Collision Vibration Research Articles

Study on the sound radiation characteristics of polygonal wear wheels of CRH3 high-speed train

Abstract Due to the increase in train operating speed, the phenomenon of collision vibration between wheels and rails becomes more and more obvious, and the degree of wheel wear increases dramatically. As a result, the wheel-rail noise problem has become more and more complex. The wheel polygonal wear is also widespread on the train. For the wheel in the form of polygonal wear of the wheel-rail vertical force, combined with the principle of wheel-rail noise, we conduct an in-depth study. An aerodynamic mutual coupling model for CRH3 high-speed vehicles is proposed. The role of the amplitude of 0.03 mm, i.e., the twentieth-order polygonal abrasion rate on the wheel-rail force is analyzed at the speed class of 200~350 km/h, and the acoustic radiation characteristics of the wheels are investigated at different speed classes. The results show that under different speed classes, when the wheel polygon order is in the twentieth order, the wheel-rail vertical force rises with the increase of speed, and the wheel sound power is also affected by a great change. There is a significant increase in the sound power from the low frequency of 20 Hz to 100 Hz and a peak in the mid-frequency up to 1, 000 Hz. Secondly, when the wheel radiated sound pressure levels at different speed levels, significant changes also occurred, with the sound pressure reaching a maximum of 110 dB at 350 km/h.

RBF Neural Network for Chaotic Motion Control of Collision Vibration System

Aiming at the control problem of chaotic motion of a kind of collision vibration system with gap, a chaotic motion control of collision vibration system based on RBF neural network is proposed. Firstly, the system mechanical model and chaotic motion are introduced, and then a chaotic controller based on RBFNN is designed to control and simulate the chaotic attractor. The model information of the system is not used in the control method. In this paper, the model of the system is used only to generate the input / output data of the system, and it is not used for the design of the controller. The parameters of AHGSA algorithm are set as follows: the population size is 30, the maximum number of iterations is 100,G0, a = 18, and the proportional coefficient P = 0.96. Small disturbances are applied to the controllable parameter ωof the system to suppress the chaotic motion of the system and make the system tend to stable periodic motion. In order to more clearly show the control effect of chaotic motion, the chaotic motion is controlled when the system iterates 400 times. The results show that the chaotic motion can be quickly controlled to periodic 1-1 motion, the phase diagram is a closed curve, and there is a peak in the spectrum diagram. Chaotic motion can be quickly controlled as periodic 2-2 motion, the phase diagram is two closed curves, and two obvious peaks appear in the spectrum diagram. The proposed method can effectively control the chaotic motion of the system, and the expected target can be not only the fixed point of period 1, but also other periodic orbits.

Precision Data-Driven Collision Localization with a Dedicated Matrix Template for Electric Vehicle Automatic Charging

With the increasing maturity of autonomous driving technology and automated valet parking, public awareness of robot-based automatic charging for electric vehicles has gradually increased. The positioning of the charging port for electric vehicles is a prerequisite for achieving automatic charging. The common approach is to use visual methods for charging port positioning. However, due to factors such as external light conditions, humidity, and temperature, the visual system may experience insufficient positioning accuracy, leading to difficulties in executing the charging plug-in task. To address this issue, this paper proposes a data-driven collision localization method based on the vibration signal generated by the contact. During the data collection process, we first introduce a collision point matrix template suitable for automatic charging plug-in. This template covers the entire charging port and supports the acquisition of dense collision vibration data. Using this collision point matrix template, the collision localization problem can be transformed into a classification problem of collision vibration information corresponding to different collision points. Then, the collision vibration data obtained, based on this template, are used to train the collision localization model, which mainly consists of an echo state network (ESN) and support vector machine (SVM). The AUBO-i5 6-DOF articulated robot is employed to test the proposed collision localization method under different joint configurations. The simulated experimental results demonstrate the effectiveness of the proposed collision localization method, showcasing a promising localization accuracy and root mean square error (RMSE).

Impact-meshing vibration characteristics of high-speed gear systems with Backlash

The meshing process includes high-speed impact between the teeth. The vibration and noise in the gear transmission become prominent owing to the backlash between gears. Currently, the concentrated mass model is primarily used to analyse the vibration and noise mechanism of gear transmission, and it is difficult to effectively explain high-speed gear collision. In this study, an improved impact vibration model was applied to the meshing state of a high-speed gear. The gear transmission was simplified as a collision vibration system with absolute and traversable boundaries, and the piecewise-smooth dynamics model of the gear system is established. A mapping dynamic analysis method was then used to describe the impact and meshing boundary of gears. The impact-meshing situation of the gear system was observed, and the vibration response of the system under different speeds and loads was analysed using numerical simulation. The results revealed that the main source of the gear vibration was the meshing frequency of a gear pair. The resonance generated by the modulation of the rotation and meshing is the main reason for the long-term impact-meshing phenomenon of the gear transmission system. The results of this study are of great significance as they reveal the vibration characteristics of a high-speed gear transmission system.

Effect of asymmetric shroud gap and shroud friction coefficient on vibration response of shrouded blades

Based on the problem of shroud gap and shroud friction having impact on the blade collision vibration, a three-blade dynamic analysis model considering shroud friction and asymmetric gap is established in the present work. In order to study the effect of asymmetric gap and shroud friction coefficient on the vibration of the twisted shrouded blade in practice. The differential equations of shroud oblique collision between the twisted shrouded blade and adjacent blades were established, and a nonlinear Hertz contact force and an exponentially decaying friction model were used to describe the shroud contact collision force and friction, respectively. Numerical simulation and experiment are used to verify the vibration response of the blade under different gaps. The results show that the shroud movement under the asymmetric gap is more complicated than symmetric gap. The presence of shroud friction causes the passive blades to enter a cyclic motion. And shroud friction coefficient increases will decrease the amplitude of the blade.

Dynamic characteristics of wheel–rail collision vibration for high-speed train under crosswind

ABSTRACT This paper focuses on the dynamic characteristics of wheel–rail collision vibration for high-speed train under crosswind. The wind load model is established by using fast Fourier transform harmonic synthesis method and Davenport coherence function, the lateral displacement of wheelset of high-speed train under crosswind is calculated, the dynamic model of wheel–rail collision vibration system of high-speed train under crosswind is established. The effects of vibration frequency, wheel–rail clearance and lateral damping on the characteristics of wheel–rail lateral clearance impact vibration system of high-speed train are discussed. Numerical simulation results show that the impact velocity of wheelset collision on left and right rails increases with the increase of vibration frequency. When ω > 3.3, the system changes from chaos state to single period stable state through inverse doubling bifurcation; when b < 0.0033, it is in a chaos state, and with the increase of b, the inverse doubling bifurcation occurs until the hunting motion of the wheel–rail system is in a stable state; when , the system is in a stable single period operation state, and with the continuous increase of , it begins to have hop bifurcation, enters a multi-period and chaos state, and finally it is in a stable single period operation state.

Study on Dynamic Characteristics and Parameter Influence of a Kind of Bilateral Restraint Impact Vibration System

In this paper, the hinge in the articulated structure is studied, the gap hinge is described as a nonlinear bilateral constraint, and the equivalent modeling and analysis of the hinge connection collision vibration are carried out based on the Lankarani–Nikravesh nonlinear contact force model. With the help of the method of nonlinear system dynamics analysis research, the Poincaré mapping of hinge joint collision vibration is constructed, the bifurcation diagram of the system with different parameters is solved, and the variation law of the system motion and the influence of parameters are analyzed by combining the time response diagram, phase diagram, Poincaré cross section diagram, and spectrum diagram of the typical motion of the system. The simulation results show that the system moves in a single degree of freedom and varies with parameters with multiplicative period bifurcation and rubbing edge bifurcation leading to chaos; the system’s periodic motion has shock state mutation and mirror jump transformation.

Pipeline Inspection Gauge Positioning System Based on Optical Fiber Distributed Acoustic Sensing

To maintain pipeline transportation’s optimal efficiency and safety, pipelines must be regularly inspected and cleaned by the pipeline inspection gauge (PIG). Since the PIG passes through the whole pipeline, which is generally tens of kilometers, observing where the PIG is working in real-time is necessary. When the PIG passes through the pipe joint, the vibration signal will generate by the collision between the PIG and the girth weld, which can transmit along the fiber cable besides the pipeline. In this paper, we demonstrate that the optical fiber distributed acoustic sensing (DAS) can acquire the collision vibration in terms of the V pattern in the waterfall diagram, whose vertex is the collision position of PIG. The vertex will not exist when the cable positions are far away from the pipeline, which is relatively common in practice. We proposed an algorithm based on the clustering algorithm and the Hough transform to detect the position of the PIG even when the vertex of the V pattern does not exist. A field experiment shows that the proposed positioning algorithms applied to the DAS can effectively track the PIG online.

Real-time prediction of upcoming respiratory events via machine learning using snoring sound signal.

The aim of the study was to inspect the acoustic properties and sleep characteristics of a preapneic snoring sound. The feasibility of forecasting upcoming respiratory events by snoring sound was also investigated. Participants with habitual snoring or a heavy breathing sound during sleep were recruited consecutively. Polysomnography was conducted, and snoring-related breathing sound was recorded simultaneously. Acoustic features and sleep features were extracted from 30-second samples, and a machine learning algorithm was used to establish 2 prediction models. A total of 74 eligible participants were included. Model 1, tested by 5-fold cross-validation, achieved an accuracy of 0.92 and an area under the curve of 0.94 for respiratory event prediction. Model 2, with acoustic features and sleep information tested by Leave-One-Out cross-validation, had an accuracy of 0.78 and an area under the curve of 0.80. Sleep position was found to be the most important among all sleep features contributing to the performance of the 2 models. Preapneic sound presented unique acoustic characteristics, and snoring-related breathing sound could be deployed as a real-time apneic event predictor. The models, combined with sleep information, serve as a promising tool for an early warning system to forecast apneic events. Wang B, Yi X, Gao J, etal. Real-time prediction of upcoming respiratory events via machine learning using snoring sound signal. J Clin Sleep Med. 2021;17(9):1777-1784.

Tactile feedback system of high-frequency vibration signals for supporting delicate teleoperation of construction robots

ABSTRACT This study proposes a methodology to deliver contact information on construction robots to the remote operator by transmitting measured collision vibrations, which are often beyond the human-perceivable range. We focus on the human capacity to discriminate the envelope of high-frequency vibrations as an essential cue to perceive contact materials and collision conditions. The proposed method preserves the envelope shapes with amplitude-modulated waves with a single carrier frequency in the human sensitive range. In the preliminary experiments, a miniature shovel digging experiment confirmed that the proposed method improves the discriminability of the contact materials and sliding velocities. A psychophysical experiment also showed that the participants could discriminate the envelope differences irrespective of the carrier frequency. The proposed method was applied to the tactile transmission system for a construction robot developed in the ImPACT program. A vibration sensor was attached on the robot arm, and the vibrotactile feedback was applied to the operator's wrist. Performance evaluations under a delicate teleoperated task (insertion of a bar into bricks) showed that the peak force was reduced by the proposed method significantly for two out of the three participants. The results show that our proposal could improve the maneuverability of teleoperation.

DETECTING NONLINEAR AND NONSTATIONARY PROPERTIES OF POST-APNEIC SNORING SOUNDS USING HILBERT–HUANG TRANSFORM

This study focuses on patients with severe obstructive sleep apnea syndrome (OSAS), and clarifies the existence of nonlinear and nonstationary properties in post-apneic snoring sounds. Many researchers have tried to discover intrinsic properties of the snoring sounds in OSAS patients for the past decades using linear frequency analysis, but no one has shown any evidence of the existence of nonlinearity and nonstationarity based on the quantitative evaluation of the post-apneic snoring sounds. In this study, Hilbert–Huang transform (HHT), which is designed for analyzing nonlinear and nonstationary signals, is adopted to generate a time-frequency map and the temporal variation in the spectral density is quantitatively evaluated using the averaged Kullback–Leibler divergence (AKL). As a result, for six OSAS patients, there is a tendency that most of AKL calculated from post-apneic snores are higher than those from non-apneic snores, which indicates that post-apneic snores are more nonstationary. In addition, we also evaluated the difference between the HHT time-frequency maps and spectrograms using short-time fourier transforms (STFT). Such analyses revealed that frequency fluctuations inherent to snoring can be adequately represented through HHT, but not with STFT. These nonlinear and nonstationary properties seem to be highly related to the physiological phenomena of OSAS, two of which are the explosive airflow after reopening of the closed airway and the collision vibration of the soft tissues.

Vibration Test of Single Coal Gangue Particle Directly Impacting the Metal Plate and the Study of Coal Gangue Recognition Based on Vibration Signal and Stacking Integration

In order to realize the recognition of coal gangue in the top coal caving process, a scheme of the coal gangue recognition based on the collision vibration signal between coal gangue and the metal plate is proposed in this paper, a systematic and standardized impacting test between coal gangue particles and the metal plate is designed for the first time, the vibration signal standardized processing method by the signal intercepting and the coal gangue impact vibration signal recognition algorithm by stacking integration are innovatively proposed. First, a single particle impact on the metal plate test-bed was designed and constructed. Then 1,000 groups coal and 1,000 groups gangue impact on the metal plate tests were carried out respectively, and the vibration acceleration signals of the metal plate were collected. After that, through the signal intercepting, calculating the time-domain characteristics and HHT processing of the vibration signal, 10 time-frequency characteristics, such as the variance of the intercepted signal and the Hilbert marginal spectrum energy value, are determined to form the feature vector. Finally, based on the two different type of the signal samples, the intercepted signal feature vector, and the original intercepted signal, coal gangue recognition by the seven machine learning algorithms, including the decision tree (DT), random forest (RF), XGBoost, long short-term memory (LSTM), support vector machine (SVM), factorization machine (FM), and stacking integration is carried out respectively, and the basis for selecting recognition schemes is discussed. The results show that the coal gangue recognition rate with the same recognition algorithm by using the intercepted signal samples is higher than that of the feature vector samples, the Staking integration algorithm based on the same sample has the highest recognition rate, and the Staking integration algorithm based on the feature vector has the most significant comprehensive advantage in top coal caving process.

Reducing sound of tactile display for high-frequency collision vibrations

Reducing sound of tactile display for high-frequency collision vibrations

Contact Response Analysis of Vertical Impact between Elastic Sphere and Elastic Half Space

At present, the contact problem between the particle and the plane plate is generally equivalent to the rigid sphere impacting the elastic half space or the elastic sphere impacting the rigid surface. However, in the actual contact process, there will be no rigid body, and both contact and contacted object will deform and absorb energy. The research results obtained from the equivalent of the contact material to the rigid body are less accurate. In order to obtain the accurate mechanical relation and contact response, we took the research of impact between particles and the metal plate as a breakthrough in which the particle is equivalent to an elastic sphere and the metal plate is equivalent to an elastic half space and established the theory of vertical impact contact between elastic sphere and elastic half space by the Hertz contact theory. Through the dynamic simulation of an elastic sphere which has similar properties with rock impacting target in elastic half space in LS‐DYNA, the correctness of the established theory and the feasibility of the contact process simulated by LS‐DYNA are verified. Based on the established theory and 3D simulation, we studied the influence law of material parameters on the contact response and analyzed the differences of the collision vibration signals caused by the different contact objects. From the above research results, we obtain that the theoretical model is more accurate to predict the maximum contact force and contact displacement in this paper than traditional Hertz theory. And the sphere radius and both contact objects’ elastic modulus have larger influence on the contact response than sphere density, while the Poisson’s ratio has the smallest influence on the contact response results. Different material properties will cause the different contact response. The conclusions of this paper provide a theoretical calculation method for contact and a 3D simulation method for elastic half space and provide theoretical guidance for the differences analysis of the vibration signal.

Time Constant Discrimination of Collision Vibration

When we tap on the surface of the objects, damped collision vibrations occur. We can distinguish the materials by the perception of these collision vibrations. However, the discrimination ability is limited and unclear. This study investigated Just Noticeable Difference (JND) of the time constant, which is a reasonable factor relating for discriminating collision vibrations. We conducted psychophysical experiments to evaluate JNDs for two referenced time constants (10.8 and 50 ms) among five frequencies (150, 250, 500, 800 and 1000 Hz). The results showed that there were significant differences among reference time constant and we should use large step rate at the low time constant range.

周期励振を受ける無減衰2自由度系の衝突振動解析（1/2次分数調波共振の解析解導出）

Collision vibration systems are usually modeled as a nonlinear spring whose characteristics are described by the broken line model. These systems are called piecewise-linear systems. A piecewise-linear system is highly nonlinear, and it is usually difficult to predict the system response using any general analytical solution. If the effects of design parameters such as clearance size and dynamic nonlinearity of the systems are known, the structures can be designed to be safer and more comfortable. In a previous paper, forced collision vibration for 2nd order super harmonic resonance in a mass-spring system for two-degree-of-freedom was analyzed. The restoring force, which is generated when a mass collides elastically to another mass, was modeled as an asymmetric piecewise-linear system. In this research, the 1/2nd order sub-harmonic resonance is treated for the same system in the previous research. In order to analyze resulting vibration for the 1/2nd order sub-harmonic resonance, the Fourier series method is applied and analytical solutions for this system are derived. Next, following the analytical solutions, numerical calculations are performed, and the resonance curves are constructed by using resulting vibration. Effects of amplitude ratio of excitation, nonlinearity of the system and mass ratio on the resonance curves are shown numerically. For verification of the analytical solutions, numerical simulations are performed by the Runge-Kutta method, and numerical results based on analytical solutions are compared with numerical simulation results on the resonance curves. As a result, the analytical solutions are in a fairy good agreement with the numerical simulation results.

Nonlinear Vibroimpact Characteristics of a Planetary Gear Transmission System

In order to research the vibroimpact characteristics of a planetary gear transmission system under high speed and lightly loaded conditions, a new modeling method is proposed. In the modeling process, linear spring was used to simulate gear mesh elasticity under heavy load cases, and Hertz contact theory was used to calculate the contact force of gear pair under light load cases. Then, effects of the working conditions on the system vibroimpact characteristics are analyzed. The results show that, with input speed growing, the mesh force produced obvious fluctuations on the resonance frequencies of the sun gear and carrier torsion vibration, ring gear’s transverse vibration under the heavy load. Under light load condition, the collision vibration occurs in the gear pair; the changing trend of the contact force shows strongly nonlinear characteristics. The time of mesh-apart in gears pair decreases gradually as the load is increased; until it reaches collision vibration threshold value, the gear pair is no longer mesh-apart. With increasing of the input speed, the time of mesh-apart is decreased gradually; the fluctuation amplitude of contact force shows a linearly increasing trend. The study provides useful theoretical guideline for planetary gear transmission low-noise design.

がたのある2自由度ばね-質量系の強制振動解析

Collision vibration systems are usually modeled as a nonlinear spring whose characteristics are described by the broken line model. These systems are called piecewise-linear systems. A piecewise-linear system is highly nonlinear, and it is usually difficult to predict the system response using any general analytical solution. If the effects of design parameters such as clearance size and dynamic nonlinearity of the systems are known, the structures can be designed to be safer and more comfortable. This paper deals with forced collision vibration in a mass-spring system for two-degree-of-freedom. The analytical model is mass-damper-spring system having two masses in which one mass is subjected to an exciting vibration with arbitrary functions. Then the restoring force, which has characteristics of an asymmetric piecewise-linear system, collides elastically to another mass when amplitude of the mass increases farther than clearance. In order to analyze resulting vibration and colliding force, the Fourier series method is applied and analytical solutions for this system are derived. Next, following the analytical solutions, numerical calculations are performed. Effects of amplitude ratio of excitation, nonlinearity of the system and mass ratio on the resonance curve and colliding force are shown numerically. For verification of the analytical solutions, numerical simulations are performed by the Runge-Kutta method, and numerical results based on analytical solutions are compared with numerical simulation results. As a result, the analytical solutions are in a fairy good agreement with the numerical simulation results.

618 減衰を考慮した2自由度ばね-質量系の衝突振動解析(機械力学・計測制御VI)

618 減衰を考慮した2自由度ばね-質量系の衝突振動解析(機械力学・計測制御VI)

周期励振を受ける無減衰2自由度系の衝突振動解析（第2次高調波共振の解析解導出）

周期励振を受ける無減衰2自由度系の衝突振動解析（第2次高調波共振の解析解導出）