Thermal-structural Coupling Analysis Research Articles

Thermal–Structural Coupled Analysis and Design of a Reentry Capsule with Ablative Thermal Protection Systems

Thermal–Structural Coupled Analysis and Design of a Reentry Capsule with Ablative Thermal Protection Systems

Coupled thermal-structural analysis of an axle mounted C/C-SiC brake disc for high-speed trains

This paper examines the thermal and structural characteristics of high-speed train axle-mounted brake discs. Initially, investigate the mechanical and thermophysical properties of C/C-SiC composites. Then, dynamic data including temperature and friction coefficients of brake discs under various pressures and speeds were obtained using a full-scale train brake dynamometer. Based on the above test data, a finite element model of the C/C-SiC brake disc under emergency braking conditions at 350 km/h is established using ABAQUS software. The accuracy of the finite element model was validated through experiments, followed by a thermal-structural coupling analysis of the brake discs. Simulation results indicate the highest temperature of the brake disc occurred at 68.80 s, reaching 869.90 °C; the maximum thermal stress reached 165.44 MPa at 80.54 s; the maximum axial deformation measured 97.56 μm at 91.03 s. Although the times at which the highest temperature, maximum thermal stress and maximum axial deformation occurred were not synchronised, the overall trend was consistent. Based on the verification of experimental and simulation results, it has been confirmed that the brake disc meets the requirements of a 350 km/h high-speed train. This provides a solid theoretical foundation for the structural design and iterative upgrades of high-speed train brake discs.

Research on thermal characteristics modeling for feed system of CNC machine tool considering thermal parameter correction

Feed system is an essential part of machine tools for controlling cutting. The thermal characteristics of the feed system has a significant impact on the machining accuracy for machine tool. To predict the temperature distribution of the feed system accurately, a dynamic thermal analytical approach for feed system is proposed in this paper, which considers the dynamic change process of the bearing and nut heat source affected by thermal deformation. Taking the feed system of machine tool as the research object, the heat source calculation method and stress modeling process considering the influence of thermal deformation is proposed. The thermal-structural coupling analysis of the feed system and the corresponding experimental data are presented. With the comparison of the simulation and test results, it is concluded that the simulation result of the feed system thermal characteristics analysis is in good agreement with the experimental data, and the established model and method can effectively improve the simulation accuracy of the feed system.

Prediction of thermal errors in a motorized spindle in CNC machine tools by applying loads based on heat flux

The thermal errors of a motorized spindle are seen as a source of significant errors in computer numerical control (CNC) machine tools, and motion errors, geometrical errors, among others, that are consequences of the thermal errors in the spindle. A predictive model of the thermal errors of a motorized spindle is proposed using a loading method based on heat flux. At first, a finite element model for the steady-state and transient thermal-structure coupling analysis of a motorized spindle is established, in which the loading method based on heat flux is adopted to assign the total amount of heat to the ball, an inner race, and an outer race of angular-contact ball bearing proportionally. The response values of sample points are obtained by simulation, and then a response surface model for the prediction of the steady-state elongation of the spindle thermal deformation under the influences of four factors including rotational speed of a bearing, coolant temperature, ambient temperature, and preload is constructed. The simulation and experimental results indicate that predictive error of the steady-state elongation of the spindle thermal deformation is only 3.81 μm, and the thermal equilibrium time in the transient thermal-structure coupling analysis is almost same to the experimental result. The response surface model can predict steady-state errors arising from the changes in working conditions and corresponding changes of the spindle.

Effect of the reflector system thermal behavior on the pointing accuracy of large radio telescopes

The thermal behavior of the reflector system under solar radiation has great effects on the pointing accuracy of large radio telescopes. To estimate the dynamic pointing error of large radio telescopes caused by the thermal behavior of the reflector system under solar radiation, the nonuniform temperature field and the thermal deformation of the Wuqing 70 m radio telescope (WRT70) on three specific sunny days are first simulated by finite-element (FE) software. Then the pose variations of the reflector system are calculated equivalently based on the FE thermal-structural coupling analysis of the reflector system. Finally, the dynamic pointing errors of the WRT70 on three specific sunny days, caused by the thermal behavior of the reflector system, are estimated according to the beam deviation factor. The research results show that the rotations of the main reflector and the offsets of the subreflector on sunny days have great influences on the pointing error of large radio telescopes. In addition, the pointing error caused by the rotations of the main reflector and the pointing error caused by the offsets of the subreflector cancel each other out, but the pointing error caused by the rotations of the main reflector plays a dominant role. Furthermore, the effect of the thermal behavior of the reflector system on the pointing accuracy of large radio telescopes is less than the influence of the thermal behavior of the alidade. These findings could provide valuable references for the compensation of dynamic pointing errors of large radio telescopes.

Gas–thermal–solid coupling analysis of a hypersonic inflatable reentry and descent system

Hypersonic reentry has a severe flight environment during spacecraft return. To analyze the influence of pneumatic loads on the flexible structure under the extreme load condition during the deceleration process of inflatable reentry and descent system, fluid–and thermal–solid couplings have been studied. In addition, the stress and structural deformation distributions and the temperature distribution of each functional layer of the flexible thermal protection system were obtained in this study. The influence of flight conditions and structural parameter changes on inflatable structure performance was studied, and the transient response mechanism of the pneumatic load to the inflatable structure was revealed. Ballistic analysis combined with engineering algorithm was used to predicted the flight envelope. The fluid-solid thermal coupling method in Workbench is utilized to realize the real-time transfer of aerodynamic and thermal loads to flexible structures. And the loose coupling method was applied to carried out the one-way transfer of aerodynamic load and thermal load to the surface of flexible structure. The results showed that the mechanical–thermal–structural coupling analysis method could predict the mechanical properties of flexible inflatable deceleration structures, which can provide references for the aerodynamic configuration and thermal protection design under extreme flight conditions.

Design of Quadruple Offset Butterfly Valve Used in Power Plants

The elliptical disc is a specific characteristic of a triple offset butterfly valve (TOBV), but the structure of the elliptical disc leads to a non-uniform distribution of contact at the closing position with non-uniform wear. On the other hand, the continuous processing of elliptical sections to finish the entire disc contour is expensive compared to the processing of a circular section. In the present study, to improve the above disadvantages of an elliptical disc, an elliptic cone function was established to describe the quadruple butterfly valve (QOBV) disc shape, which has a circular section disc. In addition, some designs of a fixed thickness (7 mm) laminated seal for good sealing were proved. Sealing performance simulations were carried out using the thermal–structural coupling analysis. The best design of the QOBV showed that the maximum contact pressure was 37.2% lower than the TOBV using the seven-way laminated seal layers (thickness of A240–316 stainless and graphite was 1.3 mm and 0.6 mm, respectively). Compared to TOBV, the QOBV disc operation during the opening and closing process was faster and smoother. The disc can be applied widely to various industrial fields, engine exhaust systems, and turbine and power plants under severe environments.

Research on optimal multivariate thermal error modeling based on finite-element analysis

To improve the nonlinear fitting ability of multiple linear regression model in thermal error prediction of machine tools, an optimized thermal error modeling method based on test and simulation is proposed in this paper. Firstly, the finite-element analysis is used to complete the thermal-structure coupling analysis of the CNC machine tool. Based on the simulation results of temperature and deformation field of the machine tool, temperature-sensitive points (TSPs) are selected with fuzzy cluster analysis and correlation analysis. According to the simulation results, TSPs of the machine tool are fitted by quadratic polynomial from temperature to deformation. Finally, taking the deformation value of TSPs as the intermediate variable, the multiple linear regression model is established, and the optimized quadratic multiple regression thermal error model is obtained. The results show that the prediction curve of the optimized thermal error model based on on test and simulation is closer to the test curve, and the fitting index is better than that obtained from the traditional model. This method can effectively improve the nonlinear fitting ability of the thermal error model of CNC machine tools. Based on the thermal error model established in this paper, the compensation value of thermal error can be obtained by inputting the real-time measured temperature data of TSPs, which can effectively improve the machining accuracy of CNC machine tools.

Finite Element Analysis of Damage of Cylindrical Roller Bearing of Main Shaft of Shot Blasting Machine

The main shaft of shot blasting machine mainly uses cylindrical roller bearing as the supporting part. The influence of stress, strain and temperature on bearing damage was studied by thermal structural coupling analysis of the bearing through finite element simulation. The causes and main damage forms of bearing surface were verified by super depth of field observation and finite element analysis. It is found that there exists pyramidal strain in the contact area between inner and outer raceway and roller, and its distribution form is continuous point distribution. The stress concentration is mainly distributed in the contact area between the roller face and the retaining edge, and the roller temperature is more concentrated in the area near the end face. The maximum length and depth of spalling pit on racetrack surface were 572.2μm and 14.15μm respectively. The maximum width and depth of the scratches on the roller surface are 386.7μm and 10.7μm, and the damage degree of the roller surface is not uniform. The thermo-structural coupling analysis is used to simulate the running state of bearings, which is of guiding significance to analyze the failure forms of bearings and improve the service life of bearings.

Application of Probabilistic Approach to Investigate Influence of Details in Time History of Temperature Changes on the HCF Life of Integrated Bridge Steel Piles Installed on Water

This research estimates the high-cycle fatigue (HCF) life of integrated concrete bridge installed on water due to temperature changes. To this end, CATIA software was used to geometrically model of a real-scale bridge. Next, thermal–structural coupling analysis was performed by finite element (FE) simulation in ANSYS WORKBENCH software. The comparison technique with experimental data was used to validate the simulation. Afterward, thermal analysis was performed due to air temperature changes in different modes, including the average monthly temperature changes (large variations) as well as the maximum and minimum monthly temperature changes (small variations). The results showed that the most changes in deck length and subsequent maximum deviation in the upper part of steel piles were related to the three warm seasons in the presence of the water. Eventually, a probabilistic approach was employed to find variable amplitude fatigue lifetime of the component based on the number of annual loading blocks. To achieve the high-accuracy response, the effective parameters of the proposed probabilistic approach, including order of Fourier series and the stress range, were optimized automatically. In addition, to obtain HCF behavior of raw material, axial tension–compression fatigue tests were performed on the standard specimens fabricated from steel piles. The results revealed that considering small variations in the calculation of structural fatigue life led to a 550% reduction in life compared to structural analysis due to large variations. In addition, the obtained results were compared with the finite element results.

Thermal Error Analysis of Machine Tool Spindle Based on BP Neural Network

With the continuous improvement of the accuracy of machine tools, the proportion of the thermal error of machine tools in the total error is increasing. In this paper, the thermal error of horizontal machining center is analyzed by finite element simulation, a three-dimensional model is established in SolidWorks, and some details (such as bolt holes) are simplified and imported into ANSYS Workbench to determine the heat generation model, heat dissipation model, convection heat transfer coefficient and other boundary conditions. On the basis of the temperature field, the thermal-structural coupling analysis is carried out, and the temperature cloud field of the whole machine tool is obtained through the analysis, which provides a theoretical basis for the experimental design. Then, the data are divided into four categories by fuzzy cluster analysis, and finally, the thermal error model is established by BP neural network based on time series. It provides a theoretical reference for the compensation of thermal error.

Effect of Groove Texture on Deformation and Sealing Performance of Engine Piston Ring

During the present study, a double groove texture was designed on the surface of a piston ring to improve the sealing performance between the piston ring and cylinder liner. The experimental design method was used to fabricate the test plan according to the groove width, depth, and spacing. By using the thermal–structural coupling analysis method, the finite element analysis of the standard piston ring and the textured piston ring was carried out to simulate the deformation state of the cylinder liner system of the piston ring group during the working stroke. The piston rings with different parameters designed by the test scheme were manufactured by wire electrical discharge machining, and the self-made experiment device carried out the sealing test. The results showed that the groove texture could improve the sealing performance of the piston ring, and the analyzed results demonstrated that the groove texture had little effect on the maximum deformation of the piston ring. Still, it could significantly reduce the minimum deformation of the piston ring group. A piston ring with groove texture would improve the sealing performance and reduce the deformation during the work stroke. During the test, the average deformation of the No.7 piston ring group, with a groove depth of 1 mm, a groove width of 0.5 mm, and a groove spacing of 0.1 mm, was the smallest, about 29.6% lower than that of the standard piston ring group. The sealing performance of the No.7 piston ring group was the best, and the reduction rate of the top gas leakage rate was 52.18%. During the present study, the sealing performance of the piston ring was improved by designing the grooved structure on the piston ring surface, thereby improving the fuel economy and power performance of the engine. The present study could provide a reference for the engineering field to design a piston ring with high sealing performance.

Electrode Layout Optimization and Numerical Simulation of Cast Conductive Asphalt Concrete Steel Bridge Deck Pavement.

In order to obtain the optimal electrode layout and ice melting effect of cast conductive asphalt concrete steel bridge deck pavement, firstly, pouring conductive asphalt concrete was prepared; secondly, different electrode materials and layout methods were selected to test the heating rate of the specimen from start to 120 min, and the electrode materials and layout methods were optimized. Then, the finite element analysis software ANSYS was used to build the model for heating and ice melting simulation, and the indoor test was used to further verify the ice melting effect of the cast conductive asphalt coagulation with or without the insulation layer. Finally, the thermal-structural coupling analysis of cast conductive asphalt concrete steel bridge deck pavement was carried out using ANSYS finite element software. The results showed that the stainless steel electrode material had the best heating effect, and the electrode thickness in the range of 0.1~3mm had no effect on the heating effect. The intermediate heating rate of the upper surface of the stainless steel sheet electrode cast conductive asphalt concrete in the left and right external electrodes was 8 °C/h, while the intermediate heating rate of the upper surface of the stainless steel mesh electrode cast conductive asphalt concrete was 12.9 °C/h. The layout of the left and right buried stainless steel metal mesh was able to effectively improve the snow melting efficiency; ANSYS finite element ice melting simulation was used to obtain the variation law of ice melting efficiency and a temperature field of cast conductive asphalt concrete. The indoor ice melting test showed that when melting the same thickness ice layer at 50 V voltage, it took 240 min with an insulation layer and 720 min without an insulation layer, which was three times that of the ice with an insulation layer, which further verifies the superiority of its ice melting effect. The most unfavorable load position of pavement under load and temperature field was determined. The maximum tensile stress and compressive stress of the pavement surface were transverse, and the maximum shear stress of the pavement bottom was transverse.

Analysis of ACCC failure of composite core glass transition temperature reduction due to brittle damage

The failure analysis of the Aluminum Conductor Steel Reinforced (ACSR) was often based on conventional failure methods such as strength and fracture, and the failure analysis of the Aluminum Conductor Composite Core (ACCC) usually followed the analysis methods of the ACSR. This research proposed a new ACCC failure mode based on the glass transition temperature (Tg) of composite materials. In this paper, a fracture accident of a 500 kV overhead transmission line was discussed. Firstly, impact test found that composite core of the ACCC was more brittle than steel core of the ACSR, and the brittle damage of the composite core was inferred as the cause of the accident in combination with fracture analysis. Then, thermal-structural coupling analysis showed that the axial stress of aluminum wires increased to 33 MPa after the brittle damage of the composite core. Subsequently, thermoelectric coupling analysis showed that the operating temperature (T) of conductor was raised to 151 °C after the increment of the axial stress of the aluminum wires. Finally, in dynamic mechanical analysis, it was shown that the Tg of faulty composite core was reduced to 146.3 °C. According to investigation, the T of conductor was greater than the Tg of epoxy resin in the faulty composite core, resulting in a decrease in the tensile strength of the composite core, which eventually led to the ACCC failure. The failure mechanism proposed in this paper can provide a reference for the prevention and maintenance of ACCC lines in power grid system.

Frost Heaving Damage Mechanism of a Buried Natural Gas Pipeline in a River and Creek Region.

When the buried pipeline passes through the permafrost zone, the phenomenon of frost swelling occurs in the permafrost zone, which causes a certain degree of bending and deformation of the pipeline. As a result, the pipeline’s structural safety is compromised, and the pipeline finally fails during operation, posing a serious hazard to the natural gas pipeline’s operation. Whereas the theoretical research on soil frost heave is relatively comprehensive, the applied research on engineering problems is not yet complete. Therefore, it is necessary to predict frost heaving through experiments and numerical simulation, and put forward reasonable control measures for existing or potential problems. For the problem of pipeline damage caused by frost swelling of soil in the natural gas high-pressure regulator station in a river and creek region, the Drucker–Prager elastic-ideal plastic model of soil was selected for finite element analysis, and a reasonable finite element model of pipe-soil was established in this paper. Through the temperature field analysis, it was found that the soil around the buried pipe is affected by the pipeline and is lower than its freezing temperature, which makes the soil freeze and swell. Furthermore, through the thermal–structural coupling analysis, it was found that the buried pipe is affected by the freezing and swelling of the soil and the structure is greatly likely to be damaged. In addition, by analyzing the temperature distribution and frost heave deformation of the soil around the pipeline, as well as the deformation and force of the pipeline at different pipe temperatures, this paper also determined the ideal temperature for preventing frost heave damage to natural gas at high-pressure regulator stations as −1 °C. Finally, based on the results of the abovementioned analysis, the heating method was determined to improve the frost damage phenomenon at the high-pressure regulator. The results of the anti-frost and swell study were used to conduct field trials at natural gas high-pressure regulator stations where frost and swell had occurred. By adding heating furnace to increase inlet temperature, frost heaving of gas transmission pipeline can be effectively prevented. The results of the research provide a reference for both existing and new natural gas pipelines, and also accumulate experience for winter maintenance design and construction of pipeline engineering in seasonally frozen soil areas.

Thermal-structural coupling analysis of motor rotor under extreme variable working conditions

Thermal-structural coupling analysis of motor rotor under extreme variable working conditions

Effect of quartz crystal thermal stress on its performance in active temperature control quartz crystal microbalance dew point sensors

For accurate dew point identification in active temperature control quartz crystal microbalance (QCM) dew point measurement, the influence of quartz crystal thermal stress effect on its vibration performance was studied. The finite element analysis (FEA) based on thermal structure coupling analysis was conducted to analyze the thermal stress effect of quartz crystal with different parameters. The FEA results showed that the quartz crystal thermal stress had a great influence on its vibration properties, and the influence was related to its temperature values as well as the structural parameters. The diameter, resonant frequency, and the temperature applied region on the non-electrode of the quartz crystal had an influence on its thermal stress effect. Among the above factors, the diameter of the quartz crystal played the main role, and the quartz crystal with a small diameter was less susceptible to thermal stress. Experiments of quartz crystal with different structure parameters were carried out to study the thermal stress effect on its dew point measurement performance, and the results showed that the quartz crystal with a small diameter was less affected by the thermal stress effect and exhibited more obvious dew point recognition features as well as better measurement accuracy and stability.

Thermal–Structural Coupling Analysis of Subsea Connector Sealing Contact

Taking a subsea collet connector as an example, the contact characteristics of the sealing structure of the subsea connector under thermal–structural coupling were studied. Considering the heat transfer problem of the subsea connector in deep water, the heat transfer model of seawater layer between sealing structures was established, and the relationship between equivalent thermal conductivity, composite heat transfer coefficient, and temperature was determined. The steady-state temperature field distribution of the connector under the action of the internal high-temperature oil and gas and external low-temperature seawater was obtained. Considering the stress and deformation of the subsea connector under the thermal load, the thermal–structural coupling analysis model of the steady-state temperature field was established, and the thermal stress theoretical analysis and numerical simulation of the key sealing structures of the connector were compared and verified. Analysis of coupled stress calculation, for example, under a steady-state temperature field, was carried out on the sealing structure of the subsea connector. At the same time, the pressure shock mode under a steady temperature field was analyzed, which showed that the lenticular sealing gasket is sensitive to high pressure under high-temperature conditions.

Thermal–Structural Coupling Analysis for Multiple Honeycomb Plates Connected by Hinges

The dynamical model of multiple honeycomb plates connected by hinges, including the thermal–structural coupling effect, is investigated in this paper. Under the assumption of small deformations and strains, the classical plate theory is used to establish the dynamical model of the honeycomb plate. The Chebyshev polynomial is adopted to describe the deformation of the plate and the linear torsional spring to represent the elastic hinge. Using the Rayleigh–Ritz method, the characteristic equation of the honeycomb sandwich structure is derived, from which the natural frequencies are obtained. Considering the thermal effect of the plate, the thermal–structural coupling dynamical equation is obtained. The thermal conduction in the thickness direction is calculated by the finite difference method. The present model is validated by comparing with the result generated by an equivalent orthotropic plate model established by the finite element (FE) software MSC Patran. The response analysis reveals the important effect of the metal skin and the hinge stiffness on the dynamic characteristics of the honeycomb sandwich structure. Numerical simulations reveal thermal–structural coupling features for the multi-honeycomb-plate structure from the perspective of the change in dynamic characteristics and the distribution of the temperature gradient. The thermal–structural coupling calculation method adopted herein can be used to solve the thermal conduction of the plate. It serves as the theoretical method for analyzing the dynamical behavior of the solar panel subjected to the solar heat.

Optimal design of the disc vents for high-speed railway vehicles using thermal-structural coupled analysis with genetic algorithm

Braking devices are devices that convert kinetic energy into thermal energy using frictional force. A disc-type brake uses the frictional force to brake and can be used in a wide range of applications, such as automobiles, railway vehicles, and aircraft. However, heat dissipation of the disc has been considered a major problem. High temperatures during the braking process cause thermal stress and deformation problems of the disc because the physical properties of metal composing the disc change drastically with temperature. In this study, vents were applied on the disc surface to increase their heat dissipation performance. In general, vents are structurally susceptible to stress and deformation. However, heat dissipation is essential because the disc surface rises to high temperatures. Therefore, a thermal-structural coupled analysis was performed using the computational fluid dynamics and finite element method methods. Five different rotational speeds and surface temperatures of the disc were considered. Design of experiments was used to determine an optimized design utilizing the data from the coupled analysis, and Latin hypercube sampling was used to generate samples from a set of N regions. And the genetic algorithm was used to conduct a sensitivity analysis of the design parameters. The optimized design was determined for harsh conditions. The diameters of vents were selected 6.87 mm, 6.12 mm, and 5.99 mm in a radial direction through the optimization. Thermal stress and deformation acting on the disc were reduced in the optimally designed disc. The optimized disc model experiences a 7.01% decrease in maximum equivalent stress when compared to the original disc. The model also decreased by 7.63% in maximum equivalent elastic strain. So, through enhanced convection-induced heat dissipation, the vents can be considered as a new way to prevent problems with the thermal stress and deformation that were apparent at high temperatures.