Numerical Vibration Analysis Research Articles

Experimental and Numerical Analysis of Vibrations Induced by a Twin Tunnel, Underground Railway

Experimental and Numerical Analysis of Vibrations Induced by a Twin Tunnel, Underground Railway

Study on high-speed vibration cutting of titanium alloy considering cutting edge radii

Ultrasonic vibration cutting (UVC) is an advanced machining method used to improve machining performance and surface quality in the manufacturing industry. However, the separation characteristic disappears when the cutting speed exceeds the maximum vibration speed, which limits its wide application in high-speed machining. Therefore, this study used the finite element method (FEM) to study the high-speed vibration cutting (HVC) processing performance of titanium alloys. High-speed vibration cutting is a precision machining method with a smaller cutting depth and feed rate, so it is necessary to consider the influence of the cutting edge radii on the cutting process. The cutting edge radii on high-speed vibration cutting and the impact of the traditional cutting process are discussed. The results show that the change in the minimum uncut chip thickness caused by changing the cutting edge radii during precision cutting has a significant influence on the experimental results. In addition, a simulation model was established, and comprehensive numerical analysis and comparison of high-speed vibration cutting, ultrasonic vibration cutting, and conventional cutting (CC) were performed to tool wear, cutting temperature, cutting force, and stress distribution. The simulation results indicate that the tool wear depth of traditional cutting during high-speed cutting is up to three times that of high-speed vibration cutting. High-speed vibration cutting weakens the influence of the cutting edge radii, but this new vibration cutting method did not significantly reduce the cutting temperature under dry cutting conditions.

Numerical analysis of vortex-induced vibration on a flexible cantilever riser for deep-sea mining system

The flexible cantilever riser, as a special form of the marine riser, can be encountered in a deep-sea mining system, where the bottom of the long vertical lifting pipeline is connected with the intermediate warehouse. The main objective of this paper is to investigate the effects of the bottom weight caused by the intermediate warehouse and the flow speed on the dynamic responses of the cantilever pipeline. A quasi-3D coupling algorithm based on the discrete vortex method and finite element method is employed to calculate the unsteady hydrodynamic forces and vortex-induced vibrations of this pipeline in the time domain, respectively. We first simulate the VIV of a long flexible riser with two fixed ends in a stepped flow to validate the feasibility of the present method. Then, systematic simulations of cross-flow VIV of the cantilever riser are carried out under a wide range of bottom weights and different current speeds. The number of the vibration mode shows the decreasing tendency with the increase of the bottom weight. In a certain range of the weight, the number of the dominant mode remains unchanged, while the vibration amplitude declines with increasing weight. An amplitude jump phenomenon can be observed when the transition of the dominant mode in two contiguous mode clusters occurs. Moreover, the higher-order modes are excited with the increase of the current speed.

Experimental and numerical vibration analysis of surface mechanical attrition treatment

The surface mechanical attrition treatment creates a nanocrystal layer with improved mechanical properties without changing the surface chemistry. Vibration produces residual stresses in a layer close to the surface by successive impacts on the material surface. Vibration treatments represent a “green” alternative to surface treatments without the use of chemicals and high temperatures. Depending on the operating frequency and amplitude of a particular vibration platform, the most decisive parameter to be controlled for the efficiency of the application is the velocity. Vibration platforms in the SMAT process are ultrasonic and mechanically based platforms. This work presents a vibration platform where velocity is below 1 m/s, which is the lowest operating speed defined in the SMAT process. This work includes both analytical and numerical solutions to the natural frequency values of the vibrating table. The operating conditions were determined by finding the natural frequency values. The amplitude, velocity, and acceleration relations of the vibrating table that will occur during the process were found using the frequency response analysis method. ANSYS and MATLAB were used for numerical and analytical solutions, respectively. Numerical and analytical results were in agreement with the experimental modal analysis.

Numerical Analysis of Flow-Induced Vibration of Deep-Hole Plane Steel Gate in Partial Opening Operation

Hydraulic steel gates are the core adjustment mechanism for water conservancy projects, the safety of which is related to the safety of the entire water conservancy project. In this study, the issue of flow-induced vibration under the influence of pulsing water pressure when the deep-hole plane steel gate construction is partially opened is investigated using a numerical calculation approach of CFD–CSD coupling. The time-history pulsating pressure loads of each part are first determined by tracking the upstream, bottom, and downstream pulsating water pressure loads under partially open operation conditions of the gate. The impact of the water in front of the gate on the natural vibration mode and frequency of the gate is then investigated based on the analysis of the dry/wet modes of the gate structure. Additionally, the hydrodynamic load is applied to the finite element model of the gate structure while taking into account the fluid–structure coupling effect, and the results of the gate flow-induced vibration response are obtained. Three typical local opening relative openings are chosen, with the operating state of the design water head (Hs = 70 m) of a deep-hole plane steel gate as an example. According to the analysis’s findings, the gate’s natural vibration frequency is greatly lowered under the influence of the water in front of it, and its amplitude increases by 50%. The pressure value pressing on the gate changes dynamically as it is partially opened and discharged. The maximum dynamic displacement value and the maximum dynamic stress value of the gate both appear in the middle and lower part of the gate under the condition of partial opening, and both occur when the relative opening is e/H = 0.125. The maximum displacement value is 3.43 mm, and the maximum stress value is 161 MPa. The maximum dynamic displacement and dynamic stress of each gate component steadily decrease with an increase in the relative openness. The gate dynamic response analysis approach described in this research can serve as a guide for hydraulic engineering design.

Blast-induced ground vibrations: a dynamic analysis by FEM

The peak particle velocities (PPV) are fundamental for understanding and managing the levels of blast-induced ground vibrations and their effects on adjacent structures. Given that numerical analysis of seismic vibrations has been demonstrated to be a method that can significantly contribute to predicting PPV, this study adopts a numerical approach using the finite element method (FEM) to assess blasting-induced ground vibration in rock masses. A dynamic module of the stress-strain analysis based on the FEM displacement formulation is developed in ANLOG software to estimate the variations of displacement, velocity, strain, and stress induced by blasting. The dynamic modulus implemented is verified using two verification examples. After, ANLOG is used in an application example to estimate seismic vibrations induced by blasting and to define the attenuation law for a limestone quarry near an urbanized area in Spain. The effect of Rayleigh damping coefficients (α and β) on the PPV levels estimated by ANLOG was investigated, and the most appropriate numerical attenuation law is then obtained. The numerical analysis presents satisfactory results for elastic-wave propagation induced by blasting and the peak particle velocity values obtained shows good agreement with field and the numerical results available in the specialized literature. The results indicate that ANLOG can perform personalized analysis of rock mass under blast-induced dynamic stress taking into consideration the geological and geomechanical characteristics particular to each medium as well as the blast parameters.

Numerical Analysis of Flow-Induced Vibration of Heat Exchanger Tube Bundles Based on Fluid-Structure Coupling Dynamics

According to the needs generated by the industry, there is an urgent need to investigate the flow vibration response law of the elastic tube bundle of heat exchangers subjected to the coupling effect of shell and tube domain at different inlet flow velocities. In this paper, based on the continuity equation, momentum equation, turbulence model, and dynamic grid technology, the vibration response of the elastic tube bundle under the mutual induction of shell and tube fluids is studied by using pressure-velocity solver and two-way fluid-structure coupling (FSC) method. The results show that the monitoring points on the same connection block have the same vibration frequency, while the vibration amplitude is different. Monitoring point A is the most deformed by the impact of fluid in the shell and tube domain. When the inlet velocity( v shell = v tube = 0.15 , 0.4, 0.5 m/s) of shell and tube is low, the amplitude of tube bundle vibration in the Y direction is greater than that in X and Z direction, and the tube bundle produces periodic vibration in the vertical direction. The vibration equilibrium position of the tube bundle along the shell flow direction gradually moves up with the increase of the inlet velocity. The amplitude in the Y -direction of the elastic bundle decreases with the increase of shell-side and tube-side velocity. The relationship between the vibration amplitude in the Y direction and the entrance velocity is a linear function.

Nonlinear Numerical Analysis of Vortex-Induced Vibration of A Three-Dimensional Deepwater Steep Wave Riser with Large Deformation Features

Nonlinear Numerical Analysis of Vortex-Induced Vibration of A Three-Dimensional Deepwater Steep Wave Riser with Large Deformation Features

Study for the cross-flow coupling mechanism of tandem cylinder groups at low Reynolds number

A numerical analysis of flow-induced vibrations for tandem cylinder groups which include two and three tandem cylinders with a spacing ratio of L/D = 5.5 (where L is the distance between the circular cylinders and D is the circular diameter) in planar shear flow is carried out. The cylinders can only vibrate freely in the cross-flow direction. A finite element method called four-step semi-implicit characteristic-based split (4-SICBS) is used to solve the Navier-Stokes equation. On the other hand, in order to maximize the oscillation response of the dynamic system, the damping ratio of it is ξ = 0. And the mass ratio of structure is set to mr = 2.0. The four main parameters, such as the number of cylinders (Num = 2, 3), Reynolds number (Re = 100, 160), the shear ratio (k = 0.0, 0.05, 0.1) as well as the reduced velocity (Ur = 3–30) are mainly studied the dynamic behaviors, frequency and spectrum characteristics, phase characteristics as well as energy characteristics of tandem cylinder groups. The results show that vibration responses of the upstream cylinders in tandem cylinder groups are similar to that of a single cylinder, while the parameters play a key role in flow-induced vibrations of the midstream and downstream cylinders. As Re = 100, the downstream cylinder of two tandem cylinders and the midstream cylinder of three tandem cylinders are in the state of increasing and then decreasing, and the downstream cylinder of three tandem cylinders has a larger vibration response with the change of k. As k = 0.1, the amplitude drops to zero with the increase of Ur. In addition, the situation becomes more complicated with the increase of Re. For the downstream cylinder of three tandem cylinders at Re = 160, there are two peaks of the cross-flow amplitude. The oscillation remains strong at larger Ur for the case of k = 0.1. Finally, the interactions between cylinders are revealed, together with the vortex dynamic mechanism underlying the oscillation characteristics of tandem cylinders exposed to planar shear flow.

Free vibration analysis of polymer pin-reinforced foam core sandwich composite panels

This study deals with numerical and experimental free vibration analysis of through-the-thickness cylindrical polymer pin-reinforced foam core sandwich composite panels of two different core thicknesses. Four different pin-reinforcement configurations with varying pin diameters and pin center distances were used. First five non-zero eigenfrequencies were retrieved along with their eigenmodes in the numerical analysis. Experimental modal analysis was done for the validation of the numerical analysis. The results revealed that the pin-configuration with the densest pin allocation and the biggest pin diameter provided the highest natural frequencies, and the non-reinforced composites had the lowest natural frequencies. The increase in the pin diameter had a slightly more pronounced effect on the increase of the eigenfrequencies than the increase in the pin’s densities. This work also demonstrated the impact of the core thickness on the natural frequencies.

Synchronous properties of the friction phenomenon

The phenomenon of frictional slipping and sticking is one of crucial problems in mechanical engineering. This paper is focused on the numerical analysis of vibrations induced by friction in oscillator model which assumes an influence of the normal degree of freedom on the friction force. Analysis of Poincare maps, time courses and corresponding spectrum of Lyapunov exponents of the proposed three degrees of freedom dynamical system is demonstrated. It is revealed that the friction force, acting on the main slider, reflects dynamic behavior of the system response, i.e., some synchronous correlation between them is observed, even in the range of hyperchaotic behavior of the system, characterized by two positive Lyapunov exponents. On the other hand, an interesting effect of the coexistence of irregular friction force at the contact point of the frictional brush and ground surface with the regular response of the system in the quasi-periodic regime is reported.

Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Numerical analysis of vehicle-bridge coupling vibration concerning nonlinear stress-dependent damping

Numerical Analysis of Flow-Induced Vibration of Heat Exchanger Tube Bundles Based on Fluid-Structure Coupling Dynamics

Numerical Analysis of Flow-Induced Vibration of Heat Exchanger Tube Bundles Based on Fluid-Structure Coupling Dynamics

INFLUENCE OF ACOUSTIC PRESSURE WAVE ON FLAT GYRO SUSPENSION ELEMENTS

The nature of the interaction of sound with an obstacle is revealed. The dynamic characteristics of the plate under an acoustic pressure wave are investigated. A thin isotropic plate was chosen as a mechanical model for the interaction of sound with a flat barrier. The questions of the influence of mechanical impedance for the symmetric and antisymmetric components of sound pressure are considered. Numerical analysis of bending vibrations of the shadow side of the plate is carried out. The value of the lengths of the modulating waves of the main bending vibrations is established

Numerical and experimental study on multi-axis Dynamic Vibration Absorber with multidirectionally supported mass

Multi-mode damping of elastic vibration is required for efficient vibration reduction of lightweight structures. In this study, a multi-axial dynamic vibration absorber (DVA) is made, and the possibility of multi-mode damping is investigated. The multi-axial DVA consists of a mass sphere supported in multi-directions by eight springs, and the mass sphere vibrates in multi-directions: this yields multi-mode damping. From the theoretical analysis, it is shown that the natural frequency in each axis can be adjusted by changing the dimension ratio of the frame connecting the fixed points of these eight springs. In this paper, the numerical vibration analysis of the multi-axial DVA was firstly carried out using a finite element (FE) commercial software Ansys to check the theoretical analysis. The numerical results showed that introducing "slip" is necessary at the contact area between the supporting springs and the mass sphere. Based on the results of the FE analysis, a multi-axial DVA was developed and attached to a model of the underframe of a railway vehicle. Finally, a series of excitation tests for the underframe model was conducted, and the multi-modal damping was confirmed.

Theoretical and Numerical Analysis of Coupled Axial-Torsional Nonlinear Vibration of Drill Strings

Based on a lumped parameter model with two degrees of freedom, the periodic response of the coupled axial-torsional nonlinear vibration of drill strings is studied by HB-AFT (harmonic balance and alternating frequency/time domain) method and numerical simulations. The amplitude-frequency characteristic curves of axial relative displacement and torsional relative angular velocity are given to reveal the mechanism of bit bounce and stick-slip motion. The stability of periodic response is analyzed by Floquet theory, and the boundary conditions of bifurcation of periodic response are given when parameters such as nominal drilling pressure, angular velocity of turntable, and formation stiffness are varied. The results show that the amplitude of the periodic response of the system precipitates a spontaneous jump and Hopf bifurcation may occur when the angular velocity of the turntable is varied. The variation of parameters may lead to the complex dynamic behavior of the system, such as period-doubling motion, quasiperiodic motion, and chaos. Bit bounce and stick-slip phenomenon can be effectively suppressed by varying the angular velocity of turntable and nominal drilling pressure.

Numerical analysis and physical consideration of vocal fold vibration by modal analysis

Vocal fold vibration is self-excited vibration due to the interaction between the vocal folds and expired air. To analyze vocal fold vibration, several models comprising masses and springs have been proposed to date, but with those models it is difficult to determine parameter values and calculate the phenomenon in detail. Also, several researchers have analyzed vocal fold vibration using the finite element method (FEM) and the finite volume method, but such large-degree-of-freedom analyses incur high computational cost. To solve these problems, we propose a vocal fold vibration analysis model based on modal analysis. The natural modes of the vocal folds are obtained by FEM, and the air is simulated by a one-dimensional model based on Bernoulli's equation. In this approach, because the natural modes are obtained by FEM, parameters based on actual physical properties (Young's modulus, etc.) can be used, and the calculation cost is relatively low because of the modal and one-dimensional fluid analyses. To validate the proposed model, its results are compared with those from experiments on silicone vocal folds and simulations using ANSYS software, and the results correspond. Furthermore, the necessary conditions for the vocal folds to enter two particular modes of self-excited vibration are derived mathematically, and those two modes are confirmed to be dominant in the periodic solution region.

Numerical and experimental vibration analysis of different types of adhesively bonded joints

Recently, in most structures, such as aircraft, spacecraft, transport vehicles and mechanical systems etc., adhesive-bonded composite structures have been frequently preferred because of their lightweight and durability. The construction of these structures, such as the truss system of a space station, is mainly carried out using composite plates, beams and adhesively bonded joints. Many different joints, such as lap joint, double-strap joint etc., used in these structures aforementioned. The designs, which consist of adhesively bonded joints, should have adequate inherent damping capability to suppress vibration and acoustics response caused by external excitations. The focus of the analysis is to reveal the effective bonding type in terms of the design and energy absorption capacity of the structures connected with different types of adhesive bonds. The effects of geometrical parameters such as the thickness of the adhesive, overlap length, number of layers, fibre orientation and the adherent thickness on natural frequency and damping were investigated employing both the finite element method and the experimental analysis. The frequencies and damping ratios of the adhesive bonding structures predicted using the finite element method were compared with those measured experimentally. The coordination of the numerical and experimental techniques has provided an ability to scrutinise the dynamic response of bonded structures with different adhesive bonding joint. The findings revealed by this work will be effective to conduct the design and optimisation of adhesively bonded different joints only when material properties and basic dimensions are regarded.

Numerical and Experimental Vibration Analysis of an Additive Manufactured Sensor Mounting Unit for a Wireless Valve Position Indication Sensor System

Nuclear power plants have a very large catalog of regularly manipulated manual valves. To achieve the desired performance and operating margins, skilled technical staff use these valves to control, start, stop, regulate, and throttle the flow of various fluids through plant systems. Wireless valve position indication (VPI) sensor system technology would enable online monitoring of manual valve positions. Using additive manufacturing techniques, the wireless VPI sensor system is retrofitted onto existing manual valves using a sensor mounting unit (SMU). The structural stability of the retrofitted SMU is important for reliably measuring valve position with the wireless VPI sensor system. This paper presents the design, numerical modeling, and experimental validation of SMUs for rising stem gate and rising handle globe valves. Three types of materials, i.e., ULTEM 9085, chopped carbon fiber reinforced nylon, and continuous carbon fiber reinforced nylon, were used to three-dimensionally print the SMUs. The free vibration responses of these SMUs are presented in this paper. The results show how the choice of design, material, and other printer parameters impact SMU vibration responses, especially for the first and second eigenfrequencies. Next, performance of the SMUs is evaluated through both numerical and experimental vibration analysis, and then, the consistency of outcomes using each analysis type is presented. In terms of the stiffness-to-weight ratio and eigenfrequencies, the research shows the SMU printed with 5% continuous carbon fiber reinforced nylon fared significantly better than those printed from the other two materials.

Numerical analysis of propeller-excited plate vibrations

Intense vibrations excited by a propeller worsen the structural reliability of a ship. In this study, a ship hull is modeled as a simple rectangular plate to study propeller excitation vibrations. The interaction between a rectangular plate and propeller is studied, considering the fluid–structure interaction. The turbulence in the flow field is modeled by detached eddy simulations. The results show that in the propeller wake, the pressure fluctuations corresponding to the blade passing frequency (BPF) of the propeller are dominant. In the flow field near the plate, the pressure fluctuations corresponding to the natural frequencies of the plate are dominant. The plate vibrations under a propeller exciting force contain vibrations corresponding to the BPF of the propeller and natural frequencies of the plate. The vibrations of the plate can be divided into vibrations caused by propeller rotation and natural vibrations. The excitation force from the propeller changes the mode shapes of the plate. The vibrations excited by the propeller wake decrease as the distance between the propeller and the plate increases.