Hydraulic Vibration Research Articles

Hydraulic Simulation Analysis of Sonic Drilling Hydraulic Vibration Head

The hydraulic vibration head is the core component of sonic drilling rig, and the performance of its hydraulic system influences the technology of sonic drilling directly. The structure and hydraulic system of the hydraulic vibration head are designed, and the AMESim model of the hydraulic system is established in the paper. The hydraulic vibration system is simulated and analyzed to find out the influence rule of vibration frequency on the system performance. The results show that the larger the vibration frequency f is, the smaller the amplitude H is, and the displacement response of the vibrating piston approximates the sine curve.The velocity and acceleration of the vibrating piston accordingly increased, and the exciting force F of the vibrating piston increased significantly.

Vibration Information Acquisition and Representation Control Strategy for Construction Vehicle Driver Seat

Vibration information acquisition and representation control strategy in the experiment of construction of vehicle driver seat are investigated in this study. An improved adaptive algorithm of multisensor attitude data fusion is proposed. The nonlinear equations of vehicle attitude quaternions are constructed by using the test information of accelerometers and magnetometers. Then, a complementary filter is used to fuse the obtained attitude with gyroscope information to obtain attitude information during vehicle travel. Weight matrix and filter coefficients in the algorithm are adjusted with vehicle motions to ensure accuracy of attitude measurement under static, low‐, and high‐acceleration conditions. The vehicle vibration displacement information is reconstructed by the low‐frequency attenuation integration method on the basis of attitude measurement to inhibit integral trend items and reduce vibration displacement reconstruction errors. The three‐state controller is designed to control a six‐degree‐of‐freedom hydraulic simulated vibration test bed, and the obtained vibration signal is used as an excitation signal to perform a vibration representation control test. Finally, results verify that the proposed method demonstrates favourable data fusion and representation accuracy.

Effects of Structure Parameters on Abnormal Opening of Pilot-Operated Relief Valve Under Alternating Pressure

Hydraulic vibration excitation has been widely regarded as a promising method of excitation because of its high power density and large output force. However, the alternating pressure in the hydraulic vibration exciter could cause the pilot-operated relief valve (PRV) to open abnormally, which presents a new challenge to the normal operation of the PRV. To determine the abnormal opening characteristics of the PRV under alternating pressure, the effects of structure parameters of the PRV (including diameters of orifices 1 and 2, volume of the pilot valve inlet, volume of the main valve spring chamber, area ratio of the main spool, and main spring pre-compression force and stiffness) on its abnormal opening displacement under alternating pressure were numerically investigated. The calculation results indicate that the abnormal opening of the PRV will be effectively decreased by appropriately increasing the diameter of orifice 1, decreasing the pilot valve inlet and main valve spring chamber volumes, and increasing the area ratio of the main spool and the main spring pre-compression force. The influence of the orifice 2 diameter on the abnormal opening of the PRV is dependent on the diameter range of orifice 1. The reasonable diameters of orifices 1 and 2 are in the range of 0.8-1.2 mm. The influence of the main valve spring chamber volume is more significant than the pilot valve inlet volume. The influence of the main spring stiffness is not significant.

Design and analysis of an active‐controlled hydraulic low‐frequency vibration isolator

This study proposes an active-controlled hydraulic low-frequency vibration isolator. The vibration isolator can achieve large equivalent mass and quasi-zero dynamic stiffness by combining the fluid inerter with the hydraulic active compensation. Thus, good vibration isolation performance at ultra-low frequency can be realised. The model for the dynamics of the device is set up. The principle of low-frequency vibration isolation is explicated. The natural frequency and its influencing factors are analysed. Finally, preliminary experimental research works are carried out. The results indicate that low-frequency vibration can be effectively isolated by the device proposed in this study.

Crestal Sinus Floor Augmentation Using Hydraulic Pressure and Vibrations: A Retrospective Single Cohort Study.

To evaluate the sinus membrane perforation and implant survival rate after crestal minimally invasive sinus floor augmentation using hydraulic pressure and vibrations. In this retrospective single cohort study, all patients who underwent minimally invasive sinus floor augmentation between 2007 and 2015 using hydraulic pressure and vibrations were included. The sinus membrane is elevated by physiologic saline at 1.5 bar. The fluid is then set into vibration to further separate the sinus membrane from the bony floor. The endpoints were sinus membrane perforation and the survival rate of implants. The hydraulic pressure and vibration technique was applied in 156 patients. Seven patients with perforations of the sinus membrane were treated with the lateral window approach and excluded from the follow-up analysis. In the remaining 149 patients, 184 crestal sinus floor augmentations were performed and 184 implants were placed. In 10 of these 184 cases, a perforation was suspected in the postoperative computed tomography (CT) scan. In total, the perforation rate was 8.9% (17/191). Nineteen implants were lost during the follow-up period ranging from 0.2 to 8.4 years with a median of 2.3 years. The cumulative implant survival rates after 1, 3, and 5 years were 94.4%, 87.7%, and 87.7%, respectively. No severe perioperative complications were noted. The hydraulic pressure and vibration technique allows a minimally invasive crestal sinus augmentation with a perforation rate less than 10% and implant survival rates of approximately 90%.

Experimental Study on the Performance of Hydraulic Vibration Assisted Broaching (HVAB) Based on Piezoelectric Sensors

In order to improve the keyway broaching process and verify the feasibility of vibration-assisted broaching process, an experimental study on a novel hydraulic vibration assisted broaching (HVAB) system with double-valve electro-hydraulic exciter (DVEHE) is proposed in this paper. The performances of HVAB at different excitation frequencies were compared from three aspects: (a) the cutting force under the different vibration frequencies, (b) the surface roughness of the workpiece, and (c) the flank face wear of the tool. For precision on-line measurement of larger broaching forces, four piezoelectric sensors were fixed on the broaching machine. The experimental results show that HVAB can effectively improve the performance of the broaching process, approximately reduce the broaching force by as much as 9.7% compared to conventional broaching (CB) and improve the surface quality of workpiece. Some explanations are offered to support the observations.

Torsional Vibration Analysis of Hydro-Generator Set Considered Electromagnetic and Hydraulic Vibration Resources Coupling

The torsional vibration characteristics of the hydro-generator set considering the electromagnetic and hydraulic vibration resources coupling are studied. The moment of rotation consists of water flow driving and magnetic torques caused by the air gap magnetic field in the generator rotor in the case of ignoring the mechanical friction. A coupling torque vibration model of hydro-generator shaft system was established. The model considered the coupling action of hydraulic and electromagnetic excitations, as well as the elastic effect of rotor spiders. The influences of the rotor moment inertia, rotor stiffness, and mass of turbine water added into the torsional natural vibration of the unit shaft system were studied. The effect of hydraulic excitation frequency on torsional vibration response was also investigated. The frequency response curves of shaft torque, torsional vibration angle, and electromagnetic torque were presented. The electromagnetic and hydraulic coupling resonance was studied when hydraulic excitation frequency was equal to zero and first-order frequencies. The excitation electric current and internal active power angle on torsional vibration was further analyzed. This study provides an analysis model and method considering the coupling of electromagnetic and hydraulic vibration resources for design and stable operation of water turbine generator sets.

Design, Analysis, and Experimental Evaluation of a Magnetorheological Damper With Meandering Magnetic Circuit

This paper presents a novel magnetorheological (MR) damper with a meandering magnetic circuit, referred to as MMCMRD, to improve the damping force performance of an MR damper. The magnetic flux path of the MMCMRD is guided by magnetically conductive and non-magnetically conductive elements. A theoretical model of the MMCMRD is built, and a finite-element analysis is performed to verify the principle of the MMCMRD. The damping force characteristics of the MMCMRD are experimentally tested on a hydraulic vibration system and compared with the theoretical results. The experimental results show that the controllable damping force of the MMCMRD under an excitation velocity of 0.0628 m/s is as high as 3400 N, which is considerably higher than that of the traditional MR damper. The equivalent damping and damping coefficient of the MMCMRD are both larger than those of the traditional MR damper when the input current exceeds 0.75 A. The research results show that the principle of the MMCMRD can improve the efficiency of the MR damper, and the damping force performance of the MMCMRD is accurately described by the theoretical model.

Fluid hammer analysis with unsteady flow friction model in coiled tubing drilling

Hydraulic vibrator is a useful tool to reduce the mechanical friction and increase the lateral-reach in coiled tubing drilling (CTD). This paper proposes an unsteady friction model to study the interaction between the fluid hammer and the axial vibration of CT with multi-boundary conditions. The proposed model considers the unsteady friction term and comprises the continuity and momentum conserve equations, which are solved by the method of characteristics. Then a series of laboratory experiments with a hydraulic pulse cavitation vibration tool was conducted to validate the model, the simulated results are in good agreement with the experimental measurement. Finally, the characteristic of periodic flow generation and propagation, as well as the effect of crucial flow parameters on the axial vibration are analyzed with the proposed model. The results show that the actual pressure pulse at different positions is the sum of the forward-traveling wave and return wave. Although the magnitude of drag force induced by hydraulic vibrator is not affected by the frequency of flow area, it increases exponentially with flow rate while decreases exponentially with minimum flow area ratio.

Discussion on Stochastic Analysis of Hydraulic Vibration in Pressurized Water Diversion and Hydropower Systems

Hydraulic vibration exists in various water conveyance projects and has resulted in different operating problems, but its obvious effects on system’s pressure head and stable operation have not been definitively addressed in the issued codes for engineering design, especially considering the uncertainties of hydraulic vibration. After detailed analysis of the randomness in hydraulic vibration and the commonly used stochastic approaches, in the basic equations for hydraulic vibration analysis, the random parameters and the formed stochastic equations were discussed for further probabilistic characteristic analysis of the random variables. Furthermore, preliminary investigation of the stochastic analysis of hydraulic vibration in pressurized pipelines and possible self-excited vibration in pumped-storage systems was presented for further consideration. The detailed discussion indicates that it is necessary to conduct further and systematic stochastic analysis of hydraulic vibration. Further, with the obtained frequencies and amplitudes in the form of a probability statement, the stochastic characteristics of various hydraulic vibrations can be investigated in detail and these solutions will be more reasonable for practical applications. Eventually, the stochastic analysis of hydraulic vibration will provide a basic premise to introduce its effect into the engineering design of water diversion and hydropower systems.

Damping Characteristic Analysis and Experiment of Air Suspension with Auxiliary Chamber

In this paper, the damping characteristics of air suspension with auxiliary chamber are studied. A single degree of freedom nonlinear mathematical model of air suspension with auxiliary chamber was established based on theories of aerodynamics, engineering thermodynamics and fluid dynamics. Secondly, the damping characteristics are simulated by Matlab/Simulink, and the relationship of relative damping coefficient and natural frequency with the opening degree of throttle hole under different excitation amplitude were discussed, a basic control strategy for damping control of air suspension with auxiliary chamber was proposed. Finally, the relation between valve opening and driving voltage of proportional flow control valve was studied experimentally, the hydraulic vibration test bench was set up and the damping characteristics experiment of air suspension with auxiliary chamber was carried out, the nonlinear mathematical model and simulation results were also verified at the same time. The results showed that experiment and the simulation have good consistency, verifying the correctness of the established mathematical model. The research would provide a theoretical reference for how to design and control of air suspension with auxiliary chamber.

A hydraulic fault diagnosis method based on sliding-window spectrum feature and deep belief network

The vibration signal of hydraulic system contains abundant state information, so vibration testing technology is an effective way to realize the fault diagnosis of hydraulic system. However, the mapping relation between signal characteristic and system state is complex and the expression meaning of characteristic is obscure, which brings a great challenge to the hydraulic fault diagnosis. The DBN, a newly proposed deep learning model, has an advantage of autonomously learning and reasoning. And it is good at studying the concealed representation of data and highlighting the feature expression. So, it is contributive to deal with the problems of large capacity data like high dimension, redundancy, and nonlinear etc. Therefore, DBN is chosen as the fault diagnosis method in this paper. Meanwhile, given that the difficulty in feature extraction of hydraulic vibration signal and the important influence of input feature vector to the diagnosing of DBN, a fast and effectively feature extraction method based on sliding-window spectrum feature (SWSF) is proposed. It is effective in remaining the integrity of feature, avoiding the risking of relative shifting of characteristic spectrum, and decreasing the dimensions of feature vector. The experimental results demonstrate that the combination of SWSF and DBN is a fast and effective approach to realize the fault diagnosis of hydraulic system.

PhD theses completed in 2017

Christian SchleihsAcoustic Design of Hydraulic Axial Piston Swashplate MachinesRWTH Aachen University, Aachen, GermanySound and vibration issues have ever since been addressed in the research and d...

Influence of vibration caused by sound on migration of sea cucumberApostichopus japonicus

Vibrations exist widely in the ocean, and the one caused by sound and biological movement plays an important role in the sensory system of marine organisms. The vibration caused by sound has many characteristics that make it a good candidate for modifying the movements of marine organisms. However, few studies have tested whether hydraulic vibration caused by sound has effects on the migration of sea cucumbers, and this has never been systematically studied previously in Apostichopus japonicus (Selenka). In order to understand whether hydraulic vibration caused by sound at different frequencies could affect the migration of sea cucumbers, in the present study, hydraulic vibration caused by sound at various frequencies was tested in the laboratory to determine their effects on the migration of A. japonicus at different sizes. The mean probability distribution was used as a statistical index to demonstrate the moving tendencies of the species. The experimental results showed that medium and small A. japonicus (<10 g ind.−1) tend to move towards the low-frequency vibration source caused by sound (100 Hz), whereas all sizes of A. japonicus tend to move backwards the high-frequency vibration source caused by sound (10 000 and 28 000 Hz). This study provides basic data on the behavioural ecology of this species, as well as theoretical reference for the design of artificial reefs and harvesting equipment for A. japonicus.

Optical fiber grating vibration sensor for vibration monitoring of hydraulic pump

In view of the existing electrical vibration monitoring traditional hydraulic pump vibration sensor, the high false alarm rate is susceptible to electromagnetic interference and is not easy to achieve long-term reliable monitoring, based on the design of a beam of the uniform strength structure of the fiber Bragg grating (FBG) vibration sensor. In this paper, based on the analysis of the vibration theory of the equal strength beam, the principle of FBG vibration tuning based on the equal intensity beam is derived. According to the practical application of the project, the structural dimensions of the equal strength beam are determined, and the optimization design of the vibrator is carried out. The finite element analysis of the sensor is carried out by ANSYS, and the first order resonant frequency is 94.739 Hz. The vibration test of the sensor is carried out by using the vibration frequency of 35 Hz and the vibration source of 50 Hz. The time domain and frequency domain analysis results of test data show that the sensor has good dynamic response characteristics, which can realize the accurate monitoring of the vibration frequency and meet the special requirements of vibration monitoring of hydraulic pump under specific environment.

基于HHT的航空发动机液压管路系统管路故障诊断研究

针对航空发动机液压管路系统在实际工作中由于振动过大产生的卡箍松脱故障，通过电磁振动台模拟宽频域液压管路基础激励环境，采用光纤光栅分步式监测系统，利用HHT方法可以对航空发动机液压管路系统振动信号中的突变信号进行有效的侦测。HHT分析方法能够反映航空发动机液压管路系统的故障振动响应的不同状态，由此进行航空发动机液压管路系统振动信号的检测具体实施步骤。最后结果表明，采用HHT方法与光纤光栅监测系统能够实现航空发动机液压管路故障的定位和判定。 The objective in this paper is to present HHT method and FBG technology to analyze the aero-engine hydraulic pipeline vibration signal under fault states. Fault diagnosis and location of aero-engine hydraulic pipeline vibration signals based on HHT method and FBG method are ap-plied through HYPERLINK electromagnetic vibration table simulating wide frequency band under clamp loosing and trip state. The results tested in aero-engine hydraulic pipe show that HHT method can clearly reflect the real vibration characteristics of hydraulic pipe under different states. This method overcomes the disadvantage of the traditional Fourier transform (FFT) which cannot obtain the instantaneous frequency of aero-engines, and provides a new idea for the non- stationary vibration information of hydraulic pipe under different states. Fault diagnosis and location of the aero-engine hydraulic pipeline are confirmed by HHT and FBG method.

Reliability assessment of the vertical roller mill based on ARIMA and multi-observation HMM

AbstractOnline running condition monitoring of the vertical roller mill (VRM) is significant to assess the equipment performance degradation and reliability. This paper proposes a performance reliability assessment method based on autoregressive integrated moving average (ARIMA) model and hidden Markov model (HMM) using the real-time sensing monitoring signals, which is designed to analyze the running state and predict the reliability of VRM. As most faults of VRM relate to hydraulic pressure of loading system and mechanical vibration, research on hydraulic monitoring and vibration monitoring is prerequisites, which determines the sensing parameters and monitoring points, provides the data base for following reliability assessment. Then ARIMA is applied to establish the performance degradation path using the historical sensing monitoring data. Finally, the multi-observation HMM is used to estimate the reliability changing trend of the equipment, the input observations of which are the predictive data from...

An experimental study of the influence of pressure pulsations in the water turbine flow path on vibration parameters of the hydraulic unit

The paper presents an experimental study of the relationship between the vibration of the water turbine unit and the pressure pulsations in the flow path. It is shown that the air injection into the flow path leads to a decrease in the hydraulic turbine vibration associated with the formation of the precessing vortex core.

Experimental Study on Variation Rules of Damping with Influential Factors of Tuned Liquid Column Damper

A tuned liquid column damper (TLCD) is a more effective form of passive control for structural vibration suppression and may be promising for floating platform applications. To achieve good damping effects for a TLCD under actual working conditions, factors that influence the damping characteristics need to be identified. In this study, the relationships between head loss coefficients and other factors such as the total length of the liquid column, opening ratio, Reynolds number, Kc number, and horizontal length of the liquid column were experimentally investigated. By using a hydraulic vibration table, a vibration test system with large-amplitude motion simulation, low-frequency performance, and large stroke force (displacement) control is devised with a simple operation and at low cost. Based on the experimental method of uniform design, a series of experimental studies were conducted to determine the quantitative relationships between the head loss coefficient and other factors. In addition, regression analyses indicated the importance of each factor affecting the head loss coefficient. A rapid design strategy of TLCD head loss coefficient is proposed. This strategy can help people conveniently and efficiently adjust the head loss coefficient to a specified value to effectively suppress vibration.

Assessment of structural condition of Libeň Bridge

The paper presents diagnostic and load tests of the Inundation bridge which is part of a group of bridges called The Libeň bridge group in Prague. The Libeň bridge group consists of two arched and several framed bridges spanning the Vltava river. One of the vaulted bridges consists of 5 arches and the other vaulted bridge (called Inundation bridge) consists of only one arch. Arched bridges are extraordinary structures with both technical and historical value. Since the inundation bridge has the largest arch of whole group, it was selected for testing purposes. The bridge is assembled with three-hinged arch made of concrete. The hinges are made of reinforced concrete and lead contact slabs. Detailed measurements of geometry and material properties were made on the bridge. Based on these measurements a computer model was created to verify the behavior of the structure. Both static and dynamic calculations were performed. Measurements of dynamic characteristics were made during normal operation and with hydraulic vibration exciter. This article will focus on comparing the results of dynamic calculation of the modeled structure and properties measured on real structure excited by hydraulic vibration exciter.