Temperature-dependent Material Properties Research Articles

The 3-D problem of temperature and thermal flux distribution around defects with temperature-dependent material properties

The analytical solution of 3-D heat conduction problem, including the temperature and thermal flux fields, is one of the important problems that have not been completely solved in solid mechanics. Considering the temperature dependence of material parameters makes the problem more difficult. In this paper, we first reduce the 3-D temperature-dependent heat conduction problem to the solution of 3-D Laplace equation by introducing the intermediate function. Then, the generalized ternary function is proposed, and the general solution of 3-D Laplace equation is given. Finally, the analytical solutions of three specific problems are obtained and the corresponding temperature-thermal flux fields are discussed. The results show that the thermal flux field of 3-D temperature dependent problem is the same as the classical constant thermal conductivity approach result, while the temperature field is different from the classical result. Thermal flux at a planar defect boundary has r?1/2 singularity, and its intensity is proportional to the fourth root of defect width. On the other hand, when blocked by a planar defect, the thermal flux distribution will re-adjusted so that it overflows at the same rate from all parts of the planar defect boundary.

The load carrying capacity of reinforced concrete columns subjected to elevated temperature using simplified method

The present work proposes a method to determine the load-carrying capacity of the reinforced concrete column at elevated temperatures. The method uses the zone method mentioned in Eurocode to determine the temperature-dependent material properties of steel and concrete. Later the design equations, as per Indian standard guidelines, are used to determine the load-carrying capacity of the column. The loads considered here include both axial loads as well as uniaxial moments. The results obtained are validated with experimental data from the literature. Once Pu and Mu are determined using temperature-dependent materials properties, interaction curves are plotted at various temperatures mentioned in the standard time–temperature curve. The results obtained are validated against the experimental results from the literature. The Paper also investigates the behaviour of reinforced columns by varying design parameters like the size of the column and the grade of concrete. The work also discusses the relevancy of the 500° Isotherm method and the zone method mentioned in Eurocode when designing columns at elevated temperatures per Indian Standard guidelines.

Numerical study on flow and heat transfer characteristics of R1233zd(E) cooled in horizontal circular tubes under supercritical pressure

Supercritical organic refrigerants have been widely used in energy conversion and waste heat recovery systems due to their excellent heat transfer characteristics. R1233zd(E), as a fourth-generation environmentally friendly alternative refrigerant, has extensive application prospects. However, there is a lack of research on the heat transfer of supercritical R1233zd(E). In this work, the flow and heat transfer characteristics of supercritical R1233zd(E) in horizontal cooling tubes, including a mini tube and three ordinary tubes, are numerically simulated. In the simulation, not only the wall thickness but also the temperature-dependent thermophysical properties of the tube wall material are considered. The simulated results indicate that the specific heat capacity distributions determine that the peak of the overall heat transfer coefficients appears at a temperature higher than the pseudo-critical temperature. The flow and heat transfer characteristics of supercritical R1233zd(E) in different tubes, especially in the mini tube, are different. The applicability of three typical buoyancy criteria to this study is discussed, and the results show that two of three typical buoyancy criteria can be used to predict the buoyancy effect of supercritical R1233zd(E) in this study, but the thresholds of mini tube and ordinary tubes are different. Finally, a new heat transfer correlation is developed for supercritical R1233zd(E) by using the piecewise fitting method with pseudo-critical temperature as the point of division. The average relative deviation of the correlation is 0.57 % and the root mean square deviation is 0.87 %.

Numerical Model of the Double-Pipe System with Protective Layer

Nowadays, higher performance is being sought in newly built power plants. The efficiency of power plants is mainly achieved by maximizing the steam parameters. Consequently, ever more expensive high-alloy steels are being used. For this reason, design concepts, in which high efficiency with lower investment costs are becoming increasingly popular. Such an innovation is the double-pipe system with a protective coating, which provides thermal insulation for the primary pipe in which the supercritical steam flows. This pipe is also cooled by an external flow by the steam with lower parameters. The article presents the developed two-dimensional numerical model. The use of the Galerkin method enables the complete transient analysis of a double-pipe system to be carried out, considering temperature-dependent material properties. The numerical model was compared with the computational fluid dynamics model. The temperature gradient in the inner pipe wall with and without coating was determined. In addition, the response of the wall temperature to a change in steam temperature was investigated. As observed, the protective layer can improve boiler performance characteristics when applied to thick-walled boiler components. It can also enable the use of less demanding steel.

Fully–coupled thermal–electric modeling of thermoelectric generators

Numerical models of thermoelectric generators require quantification of discretization uncertainty, the scrutinization of thermoelectric phenomena on model energy imbalances and simultaneous thermal–electric predictions, and the rectification of disagreement with analytic models when considering temperature-dependent material properties. Within this methods paper, two fully coupled, thermal–electric unicouple-level models are developed and evaluated over various thermal and electrical conditions to address the aforementioned issues—a numeric model in ANSYS CFX and an iterative analytic model. Model results were compared to ANSYS Thermal–Electric (TE) and ANSYS Fluent. Agreement between all models’ electrical and thermal predictions was achieved, albeit ANSYS Fluent’s thermal predictions exhibited high percent differences (7–8%) and had global energy imbalances on the order of 15% due to incongruent thermal–electrical power output predictions. ANSYS TE congruently predicts power output when considering the device’s thermal behavior and electrical performance separately, with disagreement on the order of a percent. Through incorporating all thermoelectric phenomena, ANSYS CFX’s global energy imbalances were hundredths to thousandths of a percent; exclusion of pertinent thermoelectric phenomena such as Thomson and Bridgman heating caused imbalances of tens of percent. The inclusion of Thomson heat is imperative when modeling thermoelectric devices. The analytic model’s thermal and electrical performance predictions are within ANSYS CFX’s uncertainty (2–5%), and these predictions yielded percent difference of less than 1% in comparison to ANSYS CFX when the unicouple produces ±50% maximum power. By using temperature-integrated averages of material properties, analytic modeling is sufficient for the thermal–electric characterization of unicouples with interconnectors operating under Dirichlet thermal boundary conditions.

On the Mechanical Buckling Analysis of FG-GRC Laminated Plates with Temperature-Dependent Material Properties Using Isogeometric Approach

In this paper, the isogeometric method is developed to study mechanical buckling behavior of nanocomposite plates reinforced by graphene sheets with temperature-dependent (TD) material properties in thermal environment. The plate is separately subjected to in-plane uniaxial, biaxial and shear loadings. It is assumed that the plate has different number of layers. By considering different volume fraction for each layer of graphene sheets, different functionally graded (FG) patterns of graphene sheets may be achieved. Furthermore, in some cases, it is considered that more than one FG patterns exist along the plate thickness. The energy statement of the plate is obtained using a logarithmic higher-order shear deformation theory (HSDT). Then, the isogeometric method is used to establish the desired eigenvalue problem. The comparison and convergence studies are presented for a wide range of numerical examples in all considered cases to show the correctness and ability of the solution. Afterwards, by presenting a set of numerical examples, the effects of plate significant parameters on the critical buckling load of the plate are examined. It is shown that the highest critical buckling loads occur when the plate has the minimum number of layers.

SECONDARY BUCKLING OF A HEATED CIRCULAR PLATE

Upon heating, a circular plate with immovable edge exhibits buckling, which results in ax-isymmetric postcritical bending. Progressive axisymmetric bending due to increasing thermal load in the postbuckling range leads to substantial redistribution of the stresses in the plate and occurrence of high compressive circumferential stresses in a narrow zone adjacent to the plate edge. In this case, secondary buckling can occur resulting in unsymmetric stress-strain state. The aim of the present work is to study stability behavior of the postbuckling axisymmetric equilibrium configurations of a circular plate subjected to uniform temperature rise. The plate edge is assumed to be immovable in the radial and transverse directions and elastically re-strained against bending rotation, which allows one to model the boundary conditions between two extremes of clamped and simply supported. The stability analysis is performed by the semi-analytical finite element method, where unknown displacements are approximated by truncated Fourier series in the circumferential coordinate. The geometrical nonlinearity is taken into ac-count in a quadratic approximation using the Fӧppl – von Karman nonlinear plate theory. To find equilibrium states of the plate, an iterative algorithm is proposed which requires determination of the coefficients of the first and second variations of the total potential energy. Stability of the equilibrium states is examined using the criterion of positive defineteness of the Hess matrix of the plate finite-element model. The critical temperature rise at which secondary buckling occurs is determined. The post-buckling nonlinear deformation characterized by local winkling near the plate edge is studied. The effect of boundary conditions and temperature-dependent material properties on the critical thermal load and secondary buckling modes is discussed.

Temperature-resilient anapole modes associated with TE polarization in semiconductor nanowires

Polarization-dependent scattering anisotropy of cylindrical nanowires has numerous potential applications in, for example, nanoantennas, photothermal therapy, thermophotovoltaics, catalysis, sensing, optical filters and switches. In all these applications, temperature-dependent material properties play an important role and often adversely impact performance depending on the dominance of either radiative or dissipative damping. Here, we employ numerical modeling based on Mie scattering theory to investigate and compare the temperature and polarization-dependent optical anisotropy of metallic (gold, Au) nanowires with indirect (silicon, Si) and direct (gallium arsenide, GaAs) bandgap semiconducting nanowires. Results indicate that plasmonic scattering resonances in semiconductors, within the absorption band, deteriorate with an increase in temperature whereas those occurring away from the absorption band strengthen as a result of the increase in phononic contribution. Indirect-bandgap thin ([Formula: see text]) Si nanowires present low absorption efficiencies for both the transverse electric (TE, [Formula: see text]) and magnetic (TM, [Formula: see text]) modes, and high scattering efficiencies for the TM mode at shorter wavelengths making them suitable as highly efficient scatterers. Temperature-resilient higher-order anapole modes with their characteristic high absorption and low scattering efficiencies are also observed in the semiconductor nanowires ([Formula: see text] nm) for the TE polarization. Herein, the GaAs nanowires present [Formula: see text] times greater absorption efficiencies compared to the Si nanowires making them especially suitable for temperature-resilient applications such as scanning near-field optical microscopy (SNOM), localized heating, non-invasive sensing or detection that require strong localization of energy in the near field.

Transient coupled thermo-elasticity analysis of a temperature-dependent thick-walled cylinder under cyclic thermo-mechanical loads

AbstractSeveral studies have reported the solution of the classical coupled thermo-elasticity for thick-walled cylinders under different boundary conditions; however very limited studies have been conducted on the analysis of temperature-dependent thick-walled cylinders under cyclic nonlinear boundary conditions. Therefore, this study investigates the transient response of temperature-dependent thick-walled cylinders under cyclic nonlinear thermo-mechanical loads based on classical coupled thermo-elasticity. Also, it studies the impact of considering temperature-dependent material properties (TDMP) and temperature-independent material properties (TIMP) hypotheses on the accuracy of the results. The governing equations of the classical nonlinear coupled thermo-elasticity are numerically solved based on the finite-difference method, namely the Crank-Nicolson method. Then, an experimental setup is designed to further investigate the impact of considering TDMP and TIMP through a temperature measurement of the outer surface of a machine gun barrel under burst shooting. It has been found that considering TIMP overestimates the residual temperature and residual stress values through the cylinder thickness compared with TDMP. Moreover, based on the temperature measurement, TDMP estimates results with higher accuracy of 7% than TIMP.

Response of carbon/PEEK automotive driveshafts with/without an inner isotropic layer at high temperature considering temperature-dependent material properties

Lightweight fibre-reinforced thermoplastic (FRTP) driveshafts are ideal for automotive applications. In this work, material and buckling failures of FRTP driveshafts subjected to torsion at elevated temperature are analysed by finite element modelling. Critical speed at increasing temperature is also quantified. The driveshafts comprise unidirectional carbon/polyetheretherketone (PEEK) layers with/without an inner layer of aluminium or unreinforced plastic. Temperature-dependent material properties are considered. The results demonstrate achievable performance of the fully carbon/PEEK and hybrid driveshafts, which are compared with traditional alloy counterparts. The carbon/PEEK shaft exhibits marked temperature sensitivity but satisfies the design requirements at high temperature with significant weight reduction. A hybrid shaft composed of carbon/PEEK layers over-wrapped onto an aluminium tube provides a compromise in terms of superior buckling resistance and critical speed but reduced material failure safety factor. Utilising a thick layer of unreinforced plastic to reduce fibre volume may only be suitable for low-temperature, low-speed applications.

Modelling of Web-Crippling Behavior of Pultruded GFRP I Sections at Elevated Temperatures.

The concentrated transverse load may lead to the web crippling of pultruded GFRP sections due to the lower transverse mechanical properties. Several investigations have been conducted on the web-crippling behavior of the GFRP sections under room temperature. However, the web-crippling behavior is not yet understood when subjected to elevated temperatures. To address this issue, a finite element model considering the temperature-dependent material properties, Hashin failure criterion and the damage evolution law are successfully developed to simulate the web-crippling behavior of the GFRP I sections under elevated temperatures. The numerical model was validated by the web-crippling experiments at room temperature with the end-two-flange (ETF) and end bearing with ground support (EG) loading configurations. The developed model can accurately predict the ultimate loads and failure modes. Moreover, it was found that the initial damage was triggered by exceeding the shear strength at the web-flange junction near the corner of the bearing plate and independent of the elevated temperatures and loading configurations. The ultimate load and stiffness decreased obviously with the increasing temperature. At 220 °C, the ultimate load of specimens under ETF and EG loading configurations significantly decreased by 57% and 62%, respectively, whereas the elastic stiffness obviously reduced by 87% and 88%, respectively.

The Rayleigh–Bénard problem for a fluid with pressure- and temperature-dependent material properties

The Rayleigh–Bénard problem for a fluid with pressure- and temperature-dependent material properties

Thermomechanical vibration and stability of effectively homogenized FGM beam with temperature-dependent shear correction factors

Thermomechanical characteristics in the Functionally Graded Materials (FGMs) have been investigated in depth for the precise modeling and analysis of structures in ultimate thermal environments. On this subject, the micro-mechanical interactions of particles in the mixtures of FGMs is necessary to consider the more accurate estimation of structural model. Therefore, the effective material properties are obtained by using homogenization technique based on Mori-Tanaka scheme (MTS) with temperature-dependent material properties. In this regard, present research studies detail temperature-dependent frequencies and thermal buckling behavior of beam model. Then, the physical neutral surface concept is adopted to formulate the decoupled set of stress–strain relations for the FGM models. Also, the First-order Shear Deformation Theory of Beam with rectangular cross-sectional shape including temperature-dependent shear correction factors is developed to improve the practical applications. Furthermore, the results compared with previous data, and the present model is studied in the broad range of temperatures. Specifically, the correlations of shear correction factors and neutral surface shifts are discussed for the models according to temperature and volume fractions. Finally, the thermal stability and the natural frequencies of vibration behaviors are discussed as a result of the mixture ratio for the materials. Furthermore, the mutual interactions of micro-mechanical behavior with the correction factors are especially investigated for thermomechanical analysis.

Temperature-Dependent Material Property Databases for Marine Steels—Part 3: HSLA-80

Integrated Computational Materials Engineering (ICME)-based tools and techniques have been identified as the best path forward for distortion mitigation in thin-plate steel construction at shipyards. ICME tools require temperature-dependent material properties—including specific heat, thermal conductivity, coefficient of thermal expansion, elastic modulus, yield strength, flow stress, and microstructural evolution—to achieve accurate computational results for distortion and residual stress. However, the required temperature-dependent material property databases of US Navy-relevant steels are not available in the literature. Therefore, a comprehensive testing plan for some of the most common marine steels used in the construction of US Naval vessels was completed. This testing plan included DH36, HSLA-65, HSLA-80, HSLA-100, HY-80, and HY-100 steel with a nominal thickness of 4.76 mm (3/16-in.). This report is the second part of a seven-part series detailing the pedigreed steel data. The first six reports will report the material properties for each of the individual steel grades, whereas the final report will compare and contrast the measured steel properties across all six steels. This report will focus specifically on the data associated with HSLA-80 steel.

Vibration analysis of thick-section sandwich structures in thermal environments

An ultra-light sandwich structure with a thin ceramic-based composite face sheet bonded to a thick thermal insulator is developed as an integrated thermal protection system (ITPS) structure to protect the substructure of a hypersonic flight vehicle. For vibration fatigue assessment and failure prediction, the global dynamic response of the three-dimensional ITPS structure when subjected to a combination of thermal and harmonic excitation is desired. In this study, a novel unified model for vibration analysis of a thick-section sandwich structure is proposed based on the variational asymptotic method. The original 3D sandwich structure problem is reduced to one-dimensional through-the-thickness analysis and two-dimensional (2D) reference plane analysis. The stiffness matrices, including an equivalent transverse shear matrix, are obtained; hence, a shear correction factor is not required. The mechanical response of the 2D reduced-order plate under general boundary conditions in thermal environments is investigated. The static thermal deformation and forced vibration of the sandwich structure with the temperature gradient in the thickness direction are determined using a set of algebraic orthogonal polynomials through the Gram–Schmidt procedure. The thermal deflection is first introduced into the kinematic relationship to modify the total strain energy for the sandwich plate with temperature-independent material properties. To demonstrate the validity and applicability of the model, some numerical results relating to displacements and fundamental frequencies of simply supported sandwich plates are presented and compared to those obtained by other models. The effects of temperature gradients in the thickness direction, boundary conditions, core thickness, and temperature-dependent material properties on the dynamic characteristics and forced vibration of the sandwich structure are discussed by a detailed parametric study. The global dynamic strain response is first obtained using the plate model, which is desirable to determine the 3D local stress and strain field and predict vibration fatigue failure for the ITPS structure.

Multi-scale computational method for nonlinear dynamic thermo-mechanical problems of composite materials with temperature-dependent properties

For most of materials, the properties of the materials are usually dependent on the temperature, which causes the nonlinear physical and mechanical material behaviors. In this paper, an innovative multi-scale computational method is developed for efficiently simulating nonlinear dynamic thermo-mechanical problems of composite materials. The nonlinearities of these multi-scale problems were caused by the temperature-dependent properties of each component material in the composites and the heterogeneities of composite materials are taken into account by periodic distributions of representative unit cells on the micro-scale. Firstly, a second-order two-scale (SOTS) computational model for accurately analyzing nonlinear dynamic thermo-mechanical behaviors of composite materials is established based on multi-scale asymptotic analysis and Taylor series method. The proposed SOTS computational model includes the first-order and second-order auxiliary cell problems on micro-scale, homogenized problem on macro-scale and macro–micro coupled SOTS asymptotic solutions. Then we theoretically explain the crucial importance of developing the SOTS solutions by the error analysis in the point-wise sense. Next, a rigorous error analysis with an explicit rate of the SOTS approximate solutions is given under some simplifications and assumptions in the integral sense. In addition, a multi-scale numerical algorithm is proposed in detail to effectively simulate these nonlinear multi-scale problems. Finally, several typical numerical examples are carried out to confirm the effectiveness and correctness of the proposed multi-scale numerical algorithm, especially for large-scale engineering structures. This study offers an efficient and high-accuracy multi-scale computational scheme that enables the effective simulation and analysis of nonlinear dynamic thermo-mechanical problems of composite materials with temperature-dependent properties.

Application of 2D coupled algorithms to thermally induced dynamics of temperature-dependent nanocomposite cylindrical panels under transient heat shock

The current investigation examines the thermal wave motion in a functionally graded cylindrical panel with carbon nanotubes exposed to rapid surface heating. The equivalent temperature-dependent material properties of the nanocomposite media are achieved by employing a modified homogenization technique. Due to the time-dependent nature of the applied heat function, the heat conduction equation is calculated transiently. Furthermore, due to the temperature dependency of the properties, the heat conduction equation is nonlinear and is solved by the combined finite-difference and Picard methods. The Crank–Nicolson time solving scheme is utilized to determine the temperature profile of each composite system point across time. The first-order shear deformation and Donnell strain theories regulate the system’s motion equations. The combined 2D generalized differential quadrature and Newmark procedures are implemented to numerically simulate the composite structure’s physical variables. Following verification, the effects of composite media parameters and panel characteristics on the shell reaction subjected to thermal shock are examined.

Numerical study on off-axis tensile behavior of 3D braided composites at elevated temperature

3D braided composites consolidated by heat-resistant resin are expected to become essential structural material of new generation aerospace vehicles. In this work, the thermo-mechanical behavior of 3D braided composites subjected to general off-axis tensile loadings at room and elevated temperatures is evaluated based on the meso-scale finite element (FE) model. A user-material subroutine UMAT is adopted to implement the thermal stress analysis, temperature-dependent failure initiation criteria and material properties degradation scheme of both fiber yarns and matrix. The meso-scale damage evolutions under thermal-mechanical coupling loads are simulated based on ABAQUS/Standard and the corresponding detailed failure mechanisms are revealed. The off-axial elastic moduli and strengths of 3D braided composites under elevated temperatures are also predicted. The numerical results indicate that high temperature affects the material properties mainly by weakening the matrix properties while off-axis loading affects the damage mechanisms by changing the load distribution of fiber yarn in each direction. The present work provides routine support for the numerical study of structural properties and damage behavior of other textile composites in service temperature environment.

A resistance heating assisted free space method to measure temperature-dependent electromagnetic properties of carbon fiber reinforced polymer composites

Temperature-dependent electromagnetic properties are not only closely related to the manufacturing process of carbon fiber reinforced polymer (CFRP) components, e.g., curing of CFRP composites using microwaves, but also directly determines some key performance indicators of CFRP structures like electromagnetic stealth and anti-electromagnetic interference (EMI). In this paper, we proposed a resistance heating assisted free space method to measure the temperature-dependent electromagnetic properties of both CFRP materials and structures. On this basis, the temperature-dependent electromagnetic properties of a unidirectional carbon fiber/PEEK composite material were measured in the temperature range from room temperature to 400 °C. Moreover, the temperature-dependent electromagnetic properties of a CFRP structure, i.e., a multidirectional carbon fiber/PEEK laminate covered by subwavelength resonance structures, were also measured. The results indicated that temperature has a significant effect on the electromagnetic properties of both CFRP materials and structures. Our work provides a simple and practical solution to measure the temperature-dependent electromagnetic properties of CFRP materials and structures.

Nonlinear vibration analysis of functionally graded porous circular plates under hygro-thermal loading

In this work, the nonlinear vibrations of functionally graded (FG) porous circular plates under hygro-thermal loading is studied utilizing a numerical approach. Hygroscopic stresses generated due to the nonlinear rise in moisture concentration, even and uneven porosity distributions, and temperature dependency of material properties are all taken into account. Modified Voigt’s rule of mixture is applied to obtain the hygro-thermo-mechanical properties of the FG circular plate. All material properties are assumed to be temperature-dependent using the Touloukian formula. In order to obtain the equations of motion, the first-order shear deformation theory, von-Kármán geometrical non-linearity assumption, and hygro-thermal strains are considered concurrently. After deriving the equations of motion using Hamilton’s principle, the differential quadrature method and the Newmark-beta time integration scheme are employed in conjunction with an iterative approach to solve the set of nonlinear governing differential equations of motion. The effects of various parameters including temperature distribution, plate’s thickness, porosity volume fraction, moisture concentration, and FG index are studied on plate’s maximum non-dimensional lateral deflection.