Coupling Of Temperature Fields Research Articles

Design, analysis, and optimization of PMSM for ultra-deep water pile hammer application

With the development of global deepwater oil and gas and offshore wind power resources, there is an increasing demand for ultra-deep water pile hammers (UDPH). In this paper, a permanent magnet synchronous motor (PMSM) with oil fill is proposed for UDPH on the basis of underwater 2500 m depth and 450 kJ impact energy requirements. First, the rated parameters of the PMSM are calculated based on the power required by hydraulic pumps, and then, the method of combining empirical formulas and path algorithms is used to complete the electromagnetic scheme design. Second, finite element analysis of the electromagnetic field is carried out by Maxwell under both no-load and load conditions to verify the rationality of the PMSM. Furthermore, aiming at improving efficiency and reducing cogging, parameter optimization is carried out by a robust parameter optimization design method, and the optimal parameter scheme of the PMSM is obtained. In addition, loss analysis and temperature field coupling calculations of the optimized PMSM are conducted to verify that the temperature of this motor can meet the requirements under different working conditions. Finally, a comparative analysis is conducted between the proposed PMSM and the three-phase asynchronous motor used in the underwater 2,500 m-450 kJ UDPH. The results indicate that the new PMSM introduced in this paper demonstrates significant advantages in terms of weight, volume, and efficiency; moreover, the new PMSM is reasonable and more suitable for UDPH. Therefore, the PMSM proposed in this paper is reasonable and can provide a theoretical basis for improving the traditional UDPH.

Enhanced evaporation and heat transfer of sessile droplets via coupling electric field and temperature field

Controllable evaporation of sessile droplets is essential in diverse applications, ranging from thermal management to chemical reactions and combustion. Despite considerable advances, further enhancement of droplet evaporation is still challenging. Here, an experimental system that couples uniform/non-uniform electric fields with temperature fields to enhance hydrophilic droplet evaporation is introduced. The electric field can generate Coulomb force by changing the redistribution of charges at the droplet interface, which enables highly flexible and precise control of the sessile droplet. By leveraging the uniform electric field, the droplet is stretched upwards, which increases the heat transfer thermal resistance and the vapor concentration near the droplet interface, leading to the deterioration of droplet evaporation. Whereas the application of a non-uniform electric field will flatten the droplets due to the shear effect of the corona wind on the droplet interface, and the reduction of the heat transfer thermal resistance of the droplets, as well as the vapor concentration near the interface, which promotes the droplet evaporation. The coupling of uniform electric and temperature fields could reverse the inhibition effect of droplet evaporation caused by a purely uniform electric field, and the maximum enhancement ratio reaches 5.11 times. The coupling of a non-uniform electric field and temperature field can enhance droplet evaporation up to 29.34 times. The corresponding numerical simulation study reveals the flow and temperature distribution inside the droplet. This research provides critical insights into the precise manipulation of droplet evaporation by applying an electric field.

Laws of Hydration Heat of Cement and Hydrate Stabilization in Shallow Formations of Deep Seawater.

When cementing is required in marine deepwater hydrate formations, the heat released from the hydration process of oil well cement can easily lead to hydrate decomposition. It is necessary to clarify the initial phase transition temperature of the hydrate layer under the influence of cement waiting for setting so that it can meet the stability of the hydrate layer during cementing. In this paper, based on the actual conditions of offshore deepwater cementing, the coupled temperature field model of cement sheath hydration heat source-well wall hydrate decomposition is established by considering the hydration heat release during the cement waiting process and the phase change heat absorption of the well wall hydrate. Combined with the established model, the hydrate formation in the deepwater region of the ocean was selected and matched with suitable oil well cement for simulation. Through simulation, the critical temperature range (291-295 K) for the initial phase transition of the hydrate layer at 10-15 MPa was clarified and the relationship between the critical values of cement hydration heat release to maintain hydrate stability at different initial temperatures of the formation was established. The phase stability law of hydrates in the formation under cement sheath hydration heat release was revealed, providing a theoretical basis and guidance for the development of low-hydration heat release cement slurry systems.

Observation of parity-time symmetry in diffusive systems.

Phase modulation has scarcely been mentioned in diffusive physical systems because the diffusion process does not carry the momentum like waves. Recently, non-Hermitian physics provides a unique perspective for understanding diffusion and shows prospects in thermal phase regulation, exemplified by the discovery of anti-parity-time (APT) symmetry in diffusive systems. However, precise control of thermal phase remains elusive hitherto and can hardly be realized, due to the phase oscillations. Here we construct the PT-symmetric diffusive systems to achieve the complete suppression of thermal phase oscillation. The real coupling of diffusive fields is readily established through a strong convective background, and the decay-rate detuning is enabled by thermal metamaterial design. We observe the phase transition of PT symmetry breaking with the symmetry-determined amplitude and phase regulation of coupled temperature fields. Our work shows the existence of PT symmetry in dissipative energy exchanges and provides unique approaches for harnessing the mass transfer of particles, wave dynamics in strongly scattering systems, and thermal conduction.

The Coupled Temperature Field Model of Difficult-to-Deform Mg Alloy Foil High-Efficiency Electro-Rolling and Experimental Study

In response to the challenging difficult-to-deform of magnesium foils, a high-efficiency and high-precision electro-rolling temperature field coupled model is established. This model is designed to simulate the non-annealing electric rolling (NAER) process of Mg foils under conditions of high current density, rapid temperature rise rates, and large temperature gradients. Firstly, a coupled temperature field difference model for the guide roller, roll, and Mg foil is established, based on the equipment for NAER and the electrification conditions. The Joule heat, distortion heat, and friction heat in the electric rolling process were precisely considered. Secondly, considering the peculiarity of the heat source and the heat transfer mechanism during NAER, the influence of the dynamic boundary conditions on the instantaneous temperature of the Mg foil was analyzed, which was closer to the actual situation. The experimental results show that the original model can accurately simulate the transient temperature change in Mg foils during NAER, and the error between the predicted value and the measured value is within 7.1%. According to the calculation of the model, the microstructure of completely recrystallized magnesium foil with a grain size of 4.61 μm and a texture strength of 11.3 can be obtained at an inlet temperature of 250 °C.

Observation of non-Hermitian skin effect in thermal diffusion

The paradigm shift of Hermitian systems into the non-Hermitian regime profoundly modifies inherent property of the topological systems, leading to various unprecedented effects such as the non-Hermitian skin effect (NHSE). In the past decade, the NHSE has been demonstrated in quantum, optical and acoustic systems. Beside those wave systems, the NHSE in diffusive systems has not yet been observed, despite recent abundant advances in the study of topological thermal diffusion. In this work, we design a thermal diffusion lattice based on a modified Su-Schrieffer-Heeger model and demonstrate the diffusive NHSE. In the proposed model, the asymmetric temperature field coupling inside each unit cell can be judiciously realized by appropriate configurations of structural parameters. We find that the temperature fields trend to concentrate toward the target boundary which is robust against initial excitation conditions. We thus experimentally demonstrated the NHSE in thermal diffusion and verified its robustness against various defects. Our work provides a platform for exploration of non-Hermitian physics in the diffusive systems, which has important applications in efficient heat collection, highly sensitive thermal sensing and others.

Multi-point grounding fault diagnosis and temperature field coupling analysis of oil-immersed transformer core based on finite element simulation

In this article, a fault diagnosis method is presented for identifying multi-point grounding faults in transformer cores. Based on the finite element method (FEM), the method aims to achieve non-invasive localization of these faults, thereby minimizing loss attributed to troubleshooting and maintenance downtime. Firstly, as a prerequisite for solving the coupled temperature field, an applied circuit method is employed to ascertain the internal loss of the transformer. This determination relies on investigating the influence of internal loss in the oil-immersed transformers for diagnosing under rated operating conditions. Secondly, the internal temperature distribution within the transformer and the condition of the transformer oil are comprehensively analyzed and validated by using an electromagnetic-fluid-solid coupled finite element simulation. Lastly, relying on the simulation outcomes under fault-free conditions, a fault model of the transformer core is established. Subsequently, the output data of the model are classified and localized using deep belief networks. This approach resolves the problems associated with masking transformer fault data signals and acquiring data. The results indicate that the temperature data obtained from the temperature field simulation exhibit an error of less than 2.6% when compared to actual values. The fault localization accuracy for multiple grounding points in the iron core of oil-immersed transformers reaches 96.4%, confirming the practicality and effectiveness of this method.

Study on coupled heat-water-vapor transfer in buffer material based on SPH method

To study the hydrothermal evolution law in buffer materials, based on the heat balance equation of unsaturated soil and the quality control equation of water migration, a coupled heat-water-vapor model of unsaturated soil is proposed. This model comprehensively considers the transition process of water vapor, the heat transfer caused by water flow and vapor migration, as well as the influence of temperature potential on water flow and vapor migration. The smoothed particle hydrodynamics (SPH) method can be used to calculate their evolution process conveniently. In the solution, the vapor content of heat balance equation is solved first, and then the water content and temperature field are solved, so as the coupling of temperature field between water and vapor field is implemented. The rationality of the model is verified by the tested results of soil column test. According to the established theoretical model, the heat-water-vapor three-field coupling problem of the buffer material in the repository was simulated and studied, and the hydrothermal evolution law inside the buffer material was revealed. On this basis, the influence of the change of groundwater pressure and heat source temperature on the hydrothermal evolution law of buffer material was further analyzed.

Water Based Mn-Zn Magnetic Fluid Heat Dissipation Capacity Testing Platform

Manganese zinc magnetic fluid is a temperature sensitive magnetic fluid that can regulate its flow behavior using temperature and magnetic fields. However, there is currently no testing platform for evaluating the heat dissipation ability of this magnetic fluid working fluid by coupling temperature and magnetic fields. This article establishes two experimental testing platforms for applying magnetic fields, namely a circulating pipeline and a temperature equalization plate. Compared with deionized water, evaluate the average temperature and heat dissipation ability of water-based manganese zinc magnetic fluid. The test results show that the heat dissipation start time of the manganese zinc magnetic fluid loop pipe is better than that of deionized water. Under the action of magnetic field (500Gs), the average temperature of the circulating pipeline decreases by 7.2% (heat source power 15W); Under the action of a magnetic field (3000Gs), the thermal resistance of the homogenizing plate (filled with 48% water-based manganese zinc magnetic fluid) decreases by about 16.7% (heat source power 140W). The water-based manganese zinc magnetic fluid working fluid exhibits better heat transfer performance than the deionized water working fluid under high heat source power. The experimental results prove that the designed water-based manganese zinc magnetic fluid working fluid heat dissipation capacity testing platform has reliable experimental quantification results.

The interaction between cross-flow induced vibration and convection heat transfer in tube bundle at subcritical Reynolds number

This work numerically investigates the interaction between flow-induced vibration (FIV) and forced convection heat transfer in tube bundle with a pitch ratio of 1.5 at subcritical Reynolds number (Re = 5 × 103-3 × 104). The range of reduced velocity is 0.53 ≤ Vr ≤ 2.71. The mass-damping parameter of coupling system is 0.07. The three-dimensional refined FIV simulation considering fluid viscous damping has been validated by the literature experiment to capture three continuous FIV mechanisms, namely turbulence-induced vibration, vortex-induced resonance and fluidelastic instability. The heat transfer and pressure drop in tube bundle are validated by the experiment. The coupling of Navier-Stokes equations, energy equations and vibration equations is solved by under-relaxation algorithm. The results of vibration response, the change of damping for the coupling system, flow field and temperature field, heat transfer and pressure drop are presented and delineated in this paper. The results show that for the low velocity turbulence-induced vibration, the interaction between FIV and flow heat transfer is negligible due to the weak fluid–solid interaction. In vortex-induced resonance region, the wall heating makes each row tube be out of phase by affecting the vortex shedding and reduces the positive feedback of resonance, which reduces the amplitude. The wall heating reduces the damping of coupling system, which causes an earlier transition from vortex-induced resonance to fluidelastic instability and a faster increase of amplitude in fluidelastic instability. In both vortex-induced resonance and fluidelastic instability, the vibration of tube bundle dominates the vortex shedding by the natural frequency, and further dominates the change of heat transfer. The best performance of enhanced heat transfer induced by FIV is located in vortex-induced resonance region, in which the time–space averaged Nusselt number is increased by 8.83%. Due to the redistribution of flow field and the elimination of deflective flow pattern, compared with vortex-induced resonance, the increasing ratio of heat transfer induced by FIV is lower and the increasing ratio of pressure drop induced by FIV is higher in the fluidelastic instability.

Characterization of magneto-thermo-hydrodynamic lubrication of metal liquid film at armature/rail interface

Utilizing the magneto-thermo-hydrodynamic lubrication theory, this study investigates the armature/rail(A/R) interface under high-intensity currents and transient high-temperature conditions. A magneto-thermo-hydrodynamic lubrication model is established using the finite difference method, coupling electromagnetic field, temperature field, and hydrodynamic lubrication theory, to depict the lubrication mechanism of the A/R interface under the influence of electromagnetic and thermal interactions. The characteristics of magneto-thermal diffusion for the armature/ rail, and the dynamic lubrication properties of the metal liquid film at the interface, are analyzed, to investigate how to improve the contact state of the A/R interface and enhance the stability of the electromagnetic rail launch. The findings are of significant importance for predicting frictional and thermal losses at the A/R interface and enhancing its performance.

High efficient PEC performance via mechanical stress field and temperature field coupling assisted Ba0·7Sr0·3TiO3 under visible light irradiation

Limited carriers migration and separation efficiency are key factors affecting the photo-electric catalysis performance of semiconductors. In this paper, the mechanical stress field and temperature field are combined to realize the piezo-pyro-photo-electric catalysis by using the coupling effect of the two external fields, which greatly improves the catalysis performance of Ba0·7Sr0·3TiO3 semiconductor. At 20–50 °C alternating heating and cooling, ultrasonic excitation, light and bias conditions, the current density of Ba0·7Sr0·3TiO3 increased to 1.01 mA cm−2. It is 1.22 and 1.31 times higher than that of piezo-photo-electric catalysis (0.83 mA cm−2) under single mechanical stress field and pyro-photo-electric catalysis (0.77 mA cm−2) under temperature field, respectively. The coupled external stimulation is beneficial to the improvement of photo-electric catalysis performance. Due to the presence of polarization charge imbalance and piezoelectric/pyroelectric polarization induced built-in electric field piezoelectric/pyroelectric potential, thereby increasing the total concentration of carriers, accelerating the separation and transfer efficiency of carriers. This study realizes the synergistic utilization of various clean energy sources such as solar energy, thermal energy, mechanical energy and electrical energy, and provides a key idea for designing electrodes with excellent catalytic performance.

Thermoelastic damping in micro-scale T-, U- and Z-shaped frame structures using wave propagation approach

Studying the thermo-mechanical coupling behavior and establishing the thermoelastic damping (TED) model are essential for improving the quality factor of the microelectromechanical resonator. In this work, an analytical TED model for planar frame resonators is first developed using the wave propagation approach. The method is illustrated for typical T-, U- and Z-shaped frame structures and can be extended to more complex frame structures. The frame is viewed as a set of beam segments interconnected by rigid joints, each following the Euler-Bernoulli beam theory. Based on the wave propagation approach, the wave transmission and reflection properties at discontinuities are determined taking into account the flexural and longitudinal motions. The displacement fields of the frame structure are established for both free and forced vibrations. The coupled temperature field of the frame is obtained by solving for the temperature variation arising from the flexural and longitudinal vibrations separately. Finally, the expression of TED is achieved by its energy definition. The validity of the present TED model is confirmed by comparison with finite element (FE) simulations. Numerical results indicate that the TED behavior of frame structures is too complicated to be predicted by previous TED models of simple structures. The often-overlooked longitudinal motion will cause a dramatic TED reduction around specific frequencies. The overall TED is determined by all segments together, and the influence of a segment is reflected by its energy share. Moreover, the effects of different boundary conditions and geometric parameters on TED are evaluated. Practical conclusions to guide the design of high Q-factor resonators are drawn based on the TED behavior of frame structures as summarized from the numerical study.

Research on digital twin modeling method of transformer temperature field based on POD

For the calculation of transient fluid–solid coupling temperature field of transformer, the traditional Galerkin finite element full order model has the defect that the calculation time is up to hours-level, which is difficult to meet the timeliness requirements of the digital twin model. Firstly, the implementation architecture of transformer digital twin based on IoT is established, and the necessity of multiphysical field simulation and model reduction technology for building the digital twin model is introduced. Then, based on the method of transformer digital twin implementation,it is proposed to combine the proper orthogonal decomposition (POD) with the finite element (FE) to establish the Galerkin FE full order model for the governing equation of the transient temperature field, the reduced order mode composed of the first several bases is intercepted to build the reduced order model of transient fluid–solid coupling temperature field. Finally, the POD reduced order model is applied to calculate the temperature rise of a transformer. According to the actual transformer temperature rise test, the temperature values of different measuring points are selected to compare the calculation error and time of the reduced order model and the full order model. The results show that the error between the third order model and full order model meets the criterion of POD truncation error, and the calculation time is shortened by 192 times, which can meet the seconds-level calculation requirements.

Editorial for Special Issue of Field‐assisted Materials Processing: Recent Innovations and Microstructural Evolution

Materials processing, an important branch of materials science and engineering, converts raw materials into practical materials and their products for technological applications. These processing methods are developed to satisfy the service needs based on sound scientific theory. Different processing conditions confer practical materials with controllable microstructures and thus specific mechanical and functional properties. Therefore, developing novel processing methods and exploring the interaction between microstructure and properties under different processing conditions have received much attention in the scientific community, especially in recent years. With the rapid progress of modern science and technology, novel materials processing technologies involve the coupling of multi-physics field, including temperature, stress, electric field, magnetic field, gravity, ultrasonic field, microwave field, etc. The multi-physics field can give rise to some unique thermodynamic and kinetic behaviors during materials processing and thus lead to novel microstructures, such as refined grains, bimodal/multi-modal microstructure, heterogeneous microstructure, etc. Thus, the field-assisted materials processing technology is considered a revolutionary method to fabricate competitive high-performance practical materials. A large and wide group of researchers have been engaged in the study of multi-physics field-assisted materials processing technology and produced remarkable results. The current special issue of Field-assisted Materials Processing: Recent Innovations and Microstructural Evolution collects 28 original research articles and reviews on recent developments in metallurgy and materials, especially in field-assisted materials processing. These articles are representative of some cutting-edge results around the world, with contributions from different countries across the globe. To be specific, laser additive manufacturing coupling temperature and laser field is capable of producing complex products with high efficiency and high precision by high energy and highly focused laser heat source. The influence of laser parameters on associated microstructure evolution and properties during laser additive manufacturing is explored in pure Cu (Adv. Eng. Mater. 2021, 2101138), high-entropy alloys (Adv. Eng. Mater. 2022, 2200131), 316L stainless steel (Adv. Eng. Mater. 2022, 2200641), Inconel alloy (Adv. Eng. Mater. 2022, 2200492), and NiTi shape memory alloys (Adv. Eng. Mater. 2022, 2200504). Spark plasma sintering, which couples temperature-stress-electric field as an integral, is used to fabricate tungsten alloys (Adv. Eng. Mater. 2022, 2200615), Zr-based amorphous alloys (Adv. Eng. Mater. 2022, 2200557), Al-based composites and Ti-Zr-Ni alloys (Adv. Eng. Mater. 2022, 2200327) for enhancing the properties and elucidating the densification mechanisms. Furthermore, magnetic field is the most widely applied energy field among the field-assisted processing methods because of the low cost, convenience and special magnetic effects. Li et. al prepared SmCo-based thin films by magnetic field-assisted magnetron sputtering and the grain refinement under the external magnetic field has largely increased the coercivity (Adv. Eng. Mater. 2022, 2101456). Also, Xu et. al. (Adv. Eng. Mater. 2022, 2200682) summarized the application and influence of magnetic field in various welding techniques, and especially, the effects of the Lorentz force on the arc, molten pool, and dendrite solidification are clarified. In addition, electric field is also utilized to improve the productivity and efficiency of the manufacturing process. Izadpanah et. al (Adv. Eng. Mater. 2022, 2200425) reviewed the investigations on the influence of electrical current parameters on the forming ability, especially through computer simulation approaches, aiming to reach consensus on the underlying mechanisms of the electric effect on formability. This special issue presents some recent developments and achievements in materials science and processing engineering and is helpful to further promote the innovation of scientific research in related fields. We would like to express our sincere gratitude to all the authors of the articles and the editorial staff of Advanced Engineering Materials for producing excellent articles and highly efficient editorial help. We anticipate that more creative attempts on various energy fields-assisted processing techniques and in-depth studies on the effects of multi-physics field on microstructure evolution and associated properties can be expected in the near future.

Modelling of Coupled Temperature Field in Multi-Modal Thermal Process and Its Analytical Solutions

Modelling of Coupled Temperature Field in Multi-Modal Thermal Process and Its Analytical Solutions

Study on the Formation of the Crater and Modified Layer in EDM Titanium Alloys Based on Fluid–Solid Coupled Temperature Field Model

Study on the Formation of the Crater and Modified Layer in EDM Titanium Alloys Based on Fluid–Solid Coupled Temperature Field Model

LES simulation on heavy liquid metal flow in a bare rod bundle for assessment of turbulent Prandtl number

The Westinghouse Electric Company, together with an international team, is developing its next-generation high-capacity nuclear power plant based on lead-cooled fast reactor technology. In general, the Prandtl number of a heavy metal fluid is two orders of magnitude lower than that of water. Because of the low Prandtl number of lead, the thermal boundary layer in the temperature field is much thicker than the viscous boundary layer in the velocity field. Existing engineering turbulence models all use the Reynolds analogy for coupling temperature and velocity fields, but it is not valid for Heavy Lead Metal flow. Therefore, the selection of an appropriate turbulent Prandtl number (Prt) is crucial for lead fluid simulation. The conventional choice of Prt as a constant value of 0.9 is not valid for low-Prandtl-number fluid flow. This paper aims at using an advanced high-fidelity numerical approach, Large Eddy Simulation (LES), to provide detailed insight into the physics of the flow and the associated heat transfer in a rod bundle with liquid metal flows. The results for the global Nusselt number with different Prt values (0.9 ∼ 3.0) indicate that a higher Prt can reduce the predicted Nusselt number by up to 44.1 %. The detailed temperature distributions obtained with RANS and LES are compared to better understand the deviation introduced by the turbulence model. For turbulent flow, the correlations for Nusselt number proposed by Cheng and Tak (2006) are in good agreement with the simulation, especially for a Peclet number < 1000. The analysis shows that the RANS model with Prt = 1.5 shows better agreement on the prediction of local temperature distribution and global Nusselt number. Although the modified local turbulent Prandtl number model shows some improvement over the constant Prt model, the development of a more sophisticated local turbulent Prandtl number model is necessary for further applications.

Tunable β-crystals formation from transcrystallinity to cylindrites at PP/PE interface via using melt penetration engineering

Transcrytallinity plays a critical role in the interfacial crystalline morphology. However, it is rather rare to observe transcrytallinity grown from completely molten surface without using nucleating agent. Herein, we utilize melt penetration engineering to provide a sheared polymeric melt interface in order to tailor interfacial polypropylene (PP) crystalline morphology from β-transcrystals (β-TC) to β-cylindrites. The investigated system containing polymorphic PP as penetrating phase and polyethylene (PE) as penetrated layer were selected. Interestingly, we can clearly observe a continuous and ordered β-transcrystals (β-TC) at PP/PE interface and morphological transition from β-TC to β-cylindrites upon using higher molecular weight PE as the penetrated melt. Foreign PE surface plays an indispensable role in transcrystallinity formation since only α-spherulites were developed during identical PP penetrating PP process. The effects of surface-induced crystallization as well as coupling flow and temperature field have been discussed, in order to offer an insight on interfacial morphological transition. Consequently, melt penetration engineering can provide a facile and scalable route to achieve designed interfacial morphology from β-TC to β-cylindrites, which opens a new perspective to develop interfacial crystalline morphology. • Melt penetration to design interface. • Tunable structure from transcrystal to cylindrite. • β-interfacial morphology is developed.

Temperature damage regularity of granite based on micro-inhomogeneity

Enhanced geothermal system (EGS) is the primary means during Dry Hot Rock development. It is necessary to build an underground heat exchange area during its construction, and the temperature of underground rock will change significantly, thus, the mechanical properties of those rocks underground will be affected. In order to judge whether the mechanical properties under temperature are related to the crystal structure of granite, we firstly used the crystalline rock heterogeneity coefficient H to describe the crystal structure of granite. Then, the discrete element software was used to construct the GBM equivalent crystalline model and the thermal temperature field coupling model. Finally, the temperature effect test was carried out to explore the law of heterogeneity coefficient H and damage and fracture development. The results show that: 1) the variation of granite heterogeneity coefficient H and temperature will lead to the decline of mechanical properties of rock samples. 2) At the same temperature, the damage value D increases with the increase of the H value. This phenomenon is more apparent when the temperature is greater than 400°C. 3) The microcracks caused by temperature change are mainly tensile. The H value increases the number of microcracks in the crystal. 4) The damage phenomenon caused by temperature change will be affected by heterogeneity. When the temperature is high, the crystal will denature, and the stress concentration caused by heterogeneity is easier to be reflected.