In this contribution we discuss the stability of thin, axi-symmetric, shallow bimetallic shells in a non-homo- geneous temperature field. The presented model with a mathematical description of the geometry of the syst...In this contribution we discuss the stability of thin, axi-symmetric, shallow bimetallic shells in a non-homo- geneous temperature field. The presented model with a mathematical description of the geometry of the system, displacements, stresses and thermoelastic deformations on the shell, is based on the theory of the third order, which takes into account not only the equilibrium of forces on a deformed body but also the non-linear terms of the strain tensor. The equations are based on the large displacements theory. As an example, we pre- sent the results for a bimetallic shell of parabolic shape, which has a temperature point load at the apex. We translated the boundary-value problem with the shooting method into saving the initial-value problem. We calculate the snap-through of the system numerically by the Runge-Kutta fourth order method.展开更多
The deformation characteristics and thermal response of anchor rods are crucial for ensuring the stability and safety of surrounding rock support structures.However,existing research has predominantly concentrated on ...The deformation characteristics and thermal response of anchor rods are crucial for ensuring the stability and safety of surrounding rock support structures.However,existing research has predominantly concentrated on the mechanical performance of anchor rods,with limited attention to the coupled evolution of strain and temperature fields during tensile deformation.This knowledge gap hinders a comprehensive understanding of the synergistic mechanical-thermal response mechanisms in anchor rods under loading conditions.To address this limitation,the present study systematically investigated the evolution of strain and temperature fields,along with their correlation,during the test of micro-negative Poisson's ratio(NPR)and ordinary Poisson's ratio(PR)anchor rods.Digital image correlation(DIC)and infrared thermography(IRT)techniques were employed for this exploration.The uniaxial tensile tests were conducted at two different rates,and the ordinary PR anchor rod(Q235 anchor rod)was established as a control group for comparative analysis.The findings reveal that the micro-NPR anchor rod exhibit strain localization at multiple locations during the tensile process,whereas Q235 anchors show local strain concentration in only one region.The standard deviation evolution curves for both the strain and temperature field exhibit two distinct phases in the two anchor rods.The evolution patterns between these two types of curves are basically consistent.The two standard deviation curves for the micro-NPR anchor rod display a wavy increase in the second phase,while for the Q235 anchor rod,they increase steadily until the specimen is damaged.The correlation analysis reveals that the standard deviations of strain and temperature differences for both types of anchor rods are significantly correlated.These findings demonstrate the synergistic evolution mechanism of deformation and thermal response,providing a potential foundation for utilizing thermal monitoring to assess the stability of rock support structures.展开更多
In ultrasonic non-destructive testing of high-temperature industrial equipment,sound velocity drift induced by non-uniform temperature fields can severely compromise defect localization accuracy.Conventional approache...In ultrasonic non-destructive testing of high-temperature industrial equipment,sound velocity drift induced by non-uniform temperature fields can severely compromise defect localization accuracy.Conventional approaches that rely on room-temperature sound velocities introduce systematic errors,potentially leading to misjudgment of safety-critical components.Two primary challenges hinder current methods:first,it is difficult to monitor real-time changes in sound velocity distribution within a thermal gradient;second,traditional uniform-temperature correction models fail to capture the nonlinear dependence of material properties on temperature and their effect on ultrasonic velocity fields.Here,we propose a defect localization correction method based on multiphysics coupling.A two-dimensional coupled heat transfer–wave propagation model is established in COMSOL,and a one-dimensional steady-state heat transfer condition is used to design a numerical pulse–echo experiment in 1020 steel.Temperature-dependent material properties are incorporated,and the intrinsic relationship between sound velocity and temperature is derived,confirming consistency with classical theories.To account for gradient temperature fields,a micro-element integration algorithm discretizes the propagation path into segments,each associated with a locally computed temperature from the steady-state heat conduction solution.Defect positions are dynamically corrected through cumulative displacement along the propagation path.By integrating heat conduction and elastic wave propagation in a multiphysics framework,this method overcomes the limitations of uniform-temperature assumptions.The micro-element integration approach enables dynamic tracking of spatially varying sound velocities,offering a robust strategy to enhance ultrasonic testing accuracy in high-temperature industrial environments.展开更多
During the process of rail grinding,the local high temperature generated in the grinding contact area can affect the physical properties of the rail,thereby affecting its service performance.Therefore,studying the tem...During the process of rail grinding,the local high temperature generated in the grinding contact area can affect the physical properties of the rail,thereby affecting its service performance.Therefore,studying the temperature field of rail grinding is of great significance for improving the quality of rail grinding.In this paper,a calculation model for the grinding depth and contour of the semi elliptical contact area was established based on the contact geometry relationship between the steel rail and the abrasive belt for the first time,and the influence of grinding process parameters on the parameters of the contact area was elucidated.Combined with the characteristics of steel rail abrasive belt grinding process,a calculation model for heat flux density in the semi elliptical contact area was obtained and verified.Based on the above research results,the temperature field of the moving surface heat source with continuous action in the semi elliptical contact area is solved by discretization.Research has shown that under the set grinding process parameters,the simulation and theoretical temperature changes of the rail grinding surface in the semi elliptical contact area are similar and almost reach the maximum temperature at the same time.The relative error between the simulation and theoretical maximum temperature is 6.14%.Comparative analysis of theoretical calculations and simulation of maximum temperature under different grinding speeds shows good consistency in size and trend.The correctness of the above theoretical model has been verified through existing research results.This study proposes a new method for calculating the tem-perature field in the actual semi elliptical grinding area considering the rail profile,which has important the-oretical significance for the calculation of the temperature field and stress field in the grinding area.展开更多
As underground mining advances to greater depths,cemented paste backfill(CPB)is increasingly subjected to complex thermo-mechanical loading conditions,including multiaxial stress states and elevated temperatures.This ...As underground mining advances to greater depths,cemented paste backfill(CPB)is increasingly subjected to complex thermo-mechanical loading conditions,including multiaxial stress states and elevated temperatures.This study investigates the coupled effects of field-representative vertical self-weight and horizontal rockwall closure stresses,along with in-situ temperatures,on the mechanical behavior and pore water pressure(PWP)evolution of CPB.Experiments were conducted using a novel apparatus capable of controlling multiaxial stress and temperature during curing,replicating in-situ stress paths and thermal profiles typical of deep mine environments.Results show that multiaxial stress enhances CPB strength and stiffness by promoting denser particle packing,reducing porosity,and increasing frictional resistance.Elevated temperatures independently accelerate early-age cement hydration,further improving bond strength and stiffness.When combined,multiaxial stress and elevated temperature produce a synergistic enhancement in unconfined compressive strength(UCS)and elastic modulus,as confirmed by two-way ANOVA and synergy index analysis.PWP responses were also highly sensitive to thermo-mechanical conditions.The evolution of positive and negative PWP was governed by the interplay of thermal expansion,hydration-induced desaturation,and mechanical compaction.Multiaxial stress amplified early positive PWP and delayed its dissipation,whereas elevated temperature accelerated hydration and reduced pore pressure,leading to enhanced suction at later ages.A transient“stress-induced resaturation”effect was observed under late-stage excessive horizontal stress but was mitigated by elevated temperatures.These findings provide critical insights into the coupled mechanical and hydraulic behavior of CPB under realistic field conditions and offer guidance for optimizing backfill design,binder content,and barricade stability in deep mining applications.展开更多
With the continuous upgrading of traditional manufacturing industries and the rapid rise of emerging technology fields,the performance requirements for the permanent magnet synchronous motors(PMSMs)have become higher ...With the continuous upgrading of traditional manufacturing industries and the rapid rise of emerging technology fields,the performance requirements for the permanent magnet synchronous motors(PMSMs)have become higher and higher.The importance of fast and accurate electromagnetic thermal coupling analysis of such motors becomes more and more prominent.In view of this,the surfacemounted PMSM(SPMSM)equipped with unequally thick magnetic poles is taken as the main object and its electromagnetic thermal coupling analytical model(ETc AM)is investigated.First,the electromagnetic analytical model(EAM)is studied based on the modified subdomain method.It realizes the fast calculation of key electromagnetic characteristics.Subsequently,the 3D thermal analytical model(TAM)is developed by combining the EAM,the lumped parameter thermal network method(LPTNM),and the partial differential equation of heat flux.It realizes the fast calculation of key thermal characteristics in 3D space.Further,the information transfer channel between EAM and TAM is built with reference to the intrinsic connection between electromagnetic field and temperature field.Thereby,the novel ETcAM is proposed to realize the fast and accurate prediction of electromagnetic and temperature fields.Besides,ETcAM has a lot to commend it.One is that it well accounts for the complex structure,saturation,and heat exchange behavior.Second,it saves a lot of computer resources.It offers boundless possibilities for initial design,scheme evaluation,and optimization of motors.Finally,the validity,accuracy,and practicality of this study are verified by simulation and experiment.展开更多
This study examines the influence of magnetic field and temperature on the transient voltage of a polycrystalline silicon radial junction solar cell in a dynamic regime under multispectral illumination. Radial junctio...This study examines the influence of magnetic field and temperature on the transient voltage of a polycrystalline silicon radial junction solar cell in a dynamic regime under multispectral illumination. Radial junction solar cells represent a major advancement in photovoltaic technologies, as they optimize light absorption and charge collection efficiency. The focus is on the impact of the magnetic field and temperature on the decay of transient voltage, which provides crucial information on recombination processes and the lifetime of minority carriers. The results reveal that the magnetic field tends to increase the transient voltage by directly affecting the transient electron density. Indeed, for B > 7 × 10−5 T, the magnetic field prolongs the relaxation time by increasing the transient voltage amplitude. Additionally, rising temperatures accelerate (ranging from 290 K to 450 K) recombination processes, thereby reducing the transient voltage, although this effect is moderated by the presence of a magnetic field. The study highlights the complex interaction between magnetic field and temperature, with significant impacts on the transient behaviour.展开更多
In the electroslag remelting(ESR)process,it mainly relies on thermal experiments or analysis via mechanistic models to realize the physical fields simulation of the electromagnetic field and temperature field coupled ...In the electroslag remelting(ESR)process,it mainly relies on thermal experiments or analysis via mechanistic models to realize the physical fields simulation of the electromagnetic field and temperature field coupled transfer,which has the limitations of high cost,a large amount of calculating data and high computing power requirements.A novel network based on physics-informed neural network(PINN)was designed to realize the fast and high-fidelity prediction of the distribution of electromagnetic field and temperature field in ESR process.The physical laws were combined with the deep learning network through PINN,and physical constraints were embedded to achieve effective solution of partial differential equations(PDEs).PINN was used to minimize the loss function consisting of data error,physical information error and boundary condition error.The physical laws and boundary condition constraints in the ESR process were considered to maintain high PDE solution accuracy under different spatial and temporal resolutions.Automatic differentiation(Autodiff)technique and gradient descent algorithm were used to optimize the network parameters.The experimental results show that compared with the mechanistic models,PINN can effectively replace thermal experiments to realize the physical field simulation of ESR process with only a few experimental data,which can avoid the disadvantages of pure data-driven network simulation that requires a large amount of training data.Moreover,the solution of PINN has good physical interpretability and reliability of simulation results.For simulating electromagnetic field and temperature field distribution,the training time of the network is only 140 and 203 s,and the regression indicators of root mean square error can reach 12.65 and 13.76,respectively.展开更多
The accessory gearbox is a vital component of aviation engines, and its power loss, flow characteristics, and temperature distribution significantly influence engine performance, particularly under high-temperature an...The accessory gearbox is a vital component of aviation engines, and its power loss, flow characteristics, and temperature distribution significantly influence engine performance, particularly under high-temperature and high-speed conditions. However, research on the thermal and flow characteristics of entire transmission systems remains limited. This study presents a mathematical model designed to evaluate power loss and heat generation within the transmission system of an accessory gearbox. The Moving Particle Semi-Implicit(MPS) method, a Lagrangian numerical technique for fluid dynamics, was utilized to calculate the flow field of the gearbox and determine the surface convective heat transfer coefficient under stable flow conditions. Subsequently, a three-dimensional finite element thermal network method was employed to calculate the gearbox temperature distribution. This method captures detailed temperature fields of key components while estimating other components using lumped parameters, effectively balancing accuracy and efficiency in temperature field calculations. The results indicate that rotational speed has a greater impact on total power loss than the oil inlet temperature. The bevel gears, which are responsible for power input, along with the input shaft bearings, are the primary contributors to power loss, collectively accounting for nearly 50% of the total power loss. This research introduces a predictive method for examining the thermal and flow characteristics of aviation transmission systems, facilitating rapid forecasting of the flow field, temperature distribution, and power consumption.展开更多
With the intelligent transformation of process manufacturing,accurate and comprehensive perception information is fundamental for application of artificial intelligence methods.In zinc smelting,the fluidized bed roast...With the intelligent transformation of process manufacturing,accurate and comprehensive perception information is fundamental for application of artificial intelligence methods.In zinc smelting,the fluidized bed roaster is a key piece of large-scale equipment and plays a critical role in the manufacturing industry;its internal temperature field directly determines the quality of zinc calcine and other related products.However,due to its vast spatial dimensions,the limited observation methods,and the complex multiphase,multifield coupled reaction atmosphere inside it,accurately and timely perceiving its temperature field remains a significant challenge.To address these challenges,a spatial-temporal reduced-order model(STROM)is proposed,which can realize fast and accurate temperature field perception based on sparse observation data.Specifically,to address the difficulty in matching the initial physical field with the sparse observation data,an initial field construction based on data assimilation(IFCDA)method is proposed to ensure that the initial conditions of the model can be matched with the actual operation state,which provides a basis for constructing a high-precision computational fluid dynamics(CFD)model.Then,to address the high simulation cost of high-precision CFD models under full working conditions,a high uniformity(HU)-orthogonal test design(OTD)method with the centered L2 deviation is innovatively proposed to ensure high information coverage of the temperature field dataset under typical working conditions in terms of multiple factors and levels of the component,feed,and blast parameters.Finally,to address the difficulty in real-time and accurate temperature field prediction,considering the spatial correlation between the observed temperature and the temperature field,as well as the dynamic correlation of the observed temperature in the time dimension,a spatial-temporal predictive model(STPM)is established,which realizes rapid prediction of the temperature field through sparse observa-tion data.To verify the accuracy and validity of the proposed method,CFD model validation and reduced-order model prediction experiments are designed,and the results show that the proposed method can realize high-precision and fast prediction of the roaster temperature field under different working conditions through sparse observation data.Compared with the CFD model,the prediction root-mean-square error(RMSE)of STROM is less than 0.038,and the computational efficiency is improved by 3.4184×10^(4)times.In particular,STROM also has a good prediction ability for unmodeled conditions,with a prediction RMSE of less than 0.1089.展开更多
To address the issue of uneven temperature distribution in shale gas oil-based drill cuttings pyrolysis furnaces,a numerical model was developed using Fluent software.The effects of nitrogen flow rate,heating tube spa...To address the issue of uneven temperature distribution in shale gas oil-based drill cuttings pyrolysis furnaces,a numerical model was developed using Fluent software.The effects of nitrogen flow rate,heating tube spacing,and furnace dimensions on the internal temperature field were thoroughly analyzed from a mechanistic perspective.The results indicated that non-uniform radiation from the heating tubes and flow disturbances induced by the nitrogen stream were the primary causes of localized heat concentration.Under no-load conditions,the maximum deviation between simulated and on-site measured temperatures was 1.5%,validating the model’s accuracy.Further-more,this study investigated the trade-offs between temperature uniformity,energy consumption,and construction costs.The findings provide a crucial design basis and a reliable simulation platform for developing and optimizing pyrolysis equipment.展开更多
In the industrial roller kiln,the time-delay characteristic in heat transfer causes the temperature field to be affected by both the current and historical temperature states.It presents a poor control performance and...In the industrial roller kiln,the time-delay characteristic in heat transfer causes the temperature field to be affected by both the current and historical temperature states.It presents a poor control performance and brings a significant challenge to the process precise control.Considering high complexity of precise modeling,a data-driven time-delay optimal control method for temperature field of roller kiln is proposed based on a large amount of process data.First,the control challenges and problem description brought by time-delay are demonstrated,where the cost function for the time-delay partial differential equation system is constructed.To obtain the optimal control law,the policy iteration in adaptive dynamic programming is adopted to design the time-delay temperature field controller,and neural network is used for the critic network in policy iteration to approximate the optimal time-delay cost function.The closed-loop system stability is proved by designing the Lyapunov function which contains the time-delay information.Finally,through establishing the time-delay temperature field model for roller kiln,the effectiveness and convergence of the proposed method is verified and proved.展开更多
Optical temperature sensor materials face great challenges in terms of temperature measurement sensitivity and applicability in extreme environments.To overcome these problems,Er^(3+)∕Yb^(3+)co-doped La_(2)O_(3)-TiO_...Optical temperature sensor materials face great challenges in terms of temperature measurement sensitivity and applicability in extreme environments.To overcome these problems,Er^(3+)∕Yb^(3+)co-doped La_(2)O_(3)-TiO_(2)-Ga_(2)O_(3)-ZrO_(2)(LTGZ)glasses were designed and synthesized using the aerodynamic levitation method.In the glass system,the strongest intensity of upconversion luminescence was measured on 3.0Yb^(3+)∕0.5Er^(3+)(mole fraction)co-doped LTGZ glasses.In the temperature range of 300 to 700 K,the maximum relative and absolute sensitivities were 2.71%and 0.56%K^(−1),respectively.The temperature reliability was proved through variable temperature cycling tests.More importantly,to our knowledge,it is the first time to investigate the optical temperature measurement capability under a high magnetic field in this as-designed sensor.By applying the magnetic field up to 42 T,the relative sensitivity changes from 1.79%to 1.58%K^(−1),revealing that the temperature sensitivity of the sensor remains stable even in high magnetic fields.The results of the study provide a reference for the selection of temperature measurement materials in the field of optical temperature sensing,and the designed temperature sensor can be used for temperature measurement in extreme environments,especially in strong magnetic field conditions,which provides an important value for the development of special optical temperature sensors.展开更多
Electron beam welding of Ti-15-3 alloy to 304 stainless steel （STS） using a copper filler metal was carried out. The temperature fields and stress distributions in the Ti/Fe and Ti/Cu/Fe joint during the welding pro...Electron beam welding of Ti-15-3 alloy to 304 stainless steel （STS） using a copper filler metal was carried out. The temperature fields and stress distributions in the Ti/Fe and Ti/Cu/Fe joint during the welding process were numerically simulated and experimentally measured. The results show that the rotated parabola body heat source is fit for the simulation of the electron beam welding. The temperature distribution is asymmetric along the weld center and the temperature in the titanium alloy plate is higher than that in the 304 STS plate. The thermal stress also appears to be in asymmetric distribution. The residual tensile stress mainly exists in the weld at the 304 STS side. The copper filler metal decreases the peak temperature and temperature grade in the joint as well as the residual stress. The longitudinal and lateral residual tensile strengths reduce by 66 MPa and 31 MPa, respectively. From the temperature and residual stress, it is concluded that copper is a good filler metal candidate for the electron beam welding of Ti-15-3 titanium alloy to 304 stainless steel.展开更多
A mathematical model is developed for simulating the heat transferring behavior in a direct metal laser sintering process. The model considers the thermal phenomena involved in the process, including conduction, radia...A mathematical model is developed for simulating the heat transferring behavior in a direct metal laser sintering process. The model considers the thermal phenomena involved in the process, including conduction, radiation, and convection. A formula for the calculation of the heat conductivity of a sintering system containing solid phase, liquid phase, and gas phase is given. Due to the continuous movement of the laser beam, a local coordinate system centered on the laser beam is used to simplify the analytical calculation. Assuming that it is approximately a Gaussian laser beam, the heat conduction equation is resolved based on the assumption of the thermal insulating boundary conditions and the fixed thermal physical parameters. The FORTRAN language is employed to compile the program to simulate the temperature field in the direct copper powder sintering process. It shows a good agreement with the preliminary experimental results.[KH3/4D]展开更多
Aim To analyse the static temperature field ofthe solid rubber tire(SRT).Methods The mechanical and thermal FE models were developed and analyzed respectively with the FE software ANSYS.Results The maximum temperature...Aim To analyse the static temperature field ofthe solid rubber tire(SRT).Methods The mechanical and thermal FE models were developed and analyzed respectively with the FE software ANSYS.Results The maximum temperature becomes higher with the higher with the higher velocity of tire and scales down slightly with the higher convection coefficients.The mixed models are reasonable.Conclusion The study on static temperature field is important and reasonable.It gives the fundament for life analysis of SRT.展开更多
The solar temperature field of a large three-span continuous bridge with steel-concrete composite box girder and variable cross-section is measured to verify a calculation method for the temperature field of steel-con...The solar temperature field of a large three-span continuous bridge with steel-concrete composite box girder and variable cross-section is measured to verify a calculation method for the temperature field of steel-concrete composite beams. The test results show that the temperature of an external steel web- plate is higher than that of an internal web-plate due to the difference in solar radiation. Air temperature inside the box matches the average temperature of the whole steel box. Based on actual measurements, a transient thermal analysis with multiple boundary conditions is also carried out by a software program ANSYS. Convective boundary situation and states of solar radiation on steel web plates in different situations are determined in the analysis. The feature of the temperature field is preliminarily achieved through a comparative study between the actual measurement and the finite element analysis. The computed results are in good consistence with the actual measurement results, with the maximum difference within 2 ℃. This indicates that the theoretical calculation method is reliable and it provides a foundation for further research on temperature field distribution in the steel-concrete composite box girder.展开更多
In the analysis of functionally graded materials （FGMs）, the uncoupled approach is used broadly, which is based on homogenized material property and ignores the effect Of local micro-structural interaction. The high...In the analysis of functionally graded materials （FGMs）, the uncoupled approach is used broadly, which is based on homogenized material property and ignores the effect Of local micro-structural interaction. The higher-order theory for FGMs （HOTFGM） is a coupled approach that explicitly takes the effect of micro-structural gradation and the local interaction of the spatially variable inclusion phase into account. Based on the HOTFGM, this article presents a quadrilateral element-based method for the calculation of multi-scale temperature field （QTF）. In this method, the discrete cells are quadrilateral including rectangular while the surface-averaged quantities are the primary variables which replace the coefficients employed in the temperature function. In contrast with the HOTFGM, this method improves the efficiency, eliminates the restriction of being rectangular cells and expands the solution scale. The presented results illustrate the efficiency of the QTF and its advantages in analyzing FGMs.展开更多
H13 powder is cladded on steel P20 （base） by continuous COe laser, and the influence of technological pa rameters such as the laser power is analyzed. The 3-D model of synchronous powder feeding is built under Gauss...H13 powder is cladded on steel P20 （base） by continuous COe laser, and the influence of technological pa rameters such as the laser power is analyzed. The 3-D model of synchronous powder feeding is built under Gauss heat source. The simulative results in the heat affected zone are compared with the experimental ones, and the average er rors of width and depth are 15% and 4.5%, respectively. It is found that the simulative results provide basic data for investigating of laser cladding further.展开更多
文摘In this contribution we discuss the stability of thin, axi-symmetric, shallow bimetallic shells in a non-homo- geneous temperature field. The presented model with a mathematical description of the geometry of the system, displacements, stresses and thermoelastic deformations on the shell, is based on the theory of the third order, which takes into account not only the equilibrium of forces on a deformed body but also the non-linear terms of the strain tensor. The equations are based on the large displacements theory. As an example, we pre- sent the results for a bimetallic shell of parabolic shape, which has a temperature point load at the apex. We translated the boundary-value problem with the shooting method into saving the initial-value problem. We calculate the snap-through of the system numerically by the Runge-Kutta fourth order method.
基金supported by State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining&Technology,Beijing(Grant No.SKLGDUEK2120)。
文摘The deformation characteristics and thermal response of anchor rods are crucial for ensuring the stability and safety of surrounding rock support structures.However,existing research has predominantly concentrated on the mechanical performance of anchor rods,with limited attention to the coupled evolution of strain and temperature fields during tensile deformation.This knowledge gap hinders a comprehensive understanding of the synergistic mechanical-thermal response mechanisms in anchor rods under loading conditions.To address this limitation,the present study systematically investigated the evolution of strain and temperature fields,along with their correlation,during the test of micro-negative Poisson's ratio(NPR)and ordinary Poisson's ratio(PR)anchor rods.Digital image correlation(DIC)and infrared thermography(IRT)techniques were employed for this exploration.The uniaxial tensile tests were conducted at two different rates,and the ordinary PR anchor rod(Q235 anchor rod)was established as a control group for comparative analysis.The findings reveal that the micro-NPR anchor rod exhibit strain localization at multiple locations during the tensile process,whereas Q235 anchors show local strain concentration in only one region.The standard deviation evolution curves for both the strain and temperature field exhibit two distinct phases in the two anchor rods.The evolution patterns between these two types of curves are basically consistent.The two standard deviation curves for the micro-NPR anchor rod display a wavy increase in the second phase,while for the Q235 anchor rod,they increase steadily until the specimen is damaged.The correlation analysis reveals that the standard deviations of strain and temperature differences for both types of anchor rods are significantly correlated.These findings demonstrate the synergistic evolution mechanism of deformation and thermal response,providing a potential foundation for utilizing thermal monitoring to assess the stability of rock support structures.
基金supported by the following projects:National Natural Science Foundation of China[U24A20135]Science and Technology Program of the State Administration for Market Regulation[2024MK016]+9 种基金Basic Scientific Research Fund Project for Higher Education Institutions of Inner Mongolia(2024YXXS057)Key Project of Natural Science Foundation of Inner Mongolia[2023ZD12]2023 Inner Mongolia Autonomous Region Key R&D and Achievement Transformation Program[2023YFHH0090]Natural Science Foundation of Inner Mongolia[2022MS05006]Talent Development Fund of Inner Mongolia Autonomous RegionFundamental Research Funds for Universities[2023RCTD012]Fundamental Research Funds for Universities[2023QNJS075]Inner Mongolia Autonomous Region Postgraduate Research Innovation Project[KC2024053B]Fundamental Research Funds for Universities[2024YXXS012]Open Project of the National Key Laboratory of Special Vehicle Design and Manufacturing Integration Technology[GZ2023KF012].
文摘In ultrasonic non-destructive testing of high-temperature industrial equipment,sound velocity drift induced by non-uniform temperature fields can severely compromise defect localization accuracy.Conventional approaches that rely on room-temperature sound velocities introduce systematic errors,potentially leading to misjudgment of safety-critical components.Two primary challenges hinder current methods:first,it is difficult to monitor real-time changes in sound velocity distribution within a thermal gradient;second,traditional uniform-temperature correction models fail to capture the nonlinear dependence of material properties on temperature and their effect on ultrasonic velocity fields.Here,we propose a defect localization correction method based on multiphysics coupling.A two-dimensional coupled heat transfer–wave propagation model is established in COMSOL,and a one-dimensional steady-state heat transfer condition is used to design a numerical pulse–echo experiment in 1020 steel.Temperature-dependent material properties are incorporated,and the intrinsic relationship between sound velocity and temperature is derived,confirming consistency with classical theories.To account for gradient temperature fields,a micro-element integration algorithm discretizes the propagation path into segments,each associated with a locally computed temperature from the steady-state heat conduction solution.Defect positions are dynamically corrected through cumulative displacement along the propagation path.By integrating heat conduction and elastic wave propagation in a multiphysics framework,this method overcomes the limitations of uniform-temperature assumptions.The micro-element integration approach enables dynamic tracking of spatially varying sound velocities,offering a robust strategy to enhance ultrasonic testing accuracy in high-temperature industrial environments.
基金Supported by National Natural Science Foundation of China(Grant No.52275399).
文摘During the process of rail grinding,the local high temperature generated in the grinding contact area can affect the physical properties of the rail,thereby affecting its service performance.Therefore,studying the temperature field of rail grinding is of great significance for improving the quality of rail grinding.In this paper,a calculation model for the grinding depth and contour of the semi elliptical contact area was established based on the contact geometry relationship between the steel rail and the abrasive belt for the first time,and the influence of grinding process parameters on the parameters of the contact area was elucidated.Combined with the characteristics of steel rail abrasive belt grinding process,a calculation model for heat flux density in the semi elliptical contact area was obtained and verified.Based on the above research results,the temperature field of the moving surface heat source with continuous action in the semi elliptical contact area is solved by discretization.Research has shown that under the set grinding process parameters,the simulation and theoretical temperature changes of the rail grinding surface in the semi elliptical contact area are similar and almost reach the maximum temperature at the same time.The relative error between the simulation and theoretical maximum temperature is 6.14%.Comparative analysis of theoretical calculations and simulation of maximum temperature under different grinding speeds shows good consistency in size and trend.The correctness of the above theoretical model has been verified through existing research results.This study proposes a new method for calculating the tem-perature field in the actual semi elliptical grinding area considering the rail profile,which has important the-oretical significance for the calculation of the temperature field and stress field in the grinding area.
基金the University of Ottawa, the China Scholarship Council and the Natural Sciences and Engineering Research Council of Canada (NSERC) for their financial support.
文摘As underground mining advances to greater depths,cemented paste backfill(CPB)is increasingly subjected to complex thermo-mechanical loading conditions,including multiaxial stress states and elevated temperatures.This study investigates the coupled effects of field-representative vertical self-weight and horizontal rockwall closure stresses,along with in-situ temperatures,on the mechanical behavior and pore water pressure(PWP)evolution of CPB.Experiments were conducted using a novel apparatus capable of controlling multiaxial stress and temperature during curing,replicating in-situ stress paths and thermal profiles typical of deep mine environments.Results show that multiaxial stress enhances CPB strength and stiffness by promoting denser particle packing,reducing porosity,and increasing frictional resistance.Elevated temperatures independently accelerate early-age cement hydration,further improving bond strength and stiffness.When combined,multiaxial stress and elevated temperature produce a synergistic enhancement in unconfined compressive strength(UCS)and elastic modulus,as confirmed by two-way ANOVA and synergy index analysis.PWP responses were also highly sensitive to thermo-mechanical conditions.The evolution of positive and negative PWP was governed by the interplay of thermal expansion,hydration-induced desaturation,and mechanical compaction.Multiaxial stress amplified early positive PWP and delayed its dissipation,whereas elevated temperature accelerated hydration and reduced pore pressure,leading to enhanced suction at later ages.A transient“stress-induced resaturation”effect was observed under late-stage excessive horizontal stress but was mitigated by elevated temperatures.These findings provide critical insights into the coupled mechanical and hydraulic behavior of CPB under realistic field conditions and offer guidance for optimizing backfill design,binder content,and barricade stability in deep mining applications.
基金supported by the Project of National Natural Science Foundation of China under Grant 52077122。
文摘With the continuous upgrading of traditional manufacturing industries and the rapid rise of emerging technology fields,the performance requirements for the permanent magnet synchronous motors(PMSMs)have become higher and higher.The importance of fast and accurate electromagnetic thermal coupling analysis of such motors becomes more and more prominent.In view of this,the surfacemounted PMSM(SPMSM)equipped with unequally thick magnetic poles is taken as the main object and its electromagnetic thermal coupling analytical model(ETc AM)is investigated.First,the electromagnetic analytical model(EAM)is studied based on the modified subdomain method.It realizes the fast calculation of key electromagnetic characteristics.Subsequently,the 3D thermal analytical model(TAM)is developed by combining the EAM,the lumped parameter thermal network method(LPTNM),and the partial differential equation of heat flux.It realizes the fast calculation of key thermal characteristics in 3D space.Further,the information transfer channel between EAM and TAM is built with reference to the intrinsic connection between electromagnetic field and temperature field.Thereby,the novel ETcAM is proposed to realize the fast and accurate prediction of electromagnetic and temperature fields.Besides,ETcAM has a lot to commend it.One is that it well accounts for the complex structure,saturation,and heat exchange behavior.Second,it saves a lot of computer resources.It offers boundless possibilities for initial design,scheme evaluation,and optimization of motors.Finally,the validity,accuracy,and practicality of this study are verified by simulation and experiment.
文摘This study examines the influence of magnetic field and temperature on the transient voltage of a polycrystalline silicon radial junction solar cell in a dynamic regime under multispectral illumination. Radial junction solar cells represent a major advancement in photovoltaic technologies, as they optimize light absorption and charge collection efficiency. The focus is on the impact of the magnetic field and temperature on the decay of transient voltage, which provides crucial information on recombination processes and the lifetime of minority carriers. The results reveal that the magnetic field tends to increase the transient voltage by directly affecting the transient electron density. Indeed, for B > 7 × 10−5 T, the magnetic field prolongs the relaxation time by increasing the transient voltage amplitude. Additionally, rising temperatures accelerate (ranging from 290 K to 450 K) recombination processes, thereby reducing the transient voltage, although this effect is moderated by the presence of a magnetic field. The study highlights the complex interaction between magnetic field and temperature, with significant impacts on the transient behaviour.
基金supported by National Natural Science Foundation of China(52274323 and 524743495)the Postdoctoral Fellowship Program of CPSF under Grant Number GZC20240231.
文摘In the electroslag remelting(ESR)process,it mainly relies on thermal experiments or analysis via mechanistic models to realize the physical fields simulation of the electromagnetic field and temperature field coupled transfer,which has the limitations of high cost,a large amount of calculating data and high computing power requirements.A novel network based on physics-informed neural network(PINN)was designed to realize the fast and high-fidelity prediction of the distribution of electromagnetic field and temperature field in ESR process.The physical laws were combined with the deep learning network through PINN,and physical constraints were embedded to achieve effective solution of partial differential equations(PDEs).PINN was used to minimize the loss function consisting of data error,physical information error and boundary condition error.The physical laws and boundary condition constraints in the ESR process were considered to maintain high PDE solution accuracy under different spatial and temporal resolutions.Automatic differentiation(Autodiff)technique and gradient descent algorithm were used to optimize the network parameters.The experimental results show that compared with the mechanistic models,PINN can effectively replace thermal experiments to realize the physical field simulation of ESR process with only a few experimental data,which can avoid the disadvantages of pure data-driven network simulation that requires a large amount of training data.Moreover,the solution of PINN has good physical interpretability and reliability of simulation results.For simulating electromagnetic field and temperature field distribution,the training time of the network is only 140 and 203 s,and the regression indicators of root mean square error can reach 12.65 and 13.76,respectively.
基金Supported by National Natural Science Foundation of China (Grant Nos. U2141247, 52322504)Chongqing Graduate Research Innovation Project (Grant No. CYB23023)。
文摘The accessory gearbox is a vital component of aviation engines, and its power loss, flow characteristics, and temperature distribution significantly influence engine performance, particularly under high-temperature and high-speed conditions. However, research on the thermal and flow characteristics of entire transmission systems remains limited. This study presents a mathematical model designed to evaluate power loss and heat generation within the transmission system of an accessory gearbox. The Moving Particle Semi-Implicit(MPS) method, a Lagrangian numerical technique for fluid dynamics, was utilized to calculate the flow field of the gearbox and determine the surface convective heat transfer coefficient under stable flow conditions. Subsequently, a three-dimensional finite element thermal network method was employed to calculate the gearbox temperature distribution. This method captures detailed temperature fields of key components while estimating other components using lumped parameters, effectively balancing accuracy and efficiency in temperature field calculations. The results indicate that rotational speed has a greater impact on total power loss than the oil inlet temperature. The bevel gears, which are responsible for power input, along with the input shaft bearings, are the primary contributors to power loss, collectively accounting for nearly 50% of the total power loss. This research introduces a predictive method for examining the thermal and flow characteristics of aviation transmission systems, facilitating rapid forecasting of the flow field, temperature distribution, and power consumption.
基金supported in part by the National Key Research and Development Program of China(2022YFB3304900)in part by the National Natural Science Foundation of China(62394340 and 62073340)in part by the Science and Technology Innovation Program of Hunan Province(2022JJ10083).
文摘With the intelligent transformation of process manufacturing,accurate and comprehensive perception information is fundamental for application of artificial intelligence methods.In zinc smelting,the fluidized bed roaster is a key piece of large-scale equipment and plays a critical role in the manufacturing industry;its internal temperature field directly determines the quality of zinc calcine and other related products.However,due to its vast spatial dimensions,the limited observation methods,and the complex multiphase,multifield coupled reaction atmosphere inside it,accurately and timely perceiving its temperature field remains a significant challenge.To address these challenges,a spatial-temporal reduced-order model(STROM)is proposed,which can realize fast and accurate temperature field perception based on sparse observation data.Specifically,to address the difficulty in matching the initial physical field with the sparse observation data,an initial field construction based on data assimilation(IFCDA)method is proposed to ensure that the initial conditions of the model can be matched with the actual operation state,which provides a basis for constructing a high-precision computational fluid dynamics(CFD)model.Then,to address the high simulation cost of high-precision CFD models under full working conditions,a high uniformity(HU)-orthogonal test design(OTD)method with the centered L2 deviation is innovatively proposed to ensure high information coverage of the temperature field dataset under typical working conditions in terms of multiple factors and levels of the component,feed,and blast parameters.Finally,to address the difficulty in real-time and accurate temperature field prediction,considering the spatial correlation between the observed temperature and the temperature field,as well as the dynamic correlation of the observed temperature in the time dimension,a spatial-temporal predictive model(STPM)is established,which realizes rapid prediction of the temperature field through sparse observa-tion data.To verify the accuracy and validity of the proposed method,CFD model validation and reduced-order model prediction experiments are designed,and the results show that the proposed method can realize high-precision and fast prediction of the roaster temperature field under different working conditions through sparse observation data.Compared with the CFD model,the prediction root-mean-square error(RMSE)of STROM is less than 0.038,and the computational efficiency is improved by 3.4184×10^(4)times.In particular,STROM also has a good prediction ability for unmodeled conditions,with a prediction RMSE of less than 0.1089.
基金funded by the key research on industrialization technologies of low-cost highenergy-density cathode materials(project number:2023GY008)the Sichuan Provincial Science and Technology Program(project number:2024NSFSC1406).
文摘To address the issue of uneven temperature distribution in shale gas oil-based drill cuttings pyrolysis furnaces,a numerical model was developed using Fluent software.The effects of nitrogen flow rate,heating tube spacing,and furnace dimensions on the internal temperature field were thoroughly analyzed from a mechanistic perspective.The results indicated that non-uniform radiation from the heating tubes and flow disturbances induced by the nitrogen stream were the primary causes of localized heat concentration.Under no-load conditions,the maximum deviation between simulated and on-site measured temperatures was 1.5%,validating the model’s accuracy.Further-more,this study investigated the trade-offs between temperature uniformity,energy consumption,and construction costs.The findings provide a crucial design basis and a reliable simulation platform for developing and optimizing pyrolysis equipment.
基金supported in part by the Key Program of National Natural Science Foundation of China(62033014)the Application Projects of Integrated Standardization and New Paradigm for Intelligent Manufacturing from the Ministry of Industry and Information Technology of China in 2016the Fundamental Research Funds for the Central Universities of Central South University(2021zzts0700).
文摘In the industrial roller kiln,the time-delay characteristic in heat transfer causes the temperature field to be affected by both the current and historical temperature states.It presents a poor control performance and brings a significant challenge to the process precise control.Considering high complexity of precise modeling,a data-driven time-delay optimal control method for temperature field of roller kiln is proposed based on a large amount of process data.First,the control challenges and problem description brought by time-delay are demonstrated,where the cost function for the time-delay partial differential equation system is constructed.To obtain the optimal control law,the policy iteration in adaptive dynamic programming is adopted to design the time-delay temperature field controller,and neural network is used for the critic network in policy iteration to approximate the optimal time-delay cost function.The closed-loop system stability is proved by designing the Lyapunov function which contains the time-delay information.Finally,through establishing the time-delay temperature field model for roller kiln,the effectiveness and convergence of the proposed method is verified and proved.
基金supported by the Ministry of Human Resources and Social Security of the People’s Republic of China(Grant No.S20240022)the Hubei Provincial Natural Science Foundation for Innovation and Development(Grant No.2025AFD325)the Interdisciplinary Program of Wuhan National High Magnetic Field Center(Grant No.WHMFC202129).
文摘Optical temperature sensor materials face great challenges in terms of temperature measurement sensitivity and applicability in extreme environments.To overcome these problems,Er^(3+)∕Yb^(3+)co-doped La_(2)O_(3)-TiO_(2)-Ga_(2)O_(3)-ZrO_(2)(LTGZ)glasses were designed and synthesized using the aerodynamic levitation method.In the glass system,the strongest intensity of upconversion luminescence was measured on 3.0Yb^(3+)∕0.5Er^(3+)(mole fraction)co-doped LTGZ glasses.In the temperature range of 300 to 700 K,the maximum relative and absolute sensitivities were 2.71%and 0.56%K^(−1),respectively.The temperature reliability was proved through variable temperature cycling tests.More importantly,to our knowledge,it is the first time to investigate the optical temperature measurement capability under a high magnetic field in this as-designed sensor.By applying the magnetic field up to 42 T,the relative sensitivity changes from 1.79%to 1.58%K^(−1),revealing that the temperature sensitivity of the sensor remains stable even in high magnetic fields.The results of the study provide a reference for the selection of temperature measurement materials in the field of optical temperature sensing,and the designed temperature sensor can be used for temperature measurement in extreme environments,especially in strong magnetic field conditions,which provides an important value for the development of special optical temperature sensors.
基金Foundation item:Project (2010CB731704) supported by the National Basic Research Program of ChinaProject (51075189) supported by the National Natural Science Foundation of China
文摘Electron beam welding of Ti-15-3 alloy to 304 stainless steel （STS） using a copper filler metal was carried out. The temperature fields and stress distributions in the Ti/Fe and Ti/Cu/Fe joint during the welding process were numerically simulated and experimentally measured. The results show that the rotated parabola body heat source is fit for the simulation of the electron beam welding. The temperature distribution is asymmetric along the weld center and the temperature in the titanium alloy plate is higher than that in the 304 STS plate. The thermal stress also appears to be in asymmetric distribution. The residual tensile stress mainly exists in the weld at the 304 STS side. The copper filler metal decreases the peak temperature and temperature grade in the joint as well as the residual stress. The longitudinal and lateral residual tensile strengths reduce by 66 MPa and 31 MPa, respectively. From the temperature and residual stress, it is concluded that copper is a good filler metal candidate for the electron beam welding of Ti-15-3 titanium alloy to 304 stainless steel.
文摘A mathematical model is developed for simulating the heat transferring behavior in a direct metal laser sintering process. The model considers the thermal phenomena involved in the process, including conduction, radiation, and convection. A formula for the calculation of the heat conductivity of a sintering system containing solid phase, liquid phase, and gas phase is given. Due to the continuous movement of the laser beam, a local coordinate system centered on the laser beam is used to simplify the analytical calculation. Assuming that it is approximately a Gaussian laser beam, the heat conduction equation is resolved based on the assumption of the thermal insulating boundary conditions and the fixed thermal physical parameters. The FORTRAN language is employed to compile the program to simulate the temperature field in the direct copper powder sintering process. It shows a good agreement with the preliminary experimental results.[KH3/4D]
文摘Aim To analyse the static temperature field ofthe solid rubber tire(SRT).Methods The mechanical and thermal FE models were developed and analyzed respectively with the FE software ANSYS.Results The maximum temperature becomes higher with the higher with the higher velocity of tire and scales down slightly with the higher convection coefficients.The mixed models are reasonable.Conclusion The study on static temperature field is important and reasonable.It gives the fundament for life analysis of SRT.
文摘The solar temperature field of a large three-span continuous bridge with steel-concrete composite box girder and variable cross-section is measured to verify a calculation method for the temperature field of steel-concrete composite beams. The test results show that the temperature of an external steel web- plate is higher than that of an internal web-plate due to the difference in solar radiation. Air temperature inside the box matches the average temperature of the whole steel box. Based on actual measurements, a transient thermal analysis with multiple boundary conditions is also carried out by a software program ANSYS. Convective boundary situation and states of solar radiation on steel web plates in different situations are determined in the analysis. The feature of the temperature field is preliminarily achieved through a comparative study between the actual measurement and the finite element analysis. The computed results are in good consistence with the actual measurement results, with the maximum difference within 2 ℃. This indicates that the theoretical calculation method is reliable and it provides a foundation for further research on temperature field distribution in the steel-concrete composite box girder.
基金National Natural Science Foundation of China (2009ZB52028,05C52013)Ph.D. Programs Foundation of Ministry of Education of China (20070287039)
文摘In the analysis of functionally graded materials （FGMs）, the uncoupled approach is used broadly, which is based on homogenized material property and ignores the effect Of local micro-structural interaction. The higher-order theory for FGMs （HOTFGM） is a coupled approach that explicitly takes the effect of micro-structural gradation and the local interaction of the spatially variable inclusion phase into account. Based on the HOTFGM, this article presents a quadrilateral element-based method for the calculation of multi-scale temperature field （QTF）. In this method, the discrete cells are quadrilateral including rectangular while the surface-averaged quantities are the primary variables which replace the coefficients employed in the temperature function. In contrast with the HOTFGM, this method improves the efficiency, eliminates the restriction of being rectangular cells and expands the solution scale. The presented results illustrate the efficiency of the QTF and its advantages in analyzing FGMs.
基金Item Sponsored by Fund of Office of Science and Technology of Zhejiang Province of China(2008C31041)
文摘H13 powder is cladded on steel P20 （base） by continuous COe laser, and the influence of technological pa rameters such as the laser power is analyzed. The 3-D model of synchronous powder feeding is built under Gauss heat source. The simulative results in the heat affected zone are compared with the experimental ones, and the average er rors of width and depth are 15% and 4.5%, respectively. It is found that the simulative results provide basic data for investigating of laser cladding further.
