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During high-efficiency milling, the mechanical status of the tool system, consisting of the tool and tool holder, is constantly changing due to the high-speed cyclic cutting load and the self-excited vibration of the cutting force. The dynamic mechanical status has a significant impact on the relative position between the tool and workpiece, which directly affects the machining error. Clarification of the dynamics of the tool system subjected to high-speed cutting loads plays a key role for better understanding the energy transfer and offset distribution of the tool system. This paper presented a dynamic model of the tool system in high-efficiency milling process. The hierarchical structure and response characteristics of the energy consumption of milling tool system's interface were researched, the transmission path and distribution of the energy consumption were investigated, and a method for identifying the factors affecting the dynamic energy consumption of milling tool system's interface was proposed. The changing law in relative position of the tool system under the effect of high-speed cutting load was unveiled. Milling machining experiments were conducted to verify the accuracy of the proposed models. [ABSTRACT FROM AUTHOR]

To accommodate the integration of renewable energy, coal-fired power plants must take on the task of peak regulation, making the low-load operation of boilers increasingly routine. Under low-load conditions, the phase transition point (PTP) of the working fluid fluctuates, leading to potential flow instability, which can compromise boiler safety. In this paper, a one-dimensional coupled dynamic model of the combustion and hydrodynamics of a supercritical boiler is developed on the Modelica/Dymola 2022 platform. The spatial distribution of key thermal parameters in the furnace and the PTP position in the water-cooled wall (WCW) are analyzed in a 660 MW supercritical boiler when parameters on the combustion side change under full-load and low-load conditions. The dynamic response characteristics of the temperature, mass flow rate, and the PTP position are investigated. The results show that the over-fire air (OFA) ratio significantly influences the flue gas temperature distribution. A lower OFA ratio increases the flue gas temperature in the burner zone but reduces it at the furnace exit. The lower OFA ratio leads to a higher fluid temperature and shortens the length of the evaporation section. The temperature difference in the WCW outlet fluid between the 20% and 60% OFA ratios is 11.7 °C under BMCR conditions and 7.4 °C under 50% THA conditions. Under the BMCR and 50% THA conditions, a 5% increase in the coal caloric value raises the flue gas outlet temperature by 32.7 °C and 35.4 °C and the fluid outlet temperature by 6.5 °C and 9.9 °C, respectively. An increase in the coal calorific value reduces the length of the evaporation section. The changes in the length of the evaporation section are −2.95 m, 2.95 m, −2.62 m, and 0.54 m when the coal feeding rate, feedwater flow rate, feedwater temperature, and air supply rate are increased by 5%, respectively. [ABSTRACT FROM AUTHOR]

Shield tunneling can cause deformation of the interlayer soil. Traditional static methods do not consider the shield dynamic load and the construction influence on the dynamic performance of interlayer soil, resulting in inaccurate results. Therefore, this paper proposes a dynamic analysis method to assess soil deformation. Firstly, the composition and stress state of interlayer soil were monitored on site. Secondly, the dynamic triaxial tests were conducted based on the monitoring results to analyze the soil dynamic characteristics. Then, a dynamic constitutive model of the interlayer soil was constructed, which considers the change of the dynamic performance. Finally, the dynamic effect of shield on soil is simulated based on viscoelastic mechanics, and the dynamic analysis of interlayer soil deformation is realized by three-dimensional finite element method. The results indicate that the interlayer soil near the excavation face is more significantly affected during the crossing stage. Shield construction increases the dynamic strength and dynamic modulus of the interlayer soil, while reducing the damping ratio. The Hardin-Drnevich model and the logarithmic-linear model can well describe the evolution laws of dynamic modulus and dynamic strength. The dynamic analysis method is closer to real construction and has higher prediction accuracy. [ABSTRACT FROM AUTHOR]

The dynamic characteristics of an electromagnetic actuator used in a switching valve are influenced by self-induced effects, resulting in instability in its parameters when subjected to changes in working frequency, load, and other conditions. To quantitatively analyze the impact of variable working conditions, this study establishes an analytical expression for periodic signals through Fourier series expansion. It subsequently solves for transient current, yielding a new model for the response of the electromagnetic actuator under periodic signal excitation. Simulations and analyses are conducted to investigate the variation in action parameters of the electromagnetic actuator in the realm of compressor gas regulation when working conditions, such as rotation speed and load force, are altered. The results indicate that dynamic characteristics of the actuator change within the range of 8% to 35%, significantly affecting the gas regulation efficiency of the compressor. To mitigate this effect, a backstepping adaptive high frequency controller (BAHF) is proposed. Comparative assessments with the backstepping adaptive sliding model controller (BASM) and backstepping adaptive high gain controller (BAHG) reveal that the BAHF exhibits superior overall performance. An experimental platform is constructed to validate both the model's accuracy and the controller's effectiveness. The error between model simulations and experiments does not exceed 7.5%, confirming the accuracy of the model. The proposed BAHF reduces the fluctuation of compression and exhaust phase angles in the compressor by 21.6% and 6.6%, respectively, under variable working conditions. This reduction effectively suppresses the influence of working condition disturbances, yielding positive outcomes. [ABSTRACT FROM AUTHOR]

Aiming at the high-speed railway (HSR)-China Railway Track System III (CRTS III) slab ballastless track (SBT)-simply-supported bridge system, the mapping relationship between girder deformation and rail deformation had been deduced theoretically, and then, the additional irregularity of the rail was obtained. A dynamic model of the high-speed train-track-bridge (TTB) coupling system was established according to existing theory on the high-speed TTB dynamic interactions. Combined with the mapping relationship, taking the superposition of the additional irregularity and the random irregularity as excitation, the dynamic response of two train models (CRH2 and ICE3 trains) was analysed by using the high-speed TTB coupling system model. The recommended thresholds of girder deformation were given based on running safety and ride comfort indicators. The results show that the sensitivities of the two train models exposed to girder deformation were different, and the CRH2 train was more sensitive to the lateral girder deformation. The non-uniform dislocation deformation of multiple girders exerted a slightly more significant effect on the dynamic characteristics of two train models than the dislocation deformation of single girder. Under the same amplitude of girder deformation, the influences of vertical girder dislocation and vertical girder rotation on the running safety and ride comfort of trains were significantly greater than that of lateral girder dislocation and lateral girder rotation. Acceleration and wheel-rail force increase rapidly in the area of girder deformation. To guarantee running safety and ride comfort of trains, this paper proposes suggested values for girder deformation thresholds. [ABSTRACT FROM AUTHOR]

With the rapid development of wind power generation in recent years, the demand for detecting weak signals of wind turbine faults has become more urgent. This paper introduces a novel memristor chaotic circuit constructed based on third-order magnetically memristors. The Melnikov chaotic condition of this circuit is analyzed, and its dynamical characteristics are studied through phase trajectory diagrams, bifurcation diagrams, Lyapunov exponent spectra, and Poincaré maps. Leveraging the initial value sensitivity and noise immunity of chaotic systems, the memristor chaotic circuit is employed for the detection of weak signals in wind turbine faults. Using the chaotic system state transition method, we find the threshold for the circuit state to transition from chaotic state to large-scale periodic state, adjust the parameters to make the system in a critical state, input the wind turbine fault vibration signal, and detect the fault signal based on its state transition. Subsequently, the chaotic resonance method is employed, introducing the signal under test, which contains high-intensity chaotic noise, into this novel memristive circuit. This results in chaotic resonance, causing the noise components to be concentrated toward the frequency region where the weak signal under test is located, thereby enhancing the fault signal and facilitating fault identification. The results indicate that this novel memristor chaotic circuit possesses advantages such as high accuracy, strong noise immunity, straightforward operation, and clear judgment in the field of weak signal detection. This circuit shows promising applications in the field of weak signal detection. [ABSTRACT FROM AUTHOR]

Real-time quality monitoring through molten pool images is a critical focus in researching high-quality, intelligent automated welding. However, challenges such as the dynamic nature of the molten pool, changes in camera perspective, and variations in pool shape make defect detection using single-frame images difficult. We propose a multi-scale fusion method for defect monitoring based on molten pool videos to address these issues. This method analyzes the temporal changes in light spots on the molten pool surface, transferring features between frames to capture dynamic behavior. Our approach employs multi-scale feature fusion using row and column convolutions along with a gated fusion module to accommodate variations in pool size and position, enabling the detection of light spot changes of different sizes and directions from coarse to fine. Additionally, incorporating mixed attention with row and column features enables the model to capture the characteristics of the molten pool more efficiently. Our method achieves an accuracy of 97.416% on a molten pool video dataset, with a processing time of 16 ms per sample. Experimental results on the UCF101-24 and JHMDB datasets also demonstrate the method's generalization capability. [ABSTRACT FROM AUTHOR]

Dimensional deviations in the cage pocket of a roller bearing can significantly affect the bearing's dynamic performance, directly determining the positional stability of the roller. These deviations can result in roller misalignment, increasing friction and wear. Deviations arise from machining errors and deformation during motion, etc. A dynamic model of a cylindrical roller bearing that accounts for cage flexibility was developed to explore the impact of deviations. The flexible cage provides a more realistic representation compared to the rigid cage. The effects of deviations in the length and width of the cage pocket on the bearing's dynamic behavior were analyzed, and the results show that deviations in cage pocket dimensions lead to notable changes in bearing dynamics. Specifically, when the length deviation is negative and increasing, the amplitude of cage motion decreases, while both transitional and rotational speeds rise. It also causes greater fluctuations in the rotational speeds of the inner ring and rollers. Conversely, the cage's equivalent stress and the contact load decrease and the amplitude of cage motion increases with increases in width deviation. [ABSTRACT FROM AUTHOR]

To enhance the design and research work on dynamic characteristics of high-rise laminated timber buildings, this paper carried out a modal analysis study on one of the largest laminated timber buildings in China. The finite element calculating modal analysis was carried out using SAP2000 software, and the experimental modal analysis of the building was carried out via environmental excitation. The calculating modal results and the experimental modal results showed good agreement. The calculating modal frequency values were generally lower than the experimental modal frequency values. The natural frequencies obtained by the two methods appeared in the Y-direction first-order bending mode and had values of 2.03 and 2.5 Hz, respectively. The corresponding frequencies of the first-order torsional mode were 2.82 and 3.25 Hz, respectively. The distribution of the CLT core tube along the length direction of the building has an impact on the vibration mode. The six-story part shows the second-order bending form, while the four-story section only shows the first-order bending form. The above work provides a case study and reference for the simulation and modal analysis of high-rise laminated timber buildings, demonstrating the critical role of the core tube structure in such wooden buildings. This insight contributes to a better understanding of structural performance and design considerations in similar projects. [ABSTRACT FROM AUTHOR]

AbstractIn this paper, a thermo-flexible coupled dynamic model of composite laminates is established by Absolute Nodal Coordinate Formulation (ANCF). In order to solve the problem of mesh mismatch and precision inconsistency between the displacement and temperature fields in the traditional thermo-flexible coupled modeling method, the ANCF hybrid element with integrated temperature description is constructed to achieve a unified description of the displacement and temperature fields. A new ANCF thin shell element with thermal effects is proposed. Based on the first law of thermodynamics, the heat capacity matrix, thermal conduction matrix, blackbody radiation matrix, internal heat source vector, and heat flux density vector caused by solar radiation for the ANCF thin shell element considering thermal effects are derived. The dynamic equation of ANCF composite laminates under a unified description is derived, and its dynamic model is established. The thermo-flexible dynamic response of ANCF composite laminates under thermal conduction, space thermal radiation, and solar radiation is analyzed by numerical simulation. The simulation results reveal the evolution process of the transient temperature field and the phenomenon of thermal-induced vibration, thus confirming that the thermal effects have an important influence on the dynamic behavior of ANCF composite laminates. The research provides a theoretical basis for the ground test of solar panels. [ABSTRACT FROM AUTHOR]

Rock‐ice avalanches have frequently occurred in the Eastern Himalayan Syntaxis region due to climate change and active tectonic movements. These events commonly trigger catastrophic geohazard chains, including debris flows, river blockages, and floods. This study focuses on the Zelongnong Basin, analyzing the geomorphic and dynamic characteristics of high‐altitude disasters. The basin exhibits typical vertical zonation, with disaster sources initiating at elevations exceeding 4000 m and runout distances reaching up to 10 km. The disaster chain movement involves complex dynamic effects, including impact disintegration, soil‐rock mixture arching, dynamic erosion, and debris deposition, enhancing understanding of the flow behavior and dynamic characteristics of rock‐ice avalanches. The presence of ice significantly increases mobility due to lubrication and frictional melting. In the disaster event of September 10, 2020, the maximum flow velocity and thickness reached 40 m/s and 43 m, respectively. Furthermore, continuous deformation of the Zelongnong glacier moraine was observed, with maximum cumulative deformations of 44.68 m in the distance direction and 25.96 m in the azimuth direction from March 25, 2022, to August 25, 2022. In the future, the risk of rock‐ice avalanches in the Eastern Himalayan Syntaxis region will remain extremely high, necessitating a focus on early warning and risk mitigation strategies for such basin disasters. [ABSTRACT FROM AUTHOR]

The purpose of this research is to design a flexible variable stiffness damping mechanism to solve the load impact problem in the grinding process of permanent magnet electric spindle. Firstly, combined with the structure and usage scene of the grinding permanent magnet electric spindle, according to the design principles and technical indicators, a novel flexible variable stiffness vibration damping joint is proposed. Then the stiffness and energy storage model of the flexible variable stiffness damping mechanism is established, and the stiffness and energy storage characteristics of the mechanism are analyzed. The strength and dynamic characteristics of the flexible variable stiffness mechanism are analyzed by Ansys and Adams, respectively. Finally, an experimental platform for the comprehensive performance verification of the flexible variable stiffness damping mechanism is built to verify the dynamic characteristics and damping effect of the mechanism. The research results show that the designed flexible variable stiffness structure has better vibration damping effect and can improve the grinding performance of the permanent magnet electric spindle. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The wear of rotating pair is a significant factor for the failure of mechanical systems. Currently, some scholars have undertaken investigations on wear clearance, but these works often concentrate on basic systems with even wear clearance, while investigations on multibody systems with uneven wear clearances remains scarce. In addition, the research on wear clearance often focuses on theoretical exploration and computer simulation, while the test research is relatively few. Therefore, a modeling method for 9-bar mechanism with multiple uneven wear clearances is derived by using the Archard model and Lagrange method, the effects of wear times and initial clearance values on dynamic characteristics and nonlinear dynamics of mechanism considering uneven wear clearances are investigated. The test bed of 9-bar mechanism considering clearances is designed and the validity of the theoretical model has been confirmed through a comparison between the collected test data and theoretical data. This paper supplies theory for accurately predicting the dynamic characteristics of multibody system containing uneven wear clearances, and provides proof for identifying and repairing the design defects of mechanism. [ABSTRACT FROM AUTHOR]

This study aims to assess the dynamic performance of the vertical-axis wind turbine (VAWT) with the help of conventional aluminum (Al) and the boron Al metal matrix composite (MMC). The simulations were conducted using ANSYS software and involved natural frequencies, mode shapes, a mass participation factor, and Campbell plots. The results of static structural analysis show that the boron Al MMC is vastly superior to the aluminum alloy because there is a 65% reduction of equivalent stress with a 70% reduction of deformation compared to the aluminum alloy. These results show that boron Al MMC can withstand higher loads with lesser stress; the structure remains compact and rigid in its working conditions. From the findings, it can be ascertained that employing boron Al MMC improves VAWT power, efficiency, and robustness. However, the critical speed that was established in the dynamic analysis of boron Al MMC requires extraordinary control and the use of dampening systems, thereby avoiding resonance. Overall, boron Al MMC contributes to significant enhancements in the VAWTs' mechanical and operational characteristics; however, the material's complete potential can be achieved only with proper maintenance and employing the correct damping techniques. Information about these two materials will allow for a better understanding of their comparative efficacy and their potential application in the further development of VAWTs. [ABSTRACT FROM AUTHOR]

To address the challenge of measuring the dynamic characteristic parameters of the gas turbine rotor system affected by hull excitation, a vibration transmission model integrating a ship model slice, test data, and a three-dimensional entity is proposed, based on the two-dimensional slice theory, scaled ship model, and finite element model of the turbine rotor system. The transient dynamic responses of the front and rear bearing points were calculated and analyzed. Vibration response tests with significant wave heights of 0.5 m, 1.25 m, 2.5 m, and 4 m were carried out in the towing tank of the ship model to obtain the dynamic characteristic parameters of the deck position. Techniques including wavelet denoising, Fast Fourier Transform (FFT), and signal resampling were employed to filter out and reconstruct high-frequency noise, overcoming the technical challenges of a high sampling frequency and a low computational efficiency. The experimental data and simulation results were compared and analyzed, validating the accuracy of the vibration transmission model of the turbine rotor system with data and entity integration. By comparing the vibration signal values in the X and Z directions at the front and rear bearing points after vibration transmission, it is evident that the effective values of the vibration signals at the front bearing point are 0.03% to 0.1% greater than those at the rear bearing point. This model provides a theoretical basis and reference for the design of the gas turbine rotor system. [ABSTRACT FROM AUTHOR]

The article presents a combined mathematical model that allows us to determine and investigate the dynamic characteristics of the latest type of non-contact sealing for pump and compressor shafts, which eliminates leakage of pumped products, which are important from the point of view of safe operation. The proposed method is based on the laws of conservation of energy and conservation of matter. The model is based on static and dynamic calculation of operation characteristics, while its key feature is the combination of analytical, variational and numerical solutions. The materials of the article may be useful to developers of new types of contactless seals of centrifugal machines. [ABSTRACT FROM AUTHOR]

The brake system is a key component of a high-speed train, which suffers intense wheel-rail interactions caused by wheel polygonal wear (WPW) in realistic working conditions. To explore the dynamic characteristics of the disc brake systems with WPW, a rigid-flexible coupled vehicle dynamics model is proposed. The developed model systematically takes into account the flexible deformation of brake components and wheelsets, measured WPW and non-linear factors such as wheel-rail interaction, disc-pad friction and non-linear damping characteristics. It allows the dynamic behaviors of the vehicle brake system in service to be accurately and effectively revealed. The model is verified using line test data, and then the dynamic characteristics of disc brake systems with WPW are investigated in details. The results show that for vehicle speed below 80 km/h and depths of WPW below 0.04 mm, the effect of WPW on the vibration of the caliper is slight. However, as vehicle speed and wear depth continue to rise, the vibration of the caliper increases noticeably. Furthermore, the effects of vehicle speed and wear depth on brake disc vibration are more obvious, and increasing vehicle speed and wear depth will steadily deteriorate the vibration of the disc. Besides, the effect of WPW is particularly pronounced on the dynamic behavior of the brake units closer to the wheels. Overall, the influence of wheel polygon cannot be neglected in the study of dynamic characteristics of brake system. At the same time, the proposed model can also be applied in the strength evaluation of brake components and the study of the tribological behaviors within the brake interface. [ABSTRACT FROM AUTHOR]

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

AbstractComposite laminates are widely employed in the fabrication of solar panels in modern spacecraft engineering because of their superior durability, mechanical qualities, and cost-effectiveness. This research is dedicated to multibody system dynamics modeling of composite laminate solar panels, specifically the coupling system between the rigid main body and the flexible solar panels. In this study, the rigid body is modeled using the natural coordinate formulation (NCF), and for the flexible solar panel, the absolute nodal coordinate formulation (ANCF) with a 36-DOF reduced-order composite thin shell element is used to accurately capture the coupling effect of the solar panel under large motion and deformation. Compared to a 48-DOF fully parameterized thick plate element, this method efficiently avoids shear locking and improves numerical solution convergence efficiency. Based on the Kirchhoff theory and the constitutive relationship of composite laminates, a dynamic model of the multibody system is developed, taking into account the rigid-flexible coupling effect and the kinematic constraints. This work thoroughly discusses the dynamic behavior of solar panel deployment using a comparative analysis of numerical simulation and virtual prototype simulation, and the accuracy is verified. The findings indicate that the flexible characteristics and fiber orientation of composite laminates have a significant impact on the dynamic response of solar panels during deployment. Furthermore, the bang-bang attitude controller is designed, and the difference in dynamic response between the two modeling methods in controlled and uncontrolled states is studied, providing an important theoretical foundation and technical support for solar panel design and analysis. [ABSTRACT FROM AUTHOR]

This paper presents an experimental analysis of a high-response piezoelectric actuator system for the modular design of hydraulic digital fluid control units. It focuses on determining static and dynamic characteristics, forming the basis for developing a smart Industry 4.0 component that incorporates both actuator and sensor function. The design process examines the main challenges, advantages, disadvantages, and working principles to define parameters that impact the actuator's behaviour and performance. The new piezoelectric actuator system features three piezoelectric stack actuators in series, enabling simultaneous actuation and sensing by applying and measuring the electrical voltage at each piezo element. The experimental setup and test methodology are explained in detail, revealing that the new design, combined with an appropriate open-loop or closed-loop control method, offers superior actuator stroke control, high stroke resolution, and a high-dynamic step response. This paper proposes a concept of a smart piezo actuator system focused on I4.0 and an actuator administration shell, integrated with 5G and RFID technology, which will allow automatic plug-and-play functionality and efficient interconnection, communication, and data transfer between the hydraulic valve and the piezoelectric actuator system. [ABSTRACT FROM AUTHOR]

Tailings dams play a critical role in ensuring the safety of mining operations. However, earthquakes can cause breaches in these dams, resulting in significant casualties and property damage. This study investigates the dynamic response characteristics of uranium tailings dams subjected to seismic loading, employing the discrete element method. It specifically analyzes how seismic wave amplitude, frequency, and the friction angle of tailings sand affect the dams' dynamic response. The results reveal that the peak ground acceleration ratio (PGAR) exhibits an increasing–decreasing–increasing pattern with elevation. When the friction angle of the tailings sand exceeds 35°, the overall stability of the dam improves. Conversely, a friction angle below 25° significantly increases the risk of dam failure. Additionally, the dam shows a reduced dynamic response to seismic waves with frequencies exceeding 15 Hz. At lower frequencies, deformation and damage are primarily concentrated on the slope face, while at higher frequencies, damage is predominantly located at the bottom of the model. These findings provide a theoretical foundation and reference for the safe operation of tailings dams, highlighting their practical significance. [ABSTRACT FROM AUTHOR]

In this study, the seismic performance of an ancient pagoda with significant historical and cultural values in China is upgraded by using overall friction pendulum bearing (OFPB) seismic isolation technology, This technique can be used to isolate the pagoda without damaging it. By implementing the OFPB seismic isolation retrofit on the pagoda and comparing and analyzing it with the unretrofitted seismic model, the response of the pagoda under the action of nine seismic waves of three types, namely, near-field earthquakes, far-field earthquakes, and common earthquakes, is investigated. The results show that the OFPB seismic isolation technique significantly reduces the seismic response of the ghats, in which the acceleration amplification factor is reduced by a maximum of 82.46%, the inter-story displacement is reduced by a maximum of 85.15%, and the base shear force is reduced by a maximum of 96.76%. In addition, the tensile damage of the ghats with OFPB seismic isolation was significantly controlled. While the model without seismic isolation has serious damage under the same seismic action and even faces the risk of collapse. The results of the study confirm that the OFPB seismic isolation technology plays a key role in improving the seismic performance of the tower, which is of great theoretical and practical significance to the protection of the tower, and provides an effective technical way for the protection of the tower in the seismic-prone areas. [ABSTRACT FROM AUTHOR]

Machine tool vibrations play a significant role in hindering productivity during machining. The growing vibrations accelerate tool wear and chipping, cause a poor wave surface finish, and may damage the spindle bearing. Some research showed that tribological properties such as friction factors can have obvious influences on the topography of rough surfaces and the nonlinear dynamic characteristics of machine tool systems. Therefore, studying the vibration friction dynamic characteristics on the normal contact stiffness (NCS) of joints of CNC machine tools is absolutely necessary for improving the machining accuracy and precision of the whole system. The study results of NCS of joints of the CNC and the friction coefficient are discussed in this paper. The model of NCS based on fractal parameters was obtained. The models of deformations of the rough surfaces and contact surfaces were deduced. The results showed that the NCS based on the calculation method considering the elastic–plastic deformation of the asperity is much higher in precision than the methods considering only elastic or plastic deformation separately. The observations this paper described suggest that in the CNC machine tools system, higher D and G and higher friction coefficients lead to higher normal contact stresses (NCSs). [ABSTRACT FROM AUTHOR]

The scraper conveyor, essential for mechanized mining, operates in harsh underground environments and is subjected to severe impact loads from coal and rock falls. Such conditions can cause chain jamming, breakage, and other malfunctions, necessitating a detailed study of the system's dynamic behavior under impact conditions. This study investigates the dynamic characteristics of a scraper conveyor's chain drive system using a coupled ADAMS-EDEM simulation model. The model analyzes the effects of loaded coal piles on the conveyor's dynamics during normal and impact conditions. Simulations show that loaded coal piles excite the scraper's acceleration and sprocket rotation, with the greatest impact in the scraper's running direction. Longitudinal impact and contact forces on the chain ring are more significant than in other directions under both no-load and loaded conditions. A strong linear relationship exists between the falling coal mass and longitudinal impact force. The coal pile causes prominent longitudinal vibration excitation while inhibiting the overall vibration of the chain drive system to some extent. The findings provide insights for identifying failure-prone areas under impact conditions and offer theoretical guidance for optimizing scraper conveyor design. This enhances mining efficiency and safety in coal operations. [ABSTRACT FROM AUTHOR]

Copyright of Guangdong Architecture Civil Engineering is the property of Guangdong Architecture Civil Engineering Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Dynamical modeling of spur gears with typical faults is crucial research topic for understanding fault features and vibration mechanisms. Meanwhile, the lubrication plays an important role in dynamic model. In this work, a novel coupled model combined dynamic model with elastohydrodynamic lubrication model is proposed by considering typical faults action mechanisms. A modified backlash error model takes into account the deformation and oil film backlash to calculate the time-varying backlash. The Runge–Kutta, multigrid integral and five-level Dmeyer wavelet transform method are combined to calculate the lubrication properties and dynamic characteristics at each meshing position along the line of action. Influences of typical faults on the contact performance, such as pressure distribution, oil film thickness, vibration response and bifurcation chaotic behavior are studied. The results show that the typical faults have a significant impact on both the lubrication and dynamic characteristics of the system. The spatial placement of faults can significantly alter the distribution of lubrication parameters. The disturbance of gear faults cause the system attractor unfold and the phase trajectory diffuse and make the system tend to be unstable. The typical faults are more sensitive at low excitation frequencies and less affected at high excitation frequencies. The research provides a basis for the fault diagnosis and detection of gearbox. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Xi'an Jiaotong University is the property of Editorial Office of Journal of Xi'an Jiaotong University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Petroleum Machinery is the property of China Petroleum Machinery Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Because of the fast take-off speed of badminton, a single action recognition method can't quickly and accurately identify the action. Therefore, a new badminton take-off recognition method based on improved deep learning is proposed to capture badminton take-off accurately. Collect badminton sports videos and get images of athletes' activity areas by tracking the moving targets in badminton competition videos. The static characteristics of badminton players' take-off actions are extracted from the athletes' activity areas' images using 3D ConvNets. According to the human joint points in the badminton player's target tracking image, the human skeleton sequence is constructed by using a 2D coordinate pseudo-image and 2D skeleton data design algorithm, and the dynamic characteristics of badminton take-off action are extracted from the human skeleton sequence by using LSTM (Long-term and Short-term Memory Network). After the static and dynamic features are fused by weighted summation, badminton take-off feature fusion results are input into a convolutional neural network (CNN) to complete badminton take-off recognition. The CNN pool layer is improved by adaptive pooling, and the network convergence is accelerated by combining batch normalization to further optimize the recognition results of badminton take-off. Experiments show that the human skeleton model can accurately match human movements and assist in extracting action features. The improved CNN has greatly improved the accuracy of recognition of take-off actions. When recognizing real images, it can accurately identify human movements and judge whether there is a take-off action. [ABSTRACT FROM AUTHOR]

The elaborated paper presents a series of methodologies with which the dynamic characteristics (damping coefficient, damping factor) can be determined, depending on the working conditions, of a hyperelastic material using vibration theory. These methodologies can be extended to characterize any type of hyperelastic material. The main aim of this work is to develop experimental technology and methodology to characterize this type of materials like rubber to establish a series of dynamic factors like damping factor, transmissibility at resonance, pulsation at resonance, dynamic elastic constant. These characteristics are variable, depending on composition, request, etc. In conclusion, they are not available in specialized literature as are the characteristics of linear-elastic materials. The application of numerical calculation programs in carrying out resistance calculations, in the case of structures made of such materials, is also impossible to achieve, having as an impediment the lack of knowledge of the values of the material characteristics. [ABSTRACT FROM AUTHOR]

The dual-input single-output (DI-SO) cylindrical spur gear system possesses advantages such as high load-carrying capacity, precise transmission, and low energy loss. It is increasingly becoming a core component of power transmission systems in maritime vessels, aerospace, marine engineering, and construction machinery. In practical operation, the stability of the DI-SO cylindrical spur gear system is influenced by complex excitations. These excitations lead to nonlinear vibration, meshing instability, and noise, which affect the performance and reliability of the entire equipment. Hence, the dynamic performance of the DI-SO cylindrical spur gear system is thoroughly investigated in this research. The impact of excitations and nonlinear factors on the dynamic characteristics was investigated comprehensively. A comparative analysis of the gear system was conducted by establishing a bending–torsional coupling vibration analysis model under synchronous and asynchronous meshing conditions. Nonlinear factors such as periodic time-varying meshing stiffness, meshing damping, friction coefficient, friction arms, load sharing ratio, comprehensive transmission error, and backlash were considered in the proposed model. Then, the effect laws of excitations and nonlinear factors such as meshing frequency, driving load fluctuation, backlash, and comprehensive transmission error were analyzed. The results indicate that the dynamic characteristics exhibited staged stable and unstable states under different meshing frequencies and meshing conditions. At the medium-frequency meshing stage (0.96 × 104~1.78 × 104 Hz), alternating phenomena of multi-periodic, quasi-periodic, and chaotic motion states were observed. Moreover, the root mean square value (RMS) of the dynamic transmission error (DTE) in the asynchronized gear system was generally higher than that in the synchronized gear system. It was found that selecting the appropriate meshing condition could effectively reduce the amplitude of the DTE. Additionally, the dynamic performance could be significantly improved by adjusting control parameters such as driving load fluctuation (0~179 N), backlash (0.8 × 10−4~0.9 × 10−4 m), and comprehensive transmission error (7.9 × 10−4~9.4 × 10−4 m). The research results provide a theoretical guidance for the design and optimization of the DI-SO cylindrical spur gear system. [ABSTRACT FROM AUTHOR]

Water entry slamming is a complicated issue in marine engineering, characterized by significant impact loads and complex flow. This paper establishes a 3D numerical model of flat plate water entry slamming based on smoothed particle hydrodynamics (SPH), and the dynamics and flow field evolution are analyzed during water entry. The results indicate that SPH effectively captures the key dynamic characteristics of flat plate water entry. The experimental data validate the model, and the SPH particles reproduce the phenomena of jet formation, cavity development, and fluid splashing. The observed pressure is maximum at the center of the flat plate, and the maximum pressure and vertical force of the flat plate exhibit a quadratic relationship with the water entry velocity. The flow field evolution from initial jet formation at the time of slamming to droplet splashing shows obvious stages. As the water entry depth of the flat plate increases, the growth rates of the cavity width and splash height gradually slow under fluid viscosity and drag. The water entry velocity has the greatest influence on droplet splashing, whereas its influence on the jet separation point and the position of the free liquid surface is less significant. [ABSTRACT FROM AUTHOR]

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Planetary gear train is an important part of automatic transmission. The oil film between teeth is one of the key factors affecting the torsional vibration of planetary gear train. Selecting the appropriate oil film stiffness is of great significance for analyzing the nonlinear dynamic characteristics of planetary gear train. A method for analyzing the nonlinear dynamic characteristics of planetary gear system torsional vibration considering the oil film force between teeth is proposed in this paper. A 3-DOF torsional vibration model of planetary gear train considering oil film is established. In this model, the oil film between teeth is equivalent to a time-varying nonlinear spring-damper element, and nonlinear factors such as backlash and meshing error are also considered. The effects of meshing oil film thickness on oil film stiffness and damping are analyzed, and the torsional vibration characteristics of planetary gear train under different meshing stiffness, meshing damping ratio, and rotational speed are analyzed based on bifurcation diagrams. The results show that in one meshing cycle, the meshing oil film thickness first becomes larger and then becomes smaller. When the meshing oil film thickness increases, the meshing oil film stiffness and the equivalent meshing oil film damping become smaller. The torsional vibration of planetary gear train can be effectively reduced by increasing meshing stiffness, damping ratio, rotational speed within a certain range. This method provides technical support for reducing torsional vibration of planetary gear train and realizing stable transmission of planetary gear train. [ABSTRACT FROM AUTHOR]

To further investigate the role of vibration isolation structure in torpedo noise control, in this paper, a dynamic characteristic identification bench of vibration isolation materials based on a beam model was established, and the elastic modulus and damping of poly-ether-ether-ketone materials were identified and verified. The finite element model of bolt vibration isolation structure was established, and the accuracy of the model was verified. The model was applied to the connection between the torpedo engine and the shell. Combined with the vibration isolation ring modeling theory and bolt vibration isolation structure, a torpedo-powered vibration isolation simulation model was established for the first time. The simulation results show that the vibration noise of torpedoes can be reduced by 3.64 dB by comprehensively using vibration isolation rings combined with bolt connections. The results provide strong theoretical support for torpedo vibration noise control.

This study introduces a novel hydraulic mount designed to achieve broad-spectrum engine vibration isolation. While previous studies have focused on vibration isolation using hydraulic mounts, there is a scarcity of research on achieving wideband vibration isolation with such mounts. To address this gap, this article proposes a new bell plate hydraulic mount structure that includes an inertia channel, a decoupler membrane, and two bell plates. First, the study analyzes the impact of structural parameters on the dynamic characteristics of the new bell plate hydraulic mount across high and low frequencies. Second, it compares how varying the number of bell plates affects the hydraulic mount’s dynamic behavior across different frequency ranges. The findings reveal the following key points: (1) The number of bell plates has minimal influence on the low-frequency dynamic characteristics of the hydraulic mount. (2) Increasing the number of high-frequency bell plates from n = 0 to n = 2 reduces the peak dynamic stiffness of the hydraulic mount by 69.88% and decreases the hysteresis angle by 37.71%. (3) At higher frequencies, the dynamic characteristics of the hydraulic mount are notably influenced by parameters such as the equivalent cross-sectional area A m2 of the second bell plate, the surrounding equivalent cross-sectional area of the hole A t2, and the fluid inertia coefficient I t2 associated with bell plate 2.

Abstract In this study, the seismic performance of an ancient pagoda with significant historical and cultural values in China is upgraded by using overall friction pendulum bearing (OFPB) seismic isolation technology, This technique can be used to isolate the pagoda without damaging it. By implementing the OFPB seismic isolation retrofit on the pagoda and comparing and analyzing it with the unretrofitted seismic model, the response of the pagoda under the action of nine seismic waves of three types, namely, near-field earthquakes, far-field earthquakes, and common earthquakes, is investigated. The results show that the OFPB seismic isolation technique significantly reduces the seismic response of the ghats, in which the acceleration amplification factor is reduced by a maximum of 82.46%, the inter-story displacement is reduced by a maximum of 85.15%, and the base shear force is reduced by a maximum of 96.76%. In addition, the tensile damage of the ghats with OFPB seismic isolation was significantly controlled. While the model without seismic isolation has serious damage under the same seismic action and even faces the risk of collapse. The results of the study confirm that the OFPB seismic isolation technology plays a key role in improving the seismic performance of the tower, which is of great theoretical and practical significance to the protection of the tower, and provides an effective technical way for the protection of the tower in the seismic-prone areas.

Although various vibration energy harvesters have been designed over the past few decades, efforts to develop efficient, broadband energy harvesters continue. This work provides a detailed insight into a bistable vibration harvester subjected to correlated Gaussian white noise, with the friction between the rack and pinion described by the slip-stick model. Using the harmonic balance method, the frequency response curve of the amplitude under different mass ratios is discussed. The system response will be enhanced with an increased mass ratio for sinusoidal excitation, but not in the case of random excitation. By employing the stochastic average of the energy envelope, the dynamical governing equation of the harvester is solved, and the probability density functions (PDFs) under different damping coefficients, nonlinear stiffness of the restoring force, and excitation intensities are derived. The results are compared with those from Monte Carlo simulations (MCS) and show good accuracy. The results reveal the presence of P-bifurcations. When the nonlinear stiffness and damping coefficient vary, the number of peaks in the PDFs of system displacement and velocity changes. By adjusting the system parameters, the motion of the system can be significantly enhanced. [ABSTRACT FROM AUTHOR]

Uncompacted saturated loess retains its residual pore structure without artificial compaction, making it highly sensitive to environmental changes such as dehydration-rehydration cycles. This study investigates the dynamic characteristics of uncompacted saturated loess in the Xi'an area, where infrastructure projects are commonly affected by the soil's instability. Dynamic triaxial tests were conducted under varying confining pressures and dehydration-rehydration cycles to examine the dynamic stress–strain relationship, dynamic modulus, and damping ratio variation. The methodology involved multi-stage loading using dynamic triaxial equipment, with cycles of drying and rehydration applied to replicate field conditions. A hyperbolic tangent function was used to model the dynamic stress–strain behavior, and structural parameters m1​ and m2​ were introduced to quantify the soil's stability and variability. Key findings show that dynamic stress increases with dehydration-rehydration cycles, while dynamic modulus and damping ratio decrease, especially during the initial cycles. The results provide critical insights into the behavior of uncompacted saturated loess under dynamic conditions, offering practical guidelines for managing soil stability in infrastructure projects across the Xi'an region. [ABSTRACT FROM AUTHOR]

Aiming at the problem that there exist lacks of analysis of the elastic properties of screen panel materials and research on the influence of mineral impact on the deflection changes of screen panel in response to the theory of large deflection deformation of flip-flow screen surface. Considering the scalability of the flip-flow screen panel material, a theoretical model of large deflection nonlinear elastic deformation of the screen panel is established. Combining with the external excitation sine displacement function, the time-domain expression of the screen panel with different amplitudes and frequencies is proposed for the first time. A testing platform for the dynamic characteristics of the flip-flow screen panel is built to verify the accuracy of the theoretical model in describing the deflection change process of the screen panel, and the optimal vibration parameters of the large deflection elastic deformation theory in describing the dynamic characteristics of the screen panel is clarified using the response surface optimization method. Based on the theory of large deflection elastic deformation of unloaded screen panel, a deflection variation theory of screen panel when particles collide with screen panel is proposed, and the deflection curve of screen panel with different motion states under particle impact force is calculated. Then the influence of different physical parameters on the local deformation degree of the collision point between the screen panel and mineral particles is revealed, and the accuracy of the theoretical expression of the deflection change of the screen panel under the collision of particles is verified through simulation experiments in describing the dynamic characteristics of the screen panel using different initial constraints. The research results show that the error rate of the experiments and theory of large deflection elastic deformation of screen panel under dynamic conditions is below 6%. The theoretical and experimental error rates of large deflection elastic deformation of the screen panel under dynamic conditions decrease with the increase of amplitude and frequency, but this change is nonlinear. When the amplitude is 7.33 mm and the frequency is 11.75 Hz, the error rate between the theoretical and experimental values at each measuring point reaches the lowest, and the average error rate at the midpoint of the screen panel is less than 3%. The incident angle of particles, the position of the impact point, the installation angle of the screen panel, and the operating state are important factors that affect the degree of local deformation of the screen panel during impact. Theoretical proof is shown that when the inclination angle and particle incidence angle of the screen surface installation are large, and the screen panel near the midpoint position move to the highest point, the collision between particles and the screen panel can obtain the maximum initial kinetic energy, and there is an average error of less than 4 mm between deflection deformation theory of the screen panel after collision in describing the impact point position and simulation results.

[Introduction] With the establishment of the energy Internet architecture mainly relying on new energies, HVDC transmission has become an important way of power transmission, power grids present a new characteristic of "strong DC and weak AC". Synchronous condensers have unique advantages in dealing with the issue of "strong DC and weak AC" by virtue of their dynamic performance such as fast reactive power response and strong voltage support capability. [Method] To study the application of synchronous condensers in HVDC works, this paper summarized the development of synchronous condensers, introduced the current development status of several major types of synchronous condensers in China, such as synchronous condensers for transforming thermal power units, new-generation large-capacity synchronous condensers, distributed synchronous condensers, analyzed the working principle and dynamic characteristics of synchronous condensers. Then the paper summarized the virtues of synchronous condensers when compared with other reactive power compensation devices such as SVC, the application scenarios, existing configuration strategies of large-capacity synchronous condensers and distributed synchronous condensers. [Result] Finally, a simulation model of DC transmission system with synchronous condensers is built on the PSCAD/EMTDC platform. The simulation verify the suppression capability of synchronous condensers for commutation failure at the sending end and transient overvoltage at the receiving end caused by commutation failure, as well as the dynamic reactive power compensation capability under lagging phase operation. [Conclusion] The analysis shows that synchronous condensers have adequate suppression of transient overvoltage and commutation failure and their reactive power response speed and dynamic reactive power support capability will not be affected by lagging phase operation, which contributes to their prospect of engineering application for steady-state compensation in converter stations.

Abstract As a new grinding and maintenance technology, rail belt grinding shows significant advantages in many applications. The dynamic characteristics of the rail belt grinding vehicle largely determines its grinding performance and service life. In order to explore the vibration control method of the rail grinding vehicle with abrasive belt, the vibration response changes in structural optimization and lightweight design are respectively analyzed through transient response and random vibration simulations in this paper. Firstly, the transient response simulation analysis of the rail grinding vehicle with abrasive belt is carried out under operating conditions and non-operating conditions. Secondly, the vibration control of the grinding vehicle is implemented by setting vibration isolation elements, optimizing the structure, and increasing damping. Thirdly, in order to further explore the dynamic characteristics of the rail grinding vehicle, the random vibration simulation analysis of the grinding vehicle is carried out under the condition of the horizontal irregularity of the American AAR6 track. Finally, by replacing the Q235 steel frame material with 7075 aluminum alloy and LA43M magnesium alloy, both vibration control and lightweight design can be achieved simultaneously. The results of transient dynamic response analysis show that the acceleration of most positions in the two working conditions exceeds the standard value in GB/T 17426-1998 standard. By optimizing the structure of the grinding vehicle in three ways, the average vibration acceleration of the whole car is reduced by about 55.1% from 15.6 m/s2 to 7.0 m/s2. The results of random vibration analysis show that the grinding vehicle with Q235 steel frame does not meet the safety conditions of $$3\sigma$$ 3 σ . By changing frame material, the maximum vibration stress of the vehicle can be reduced from 240.7 MPa to 160.0 MPa and the weight of the grinding vehicle is reduced by about 21.7% from 1500 kg to 1175 kg. The modal analysis results indicate that the vibration control of the grinding vehicle can be realized by optimizing the structure and replacing the materials with lower stiffness under the premise of ensuring the overall strength. The study provides the basis for the development of lightweight, diversified and efficient rail grinding equipment.

The compound rotor system of a mechanically rectified permanent magnet generator is the key structure to realize the rectification function. The dynamics of the compound rotor system under bidirectional input conditions are studied to analyze the vibration deformation degree of each component of the rotor system and to ensure the uniform distribution of the shunt load of each planetary gear. In this paper, based on the theory of concentrated mass parameters, a dynamic model of the compound rotor system under the condition of bidirectional input is established. The model is solved with the Runge-Kutta numerical integration method. The dynamics of each component under the condition of bidirectional input are obtained. The results show that the oscillations of torsional displacement of each component of the compound rotor system are all about 25 μm, and the standard deviations of the meshing forces of each planetary shunt are all about 200 N during the two-way input, indicating that the vibration degree of the compound rotor system is similar; The load sharing coefficient of meshing forces decreases obviously with the increase of input torque and tends to be gentle when the torque reaches 500 N·m. Therefore, increasing the input torque can improve the dynamic meshing force and load sharing performance, so that the compound rotor system can obtain better dynamic performance under the bidirectional input condition. The research results are of great significance for the vibration and noise reduction and reliable operation of the permanent magnet generator.

Heixiluo gully, located in Suxiong Town, Ganluo County of Sichuan Province, experienced a catastrophic debris flow disaster at 8:00 a.m. on August 31, 2020, causing significant losses to local residents, as well as to the Chengdu–Kunming railway bridges and infrastructure. To Study the activity and dynamic characteristics of the debris flow in Heixiluo gully, a comprehensive analysis was conducted using field investigations, on-site observations, and high-precision DEM data from the study area. The formation conditions and activity characteristics of the “8•31” debris flow were studied, and the Massflow software was utilized to simulate and verify the debris flow, inversely simulating the dynamic evolution process of the debris flow in Heixiluo Gully, and quantitatively evaluating the dynamic characteristics of the“8•31”debris flow. The study indicates that the “8•31” debris flow mainly underwent a“snowballing” cycle of processes, including “rainfall runoff convergence-, incision and erosion on the sides, sedimentation and selection on the first-level platform, erosion on the rear side of the platform, further sedimentation and selection on the second-level platform, further incision and erosion on the rear side of the platform, bank slope collapse, blockage and collapse, river blockage, formation of barrier lakes, and dam breach discharge.” Based on the Massflow analysis of the dynamic process of the debris flow, the simulated peak discharge, flow velocity, flow depth, erosion, and sedimentation depths in each gully segment match the measured data, confirming the reliability of this method. Through this method, the dynamic characteristics of debris flow can be more intuitively analyzed, providing a theoretical basis for subsequent disaster prevention and mitigation works.

As a flexible component in high-pressure vessels and pipeline systems, bellows experience significant fluid–structure interaction effects under high-speed internal fluids and external vibrations. Nevertheless, their dynamic response mechanisms coupled with fluid–structure interaction mentioned below have not yet been clarified so far. In this work, a novel pressure-balanced metal bellow (PBMB) for low-stiffness and high-pressure resistance is firstly proposed. Several fluid–structure interaction models were considered to study the dynamic response characteristics of the PBMB. An experimental platform associated with fluid–structure interaction was established to validate the effectiveness of its vibration attenuation performance. The results indicate that the PBMB has an obvious vibration attenuation effect in the range of 5–90Hz, and super-harmonic and sub-harmonic resonance phenomena occur in the range of 90–200Hz. Under constant fluid conditions, fluid density, viscosity, flow velocity, and pressure are positively correlated with the response amplitude of the PBMB. The response of the PBMB oscillates at the fluid entry point due to both pulsating flow velocity and pulsating pressure. After several cycles, the response caused by pulsating flow velocity gradually decays and stabilizes. Thus, the impact of pulsating frequency on the stability of the response of bellows is insignificant during the initial cycles. [ABSTRACT FROM AUTHOR]

The hypersonic vehicle will be subjected to severe aerodynamic superimposed heating loads during high-speed flight, especially the control surface structure, which is structure dynamic characteristics under complex loads are the key factors affecting the safe and reliable flight of the hypersonic vehicle, and it is an effective research method to verify and evaluate through experiment. The C / SiC rudder surface structure was taken as the research object, and the structure dynamic characteristics test system under the transient thermal environment was designed and built. A typical service thermal load environment with high loading temperature and large temperature difference between the windward and leeward surfaces was built. The dynamic characteristics test of the rudder surface structure under this environment was carried out, and the change rules of the structure dynamic characteristics were obtained. The research results provide an important verification means for the research on the influence of typical service thermal environment on the dynamic characteristics of modern hypersonic vehicle control surface structure. [ABSTRACT FROM AUTHOR]