Temperature Material Properties Research Articles

Elevated temperature material properties of cold-formed advanced high strength steel channel sections

Fire safety remains a paramount concern in the design and application of cold-formed structures, making the understanding of mechanical properties of advanced high strength steel (AHSS) at elevated temperatures essential. This paper presents a comprehensive experimental investigation into the mechanical properties of cold-formed AHSS channel sections and their virgin material at elevated temperatures. A total of 60 coupon specimens were extracted from the middle of web element, the corner-flat adjunction of web element, as well as the middle of flange element of the cold-formed AHSS channel sections. Moreover, 20 additional coupon specimens were extracted from the cold-rolled AHSS sheets, which is the virgin material. Elevated-temperature tensile coupon tests were carried out by using steady-state test method under 10 different temperatures up to 800 °C. Full range of stress-strain curves were obtained for the virgin material and three locations of the cold-formed AHSS channel sections. Key mechanical properties including elastic modulus, yield stress and ultimate strength were obtained. Differences in the mechanical properties of coupons with different thicknesses and from various cutting positions were investigated. The obtained reduction factors of the studied AHSS were compared with existing design rules, including European, American, and Australian specifications, as well as predictive models from related research work. New design curves were proposed to provide an accurate and conservative estimation of the reduction in mechanical properties at elevated temperatures, and constitutive stress-strain models were also proposed.

Research on early-age temperature action and effect of wet joints in steel-concrete composite girders

Concrete wet joints, as an important component affecting the integrity and safety of composite girders, have an obvious cracking risk during the hydration reaction stage after pouring. To clarify the cracking risk, based on the measurements and numerical simulation method, the temperature action, thermal effect, and material property growth trend during the hydration reaction were analyzed, the influence law of material properties and environmental effects on the temperature action were clarified, and the special influence of the solar radiation effect on the temperature field of the concrete wet joint was point out. Results indicate that the temperature evolutions at an early age can be divided into three stages: dominated by hydration heat, co-dominated by hydration heat and solar radiation, and dominated by solar radiation. The peak temperature and the temperature difference of the wet joint at the transverse edges are larger than those at the middle position. At 72 h after pouring, the material properties of the concrete increase unevenly and are lower than the theoretical values, with the difference 0.59 MPa in elasticity modulus and the difference 0.44 MPa in tensile strength. The cracking risk on the top surface is the highest at 27 h after pouring. Adjusting the material properties is the most effective method to control the early-age cracking risk, with the crack index decreasing by 0.2 and 0.3 for every 30 kJ/kg reduction in cement exothermic energy and every 50 kg/m3 reduction in cement content. The corresponding improvement scheme by adjusting the material properties and the environmental effects can effectively control the early-age cracking risk. This study also clarifies that wet joints are different from other mass concrete elements, and solar radiation also has a significant influence on early-age cracking risk.

Pyrolysis modelling of insulation material in coupled fire-structure simulations

This paper presents a modelling approach to predict the thermodynamical and thermomechanical behaviour of structures with a layer of insulation material under fire, which takes into account the pyrolysis of the insulation and its effects on the structure. First, an existing 1D pyrolysis model is implemented and verified by theoretical and validated by experimental results. Then the model’s 1D setup is integrated into 3D Heat Transfer (HT) analyses of structures. The obtained thermodynamical results, i.e. temperatures as a function of time and the pyrolysis process, are transferred to a thermomechanical Structural Response (SR) analysis. Mechanical results are then obtained via temperature and pyrolysis-dependent material properties. The resulting HT and SR analyses are demonstrated in fire-structure simulations of facades made of sandwich panels, including their supporting frames with steel sections, and bolt and screw connections, modelled by non-linear spring elements. It is shown that in a short time window of 100 s, pyrolysis is limited to certain zones of the panel and for limited depths. Nevertheless, due to the endothermic process, it reduces expansion and bending of the panels, and consequently results in smaller displacements, and delayed failure of the connections. For longer periods, with connection failures neglected, significant pyrolysis takes place, which influences the temperature distribution in the complete interior of the sandwich panel. However, this has only a marginal effect on the structural behaviour. In conclusion, pyrolysis effects are relevant, can be modelled, and may somewhat reduce fire risks in structures. Future research can combine pyrolysis with advanced modelling of bolt and screw connections, using a two-scale method. As such, all relevant details of structures can be modelled and investigated for different fire scenarios, including fire-structure effects, all still to be validated by experiments.

One-Dimensional Crystal-Structure Te-Se Alloy for Flexible Shortwave Infrared Photodetector and Imaging.

Flexible shortwave infrared detectors play a crucial role in wearable devices, bioimaging, automatic control, etc. Commercial shortwave infrared detectors face challenges in achieving flexibility due to the high fabrication temperature and rigid material properties. Herein, we develop a high-performance flexible Te0.7Se0.3 photodetector, resulting from the unique 1D crystal structure and small elastic modulus of Te-Se alloying. The flexible photodetector exhibits a broad-spectrum response ranging from 365 to 1650 nm, a fast response time of 6 μs, a broad linear dynamic range of 76 dB, and a specific detectivity of 4.8 × 1010 Jones at room temperature. The responsivity of the flexible detector remains at 93% of its initial value after bending with a small curvature of 3 mm. Based on the optimized flexible detector, we demonstrate its application in shortwave infrared imaging. These results showcase the great potential of Te0.7Se0.3 photodetectors for flexible electronics.

Analysis of Thermomechanical Stress of High-Temperature Ignition Surface Caused by Drop–Wall Interaction at Engine Conditions

Abstract Drop–wall interaction is a complex phenomenon encountered in diverse industrial applications. An important example is fuel droplets impinging on a high-temperature ignition plug in a direct-injection compression-ignition engine. The ignition plug, comprised of heat-resistant materials, will experience thermal shock due to abrupt temperature changes. The ensuing temperature fluctuation in the solid wall induces thermal stress, and if this stress surpasses the material's strength in that mode, failure can occur. Therefore, it is imperative to analyze the temperature dynamics on the high-temperature surface to enhance material durability. This study focuses on drop–wall interactions in the engine environment. Utilizing the Smoothed Particle Hydrodynamics (SPH) method, this research simulates fuel droplet impingement on an ignition plug with various materials to characterize heat transfer, thermal penetration, and temperature distributions in the heated wall. The investigation also delves into the behavior of ceramic material, specifically silicon nitride, assessing its thermomechanical stress and durability based on the stress–number of cycles (S-N) curve. Thermal stress is computed by considering temperature gradients and material properties, while mechanical stress is evaluated based on the bending momentum and momentum flux induced by the spray. A parametric study explores diverse materials such as tungsten carbide, iron, stainless steel, carbon steel, and aluminum. Results indicate that thermal stress outweighs bending and spray-induced stress. Moreover, the analysis reveals that silicon nitride exhibits the lowest thermal stress distribution and superior durability, potentially capable of operating for infinite cycles under engine-relevant conditions.

Sampling-free computation of finite temperature material properties in isochoric and isobaric ensembles using the mean-field anharmonic bond model

The recently introduced mean-field anharmonic bond model has shown remarkable accuracy in predicting finite temperature free energies for certain potential models of fcc crystals without thermodynamic sampling. In this work, we extend the model to treat modern machine learning potentials in both isochoric and isobaric ensembles while preserving existing vibrational correlations and ensuring thermodynamic self-consistency. Testing against molecular dynamics simulations of bulk fcc Al and Cu, we find free energies with an accuracy of a few meV/atom up to the melting temperature under typical operating pressures, with similar accuracy for thermal expansion. Our sampling-free estimation is universally superior to the quasiharmonic approximation for less than ten percent of the computational cost and many orders of magnitude more efficient than thermodynamic integration. We discuss applications of the method in modern computational materials science workflows. Published by the American Physical Society 2024

A study of the 3-phase lag model to a two-dimensional isotropic micro-polar thermoelastic medium with memory-dependent properties

This article enlightens the two-dimensional (2D) isotropic micro-polar thermoelastic problem of the three-phase-lag (3PHL) model and heat conduction equation is formulated in the context of memory-dependent derivative (MDD). The equations are converted into the domain of the Laplace transform vector matrix differential equation form and solved by using the eigenvalue technique. To obtain an analytical solution of displacement, temperature, and stress components Silicon material properties are used. Inversion of the Laplace transform with Fourier series expansion technique is used to obtain the numerical solution. For obtaining graphical results Mathematica software is used. For the purpose of exhibiting the beauty of MDD in the present model comparisons are made between the time delay parameters and kernel functions (constant, linear, and non-linear kernels), respectively, over the micro-polar panel. The results obtained have a valuable impact on structural analysis, especially in the design of rotating machinery structures using accurate material properties.

Studies on the TEG with changes in temperature difference and material properties

The thermoelectric generators are solid-state devices that produce electricity. They are designed to harness unused energy, or “waste heat”. These devices were primarily utilized in military and space projects due to their reliability as a self-contained power source, requiring minimal maintenance. Additionally, they are environmentally sustainable and renewable sources of energy, emitting no air or noise pollution. According to research, Thermoelectric Generators (TEGs) have a relatively low efficiency rate of less than 5%. However, they hold the potential to effectively harness low-temperature waste heat, making them a promising energy source for the purpose of charging battery cells or super capacitors utilized in autonomous sensors. This study analyses the feasibility of generating electricity through segmented TEGs operating at temperatures below 296 K. Thermoelectric materials were studied to improve the conversion efficiency of the TEG. Furthermore, an investigation was conducted on the configuration of the thermoelectric generator. The COMSOL Metaphysics software is used to design and stimulate the segmented TEG model. This model is initially derived from an existing generator and is known for its accurate outcomes. The study revealed that using an alloy consisting of 75% Bi2Te3, and 25% as a substitute for the thermoelectric material PbSe0.5Te0.5, which led to a significant increase in conversion efficiency and output voltage. A segmented TEG model exhibited higher conversion efficiency. The model is subsequently refined by incorporating various modifications aimed at improving its conversion efficiency.

Characterization of high-temperature figure of merit for solar-thermal absorbers

The figure of merit (FOM) is a widely used metric to characterize the solar-thermal conversion performance of solar absorber layers. Many of previous works have reported FOMs estimated from the radiative properties measured at room temperature. However, advanced concentrated solar power (CSP) plants operate at very high temperatures (∼750°C), which can strongly affect the absorber’s radiative properties. The present work proposes using a 1-D conduction-based reference bar technique to directly measure the converted thermal energy to determine the FOM at high absorber temperatures (≳750°C) while operating under a large solar concentration (∼1200× suns). Using the finite difference method, we carefully analyze several key parameters influencing the design of the experimental setup, such as temperature distribution, material properties, heat loss, and sensor accuracy. In addition, a rigorous uncertainty analysis is incorporated into the FOM to ascertain the confidence level of the result. We validate this new technique on a custom-built tungsten reference bar with an oxidized Inconel 625 solar-thermal absorber. A good agreement between the model and the experiment shows the reliability of the FOM measurement with a well-defined uncertainty. The same method can be implemented to measure the high-temperature FOM of most surface or volumetric solar absorbers for CSP.

Review of the Hydrogen Permeation Test of the Polymer Liner Material of Type IV On-Board Hydrogen Storage Cylinders.

Type IV hydrogen storage cylinders comprise a polymer liner and offer advantages such as lightweight construction, high hydrogen storage density, and good fatigue performance. However, they are also characterized by higher hydrogen permeability. Consequently, it is crucial for the polymer liner material to exhibit excellent resistance to hydrogen permeation. International organizations have established relevant standards mandating hydrogen permeation tests for the liner material of type IV on-board hydrogen storage cylinders. This paper provides a comprehensive review of existing research on hydrogen permeability and the hydrogen permeation test methods for the polymer liner material of type IV on-board hydrogen storage cylinders. By delving into the hydrogen permeation mechanism, a better understanding can be gained, offering valuable references for subsequent researchers in this field. This paper starts by thoroughly discussing the hydrogen permeation mechanism of the liner material. It then proceeds to compare and analyze the hydrogen permeation test methods specified by various standards. These comparisons encompass sample preparation, sample pretreatment, test device, test temperature and pressure, and qualification indicators. Then, this study offers recommendations aimed at enhancing the hydrogen permeation test method for the liner material. Additionally, the influence of test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material is discussed. Finally, the influences of the test temperature, test pressure, and polymer material properties on the hydrogen permeability of the liner material are discussed. Future research direction on the hydrogen permeability and hydrogen permeation test method of the liner material of the type IV hydrogen storage cylinder has been prospected.

Free vibration analysis of a skew sandwich plate with bamboo biocomposite and polylactic acid core under temperature and moisture conditions

This article investigates the impact of moisture and temperature on vibration characteristics of bio-composite skew-laminated composite sandwich (SLCS) plates. The bio-composite SLCS plates with bamboo face sheets and polylactic acid (PLA) cores are biodegradable, radiolucent, lightweight, high strength, and withstand vibrations. The coupled thermo-elastic and hygro-elastic finite element (FE) model of the SLCS plate is derived using the higher-order shear deformation theory (HSDT). An initial stress stiffness matrix is developed using the nonlinear strain-displacement relations to incorporate the effect of temperature and moisture in FE modeling. Temperature and moisture-dependent material properties of bamboo fiber-reinforced biocomposite (BFB) and PLA core are employed for the analysis. A comprehensive investigation has been carried out to study the impact of moisture and temperature situations with different geometrical parameters and various skew angles on the frequency of the SLCS plate. The results indicate that the biocomposite sandwich material has excellent potential for structural applications under different environmental conditions in various applications like food processing, and biomedical applications, including MRI and CT scan beds.

Determination of elevated temperature material properties by ANN-based FE model

PurposeElevated temperature material properties are essential in predicting structural member's behavior in high-temperature exposures such as fire. Even though experimental methodologies are available to determine these properties, advanced equipment with high costs is required to perform those tests. Therefore, performing those experiments frequently is not feasible, and the development of numerical techniques is beneficial. A numerical technique is proposed in this study to determine the temperature-dependent thermal properties of the material using the fire test results based on the Artificial Neural Network (ANN)-based Finite Element (FE) model.Design/methodology/approachAn ANN-based FE model was developed in the Matlab program to determine the elevated temperature thermal diffusivity, thermal conductivity and the product of specific heat and density of a material. The temperature distribution obtained from fire tests is fed to the ANN-based FE model and material properties are predicted to match the temperature distribution.FindingsElevated temperature thermal properties of normal-weight concrete (NWC), gypsum plasterboard and lightweight concrete were predicted using the developed model, and good agreement was observed with the actual material properties measured experimentally. The developed method could be utilized to determine any materials' elevated temperature material properties numerically with the adequate temperature distribution data obtained during a fire or heat transfer test.Originality/valueTemperature-dependent material properties are important in predicting the behavior of structural elements exposed to fire. This research study developed a numerical technique utilizing ANN theories to determine elevated temperature thermal diffusivity, thermal conductivity and product of specific heat and density. Experimental methods are available to evaluate the material properties at high temperatures. However, these testing equipment are expensive and sophisticated; therefore, these equipment are not popular in laboratories causing a lack of high-temperature material properties for novel materials. However conducting a fire test to evaluate fire performance of any novel material is the common practice in the industry. ANN-based FE model developed in this study could utilize those fire testing results of the structural member (temperature distribution of the member throughout the fire tests) to predict the material's thermal properties.

Thermo-mechanical deformation and stress analysis of a rotating FG hollow cylindrical body

PurposeThe purpose of this study was to perform thermo-mechanical deformation and stress analysis in a functionally graded (FG) hollow cylinder considering steady-state temperature distribution under the effect of rotation, gravity and constant heat generation.Design/methodology/approachNavier's equation was used to solve the problem, and the obtained results were validated with benchmarks found to be in excellent agreement. The variation of temperature and other material properties such as Young's modulus, density, thermal expansion coefficient and thermal conductivity varied radially as per power-law variation.FindingsThe effect of rotation was found to be vital compared to gravity and heat generation when compared individually and in combination. The results of displacement and stresses were presented for varying grading indices.Practical implicationsFG cylinders have huge industrial applications as it opens the possibility of developing structures with a high strength/weight ratio. The present study will benefit industries in identifying the effective grading index that can be used by industries for fabricating FG structures.Originality/valueThe effect of rotation, body force and heat generation on a cylindrical body has not been studied before. Furthermore, the combined effect of rotation, body force and heat generation has been studied to understand the behaviour of cylinders operating under similar conditions.

Shear resistance and design of stainless steel plate girders in fire

In this paper, the shear resistance and design of stainless steel plate girders at elevated temperatures are investigated. A broad range of parameters influencing the structural response of stainless steel plate girders in fire are taken into account, considering (i) austenitic and duplex stainless steel grades, (ii) rigid and non-rigid end posts, (iii) different aspect ratios for the unstiffened portions of the plate girders, (iv) various web slendernesses and (v) different elevated temperature levels. The influence of these parameters on the behaviour of stainless steel plate girders at elevated temperatures is considered. Currently, there is an absence of specific design rules on the fire design of stainless steel plate girders in the European structural steel fire design standard EN 1993-1-2. Considering this, an accuracy assessment of the room temperature stainless steel plate girder design recommendations of the European structural stainless steel design standard EN 1993-1-4 applied with the elevated temperature material properties of stainless steel is performed. The results indicate that this approach leads to unsafe and scattered ultimate strength estimations for stainless steel plate girders in fire. New fire design recommendations for stainless steel plate girders that are in accordance with the existing design provisions of EN 1993-1-2 and EN 1993-1-4 are proposed. The accuracy and safety of the proposed new design recommendations are comprehensively verified against the results from nonlinear finite element modelling.

Overall deformation of steel-concrete-steel immersed structures during construction stage considering temperature effect

Temperature effect is one of the most significant factors to be considered in large-scale structures. For steel–concrete-steel composite immersed structures, the overall deformation is a closely watched indicator in the construction process. The main aim of this study is to investigate the overall deformation of steel–concrete-steel composite immersed structures during the construction stage, and thus a new numerical method comprehensively considering the temperature effect and material properties of early-age concrete is proposed. In the proposed method, a new finite element program for composite immersed structures, including thermal and structural modules, is developed in ANSYS. Firstly, the time-varying temperature distribution of the structure during the construction stage is accurately simulated by a transient thermal analysis, allowing for concrete hydration, solar radiation, air temperature, and changes of thermal properties comprehensively. Secondly, based on the ANSYS User-Programmable Features (UPFs), the stress–strain constitutive law of the concrete is redefined by modifying the material subroutine to consider the hardening and shrinkage of early-age concrete, then the overall structural deformation during the construction stage is estimated in the case that accurate temperature distribution and material properties are fully considered. Finally, a full-scale model of the composite immersed tunnel in Shenzhong Link is taken as an application case. The accuracy of simulation results is verified with the data of on-site monitoring. The results show that the temperature field of the composite immersed structure is obviously non-uniform and time-varying, and the overall contraction in lateral and longitudinal directions happens after the construction due to the variation of temperature and behaviors of early-age concrete.

Thermal buckling analysis of thin-walled closed section FG beam-type structures

In this paper, thermal buckling analysis of thin-walled, functionally graded (FG) beam-type structures with closed cross-sections and various boundary conditions is investigated. One dimensional finite element model, based on Euler–Bernoulli–Vlasov​ theory, is employed under the assumptions of large rotations and small strains. Two cases of temperature rise across the thickness of the cross-section walls are considered, which are uniform and linear. Stability analysis has been performed in eigenvalue manner and in load–deflection manner using Newton–Raphson method. Numerical results for thin-walled box beams and trapezoidal beams for two different FG materials configurations are presented to investigate the effects of temperature distribution, boundary conditions, and material properties on the critical buckling temperature and global buckling behaviour. The accuracy and reliability of the beam model is verified by comparing it with several benchmark examples. Good agreement was observed, showing possibility of further application of the proposed model which requires reduced computational time and provides greater modelling flexibility compared to commercial codes.

Understanding Solvothermal Growth of Metal-Organic Framework Colloids for CO2 Capture Applications.

A quantitative study of the synthesis of metal-organic framework (MOF) colloids via a solvothermal growth process was demonstrated using electrospray-differential mobility analysis (ES-DMA), a gas-phase electrophoresis approach. HKUST-1, a copper-based MOF (Cu-MOF), was selected as the representative MOF of the study. The effects of the synthetic parameters, including ligand concentration (CBTC), synthetic temperature (Ts), and synthetic time (ts) versus material properties of the Cu-MOF, were successfully characterized based on the mobility size distributions measured by ES-DMA. The results show that the mobility size of Cu-MOF was proportional to Ts, ts, and CBTC during the solvothermal growth. X-ray diffraction and Brunauer-Emmett-Teller analyses were employed complementarily to the ES-DMA, confirming that the increase in mobility size of Cu-MOF was correlated to the increase in crystallinity (i.e., larger specific surface area and crystallite size). The results of CO2 pulse adsorption show that the synthesized Cu-MOF possessed a good CO2 adsorption ability under 1 atm, 35 °C, and the cumulative amount of CO2 uptake was proportional to the measured mobility size of Cu-MOF. The work provides a proof of concept for the controlled synthesis of MOF colloids with the support of gas-phase electrophoretic analysis, and the quantitative methodology is useful for the development of MOF-based applications in CO2 capture and utilization.

Influence of Temperature and Moisture on Free Vibration Behavior of Skew Laminated Composite Sandwich Panels with CNTRC Core

This paper presents the influence of temperature and moisture on the free vibration characteristics of skew laminated composite sandwich (SLCS) panels. The face sheets of the panels are made of graphite–epoxy composite, while the core consists of carbon nanotube-reinforced composite. The coupled hygro-elastic and thermo-elastic relations for the SLCS shells/panels are formulated using first-order shear deformation theory. The nonmechanical stiffness matrices are represented by the initial stress stiffness matrix developed using nonlinear strain–displacement relations. The temperature and moisture-dependent material properties are considered to analyze the laminated composite sandwich spherical, hyperbolic, ellipsoid, cylindrical Shells, and flat plates. Several numerical examples are comprehensively studied to establish the influence of temperature, moisture, the volume fraction of carbon nanotubes in the core material, functional gradation types, skew angle, and edge constraints on the vibration responses of SLCS shells. Further exploration is devoted to studying the combined effect of moisture, temperature, and the geometrical parameters such as length to width ratio, length to thickness ratio, radius-to-length ratio, and the core thickness to face sheet thickness ratios on the natural frequency of the skew laminated composite sandwich panels.

Predicting virtual creep crack growth in a simulated titanium aluminide alloy microstructure containing voids, precipitates, and grain/grain boundary distortions

Over the years numerous of materials based experimental research programmes have focused on understanding the high temperature failure mechanisms and their relation to the microstructure of engineering alloys. These microstructures are complex in nature and are being continuously developed to improve creep/fatigue and oxidation strength of components at elevated temperatures. Furthermore, with the advent of additive manufacturing (AM) even more diverse microstructures which can contain voids, interstitial Titanium Aluminides (Ti-Al) and grain distortions have evolved at the sub-grain level affecting the creep strength of the alloys. Since measurements of detailed sub-grain properties are difficult to obtain and are likely to contain large levels of scatter a modelling procedure for a meso-scale model in multiaxial creep to identify creep damage is needed. The model using a grain (GR)/grain boundary (GB) scale mesh in the cracking region of a Compact Tension geometry simulates crack growth rates under different microstructural anomalies and variabilities such as voids and precipitates and grain shapes. In this model micro-cracks can randomly initiate and grow under a micro-triaxial stress state at positions where accumulated creep damage reaches critical values. A detailed sensitivity analysis of GB/GR/size/distortion/strength and void/precipitate density and distribution simulations is used to identify the likely reasons for cracking rates, crack branching and data scatter in creep test. Available high temperature material and mechanical properties from a representative Ti-Al intermetallic alloy are used to validate the model. The present analysis sets out the modelling approach and points the way to more complex microstructures which could contain a multiplicity of phases and sub-grain particles. The development of such models is likely to be the preferred approach to predict virtual creep crack growth in both welding and new additive manufacturing processes.

Experimental and Numerical Investigation of Tire Tread Wear on Block Level

Tread wear appears as a consequence of friction, which mainly depends on surface characteristics, contact pressure, slip velocity, temperature and dissipative material properties of the tread material itself. The subsequent description introduces a wear model as a function of the frictional energy rate. A post-processing as well as an adaptive re-meshing algorithm are implemented into a finite element code in order to predict wear loss in terms of mass. The geometry of block models is generated by image processing tools using photographs of the rubber samples in the laboratory. In addition, the worn block shape after the wear test is compared to simulation results.