Longitudinal Vibration Research Articles

Intelligent Method to Optimize the Frequency Modulation for Beam Pumping System Based on Deep Reinforcement Learning.

A mathematical simulation model of a beam pumping system with frequency conversion control is established, considering the influence of the real-time frequency variation on the motion law of a pumping unit, the longitudinal vibration of a sucker rod string, the crankshaft torque, and the motor power. On this basis, the key links such as state space, action space, and reward function are defined by using deep reinforcement learning theory, and an intelligent model to optimize the frequency modulation for a beam pumping system based on deep reinforcement learning is constructed. The simulation and field application results show that the frequency optimization model can significantly reduce the fluctuation amplitude of the polished rod load, crankshaft torque, motor power, and input power of the system, making the operation of the pumping system more stable and energy-saving. More importantly, the model can realize the independent learning and control of the corresponding parameters without manual intervention to ensure the normal operation of the system and improve the level of information and intelligent management of oil wells.

Structural Strength and Fatigue Strength Analysis of Roller Arm

The cone reamer is used for underhole reaming, mainly through the impact crushing and cutting of teeth to complete rock breaking, easy to produce vibration. At the same time, the underground topography is complex and rock materials are changing. Therefore, the force of the cone reamer is complex and easy to damage. According to the statistics of the field use, the main failure form is the failure of the roller arm. The reaming arm consists of two parts: a cone arm and a bearing. As for the reaming arm, it is subjected to the reaction force of rock on teeth and the support force of piston when working. When the teeth eat into the rock alternately, longitudinal vibration will be generated, so that the force of the cone arm is random impact load. Due to the instability of bit weight, additional dynamic load is caused, resulting in the piston support force is also random impact load. Thus causing the fracture of the cone arm. For bearings, reamers are used to drill stepped holes and rely on the outer teeth of the cone as opposed to the cone bit. When the teeth eat into the rock alternately, the longitudinal vibration is generated, and the rock is broken through the impact and cutting of the teeth. And the axial acceleration of the cone reamer is greater than the longitudinal acceleration, so the axial vibration is severe and the bearing bears the impact load. At the same time, the wall morphology and rock material are changing, so the bearing is subjected to random contact fatigue load. The piston cracks under the repeated action of random load, leading to fatigue failure. It can be seen from the structure characteristics and working principle of the cone reamer that the cone arm is the core functional component of the cone reamer. Therefore, abnormal failure of the above components should be avoided as far as possible. Therefore, this paper completed the simulation analysis of the cone arm, obtained the stress and strain distribution of the cone arm, and established the finite element analysis specification and safety evaluation index of the cone arm.

Natural Frequency and Modes of the Longitudinal and Torsional Vibrations in the Bars with Variable Cross Section

The paper is focused on the problem of natural frequencies and modes determination based on perturbation theory for longitudinal and torsional vibrations in bars with variable cross section. The mechanical properties and cross section geometry of the bar are changing small from the average value with regard to longitudinal coordinate. Based on the theory of small perturbations the analytical solution is obtained for natural frequencies and modes of the stationary harmonic vibrations in bars. The efficiency of the proposed method is supported by comparison and good agreement of the obtain results with a sharp solution for a given cross section profiles. It was established that the approximate solution is working good up to the ratio 2.5–3 between maximum and minimum diameter of cross section. The results of numerical simulations are aimed to estimate the geometry and elastic behavior of the metallic specimens for very high cycle fatigue experimental investigation under axial tension-compression and torsion loadings. The piezoelectric fatigue testing system and procedure is based on stationary vibration excitation in the metallic specimen at the first mode natural frequency.

A Low-Frequency Unidirectional Underwater Acoustic Transducer

A unidirectional underwater acoustic transducer has the advantage of narrower beam width. In the low-frequency field, a single transducer is usually omnidirectional because its dimension is much smaller than the wavelength of the sound waves. Here, a low-frequency unidirectional underwater acoustic transducer, the Single-Sided Radiation Flextensional Transducer (SSR FT), which is driven by a stack with the longitudinal vibration, was designed by the finite-element method. The vibration mode of the transducer was first studied and analyzed. Then, an underwater harmonic response analysis of the transducer was conducted. We found that the second resonance, corresponding to the fourth vibration mode, could be unidirectional based on a specific s br, which is the ratio of r b (the radius of the tail mass) to l maj (the inner length of the semi-major axis of the radiation surface). Finally, the effect of s br on the vibration velocity and directivity of the SSR FT was investigated. We established that the vibration velocity amplitude and phase of the shell were different at the same vibration mode but at different s br, which resulted in different directivity.

Design and optimization of a half-wavelength ultrasonic bone scalpel

Compared with traditional orthopedic surgical instruments, the ultrasonic bone scalpel (UBS) has obvious advantages in both safety and effectiveness. Based on the structure of the sandwich piezoelectric transducer, a design of half-wavelength UBS with a longitudinal vibration frequency of 22.5 kHz is proposed in this study. Firstly, the dimensions of each component of the UBS are calculated by the transmission matrix method, the initial design is verified by modal analysis, and the error is optimized by the response surface method. Then the harmonic response analysis is used to calculate the UBS’s tip amplitude, impedance and stress distribution. In addition, the influence of bolt pre-tightening force on the vibration characteristics of the UBS is analyzed. When the bolt pre-tightening force is 50-90MPa, the vibration performance of the UBS is stable, and the tip amplitude is large, which provides a reference for selecting appropriate tightening torque when the UBS is assembled. Finally, the bone-cutting experiment shows that the UBS has good cutting performance.

Determining the Influence of a Magnetic Field on the Vibration and Fuel Consumption of a Heavy Diesel Engine

Most of the fuels used in internal combustion engines are liquid fuels. The magnetic behavior of fuel leads to a change in the interaction of hydrocarbon and oxygen molecules. This study aimed to evaluate the fuel consumption and engine vibration (time domain) of the Perkins A63544 diesel engine using magnetized fuel. The vibration of an internal combustion engine can cause failure in engine components and discomfort and injury to users. Engine vibration behavior changes due to changes in fuel types and engine combustion. Therefore, in this study, the vibration behavior of the tractor engine (Perkins model, four-stroke, direct injection diesel) was evaluated in stationary mode at different engine speeds due to changes in fuel types. Three accelerometers (CTC AC102 model) were used to measure the vibration acceleration. The fuels used included diesel as a normal control and fuels that had been subjected to magnetic field intensities of 1000, 2000, 3000, and 4000 gauss. The longitudinal, vertical, and lateral vibration signals with 5 levels of engine speed were measured. The results illustrated that the vibration root mean square (RMS) values were essentially (p < 0.01) affected by the engine speed, fuel type, and their interactions. It was found that for the 4000-gauss magnetized fuel, the average vibration acceleration using the five velocity settings reduced by 15%, 15.30%, 12.40%, 12.35%, and 15.38% compared to the respective control fuels. The results showed that engine fuel consumption and specific fuel consumption decreased by 2.3% using the 4000-gauss magnetized fuel compared with the normal control fuel.

Modeling and analysis of frequency-variable 2–2 cement-based piezoelectric transducers

The 2–2 cement-based piezoelectric transducers can be used as high-performance actuators and sensors. However, the existing designs with fixed electromechanical properties cannot meet some special application requirements, such as the tuning working frequency to achieve high precision monitoring purpose. To address this issue, a type of frequency-variable 2–2 cement-based piezoelectric transducers is proposed in this paper. Theoretical models of the proposed transducer are established, and the analytical solutions of its longitudinal vibration are obtained. The theoretical models are verified by comparing their results with those of the existing literature for some special examples, and with the finite element results for a special case. In addition, the effects of the tuning resistance, the ratio of piezoelectric layer numbers between the active and passive elements, the electrical connections of piezoelectric layers, and the total number of piezoelectric layers on the electromechanical properties of transducer are discussed. It is demonstrated that the proposed frequency-variable 2–2 cement-based piezoelectric transducers can obtain a large tunable bandwidth by adjusting the appropriate ratio of piezoelectric layer numbers between the active and passive elements and their electrical connections, which provides a theoretical basis for designing and optimizing this type of transducers.

Research on longitudinal vibration suppression of underwater vehicle shafting based on particle damping

A particle damper is applied to suppress the longitudinal vibration of underwater vehicle shafting in order to reduce vibration level and improve silence and stealth of underwater vehicles. The model of rubber-coated steel particle damper was established with discrete element method and PFC3D simulation software, the damping energy consumption law of collision and friction between particle and damper and between particle and particle investigated, the effects of particle radius, mass filling ratio, cavity length, excitation frequency, excitation amplitude, rotating speed and both stacking and motion states of particles on the system vibration suppression were discussed, and the bench test was carried out to verify the law. It revealed the mechanism of longitudinal vibration suppression of particle damping, established the intrinsic relationship between of total energy consumption of particle and vibration of system, and put forward the evaluating method of longitudinal vibration suppression effect by total energy consumption of particle and vibration reduction ratio. The research results show that the mechanical model of particle damper is reasonable and the simulation data is reliable; the rotating speed, mass filling ratio and cavity length have significant effects on the total energy consumption of particle and vibration reduction ratio.

The Study of Localized Crack-Induced Effects of Nonlinear Vibro-Acoustic Modulation

The nonlinear interaction of longitudinal vibration and ultrasound in beams with cracks is investigated. The central focus is on the localization effect of this interaction, i.e., the locally enhanced nonlinear vibro-acoustic modulation. Both numerical and experimental investigations are undertaken. The finite element (FE) method is used to investigate different crack models, including the bi-linear crack, open crack, and breathing crack. A parametric study is performed considering different crack depths, locations, and boundary conditions in a two-dimensional beam model. The study shows that observed nonlinearities (i.e., nonlinear crack-wave modulations) are particularly strong in the vicinity of the crack, allowing not only for crack localization but also for the separation of the crack-induced nonlinearity from other sources of nonlinearity.

Psychoacoustic characteristics of different brake creep groan classes and their subjective noise annoyance in vehicle and half-axle tests

Brake creep groan is a severely annoying noise and vibration phenomenon. Especially on the Asian market, customer feedback about creep groan is common, indicating creep groan’s impact towards the quality impression of a car. Hence, treatment of these stick–slip-related creep groan phenomena is necessary. As numerous design conflicts exist for brake and axle, a complete mitigation of the phenomenon is often not possible. A reduction of creep groan’s annoyance by changing the noise’s level and characteristics is therefore typically aspired. One approach towards this goal could include the usage of psychoacoustics: This work deals with psychoacoustic characteristics of different creep groan classes. Low-frequency groan, high-frequency groan, and transition groan classes are compared regarding loudness, sharpness, roughness, fluctuation strength, and tonality. Standard statistic methods as well as machine learning approaches are applied on signals from vehicle tests and half-axle tests. Test results depict the different characteristics of each creep groan class. By mapping the results to the subjective rating of trained test drivers, the annoyance of different classes is compared. Low-frequency groan, dominated by longitudinal axle vibrations, is found to be least annoying. This low annoyance is best depicted by the psychoacoustic parameters loudness and roughness. Presented results allow an optimization of brake system design to reduce creep groan’s annoyance, leading to higher customer satisfaction and a more goal-oriented treatment of this NVH problem.

In-situ experiment research on environmental vibration transmission characteristics of air-rail combined airport

The rail transit and civil aviation are the important components of the comprehensive transportation system. The development of the air-rail combined transport is an important effective way for China to become a country with strong transportation network. The transportation intersection form of railway under-passing airport transportation hub gradually becomes popular, thus the environmental vibration due to the under-passing railway cannot be ignored. In this paper, a large-scale integrated transportation hub construction project was taken as an example to analyze the transmission rule of environmental vibration due to the high-speed railway at the speed of 350 km/h under-passing airport in terms of the time domain and frequency domain by means of the on-site in-situ wheel-drop test. The research results show that the vertical vibration response of the ground surface along the normal direction of the railway is greater than those of the other two directions within 40 m from the centerline of the track. A vibration amplification zone appears within 5-40 m. The longitudinal vibration response of the ground surface is greater than those of the other two directions within 40-70 m. The local vibration amplification zones appear within 5-20 m and 30-60 m. The lateral vibration level of the ground surface along the normal direction of the railway increase gradually, but attenuates at the distance of 40 m and 10 m with the maximum attenuation rate of 0.67. The vertical vibration level amplifies at the distance of 60 m. The longitudinal vibration level attenuates at the distance of 20 m with the maximum attenuation rate of 0.3, but amplifies at the distance of 40 m with the maximum amplification rate of 1.8.

Dynamic analysis and vibration control for overhead hoist transport

The OHT system is a transport device used for intra- or inter-plant transport in a fab or other factory, the load-bearing part of the goods stored under the trolley generates longitudinal vibration and lateral oscillation due to inertia force When the OHT in the air starts or stops. Firstly, the trolley dynamic model under the action of lateral thrust and longitudinal tensile force need to be established. secondly, the coupling analysis of horizontal oscillation and longitudinal oscillation on the model is carried out. Thirdly, aiming at the lateral swing and longitudinal vibration of the carriage, a double closed-loop vibration control strategy with tension control as inner loop and speed control as outer loop and carry out the simulation analysis of longitudinal vibration control is proposed. In the experiment of the ground trolley, the control strategy is applied. The simulation and experimental results show that the control method can quickly restrain the longitudinal vibration of the trolley bearing plate, reduce the pulling force of the trolley on the lifting steel belt, and avoid the large displacement of the bearing plate in the air.

Fracture of aircraft titanium alloys under high-frequency loading

The paper is devoted to the problem of fatigue failure of two-phase titanium alloy VT3-1 under the action of high-frequency cyclic loading. Samples for the tests were made from the compressor disk of aviation engine D30-Ku installed on Tupolev Tu-154 planes. Repeated alternating loading was carried out by displacements of small amplitude at 20 kHz, coinciding with the first harmonic of longitudinal elastic vibrations of the sample. Analysis of specimen fracture surfaces shows predominant subsurface fracture. Analysis of areas of fatigue nucleation allows identifying elements of microstructure associated with crack nucleation. The results of the study can be used in the interpretation of fracture scenarios of structural elements in operation. Increasing the resource of products under such loads is possible through the use of damping layers or tapes, where possible.

Development of a Self-Moving Ultrasonic Actuator With High Carrying/Towing Capability Driven by Longitudinal Traveling Wave

A self-moving ultrasonic actuator (SUA) that operated by the longitudinal traveling wave and possessed high carrying/towing capability is developed in this article. The SUA is constructed by serially clamping two longitudinal transducers onto a rectangular-rod-shaped vibrating body, and its driving feet produce elliptical motions to achieve self-movement. Here, the clamped configuration and longitudinal vibration facilitate the realization of large driving force, and the bar shape brings simple structure and low weight. Initially, the SUA is designed with two developed models to not only enhance the driving force without excessively increasing the weight, but also enable the elliptical motion shapes to approach circular ones. Subsequently, an SUA prototype with the size of 315 × 32 × 30 mm is fabricated, and its vibration properties, self-moving characteristics, and carrying/towing capability are assessed. At ∼27.8-kHz frequency and 800-V voltage, the payload and towing force reached 6 kg and 24.5 N, respectively. Moreover, the SUA yielded the payload-to-weight ratio of 10.2 and the towing force density of 41.5 N/kg, exceeding the values of most conventional ones. This article validates the longitudinal TW's potential to enhance SUAs’ carrying/towing capability, and also provides a new approach to design powerful ultrasonic/piezoelectric actuators.

Characteristics of powders that cause sound absorption in the low frequency range due to longitudinal vibration in lightweight and fine powders

In this paper, focus is placed on "lightweight and fine powders" which have small particle size and bulk density and exhibit unique sound absorption characteristics at low frequencies due to longitudinal vibration of powder particles. Theoretical analysis of the sound absorption coefficient of powder layers requires the peak frequency of sound absorption measured experimentally. In this study, we clarified the relationship between powder properties and sound absorption characteristics, and predicted the sound absorption coefficient of the powder layer from the experimental equation based on the accumulated data. This made it possible to classify powders in which sound absorption due to longitudinal vibration occurs based on the relationship between the "areal density per particle layer," which is indicated by "particle size multiplied by bulk density," and the peak sound absorption value. Moreover, from the plot of "areal density per particle layer" and "first-order sound absorption peak frequency from experiment," the experimental formula for the first-order sound absorption peak frequency was regressively obtained. By using the experimental equation obtained in this study, it was possible to show how to estimate the sound absorption coefficient from the properties of each powder alone.

Influence of Different Ship Harmonic Vibration Directions on Dynamic Response of PEMFC

For the sake of study the applicability of PEMFC on ships, a three-dimensional single channel fuel cell model was established. The vibration load was loaded on the model through dynamic grid technology and user-defined function (UDF) method. The output voltage and reactive gas distribution of PEMFC loaded in different vibration directions were compared and analyzed. The results show that ship vibration will affect the transmission of components in the battery, resulting in incomplete electrochemical reaction and degradation of PEMFC performance. The influence of vertical vibration is greater than that of longitudinal vibration and lateral vibration.

Design and test of a small high frequency ultrasonic cleaning transducer

In order to solve the problem of cleaning of complex surfaces and micro blind holes in industrial products, a small high frequency ultrasonic cleaning transducer was designed and tested. Firstly, the finite element model of the transducer was established, and the influence of structural parameters on the first order longitudinal vibration frequency was analyzed. By adjusting the structural parameters of the transducer, the first order longitudinal vibration frequency of the transducer was determined to be 58716hz.The harmonic response of the transducer was analyzed. The results showed that when the voltage amplitude applied on the piezoelectric ceramic sheet was 80V, the transducer produced resonance at 58716 Hz, and the end face of the front cover of the transducer produced an axial displacement of about 3.34 µm . The transducer was made according to the theoretical analysis results, and the frequency sweep test was carried out on the transducer. The theoretical analysis results were consistent with the test results, which showed that the designed small high frequency ultrasonic cleaning transducer could meet the requirements of high frequency cleaning.

Aerial intense ultrasonic source integrating the horn and vibrating plate

The components of conventional high-intensity aerial ultrasonic sources, including the horn, longitudinal vibrating resonance bar, and transverse vibrating plates, are usually constructed separately. In this paper, a compact ultrasonic source that integrates all component parts was developed. First, the structure of the ultrasonic source was designed by simulation analysis with the finite element method. Next, an actual ultrasonic wave source was manufactured, and its electrical characteristics, vibration characteristics, and sound pressure distribution characteristics were measured. The ultrasonic source formed a strong standing wave sound field in the air, even though the total length was one wavelength of the longitudinal vibration. For an input electric power of 10 W, a high sound pressure in the standing wave sound field of 3.44 kPa was obtained (sound pressure level of about 165 dB).

Analysis and Structure Optimization of Scissor-Type Micro-Stirrer with the Most Effective Output Performance for Thrombus Dissolution in Interventional Therapy

Compared with thrombus dissolution using only thrombolytic agents, an advanced therapy of direct stirring of the blood clot can yield shorter recanalization time and higher recanalization velocity. Our previous research presented the design of a novel micro-stirrer, which can convert longitudinal vibration into transverse vibration and eventually generate opposite transverse vibration at the end-effort, like a scissor, for efficient blood clot stirring and thrombus dissolution acceleration. Transverse vibration is the most effective movement to dissolve thrombi. However, the small size of blood vessels has strict limits, which will greatly affect the output transverse vibration. Therefore, to improve the output performance of the micro-stirrer in curved and narrow vascular spaces, the analysis and structure optimization of the micro-stirrer is expected to increase the vibration mode conversion efficiency from longitudinal to transverse mode. The design concept and theoretical analysis of the micro-stirrer are presented in detail. Aiming to obtain the optimal structure parameters of the micro-stirrer, the mathematical model is established and analyzed. Next, a series of finite element models involving important structure parameters are designed and investigated. Finally, the optimal structure parameters are obtained, and the stirring effect in a blood vessel is verified by simulation and experiment.

Semi-analytical modeling and experimental verification of a flexible varying section disk–blades system with elastic supports

A semi-analytical model of a flexible varying section disk–blades (FVSDBs) system with elastic supports is proposed, where the spin softening, centrifugal stiffening, and Coriolis force effects of the system are considered. Timoshenko beams with a stagger angle are used to simulate blades, and a varying section wheel based on plate theory is used to construct the disk. Hamilton’s principle and Galerkin method are utilized to derive the differential governing equations of the FVSDBs system. The proposed semi-analytical model accounts for the lateral vibration of the disk, and the longitudinal and lateral vibration of the blades. Besides, the validity of the proposed model has been verified by comparing the natural frequencies, mode shapes, and vibration responses obtained from the proposed model, finite element model (FEM), and experiment. The results indicate that the proposed semi-analytical model has high precision and computational efficiency, which can provide an alternative scheme for predicting the vibration characteristics of varying section disk–blades and overcoming the high computational cost of finite element models.