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With the advancement of manufacturing, the precision requirements for various high-precision processing equipment and instruments have further increased. Due to its noncontact nature, simple structure, and controllable performance, electromagnetic levitation has broad application prospects in ultra-precision instruments and ground testing of aerospace equipment. Research on vibration isolation technology using electromagnetic levitation is imperative. This paper reviews the latest research achievements of three types of passive isolators and five active isolation actuators. It also summarizes the current research status of analytical methods for passive isolators and the impact of isolator layout. This study explores current isolators' achievements, such as the development of passive isolators that generate negative stiffness and require mechanical springs for uniaxial translational vibrations, single-function actuators, and control systems focused on position and motion vibration control. Based on the current isolators' characteristics, this review highlights future developments, including focusing on passive isolators for heavy loads and multi-axis isolation, addressing complex vibrations, including rotational ones, and developing methods to calculate forces and torques for arbitrary six-DOF movements while improving speed. Additionally, it emphasizes the importance of multifunctional actuators to simplify system structures and comprehensive control systems that consider more environmental factors. This provides significant reference value for vibration isolation technology using electromagnetic levitation. [ABSTRACT FROM AUTHOR]

In order to study the vibration transfer characteristics of a dual-rotor aeroengine system, an aeroengine system dynamic model containing high- and low-pressure rotors as well as inner and outer casings is established. The Newmark- β method is used to solve the developed model and obtain the dynamic characteristics of the system. This paper proposes a dynamic model and operational transfer path analysis (OTPA) method to analyze the vibration transfer path of a dual-rotor aeroengine system. The concept of insertion loss is introduced, and Cramer's rule is used to improve the computational efficiency of dynamic equations for systems with variable stiffness and damping matrices. The vibration contribution of three vibration transfer paths is calculated separately. A dual-rotor–casing vibration transfer path test bench is built to make experimental research on vibration transfer characteristics and verify the accuracy of simulation results. The results indicated that among the three vibration transfer paths, the first vibration transfer path has the highest contribution to the vibration of the outer casing of the system. Due to the nonlinear superposition of responses, the overall response amplitude of the outer casing shows an increasing trend as the rotational speed ratio increases. The contribution rate of the three paths does not change with the rotational speed, and the vibration contribution of each path at different rotational speed ratios fluctuates slightly near the mean. [ABSTRACT FROM AUTHOR]

The technology of nuclear reactors is evolving rapidly, driven by the pursuit of more powerful and efficient systems. The Small Lead-based Reactor (SLR) represents an advanced nuclear reactor design that holds great promise for delivering enhanced power and efficiency. In the context of the SLR's fuel rod, the high-speed coolant flow within the reactor can induce vibration, potentially causing fretting wear and damage to the cladding. This study utilized the Burgreen correlation to establish an equivalence relationship between water and Lead-Bismuth Eutectic (LBE). An experiment was then conducted to simulate axial flow-induced vibration (FIV) of a simply supported fuel rod, employing an equivalent water loop. Flow-induced vibration characteristics in both the time and frequency domains were investigated at different flow speeds. The experimental results revealed a positive correlation between flow velocity and amplitude. The fuel rod exhibited low-frequency vibrations with a random pattern, registering frequencies around 14 Hz. These experimental findings can be leveraged to enhance the accuracy of numerical simulations for axial flow-induced vibration (FIV) of the fuel rod. Subsequently, the revised numerical model was applied to simulate FIV in the LBE environment using computational fluid dynamics (CFD), and the numerical results were found to be in agreement with the experimental data. [ABSTRACT FROM AUTHOR]

As a pivotal branch within the realm of differential equations, the theory of oscillation holds a crucial position in the exploration of natural sciences and the construction of modern control theory frameworks. Despite the extensive research conducted globally, focusing on individual or combined analyses of key elements such as explicit damping terms, positive and negative coefficients, time-varying delays, and nonlinear neutral terms, systematic investigations into the oscillatory behavior of even-order differential equations that concurrently embody these four complex characteristics remain scarce. This paper, by establishing reasonable assumptions, innovatively presents two crucial criteria, aiming to preliminary delve into the oscillation patterns of even-order differential equations under specific complex settings. In the course of the study, a variety of mathematical techniques, such as Riccati transformation, calculus scaling methods, and partial integration, have been utilized by the researchers to perform the necessary derivations and confirmations. [ABSTRACT FROM AUTHOR]

AbstractThe clamp plays a vital role in supporting and suppressing vibration in pipeline systems. The vibration stress analysis of clamps is an essential basis for evaluating the strength of clamps, which is crucial for ensuring the safety and stability of the aero-engine pipeline system. However, there is a lack of relevant research to analyze the vibration response of the clamp. To make up for this defect, the precise modeling and vibration stress analysis of the clamp are carried out in this article. First, simulation and experimental testing are conducted on a bracket-clamp-additional mass system under the base excitation. The maximum stress errors of simulation and experiment under the excitation of sweep-frequency and fixed-frequency are 6.64% and 23.16%, respectively. Then, the influence of different excitation amplitude and additional masses on the surface stress of the clamp is analyzed. It is found that the surface stress of the clamp increases with the increase of the additional mass, and the effect of excitation amplitude on the surface stress of the clamp has a linear law. The simulation and experiment work in this article provides a deeper insight into the physical understanding for the design of clamp-pipeline system, and the precise clamp modeling idea proposed can also be extended to other specifications of engine clamp modeling. [ABSTRACT FROM AUTHOR]

The advantages of the Gatling gun, such as high firing rate, large interception range, and wide range of use, have made it an indispensable weapon system in the defense field. At present, the analysis of shooting vibration of the Gatling gun is a challenging key point in related research. In response to the lack of research on the shooting vibration characteristics of Gatling gun weapon systems, this paper carries out a numerical simulation study of the launch dynamic characteristics of the Gatling gun based on the nonlinear launch dynamics theory of artillery. The results of muzzle disturbance under continuous shooting conditions are obtained, and the shooting density of Gatling guns under different situations is analyzed and compared based on the method of shooting density calculation. This research fills the gap in the study of launch dynamics of Gatling weapons, providing design references and theoretical support for the overall design and performance verification of Gatling guns. [ABSTRACT FROM AUTHOR]

Elevated stations are integral components of urban rail transit systems, significantly impacting passengers' travel experience and the operational efficiency of the transportation system. However, current elevated station designs often do not sufficiently consider the structural dynamic response under various operating conditions. This oversight can limit the operational efficiency of the stations and pose potential safety hazards. Addressing this issue, this study establishes a vehicle-bridge-station spatial coupling vibration simulation model utilizing the self-developed software GSAP V1.0, focusing on integrated station-bridge and combined station-bridge elevated station designs. The simulation results are meticulously compared with field data to ensure the fidelity of the model. Analyzing the dynamic response of the station in relation to train parameters reveals significant insights. Notably, under similar travel conditions, integrated stations exhibit lower vertical acceleration in the rail-bearing layer compared to combined stations, while the vertical acceleration patterns at the platform and hall layers demonstrate contrasting behaviors. At lower speeds, the vertical acceleration at the station concourse level is comparable for both station types, yet integrated stations exhibit notably higher platform-level acceleration. Conversely, under high-speed conditions, integrated stations show increased vertical acceleration at the platform and hall levels compared to combined stations, particularly under unloaded double-line working conditions, indicating a superior dynamic performance of combined stations in complex operational scenarios. However, challenges such as increased station height due to bridge box girder maintenance, track layer waterproofing, and track girder support maintenance exist for combined stations, warranting comprehensive evaluation for station selection. Further analysis of integrated station-bridge structures reveals that adjustments in the floor slab thickness at the rail-bearing and platform levels significantly reduce dynamic responses, whereas increasing the rail beam height notably diminishes displacement responses. Conversely, alterations in the waiting hall floor slab thickness and frame column cross-sections exhibit a minimal impact on the station dynamics. Overall, optimizing structural dimensions can effectively mitigate dynamic responses, offering valuable insights for station design and operation. [ABSTRACT FROM AUTHOR]

This paper endeavors to tackle the issue of horizontal vibrations encountered in high-speed and ultra-high-speed elevator cabins during operation. Given the limitations of traditional passive-control guide shoes in effectively mitigating these vibrations and the complexity and cost associated with active control systems, a novel approach involving passive-control rolling guide shoes (PCRGS) integrated with hydraulic damping is explored. The PCRGS incorporates a hydraulic actuator and hydraulic damping, which can be modeled by a mechanical and hydraulic co-simulation model using AMESim2020 software. The simulation reveals a substantial reduction in cabin vibrations equipped with PCRGS. Specifically, under pulse excitation, the reduction ranges from 26.2% to 27.5%; under white noise excitation, it varies between 14.3% and 17.1%; and under sine wave excitation, the reduction spans 21.2% to 24.1%. Notably, the system meets the stringent 'Excellent' (<=0.07 m/s2) performance criteria under sine wave excitation at lower frequencies, signifying its high effectiveness. These findings not only underscore the potential of hydraulic passive-control guide shoes in mitigating elevator vibrations but also provide invaluable guidance for their further development and refinement. [ABSTRACT FROM AUTHOR]

The electromagnet module, as a fundamental component providing levitation force for maglev trains, plays a crucial role in ensuring the stability of train operation. However, vibrations can easily occur due to the mechanical coupling between the two suspension points of the electromagnet module. To reveal the inherent instability of the system and the coupling relationship between the state variables, a state-space equation that considers the mechanical coupling between the two suspension points is established. Furthermore, a differential control algorithm based on geometric feature transformation is proposed to mitigate the structural coupling vibration. Simulation experiments are conducted to compare the dynamic characteristics of the system before and after implementing the improvement algorithm under complex conditions. At the same time, the influence of control parameters on electromagnetic vibration was analyzed, focusing particularly on vibrations resulting from parameter mismatch, offering crucial insights for enhancing system stability. Additionally, suspension tests are carried out on the high-speed double bogie test platform in the Key Laboratory of Hunan Province to further validate the effectiveness of the proposed algorithm. The proposed control framework is both effective and concise, making it easy to implement in engineering applications. This research holds significant practical value in improving the stability of maglev trains. [ABSTRACT FROM AUTHOR]

An oscillating flow past a structure represents a complex, high-dimensional, and nonlinear flow phenomenon, which can lead to the failure of structures due to material fatigue or constraint relaxation. In order to better understand flow-induced vibration (FIV) and coupled flow fields, a numerical simulation of a two-degrees-of-freedom FIV in a cylinder was conducted. Based on the Lagrangian-based dynamic mode decomposition (L-DMD) method, the vorticity field and motion characteristics of a cylinder were decomposed, reconstructed, and predicted. A comparison was made to the traditional Eulerian-based dynamic mode decomposition (E-DMD) method. The research results show that the first-order mode in the stable phase represents the mean flow field, showcasing the slander tail vortex structure during the vortex-shedding period and the average displacement in the in-line direction. The second mode predominantly captures the crossflow displacement, with a frequency of approximately 0.43 Hz, closely matching the corresponding frequency observed in the CFD results. The higher dominant modes mainly capture outward-spreading, smaller-scale vortex structures with detail displacement characteristics. The motion of the cylinder in the in-line direction was accompanied by symmetric vortex structures, while the motion of the cylinder in the crossflow direction was associated with anti-symmetric vortex structures. Additionally, crossflow displacement will cause a symmetrical vortex structure that spreads laterally along the axis behind the cylinder. Finally, when compared with E-DMD, the L-DMD method demonstrates a notable advantage in analyzing the nonlinear characteristics of FIV. [ABSTRACT FROM AUTHOR]

In view of the problem that vibration of superstructures under vibration loads of metro trains causes, this research used a metro depot and superstructure project as its background and proposed a numerical simulation method based on the impedance analytical model and finite element model to simulate and predict the vibration and secondary noise response of subway trains affecting multi-story buildings at different locations on the ground and in the superstructure. The method's accuracy was verified using real measurement data. The research shows that vibrations generated by subway operations vertically at lower floors remain relatively unchanged, then slowly attenuate before increasing near the top floors. Mitigation measures should primarily address four aspects: rails, fasteners, sleepers, and roadbed. The adverse effects of vibration can be controlled by reducing the excitation intensity of the vibration source, attenuating vibrations along the propagation path, and isolating vibrations in the foundation and interior of the building. This research method can quickly and accurately predict the vibration and noise conditions of superstructure properties and provide support for vibration and noise reduction in practical engineering. [ABSTRACT FROM AUTHOR]

During the service process of a bearingless motorized spindle (BLMS), its parameters change with both time and external conditions, leading to a decrease in the accuracy of the motorized spindle. Therefore, it is difficult to accurately describe the dynamic performance of a motorized spindle during its actual operation using deterministic parameters. In this paper, the interactions between the thermal deformation and vibration of a motorized spindle are explored. A dynamic model of the motorized spindle based on multibody dynamics and time-varying parameters is established, and a solution method for the dynamic model with uncertain parameters is investigated. Firstly, the reasons for the vibration in the BLMS are analyzed, and the influences of thermal deformation on the thermal eccentricity and inhomogeneous air gap of the BLMS are studied. A vibration model of the BLMS is established and solved to acquire the radial vibration displacement. Secondly, a discrete multibody dynamics model of the BLMS is built, and the center trajectory of the motorized spindle is attained by solving the multibody dynamics model. A prototype experimental platform of the BLMS is designed, and vibration tests are carried out. The experimental results show that the vibration amplitude of the BLMS increases with the running time and the maximum displacement exhibits a large deviation from the simulation results using the determined parameters, while there is a small deviation from the simulation results using uncertain parameters; this indicates that the solution of the multibody dynamics model of the BLMS described by uncertain parameters is closer to the experimental data. These research findings can provide a reference for the optimized design of BLMSs. [ABSTRACT FROM AUTHOR]

The vibration parameters during drilling play a critical role in enhancing drilling speed and ensuring safety. However, traditional downhole vibration sensors face limitations in their power supply methods, hindering widespread adoption. To address this challenge, our research introduces a novel solution: a hybrid downhole vibration sensor (HDV-TENG) utilizing triboelectric nanogenerators. This sensor not only enables the measurement of low- to medium–high-frequency vibrations using self-power but also serves to energize other downhole devices. We utilized a self-constructed vibration simulator to replicate downhole drilling tool vibrations and conducted a comprehensive series of sensor tests. The test results indicate that the frequency measurement bandwidth of the HDV-TENG spans from 0 to 200 kHz. Especially, the measurement errors for vibrations within the low-frequency range of 0 to 10 Hz and the high-frequency range of 10 to 200 k Hz are less than 5% and 8%, respectively. Additionally, the experimental findings regarding load matching demonstrate that the HDV-TENG achieves an output power level in the milliwatt range, representing a significant improvement over the output power of traditional triboelectric nanogenerators. Unlike traditional downhole vibration measurement sensors, HDV-TENG operates without requiring any external power supply, thereby conserving downhole space and significantly enhancing drilling efficiency. Furthermore, HDV-TENG not only offers a broad measurement range but also amplifies output power through the synergy of a triboelectric nanogenerator (TENG), piezoelectric nanogenerator (PENG), and electromagnetic power generator (EMG). This capability enables its utilization as an emergency power source for other micropower equipment downhole. The introduction of HDV-TENG also holds considerable implications for the development of self-powered underground sensors with high-frequency measurement capabilities. [ABSTRACT FROM AUTHOR]

A method that combines phase‐sensitive optical time domain reflectometry with deep learning to construct new voting fully convolution neural networks (VoteFCNs) is proposed. Compared to the traditional convolutional network, the VoteFCN can be input with data of random size and requires less parameters so that the training speed can be improved greatly. The recognition results can be more accurate and more reliable if we use classification voting count and average recognition rate as the criteria to judge network training quality. At last, the training and identification were conducted by simulating such several disturbance events: walking, raining, climbing fence, hammering the ground optical fibre and normal outdoor environments. The results show that the average test accuracy of this method is about 93.4%. [ABSTRACT FROM AUTHOR]

Introduction: The magnetic potential source of a tangential magnetizing parallel structure hybrid excitation synchronous motor (TMPS-HESM) is generated by both the permanent magnets and the excitation winding. Objectives: As the positive excitation current flows in, the radial electromagnetic force wave amplitude of the motor increases sharply, resulting in an over-limited electromagnetic vibration noise. Methods: To address this issue, a 2.5 kW TMPS-HESM is used as the object of study. First, an analytical model of the radial electromagnetic force wave of a hybrid excitation motor is developed using the Maxwell stress tensor method under the operating conditions considering armature reaction and the influence of the length of the pole piece on the air gap side and the pole eccentricity distance on the radial electromagnetic force wave was analyzed. Then, using the above variables as optimization variables, the joint simulation method of Maxwell & Workbench & optiSLang based on PSO was used to optimize the design with the mean and maximum values of average motor torque, torque pulsation, and A-weighted noise as the objectives, and the optimal structural dimension parameters were selected through the Pareto front surface. A multi-physics finite element model was established to compare the spatiotemporal distribution characteristics of radial electromagnetic force and vibration and noise spectra before and after optimization. Finally, a hybrid excitation motor vibration experiment platform was built, and the vibration acceleration on the surface of the motor casing was tested and analyzed under load and no-load conditions. Results: The results show that the adopted multi-objective optimization results can effectively weaken the electromagnetic vibration and noise of the hybrid excitation motor, and provide a reference for the design of vibration and noise reduction of related complex structure motors. [ABSTRACT FROM AUTHOR]

In order to reduce the vibration of bearings in the bearing rotor system, a set of adaptive preload device based on pneumatic control was proposed. The vibration suppression effect of preload on the rotor and bearing roller at different rotating speed was studied based on preload force and rotating speed. An active control system composed of data acquisition system and pneumatic system was developed to monitor the vibration state of the bearing in the process of rotation in real time, and the preload was adjusted timely to ensure that the vibration was suppressed to the greatest extent during the normal operation of the bearing. The rotor system equipped with an aligning roller bearing (22208CA) was tested to verify the function of the device. The experimental results show that the vibration suppression effect of the device is more than 30% when the rotor speed is less than the first critical speed, and the bearing vibration amplitude is greatly reduced. Compared with the existing intelligent bearing units, the device provides a more efficient and simple solution for vibration suppression of the rotor bearing system. [ABSTRACT FROM AUTHOR]

There are many excitation sources and complex vibration environments in combine harvesters. The coupling and superposition of different vibration signals on the plate and shell seriously affect the working parts of the body. This also reduces the reliability of the whole machine. At present, domestic and foreign research on existing harvesters mainly focuses on harvesting performance, with less research on vibration characteristics. Therefore, in this paper, the vibration response of the metal plate–shell under the two connection modes of bolt connection and welding is studied, in order to optimize the design and structure of the plate–shell structure of the combine harvester and improve the overall performance. First, the welded and bolted plates are numerically modeled using Hypermesh pre-processing functions. Then, the boundary conditions are simulated by continuous variable stiffness elastic constraint experiments. Finally, the intrinsic vibration dynamic model of the four-sided simply supported plate and four-sided solidly supported plate is established using the modal superposition method. By analyzing the modal frequencies and vibration patterns, the following results are obtained. The connection method between the plate and the frame has a significant impact on the inherent vibration characteristics of the plate. The bolt connection will make the plate's intrinsic vibration frequency higher than that of the welding method, but the effect on the plate's intrinsic vibration pattern is more minor. At the same time, in order to verify the accuracy of the model, the actual modal vibration patterns and frequencies of the same proportion of plates in the modal test are compared with the results of modal vibration patterns and frequencies obtained by Ansys. The errors of the two dynamic model analytical methods are within 1% and 3%, respectively. This result verifies the accuracy of the dynamic model of the metal plate and shell structure under different connection methods. [ABSTRACT FROM AUTHOR]

The advancement of sensor, actuator, and flight control technologies has increasingly expanded the possibilities for drone utilization. Among the technologies related to drone applications, the vibration isolator technology for payload has a significant impact on the precision of optical equipment in missions such as detection, reconnaissance, and tracking. However, despite ongoing efforts to develop vibration isolators to mitigate the impact of vibrations transmitted to optical equipment, research on drone-specific natural frequencies and payloads has been lacking. Consequently, there is a need for research on vibration isolators tailored to specific drone types and optical equipment payloads. This study focuses on exploring the correlation between the natural frequencies of drones and the weight of the payload, and proposes methods for developing and testing vibration isolators that consider both factors. To achieve this, the study measured the stiffness of vibration isolator rubbers and conducted cross-validation between random vibration tests and finite element method (FEM) analyses to verify the vibration reduction effects resulting from changes in the dynamic characteristics of vibration isolator rubbers. The rubber with a shore hardness of 70 exhibited relatively high damping and damping performance during random vibration tests. Additionally, it showed relatively high stability with only one resonance point measured within the operational frequency band. Through the findings of this study, a methodology for selecting vibration isolators for drones is proposed, aiming to enhance the stability of optical equipment. [ABSTRACT FROM AUTHOR]

Nowadays researchers are investing in electrical machines fault diagnosis area. The users and manufacturers are strong for containing diagnostic features for reliability and scalability improvement. The regular monitoring enables machine faults early detection and hence helpful for automation by providing process control. The fault detection performance and machinelearning algorithms classification are highly dependent on features involved. The aim of this paper is to solve the network mechanical vibration problem and for that a research on mechanical vibration fault diagnosis is proposed. The first is to use the vibration signal receiving device to record the vibration signal of the target device. In the process of receiving the signal, the measurement point is related to the accuracy of the received signal, so it is necessary to prepare the measurement point. Secondly, the principle of fault detection based on vibration detection is introduced. The main purpose of this method is to identify the fault characteristics, simulate the fault with MATLAB, and obtain the error time-frequency diagram behavior. The feature vector dimension obtained by the idling confirmation example is the same as that of the rotor, which is 14, including 8 relative wavelet packet intensity entropy feature indexes and higher values, minimum value, peak-to-peak value, mean value, mean square error and variance. Finally, the deficiencies of the detected vibration faults are identified and similar improvements are proposed. Improvements only reduce signal vibration, disrupting feature isolation and identifying patterns. The observed percentage accuracy for classification of faults through proposed approach is 98.2%. [ABSTRACT FROM AUTHOR]

Luxury cruise ships are high-end passenger ships with facilities on board for the leisure and entertainment of passengers, so the comfort of luxury cruise ships is a matter of great concern. In this paper, a finite element model of a new polar exploration cruise ship is established, and the wet modes of the whole ship are calculated using the virtual mass method and compared with the principal frequencies of the excitation forces to initially verify the rationality of the design of the structural vibration characteristics of the whole ship. The admittance matrix of the vibration velocity to excitation force was calculated by a frequency response analysis, and the vibration velocities at the stern plate and main engine foundations were tested during sailing. Then, the obtained propeller and main engine excitation forces were loaded into the finite element model; the vibration velocities of each compartment were calculated and compared with the compartment vibration velocity test values. The errors were within the engineering allowable range, verifying the accuracy of the excitation forces. The propeller and main engine excitation forces were loaded separately on the finite element model to calculate the vibration velocity of each cabin, and the contribution of the two excitation sources to the vibration velocity of each cabin was analyzed. It was found that the contribution of the excitation source to the cabin response was related to the relative position between the cabin and the excitation source. When the cabin was located in the cabin adjacent to or directly above a certain excitation source, the contribution of the excitation source to the cabin response was greater. When the cabin was farther away from both excitation sources, the contribution of the propeller excitation was greater. This provides a targeted reference for the preliminary vibration assessment and later vibration control of the new polar expedition cruise ship. [ABSTRACT FROM AUTHOR]

Environmental microvibrations, often originating from unidentified sources, pose a significant challenge for predicting and controlling their complex wave fields, potentially leading to measurement errors of sensitive instruments in high-precision laboratories and impacting the accuracy of experimental outcomes. Therefore, investigating effective control measures for environmental microvibrations under passive conditions is key to addressing such engineering issues. This paper presents a finite element analysis method tailored to address environmental microvibrations in the absence of apparent sources. This method involves obtaining the vibration time history at specific ground surface points through field measurements and combining the Rayleigh wave velocity attenuation character with depth at the center frequencies of one-third octave bands within the 1–100 Hz frequency range; the vibration time history at any depth in the soil is calculated. These calculated vibrations are then applied as input loads to the corresponding nodes on one boundary of the foundation–soil model, serving as the source of environmental microvibrations. The predicted results are compared with measured data and the empirical point source input method, indicating that this approach is more precise and efficient, providing valuable reference for the prediction and analysis of environmental microvibrations. In addition, utilizing this method, the study examines the effects of pile foundation parameters such as the pile length, burial depth, and concrete baseplate thickness on the vibration isolation performance of environmental microvibrations, providing guidance for designing pile foundation isolation. [ABSTRACT FROM AUTHOR]

This paper takes the frame as the research object and explores the vibration characteristics of the frame to address the vibration problem of a 1-MSD straw-crushing and residual film recycling machine in the field operation process, and an accurate identification of the modal parameters of the frame is carried out to solve the resonance problem of the machine, which can achieve cost reduction and increase income to a certain extent. The first six natural frequencies of the frame are extracted by finite element modal identification and modal tests, respectively. The rationality of the modal test results is verified using the comprehensive modal and frequency response confidences. The maximum frequency error of modal frequency results of the two methods is only 6.61%, which provides a theoretical basis for the optimal design of the frame. In order to further analyze the resonance problem of the machine, the external excitation frequency of the machine during normal operation in the field is solved and compared with the first six natural frequencies of the frame. The results show that the first natural frequency of the frame (18.89 Hz) is close to the external excitation generated by the stripping roller (16.67 Hz). The first natural frequency and the volume of the frame are set as the optimization objectives, and the optimal optimization scheme is obtained by using the Optistruct solver, sensitivity method, and grey correlation method. The results indicate the first-order natural frequency of the optimized frame is 21.89 Hz, an increase of 15.882%, which is much higher than the excitation frequency of 16.67 Hz, and resonance can be avoided. The corresponding frame volume is 9.975 × 107 mm3, and the volume reduction is 3.46%; the optimized frame has good dynamic performance, which avoids the resonance of the machine and conforms to the lightweight design criteria of agricultural machinery structures. The research results can provide some theoretical reference for this kind of machine in solving the resonance problem and carrying out related vibration characteristics research. [ABSTRACT FROM AUTHOR]

In order to effectively reduce the vibration of the product in the process of transportation, the cushioning pad is applied in the packaging of the computer case, which can not only greatly reduce the cost of the cushioning packaging design, but also promote the sales of the product. The vibration response of the key components in the computer case was tested and analyzed under the conditions of force hammer experiment and random vibration experiment, and the direct transmission rate of the buffer liner system to the key components was obtained. The excitation of three vibration levels of the standard truck vibration spectrum was used to simulate the excitation of different intensities in actual transportation, and the excitation acceleration power spectrum was obtained. The direct transmission rate quantified the vibration transmission characteristics of each buffer pad to the key components, and the size of the direct transmission rate reflected the degree of vibration energy absorption of each buffer pad to the key components. The critical buffer pad was optimized to absorb more vibration energy by increasing the buffer area of the critical buffer pad, reducing its vibration transmission capacity in the main resonance area. [ABSTRACT FROM AUTHOR]

This paper analyzes traditional vibration suppression methods in order to solve the vibration problem caused by the stiffness of flexible industrial robots. The principle of closed-loop control dynamic feedforward vibration suppression is described as the main method for solving robot vibration suppression. This paper proposes a method for time-lag filtering based on T-trajectory interpolation, which combines the T-planning curve and the time-lag filtering method. The method's basic principle is to dynamically adjust the trajectory output through the algorithm, which effectively suppresses the amplitude of the harmonic components of a specific frequency band to improve the vibration response of industrial robot systems. This experiment compared traditional vibration suppression methods with the time-lag filtering method based on T-trajectory interpolation. A straight-line method was proposed to measure the degree of vibration. The results demonstrate that the time-lag filtering method based on T-trajectory interpolation is highly effective in reducing the vibration of industrial robots. This makes it an excellent option for scenarios that demand real-time response and high-precision control, ultimately enhancing the efficiency and stability of robots in performing their tasks. [ABSTRACT FROM AUTHOR]

In drilling operations, measuring vibration parameters is crucial for enhancing drilling efficiency and ensuring safety. Nevertheless, the conventional vibration measurement sensor significantly extends the drilling cycle due to its dependence on an external power source. Therefore, we propose a vibration-accumulation-type self-powered sensor in this research, aiming to address these needs. By leveraging vibration accumulation and electromagnetic power generation to accelerate charging, the sensor's output performance is enhanced through a complementary charging mode. The experimental results regarding sensing performance demonstrate that the sensor possesses a measurement range spanning from 0 to 11 Hz, with a linearity of 3.2% and a sensitivity of 1.032. Additionally, it exhibits a maximum average measurement error of less than 4%. The experimental results of output performance measurement indicate that the sensor unit and generator set exhibit a maximum output power of 0.258 μW and 25.5 mW, respectively, and eight LED lights can be lit at the same time. When the sensor unit and power generation unit output together, the maximum output power of the sensor is also 25.5 mW. Furthermore, we conducted tests on the sensor's output signal in conditions of high temperature and humidity, confirming its continued functionality in such environments. This sensor not only achieves self-powered sensing capabilities, addressing the power supply challenges faced by traditional downhole sensors, but also integrates energy accumulation with electromagnetic power generation to enhance its output performance. This innovation enables the sensor to harness downhole vibration energy for powering other micro-power devices, showcasing promising application prospects. [ABSTRACT FROM AUTHOR]

With the rapid development of metro construction, shield machines inevitably have to traverse a variety of complex geological conditions, leading to the frequent occurrence of geological disasters, equipment failures, building vibration and other problems. Vibration, as an important feature of the shield tunneling process, has received more and more attention in recent years. This paper summarizes the relevant research progress of vibration monitoring during shield construction from 2015 to 2023. It analyzes the shield vibration generation mechanism, monitoring methods and application areas. Firstly, the shield vibration type is divided into mechanical vibration triggered by internal excitation and forced vibration triggered by external excitation, and the principles of vibration generated by shield main bearing, gearbox and disc cutter are discussed. Then, the commonly used vibration monitoring methods are outlined according to the installation location of the sensors (inside and outside of the shield). Finally, the applications of vibration signals in the diagnosis of shield faults, the identification of geologic conditions, and the evaluation of the current status of the interference with the buildings are summarized. This paper discusses the development trend of vibration monitoring during shield tunneling based on the current research situation and the current technology level, which provides valuable insights to enhance the safety and intelligence of shield construction. [ABSTRACT FROM AUTHOR]

The amplitude modulation method was used to generate a non-Gaussian road profile with prescribed power spectral density (PSD) and kurtosis. The vehicle vibration fatigue damage potential has been proven to be closely related to the amplitude modulation signal (AMS) and kurtosis of vehicle response. In this paper, the iterative method of AMS modelling based on absolute standard Gaussian distribution is first reviewed. To address the long iteration time problem, a closed-form formulation is presented to construct the AMS directly. Furthermore, by proving that the vehicle response under a slowly varying non-Gaussian road profile excitation can be regarded as the product of the same AMS and vehicle response under a Gaussian road profile excitation with the same PSD, the theoretical relationship between fatigue damage spectrum (FDS) of vehicle response under non-Gaussian and corresponding Gaussian road profiles is formulated based on the AMS. A case study is used to verify the proposed approach. The results show that a wide range of specified kurtosis of road profile can be achieved and the kurtosis of vehicle response is the same as for the road profile. Given kurtosis and fatigue exponent, the extra fatigue damage caused by non-Gaussian road profile can be derived easily from the corresponding Gaussian road profile without calculating the vehicle response, which lays the foundation for a significantly simplified and more accurate fatigue test of vehicle vibration under non-Gaussian road profile. [ABSTRACT FROM AUTHOR]

At present, coal mine tunneling technology is developing in the direction of intelligence and unmanned. The piezoelectric vibration energy harvester can convert the vibration energy generated by the cutting part of roadheader into electrical energy and realize the energy self-sufficiency of the low-power wireless sensor. In practical applications, the vibration frequency of the cutting part of roadheader is different, and the working condition is complex, resulting in the energy recovery efficiency of the vibration energy harvester is not ideal. In order to improve its adaptability and reliability, a separated excitation broadband piezoelectric vibration energy harvester is proposed in this paper. [ABSTRACT FROM AUTHOR]

Purpose: Abnormal vibrations often occur in the liquid oxygen kerosene transmission pipelines of rocket engines, which seriously threaten their safety. Improper handling can result in failed rocket launches and significant economic losses. Therefore, this paper aims to examine vibrations in transmission pipelines. Design/methodology/approach: In this study, a three-dimensional high-pressure pipeline model composed of corrugated pipes, multi-section bent pipes, and other auxiliary structures was established. The fluid–solid coupling method was used to analyse vibration characteristics of the pipeline under various external excitations. The simulation results were visualised using MATLAB, and their validity was verified via a thermal test. Findings: In this study, the vibration mechanism of a complex high-pressure pipeline was examined via a visualisation method. The results showed that the low-frequency vibration of the pipe was caused by fluid self-excited pressure pulsation, whereas the vibration of the engine system caused a high-frequency vibration of the pipeline. The excitation of external pressure pulses did not significantly affect the vibrations of the pipelines. The visualisation results indicated that the severe vibration position of the pipeline thermal test is mainly concentrated between the inlet and outlet and between the two bellows. Practical implications: The results of this study aid in understanding the causes of abnormal vibrations in rocket engine pipelines. Originality/value: The causes of different vibration frequencies in the complex pipelines of rocket engines and the propagation characteristics of external vibration excitation were obtained. [ABSTRACT FROM AUTHOR]

The inherent weakness in the deformation resistance of plastic centrifugal pumps makes them prone to vibrations. This study explores the impact of flow components on the vibrations of such pumps. Utilizing the given parameters, the primary structural parameters of the plastic centrifugal pump were calculated. The study focused on the torsional vibrations within the pump shaft transmission system, employing a silicone oil damper for vibration mitigation. A dual-mass forced torsion vibration model was developed for the pump shaft transmission system with the added damper. The optimal damping coefficient for this damper was determined, and its structural design was completed, including the creation of three-dimensional models and two-dimensional part drawings. Utilizing a ZT-3 type rotor test bench, a mathematical model correlating centrifugal pump speed with deflection was developed, and the effectiveness of various polynomials was assessed. The analysis showed that the optimal damping value for the silicone oil damper is 0.22. Compared to the system without the damper, the vibration frequency reduced by 10.45%, and the vibration amplitude decreased by 49.29%, demonstrating excellent vibration reduction effectiveness. [ABSTRACT FROM AUTHOR]

As a means of vibration reduction, the ladder track has seen broad implementation in urban rail transit. However, issues such as increased vibration noise, rail corrugation, and fastener failure have been observed in certain sections of the ladder track during later operation. To investigate the mechanisms behind these phenomena and provide comprehensive insights into the system's response to various operational conditions, this study employed vehicle-track coupled dynamic theory to establish a three-dimensional finite element model of the flexible vehicle-ladder track system. The vibration transmission and dynamic response characteristics of the vehicle-ladder track system were analyzed. The findings revealed that the vehicle-track resonance and anti-resonance phenomena were more prominent in the medium- to low-frequency range. At specific frequencies, the wheelset exhibited various vibration modes, and the fastener force was found to closely correlate with the ladder vibration mode. Furthermore, the influence of speed on diverse components of the vehicle-ladder track system, in terms of maximum vibration and the dominant vibration frequency range, differed considerably. This study provides a more comprehensive and reasonable exploration of the modeling and dynamic behavior of vehicle-ladder track systems. [ABSTRACT FROM AUTHOR]

Purpose: In response to the difficulty of dynamic vibration absorber (DVA) to realize the broadband vibration reduction of large marine mechanical equipment, an air spring dynamic vibration absorber (ASDVA) was proposed, then its damping and vibration absorption performance were studied. Methods: A piecewise integral method was used to identify the damping, and the modal tests were carried out to determine the vibration absorption frequency. Subsequently, the effects of the air pressure and the orifice opening on the vibration absorption frequency and damping were analyzed. A single-degree-of-freedom (SDOF) system model was established to analyze the influence of the damping on the vibration absorption performance, and then relevant vibration absorption performance tests were carried out. Results: The piecewise integral method is accurate in identifying the damping. The changes of the air pressure and the orifice opening affect not only the vibration absorption frequency, but also the damping. In particular, the damping reaches a maximum value at a certain orifice opening, and the vibration absorption frequency will jump from the low frequency to the higher frequency. The increase of the damping reduces the vibration absorption effect, but broadens the vibration absorption bandwidth. Conclusion: By properly adjusting the air pressure and the orifice opening, the ASDVA can obtain appropriate vibration absorption frequency and damping, thus achieving good broadband vibration reduction effect. [ABSTRACT FROM AUTHOR]

Nonlinear torsional vibration differential equation of the nested arc-shaped short spring dual mass flywheel (DMF) is established, considering the piecewise linear stiffness and damping of the spring. The first-order approximate analytical solution under sinusoidal excitation and the amplitude–frequency characteristic function are obtained by means of the average method which verified by the Runge–Kutta (R–K) method. The effects of the parameters of input excitation, inertia, and piecewise linear stiffness and damping of DMF on the resonant amplitude, resonant frequency band, and equivalent linear natural frequency of the system are analyzed. The results show that the amplitude–frequency characteristic curve bending and jumping with the changes of excitation frequency and the peak of resonant amplitude can be obviously reduced by increasing the inertia of the primary flywheel and decreasing the inertia of the secondary flywheel. The complex nonlinear dynamic phenomena such as Period 1, quasi-periodic, and chaos are obtained by analyzing the forced vibration response under the different excitation frequencies. [ABSTRACT FROM AUTHOR]

The vibration and sound radiation characteristics of the submarine pressure hull structure are important performance indicators for the acoustic design of the submarine structure. In this paper, the spectral element method is used to analyze the vibration of the shell structure. Combined with the periodic structure theory, the theoretical calculation method of the periodic ribbed shell structure is deduced, and the analytical method that can be used to calculate the vibration of the pressure shell structure is established. The feasibility of applying the spectral element method to the vibration calculation of the pressure shell structure is verified by comparing the analytical calculation and the finite element simulation. The vibration characteristics test experiment of the actual submarine pressured hull structure is carried out. The results show that the theoretical analysis is correct. Highlights: The vibration and sound radiation characteristics of the submarine pressure hull structure have an important influence on the radiated noise of the submarine. A theoretical analysis method of vibration characteristics of pressure hulled based on spectral element method and periodic structure theory is proposed. The experimental study on vibration characteristics and active control of line spectrum of the pressure hull is carried out. [ABSTRACT FROM AUTHOR]

In order to realize the vibration control of the complex structure of carbon fiber, piezoelectric cantilever carbon fiber laminates were used as the research object in this experiment. Based on Kirchhoff's thin plate theory and Hamilton's principle, the vibration state space equation of piezoelectric cantilever carbon fiber laminates was constructed using piezoelectric constitutive equations, hypothetical mode method, generalized coordinate method and state-space variables. Stress and strain analysis were carried out on the cantilever laminated plate to determine the laying position of the piezoelectric ceramic fiber sheet. The PID control method, fuzzy control method and fuzzy PID control method were used to design the controller in MATLAB, and the vibration control of the cantilever laminated plate was numerically simulated. The results show that the three controllers can effectively suppress the vibration of the laminated plate, and the fuzzy PID controller has the best vibration suppression effect, which can provide a reference for the vibration control of carbon fiber complex structures. [ABSTRACT FROM AUTHOR]

Sound and vibration are the direct carriers of running data of rotating machinery equipment. According to the principle of voiceprint monitoring, through data collection, pre-processing and extraction of eigen values, a voiceprint sample and model library of running data and voiceprint monitoring system of vibration data of large pumping station units is established by adopting convolution neural network deep learning recognition model so as to realize the real-time monitoring of the unit running data of the large pumping station. [ABSTRACT FROM AUTHOR]

For a class of embedded elastic metamaterial plate, a general vibration analysis process is given based on the idea of equivalent analysis, which combines the equivalent medium theory and the classical thin plate vibration theory. The embedded elastic metamaterial plate is treated as an equivalent homogeneous plate with abnormal effective medium parameters by using the equivalent medium theory, and then the natural vibration characteristics and steady-state vibration characteristics are investigated. The results show that the semi-analytic form of the vibration analysis process is effective, which can obtain the vibration characteristics of such heterogeneous and complex structures quickly and accurately within the medium and low frequency regions. The results also reveal the plate's anomalous behaviors that are quite different from the traditional homogeneous plates. For the natural vibration, there exists no natural frequency in the band gap and they can be formed only in the pass band. These modes tend to gather gradually when approaching the initial frequency of the band gap, and the closer to the lower band edge of the band gap, the smaller the distance between natural frequencies and the greater the modal density. Additionally, the modes of the corresponding orders before and after the band gap are identical on the macro level but completely different on the unit-cell level. For the steady-state vibration, there is no resonance peak in the band gap, the resonance peaks are distributed denser and denser when approaching the initial frequency of the band gap, and the distribution of the displacement field at corresponding order of resonance peaks before and after the band gap is also similar on the macro level. This work not only facilitates the design and analysis of elastic metamaterial plate structures, but also deepens the understanding of their extraordinary vibration characteristics and expands the design space of mode characteristics. [ABSTRACT FROM AUTHOR]

This paper accurately predicts and quantifies the vibration response characteristics of a mirror bender system with the finite element simulation and experiment. The results show that the fundamental frequency of the roll angle vibration is 24.66 Hz, and the fundamental frequency of the pitch angle vibration is 116.21 Hz. The overall error is within 11.15% in comparision with the first six natural frequencies obtained from experiments and simulations. The vertical support rod, being one of the weakest links in the overall structural stiffness, is a crucial factor limiting the increase in the natural frequency of the mirror system. Before and after the injection of cooling water, the pitch angle vibration was 123.63 and 199.04 nrad, respectively. An increase in the cooling water flow rate from 1 to 1.5 l/min has almost no effect on pitch angle vibrations. This study provides references and guidance for improving the stability of the mirror system. [ABSTRACT FROM AUTHOR]

This study investigates the vibrations of centrifugal loop dryer machines used in plastic recycling processes. These machines are characterized by large uncertainties, high vibration, and unmodeled dynamics, making the design and maintenance of real-time state estimators for their operational conditions difficult. The present study includes an analysis of the centrifugal loop dryer machines' vibration characteristics and their influence on operation results based on vibration analysis, frequency response analysis, and expert advice. Two identical loop dryers installed and operated in parallel in a single recycling line were investigated. Measurements were performed using a two-sample measurement design and based on a one-sample statistical method for estimating uncertainty in repeated measurements of data processing. Additionally, a problem connected with incorrect machine operation during high vibration, resulting in insufficient drying of loaded material, was investigated. This was defined as a situation in which some melted plastic is still too wet after mechanical drying, caused by the incorrect installation of damper elements of the holding elements. Finaly, it is recommended that a correction of the machine installation and a control measurement are carried out to determine whether the vibration in the base of the machine still exists. A simplified theoretical vibration analysis of the rotating machine was also carried out in the present paper. [ABSTRACT FROM AUTHOR]

To enhance cycling comfort, a critical investigation of vibration effects in non-motorized bicycle riding is essential, focusing on road characteristics and traffic features. The analysis of how these elements influence cycling vibrations identified 13 key factors. This study utilized non-motorized bicycle lanes in Wuhan City for empirical research. Three-axis accelerometers were attached to riders' torsos to measure vibration comfort levels. The observed road segments ranged from slightly to relatively uncomfortable. This study employed the random forest algorithm and logistic regression to analyze the influencing factors further. Six factors emerged as significant in affecting cycling comfort: the existence of dedicated non-motorized bicycle lanes, the lack of a physical barrier between non-motorized and motorized traffic, cycling speed, road surface irregularities, parking areas within non-motorized lanes, and bicycle type. This research offers valuable insights into non-motorized bicycle lane usage and contributes to the development of urban non-motorized bicycle infrastructure, supporting sustainable urban transportation. [ABSTRACT FROM AUTHOR]

As a novel form of railway transportation, maglev transportation has the advantages of a better curve negotiation ability and grade ability and lower noise and vibration than traditional urban wheel–rail transportation. Thus, it is suitable for use in urban public transportation. However, the levitation of the widely utilized electromagnet suspension (EMS) system relies on continuously active suspension force adjustment, which gives it vehicle–track-coupled vibration characteristics different to those of the traditional wheel–track transportation system. Despite many research studies focusing on maglev vehicle–track coupling vibration, the environmental vibration influences associated with the running of maglev trains are still unclear. When the vibration propagates to the surroundings beyond certain thresholds, it may lead to various vibration serviceability problems. Practical test results on the environmental vibration induced by maglev transportation are still not enough to generate convincing vibration propagation and attenuation laws. In this research, a series of in situ tests were carried out around the Shanghai maglev line; the results show that the viaduct bridge is helpful in reducing environmental vibration, and an empirical formula was proposed to predict the effect of viaduct column height. Due to the ground wave superposition, a vibration-amplifying zone was also found about 10 m away from the maglev line, in which the vibration magnitude was strong enough to be perceived by the surrounding occupants. [ABSTRACT FROM AUTHOR]

Presented herein is the free vibration analysis of functionally graded beams (FGMs) via higher-order shear deformation theory and an artificial neural network method (ANN). The transverse displacement (w) is expressed as bending (wb) and shear (ws) components to define the deformation of the beam. The higher-order variation of the transverse shear strains is accounted for through the thickness direction of the FGM beam, and satisfies boundary conditions. The governing equations are derived with the help of Hamilton's principle. Non-dimensional frequencies are obtained using Navier's solution. To validate and enrich the proposed research, an artificial neural network method (ANN) was developed in order to predict the dimensionless frequencies. Material properties and previous studies were used to generate the ANN dataset. The obtained frequency values from the analytical solution and ANN method were compared and discussed with respect to the mean error. In conclusion, the solutions were demonstrated for various deformation theories, and all of the results were thereupon tabularized and visualized using 2D and 3D plots. [ABSTRACT FROM AUTHOR]

Purpose: The full-face rock tunnel boring machines (TBM) generate intensive vibration while cutting rocks, which will lead to poor accuracy of the guidance system. Therefore, it is necessary to design an active isolation system to attenuate the vibration transmitted to the guidance system. Methods: This paper presents a single-degree-of-freedom active isolation system driven by a voice coil motor for the guidance system of TBM to work well in an intensive vibration environment. A hybrid control strategy based on feedforward control and feedback control is proposed according to the state equation of the active isolation system. Objective function based on the mounting plate acceleration is established for the linear quadratic regulator (LQR) controller. The weighting coefficients of the LQR controller are optimized by a genetic algorithm for better vibration control performance. Results: Simulations and experiments based on the proposed hybrid control strategy are carried out at excitation frequencies of 5, 8, 12, 15, 17, and 20 Hz, respectively. The results show that the designed electromagnetic active vibration isolation system has a displacement attenuation less than -17 dB and an acceleration attenuation less than -21 dB. Conclusions: The acceleration transmitted to the mounting plate under the action of the proposed active isolation system is less than 0.2 g, which meets the vibration requirements of the guidance system of TBM. [ABSTRACT FROM AUTHOR]

To research the flow-induced vibration characteristics of the natural gas loop, unsteady numerical simulation is carried out on the loop calculation model under different ambient temperatures and different flow rates, and the influence of different flow rates on the dynamic characteristics of the flow field and its induced vibration characteristics is obtained. The results show that the inherent frequency of the natural gas loop increases slightly under the action of heat–fluid–solid coupling. The maximum equivalent stress of the loop increases with the increase in ambient temperature under low flow conditions, but it is almost constant under high flow conditions. The smaller the cross-sectional area of the loop pipeline inlet, the greater the pressure, and the more significant the pressure gradient along the flow direction. The pressure pulsation of monitoring points in the pipeline under different flow rates presents different rules, and the pulsation amplitude of pipes with different diameters is different, among which the amplitude of the pipe with a diameter of 250 mm is the largest and that of the pipe with a diameter of 150 mm is the smallest. The pressure pulsation signals are concentrated in the low-frequency band of 0–10 Hz, and the range of the band decreases with the increase in the flow rate. The vibration frequency of the loop structure is close to the fluid pressure pulsation frequency and the inherent frequency under the action of heat–fluid–solid coupling, which causes a resonance of about 2 Hz. [ABSTRACT FROM AUTHOR]

During the operation of commercial vehicles, drivers are usually exposed to long-term vibrations and acquire several health problems. Moreover, the end-stop impacts caused by large-magnitude vibrations or shocks may affect driving performance and result in injuries. A study of magnetorheological (MR) seat suspension controlled by a novel tuning control strategy is conducted in this research to reduce vibrations and avoid end-stop impacts. First, the MR damper's characteristics are tested, and a mathematical model of MR seat suspension is established. Then, an improved tuning control strategy is designed based on this model. The proposed strategy has three control stages that can be adjusted according to the suspension stroke to improve seat comfort or avoid end-stop impacts. Each part of the control strategy is designed separately, and the vibration attenuation performance of this seat suspension is evaluated with a simulation for three excitations, i.e., harmonic excitation, bump excitation, and random road excitation. Finally, an experiment is conducted to verify the conclusion of the simulation. The seat suspension with the proposed control shows good performances on vibration attenuation and end-stop impact reduction. Compared with a passive seat, the vibration level is reduced by around 27% and end-stop impact is avoided when semiactive suspension with the proposed strategy is used. It also shows the best overall performance among the three experimental algorithms. Both the simulation and the experiment results indicate that the vibration attenuation performance of the seat suspension can be greatly improved with the improved tuning control strategy. [ABSTRACT FROM AUTHOR]

During the launch and separation phases, the satellite will be subjected to massive random loads and impact loads, which will quickly cause broad frequency vibrations in the thin-walled skin structure of the satellite bearing cylinder, leading to resonance in severe cases and causing fatigue and damage to the equipment and structure. A vibration suppression method of satellite-bearing cylinder based on PD (particle damping) technology is proposed to overcome the problem of abnormal vibration of satellite-bearing cylinder structure at resonance frequency excitation. Firstly, the DEM-FEM coupling model of the force-bearing cylinder and particle damper is established using the DEM-FEM coupling (discrete element method and finite element method coupling) theory. Secondly, the acceleration value response of the bearing cylinder's upper-end surface is used to evaluate the vibration-dampening effect. The particle dampers' particle diameter, particle material, particle filling ratio, and installation site parameters are then optimized for design. Finally, the ground vibration damping test of the satellite bearing cylinder was designed. According to the experimental results, after installing the best damping scheme, the vibration attenuation of the satellite bearing cylinder may achieve 32%. The peak acceleration at the first and second-order intrinsic frequencies is lowered by 78.46% and 94.3%, respectively. This result also verifies the correctness of the theoretical model and simulation model. [ABSTRACT FROM AUTHOR]

The internal beveloid gear has good scientific research value and a broad application field. However, there is a lack of research on the nonlinear vibration characteristics of internal beveloid gears. The present study establishes a nonlinear vibration model that takes into account axial vibration, gear torsional vibration, and radial support vibration. The effects of various excitation parameters on the vibration characteristics of the gear transmission system are analyzed and computed using the Runge–Kutta method. After analyzing the dynamic model of the gear pair using numerical methods, the harmonic balance method is employed to obtain the theoretical analytical solution for a single−stage gear. The obtained results are compared with the velocity and acceleration time−domain response curves obtained from the numerical method, and they show excellent agreement. [ABSTRACT FROM AUTHOR]

In order to weaken the ground vibration caused by mechanical equipment, a vibration isolation platform of nonlinear vibration isolation system is proposed. The influence of flexible foundation and nonlinear isolator parameters on the performance of nonlinear vibration isolation platform is studied. By optimizing the nonlinear parameters of the vibration isolation platform, the vibration response of equipment vibration is effectively blocked. The research results show that the structural parameters such as stiffness and damping of the nonlinear vibration isolation system affect the vibration mode of the vibration isolation platform, thus affecting the vibration response of the whole system. Applying the nonlinear vibration isolation system to the project, the impact of the vibration of the refiner on the vibration of the floor is greatly reduced. It shows that this method can be used to reduce the foundation vibration caused by the equipment, improve the operation status of the equipment, and increase the safety factor of the building. [ABSTRACT FROM AUTHOR]