a base fluid and Fe3O4 is the nanoparticles suspended in VPO. That’s why, the present study inspected the consequence of Hall current, Joule heating effect and variable thickness on these three-dimensional magnetohydrodynamics bidirectional flow of nanoliquid past on a stretchable sheet. Further, the Cattaneo-Christove heat flux and radiation impacts are also considered. The VPO−Fe3O4 nanofluid model is composed of momentum equations in x−direction, y−direction and temperature equations. The leading higher-order non-linear PDEs of the current study have been changed into non-linear ODEs with the implementation of appropriate similarity transformations. The procedure of the homotopy analysis method is hired on the resulting higher-order non-linear ODEs along with boundary conditions for the analytical solution. The significance of distinct flow parameters on the velocities in x−direction, y−direction and temperature profiles of the nanofluid have been encountered and briefly explained in a graphical form. Some important findings of the present modelling are that with the increment of nanoparticles volume fraction the nanofluid velocities in x−direction and y−direction are increased. It is also detected that higher estimations of magnetic field parameter, Prandtl number and thermal relaxation time parameter declined the nanofluid temperature. During this examination of the model, it is found that the Fe3O4-Vacuum pump oil (VPO) nanofluid enhanced the rate of heat transfer. Also, the vacuum pump oil (VPO) has many industrial and engineering applications. The current study will help to improve the rate of heat transmission by taking this into account due to which working machines will do better performance and the loss of useful energy will be decayed. Lastly, the skin friction coefficient and Nusselt number are also illustrated in a tabular form. Some major findings according to the numerical computation of the problem are that the enhancing estimations of magnetic parameter, nanoparticles volume fraction and wall thickness parameter augmented the skin friction coefficient in x−direction and Nusselt number. The reduction in skin friction coefficient of the nanofluid in y−direction is examined for Hall current and shape parameter.

Fractional Moore-Gibson-Thompson heat transfer model with two-temperature and non-singular kernels for 3D thermoelastic solid

A new model of thermoelasticity based on fractional calculus in combination with Fourier's law of heat and dual temperature theory is presented, including the Moore-Gibson-Thomson equation. In the suggested model, the heat equation is represented in a fractional integral form using the Atangana–Baleanu fractional operators. The presence of the concept of the delay parameter in the heat flow vector leads to a finite velocity of heat wave propagation. The model is then applied to investigate the thermoelastic interaction in a homogeneous thermoelastic 3D elastic solid with a thermally loaded and traction-free surface. In the field of Laplace and double Fourier transforms, analytical solutions for thermal variables were derived, which were then reversed to the time-space by means of the Honig-Hirdes procedure. The classical theories of thermoelasticity and some generalized theories as special examples can be derived from the presented model of thermoelasticity with a two-temperature and fractional derivative. Numerical values of the studied field variables were calculated and presented graphically. In order to explore the influences of relaxation time, temperature discrepancy, and fractional order parameters, certain comparisons of thermophysical variables were presented in the figures.

Bidirectional stretching features on the flow and heat transport of Burgers nanofluid subject to modified heat and mass fluxes

The characteristics of thermal transport in steady 3D flow of viscoelastic nanofluid induced by a bidirectional stretching surface are explored in this study. A new model for heat conduction is established in perspective of Buongiorno's model in combination with Cattaneo–Christov theory. The mathematical formulations in terms of partial differential equations are transformed into ordinary transformations by utilizing suitable dimensionless transformations. The homotopic technique is utilized to inspect the features of velocity components and thermal transport in the flow. The graphical representation of different physical constraints on thermal and solutal profiles is also depicted. It is observed that the transport of thermal energy deteriorates for escalating number of thermal relaxation time parameter. The solutal transport in the flow depreciates by intensifying the effects of stretching strength parameter. Moreover, it is seen that greater thermophoretic force regulates the thermal transport in the flow.

Particle shape effect on MHD steady flow of water functionalized Al2O3 nanoparticles over wedge

The demand for effectual cooling and heating systems in the automotive, aerospace and chemical industries is driving the growth of heat transfer technology. Keeping in mind the need of efficient cooling and heating systems, the purpose of the current study is to interrogate the outcome of Alumina nanoparticle shapes on the magnetohydrodynamic steady flow of Maxwell liquid, past a wedge existing with a nonlinear thermal radiation impact. A variable magnetic field is applied normal to the wedge surface. Moreover, Catteneo–Christove heat flux impact is considered in the modeling. The similarity transformation technique has been formulated to convert the elementary equations into ordinary differential equations and are then solved with the help of Runge Kutta Fehlberg fourth fifth order (RKF-45) numerical method accompanying the shooting technique. The replica of the output proclaims that more heat transfer enhancement is seen for platelet shaped nanoparticles and the rate of declination in heat transport is faster for the brick case with respect to rise in the values of thermal relaxation time parameter. The rise in values of the radiation parameter improves the heat transport rate, but a reverse trend is seen for increasing values of the magnetic parameter.

Influence of polymers on flow and heat transfer due to peristaltic waves: a molecular approach

This work aims to have an insight into the effects of polymers on flow and heat transfer due to peristaltic waves. Oldroyd-B model, based on kinetic theory, is considered to study the relation between the molecular structure of the polymers and the rheological properties. The main advantage of using this model is the inclusion of information based on molecular structure. Such inclusion in stress tensor incorporates the effects of stretching and orientation of the molecules. Some significant applications polymer-peristalsis can be found in tissue engineering, intake of food, and medicines. Approximations of long-wavelength and low Reynolds number are used to investigate the main features of the problem. Pressure gradient, velocity, temperature, trapped bolus, drag coefficient, and heat flux at the wall are studied numerically. The analysis is based on the change in important parameters like polymer concentration, relaxation time, Weissenberg number, and Brinkman number. Results show that by increasing polymer concentration parameter, Weissenberg number, and relaxation time parameter, the negative pressure gradient in the flow geometry increases. By increasing the polymer concentration parameter and time relaxation parameter, the velocity and temperature profiles increase. An increase in polymer concentration increases the size of the trapped bolus. Drag parameter at the wall decreases while heat flux increases when polymer concentration and Weissenberg number are increased.

Heat and mass transfer exploration of non-Newtonian fluid flow induced by the exponentially stretching Riga surface with the application of Generalized Fourier’s and Fick’s law

In the present article, the analysis of the transportation of thermal and solutal energy of a3D flow on second- grade fluid with porous medium by an exponentially stretching surface is presented. The chemical reaction and heat generation/absorption are considered the dominating agents for the transportation of mass and heat in the second-order fluid. Furthermore, slip boundary conditions are considered on the boundary of the surface. A novel concept of the Cattaneo-Christov heat flux theory of the flow of second-order fluid is used under the effects of the Joule heating across the Riga surface for this research examination. The prevailing nonlinear PDEs are changed into the nonlinear coupled ordinary differential equations by choosing the suitable similarity transformations. The Matlab approach Bvp4c is applied to solve the nonlinear ODEs. Physical consequences of the different emerging parameters on the thermal, concentration, and momentum boundary layer thickness are examined by graphs. The thermal and concentration profiles are decreased by enhancing the values of (thermal relaxation parameter of time) and the (parameter of solutal relaxation time), respectively.

Magnetization for Burgers’ Fluid Subject to Convective Heating and Heterogeneous-Homogeneous Reactions

The flow of Burgers’ fluid in the magnetic field new mathematical modeling is introduced in this article which is heated convectively and maintained. The thermal energy transport aspects are examined by employing the space- and temperature-related heat source. In the present investigation, the homogeneous-heterogeneous reactions will present the features of scrutiny of the fluid concentration. For the purpose of dimensionless similarity transformations, ordinary differential equations (ODEs) are utilized practically. Developed ODEs are solved by introducing the concepts of Runge–Kutta–Fehlberg’s fourth-fifth method. The graphs show the pertinent outcome. The relaxation time parameter is exhibited by diminishing the thermal distribution of Burgers’ fluid property, and this will depend on the relaxation time factor. Biot number and retardation time factor behaviors are analyzed by opposing the behavior of the material factor of Burgers’ fluid. The response of homogeneous strength is deteriorated by the concentration rate of the fluid, and this will augment the data using the heterogeneous response with greater magnitude. By using already published studies, it is investigated that the present investigation is validated.

Numerical simulation of Cattaneo–Christov heat flux model in a porous media past a stretching sheet

This analysis investigates the impact of aligned magnetic field fluid flow of nanofluid past a nonlinear porous stretching sheet. Cattaeno–Christov heat flux model is considered to investigate the heat transport mechanism in the presence of Joule heating, thermal radiation, internal heating, viscous dissipation, thermophoresis and Brownian motion phenomena. Moreover, mass transport analysis is also carried out in the company of chemical reaction parameter. The governing nonlinear partial differential equations are converted into a system of dimensionless ordinary differential equations by introducing the similarity transformations. Numerical solution is obtained by shooting approach together with RK-4 technique and Newton's method. To study the physical insight of pertinent flow parameters, graphical illustration is prepared. These results are displayed in the form of velocity profile, temperature profile, concentration profile, wall shear stress, and wall heat transfer. It is graphically seen that the flow permeability parameter is directly proportional to the fluid temperature and inversely proportional to the flow velocity. Further, Local Nusselt number increases with variation in the relaxation time parameter.

Higher Order Chemical Reaction and Radiation Effects on Magnetohydrodynamic Flow of a Maxwell Nanofluid With Cattaneo–Christov Heat Flux Model Over a Stretching Sheet in a Porous Medium

Abstract In this paper, we investigated the heat and mass transfer analysis of an MHD convection flow of Maxwell nanofluid with Cattaneo–Christov heat flux model along with a porous stretching sheet. The effects of thermal radiation, viscous dissipation, suction/injection, and higher-order chemical reaction are taken into consideration. By using similarity transformations the governing equations of the study are reduced into a system of ordinary differential equations and solved numerically by using the BVP5C matlab package. The effects of dimensionless parameters on the present study are deliberated with the aid of graphs and tables. It is found that an increase in thermal Grashof number, thermal radiation, and thermal relaxation time parameter drops the temperature field. The heat transfer rate is declined with enhancing heat source, Brownian motion and thermophoresis parameters. Also, observed that the concentration field reduces with the rising value of chemical reaction. The numerically computed values of Nusselt number and Sherwood number are validated with existing literature and found a good agreement.

Thermoelastic wave propagation in thin beams under thermal shock loading

An analytical solution is presented for the thermoelastic longitudinal and flexural wave propagation in transversely isotropic thin beams subjected to a thermal shock loading using the Lord–Shulman generalized thermoelasticity theory. The formulation considers a general through-thickness profile of the applied thermal loading, does not assume the across-thickness distribution of the temperature field and considers a general convective boundary condition at the beam surfaces. The thin beam is modeled using the Euler–Bernoulli beam theory. The governing equations of motion and the variationally consistent boundary conditions are derived from the extended Hamilton’s principle. The coupled thermoelastic equations are solved in the Laplace domain satisfying the thermal and mechanical boundary conditions using the homotopy perturbation method. The Laplace inversion to obtain the final solution in the time domain is performed numerically by using Durbin’s method. The formulation is validated by comparing the results for longitudinal wave propagation response under uniform thermal loading with those available in the literature. The developed solution is then employed to study the longitudinal and flexural wave propagation behaviour of a cantilever beam subject to uniform and non-uniform symmetric, and linear and non-linear anti-symmetric thermal shock loading applied at the free end. The effects of thermal boundary conditions at the beam surfaces and the relaxation time parameter on the response of the beam are illustrated.

Cattaneo–Christov heat flux effect on MHD peristaltic transport of Bingham Al2O3 nanofluid through a non-Darcy porous medium

The present investigation analyzes the influence of Cattaneo–Christov heat and mass fluxes on peristaltic transport of an incompressible flow. The fluid is obeying Bingham alumina nanofluid. The fluid flows between two co-axial vertical tubes. The system is expressed by a varying radially magnetic field with respect to the space. Soret effect and non-Darcy porous medium are taken into account. The governing system of equations is tackled by utilizing the approximations of long wave length with low Reynolds number and with the help of homotopy perturbation method (HPM). It is noticed that the axial velocity magnifies with an increase in the value of Bingham parameter. Meanwhile, the value of the axial velocity reduces with the elevation in the value of the magnetic field parameter. On the other hand, the elevation in the value of thermal relaxation time leads to a reduction in the value of fluid temperature. Furthermore, increasing in the value of mass relaxation time parameter makes an enhancement in the value of nanoparticles concentration. It is noticed also that the size of the trapped bolus enhances with the increment in the value of Bingham parameter. The current study has many accomplishments in several scientific areas like medical industry, medicine, and others. Therefore, it represents the depiction of the gastric juice motion in the small intestine when an endoscope is inserted through it.

A complete rate-dependent constitutive model of thermo-elasto-diffusive coupling and its application in structural dynamic responses analysis of multi-layered laminated sandwich composites subjected to axisymmetric heat and chemical shock loadings

Metal solids or composites often work in high-temperature environments, which raise higher requirements for their mechanical strength design, even for oxygen diffusion. This motivates great interests on the constitutive modeling of thermo-elasto-diffusive coupling behavior from scholars and engineers, of which the most representative one is called rate-dependent thermoelastic diffusion theory associated with temperature and molar concentration rates. However, in ultrafast heating condition, the increasingly prominent relaxation effects in elastic deformation field are still not considered in this theoretical formulation. To deal with the deficiency, present study aims to develop a complete rate-dependent constitutive model of thermoelastic diffusion by fully considering temperature rate, strain rate, and chemical potential rate. New constitutive relations and governing equations are derived within the extended thermodynamics framework. To illustrate its application values, the newly developed model is applied to investigate transient thermo-elasto-diffusive dynamic responses of multi-layered laminated sandwich composites considering perfect interfacial conditions and material constants ratios by a semi-analytical technique via Laplace transformation. The achieved results reveal that properly selecting relaxation time parameters and material constants ratios of such structure will eliminate discontinuity of deformation, adjust thermal/diffusive waves propagation, realize displacement control, regulate heat/diffusion isolation, and improve harmful stress isolation induced by heat or oxygen diffusion.