Prediction Of Vibration Response Research Articles

Vibration Response Prediction on Rubber Mounts with a Hybrid Approach

Vibration Response Prediction on Rubber Mounts with a Hybrid Approach

Study on prediction of vibration and sound pressure response due to structural modification for SEA considering variation of input power

Study on prediction of vibration and sound pressure response due to structural modification for SEA considering variation of input power

Prediction of vibration response for vehicle panel considering variation of vibrational input power using SEA

Prediction of vibration response for vehicle panel considering variation of vibrational input power using SEA

Multivariant linear regression model based response prediction in situation of unknown uncorrelated multiple sources load

In order to predict response in the situation of unknown uncorrelated multiple sources load, a new response prediction method in frequency domain is proposed. The algorithm needs no transfer function and straightforwardly looking for the inner link between the known responses and the unknown responses. In the multivariant linear regression model, the vibration data of known measuring points are used as input and the vibration data of the unknown measuring points are used as output. And the parameters of multivariant linear regression model are solved by historical training data and the least squares generalized inverse. Experiment verification results of acoustic and vibration sources on cylindrical shell showed that the proposed approach could predict vibration response effectively and satisfy industrial requirements.

An equivalent moving force model for consideration of human-structure interaction

• Human-structure interaction (HSI) is incorporated into a moving force model. • A simplified analytical approach is developed for determining the equivalent system properties. • A more comprehensive numerical approach is used to determine the optimum equivalent system properties. • Equivalent damping expressions are proposed to be used in vibration serviceability assessments of structures. • Accurate vibration assessment can now be performed with currently available commercial engineering software. To predict the vibration response of footbridges, many codes of practice use a deterministic moving force (MF) model. This approach may not be well suited for the design of slender, lightweight, low-damping, and low-frequency footbridges because it ignores the pedestrian interaction with the vibrating footbridge. On the other hand, a spring-mass-damper (SMD) model is able to incorporate human mass, stiffness, and damping into the vibration response prediction. However, the SMD model is computationally demanding and not commonly available in engineering practice. To address this shortfall, a framework is proposed to derive a computationally-efficient equivalent MF-structure system to the reference SMD-structure system such that both systems give a similar vibration response metric. Analytical and numerical approaches to the equivalent MF (EMF) system are described in detail and applied to bridges with approximately simply-supported mode shapes. A sensitivity analysis is carried out to show the effects of different pedestrian parameters on the equivalent damping of the EMF system. The effects of pedestrian damping, frequency, and weight are found to be pronounced, while those of dynamic load factors and pedestrian step length are insignificant. Finally, empirical expressions are proposed in a probabilistic framework to determine the equivalent damping for simply-supported low-frequency footbridges as a function of bridge frequency. This work should find use in the serviceability assessment of low-frequency footbridges in engineering practice.

Vibration-based identification of interphase properties in long fiber reinforced composites

The interphase properties of fiber-reinforced composite materials affect significantly the dynamic behavior of the material, and hence they have to be accounted for accurately. However, the small thickness of the interphase makes it hard to measure precisely its properties directly. In this paper, a new approach is proposed to determine the properties of the interphase by using the vibratory response of coupons made of the composite material. A model obtained from first principles combining Euler-Bernoulli beam theory and the strain energy method is used to identify interphase properties from experimental data. The model of a vibrating cantilevered beam is parameterized to obtain effective properties of the material, which include the interphase properties. The identified interphase properties are verified using composites with different fiber volume fractions. It is found that the predicted vibration response matches very well the experimental measurements; hence, the proposed approach is feasible to characterize the interphase properties.

Damping Matrix Identification by Finite Element Model Updating Using Frequency Response Data

Accurate modeling of damping is essential for prediction of vibration response of a structure. This paper presents a study of damping matrix identification method using experimental data. The identification is done by performing finite element (FE) model updating using normal frequency response functions (FRFs). The paper addresses some key issues like data incompleteness and computation of the normal FRFs for carrying out the model updating using experimental data. The effect of various levels of damping in structures on the performance of the identification techniques is also investigated. Experimental studies on three beam structures made up of mild steel, cast iron and acrylic are presented to demonstrate the effectiveness of the identification techniques for different levels of damping.

A coupling dynamics analysis method for a multistage planetary gear system

The lumped parameter and finite element methods (FEM) are two relatively common modeling approaches for the coupling vibration analysis of the planetary gear system. In order to overcome the lack of fidelity of the lumped parameter models and the high computational cost of finite element models, and in order to obtain accurate vibration response predictions to understand the coupling vibration mechanism in the planetary gear system, a comprehensive, fully coupled, dynamic modeling method is proposed by applying a virtual equivalent shaft element. The continuous planetary gear transmission system is divided into numerous shafting elements. The dynamic model of the planetary gear system is constructed applying these shafting elements, including the shaft segments and flexible ring gear, and as well as the flexible planet carrier. The proposed method is implemented on a two-stage planetary gear system, and it is verified by comparing the results to the calculations using existing lumped parameter and FEM. The quasi-static and dynamic modeling results are presented to study the dynamic behavior and coupling characteristics in-depth. The proposed method can be used to guide the design of high reliability and low vibration planetary gear systems.

An effective system-level vibration prediction analysis approach for data storage system chassis

In modern data storage systems, multiple disk drives arrays are densely located within a chassis or rack. Meanwhile, the chassis houses power suppliers, cooling fans, PCBs and switch boards too. During operation, mechanical disturbances from disk drive arm rotary motions, cross-talks between disk drives and cooling fans can generate adversely influence on a data storage system performance. In particular, the voice coil motor (VCM) torque induced by disk drive seeking operation affects not only its own but also neighbouring drives in terms of hard disk drive (HDD) throughput performance. Vibration analysis plays an important role in chassis system design for robustness which can mitigate the mechanical vibrations impact on disk drive throughput performances. In this paper, we report a finite element simulation based approach to predict vibration responses of the storage system chassis excited by operating disk drives and cooling fans. The purpose is to provide an effective vibration prediction analysis method that could aid in evaluating system-level vibration characteristics for chassis designers. An analytical model is described to formulate disk drive vibration behaviours in terms of design parameters. A full finite element model including the whole chassis structure, HDDs and its mounting mechanism components, storage controller boards and backplane board is constructed for simulation study. The mechanical disturbances are characterised by measuring VCM torque spectrums and fan operational vibration behaviours. HDD vibration responses at system-level are computed and well compared with the measurement results.

Vibration Prediction Method of Electric Machines by using Experimental Transfer Function and Magnetostatic Finite Element Analysis

This paper concerns the noise and structural vibration caused by rotating electric machines. Special attention is given to the magnetic-force induced vibration response of interior-permanent magnet machines. In general, to accurately predict and control the vibration response caused by the electric machines, it is inevitable to model not only the magnetic force induced by the fluctuation of magnetic fields, but also the structural dynamic characteristics of the electric machines and surrounding structural components. However, due to complicated boundary conditions and material properties of the components, such as laminated magnetic cores and varnished windings, it has been a challenge to compute accurate vibration response caused by the electric machines even after their physical models are available. In this paper, we propose a highly-accurate vibration prediction method that couples experimentally-obtained discrete structural transfer functions and numerically-obtained distributed magnetic-forces. The proposed vibration synthesis methodology has been applied to predict vibration responses of an interior permanent magnet machine. The results show that the predicted vibration response of the electric machine agrees very well with the measured vibration response for several load conditions, for wide frequency ranges.

Effective impulse model for prediction of vibration response of high-frequency steel staircases

Nowadays the use of steel staircases is increasing more and more even in reinforced concrete building structures because of the many advantages associated with dry construction. Typical steel staircases often exhibit high-frequency and relatively low-damping characteristics. In addition, they are subjected to footfall forces whose magnitude and pace may be quite different from those caused by walking on a building floor. However, design guides for such high-frequency steel staircases are quite limited. In this study, the effective impulse model is proposed based on full-scale vibration tests that can be used to predict the vibration response of high-frequency steel staircases. It is shown that the proposed model gives more consistent and more accurate predictions than existing comparable methods over the pace frequency range of 1.4Hz to 4.5Hz expected in staircases.

Modal density and mode counts of sandwich panels in thermal environments

A theoretical model for calculating the modal density and mode counts of sandwich panels with composite face sheets in thermal environments is presented. Governing equations are derived by applying the Hamilton’s principle based on an improved ordinary sandwich panel theory. Modal density and mode counts are calculated using the wavenumber space integration with simply supported and clamped boundary conditions taken into consideration. The accuracy of the proposed model is verified by the finite element model. Thermal effects of both thermal stresses and temperature-dependent material properties on modal density and mode counts are investigated for an aluminum honeycomb sandwich panel with simply supported and clamped boundary conditions. Results indicate that the modal density and mode counts increase with the increment of the temperature. Both of the two effects should be considered in the calculation of the modal density and mode counts of sandwich panels in thermal environments. The proposed model has a wider application scope and can contribute to the prediction of vibration response of sandwich panels in the high frequency range.

Prediction of vibration response and acoustic radiation of a thin-walled box with particle dampers using multiphase flow theory of gas-particle

In this paper, vibration response and acoustic radiation of a thin-walled box with particle dampers are predicted. First, the effects of the collisions and friction between the granular inter-particles are interpreted as an equivalent nonlinear viscous damping based on multiphase flow theory of gas-particle. Then the contribution of particle damper is estimated as an equivalent mass-damper system. Next, the model for the thin-walled box with particle dampers is implemented in the finite element method using COMSOL Multiphysics Software. Finally, the vibration response and acoustic radiation of a thin-walled box with particle dampers based on multiphase flow theory are predicted using such original and novel simulation method. An experimental verification is conducted and a good agreement is obtained between the theoretical results and the experimental data.

Vibration Response Prediction of the Printed Circuit Boards Using Experimentally Validated Finite Element Model

A spacecraft consists of a number of mechanical and electronic sub-assemblies. An electronic package is consists of printed circuit boards placed in mechanical housings which are stacked together. Electronic components are mounted on the printed circuit board (PCB). A spacecraft experiences various types of mechanical loads during its launch such as vibration, acoustic and shock loads. The understanding of dynamic behaviour provides valuable insight to a design engineer, to improve the mechanical design and product reliability when used in harsh vibration condition. Generally electronic package design for vibration loads is verified by conducting tests on actual hardware.This paper addresses on using basic FEA tool to accurately investigate the dynamic characteristics of the PCB and avoid costly testing methods which require hardware. Here the normal modes & frequency response functions (FRF) of PCB are determined and validated using vibration test on PCB. The validated model is used to predict vibration response for random vibration input. It is shown here how the responses are accurately predicted for random vibration input for a design parameter variation of PCB. The results are also validated using vibration test on PCB.

Universal response spectrum procedure for predicting walking-induced floor vibration

Floor vibrations caused by people walking are an important serviceability problem both for human occupants and vibration-sensitive equipment. Present design methodologies available for prediction of vibration response due to footfall loading are complex and suffer from division between low and high frequency floors. In order to simplify the design process and to avoid the problem of floor classification, this paper presents a methodology for predicting vibration response metrics due to pedestrian footfalls for any floor type having natural frequency in the range 1–20Hz.Using a response spectrum approach, a database of 852 weight-normalised vertical ground reaction force (GRF) time histories recorded for more than 60 individuals walking on an instrumented treadmill was used to calculate response metrics. Chosen metrics were peak values of 1s peak root-mean-square (RMS) acceleration and peak envelope one-third octave velocities. These were evaluated by weight-normalising the GRFs and applying to unit-mass single degree of freedom oscillators having natural frequencies in the range 1–20Hz and damping ratios in the range 0.5–5%. Moreover, to account for effect of mode shape and duration of crossing (i.e. duration of dynamic loading), the recorded GRFs were applied for three most typical mode shapes and floor spans from 5m to 40m.The resulting peak values as functions of frequency i.e. spectra are condensed to statistical representations for chosen probability of being exceeded over a wide range of applications. RMS (acceleration) spectra show strong peaks corresponding to the first harmonic of pacing rate followed by clear minima at approximately 3.5Hz, a second much smaller peak corresponding to the second harmonic and a steady decline with increasing frequency beginning around 5Hz. One-third octave spectra show asymptotic trends with frequency, span and damping.A comprehensive validation exercise focusing on the acceleration RMS spectra was based on a representative range of floor samples for which modal properties had been identified and walking response studied during experimental campaigns of vibration serviceability evaluation. Due to the statistical approach an exact validation would not be possible, hence measured peak RMS values were matched to distributions for the equivalent idealised structure. In the vast majority of cases the measured values, intended to represent worst-case conditions, fitted the upper decile of the corresponding simulated spectra indicating consistency with the proposed approach.

Dynamic Analysis for Rotors of a Twin-Screw Compressor with Gas-Induced Cyclic Loads

The effects of dynamic forces and elastic contacts in a pair of intermeshing rotors with the gas-induced cyclic loads based on the multibody dynamics simulation have not investigated yet. The comparison of numerical spectra of time and frequency domains of acceleration with the experimental noise spectrum of an oil-injected twin-screw compressor has not also considered. Therefore, this study proposes a new strategy, which combines the fluctuating torques and forces induced by cyclic gas pressure on the screw rotors to numerically predict vibration response in an oil-injected twin-screw compressor.

On the study of vibration of a supported railway rail using the semi-analytical finite element method

An improved rail vibration model based on the semi-analytical finite element (SAFE) method has been developed, which allows multiple layers of support and the accurate shape of the rail cross-section to be considered in the modeling. Rail supports are treated as a continuous layer of equivalent springs connected to the rail foot. Three different assumed support conditions corresponding to no support; rail pads; and rail pads, sleepers and ballast have been modeled. By determining the track parameters from a field test, this model is demonstrated to be able to determine the dispersion relations and the forced responses of both free and variously supported rails. Further, the effect of rail damping including frequency-dependent viscous damping and frequency-independent structural damping on rail vibration responses is investigated. The effect of the adopted discretization strategy on the calculation is also studied. Model results are compared with predictions from the Timoshenko beam-based rail models with the same support conditions. The results show that track support dynamic stiffness can be incorporated into the developed SAFE rail model which can then be used to represent the real track situation at a site; the rail support can significantly affect rail dispersion and frequency responses below 1kHz; the Timoshenko beam-based rail models provide an inadequate prediction of rail vibration response, particularly in the lateral direction, if response at specific frequencies is required; the rail damping has limited impact on rail vibration responses; and the number of elements has insignificant effect on the calculated rail responses and wave dispersion relations, especially away from the excitation point.

A Novel Nonlinear Time Series Prediction Method and its Application in Structural Vibration Response Prediction

A novel nonlinear time series prediction method is proposed in this paper. This prediction method is based on the Multi-dimensional Taylor Network. The structure of the Multi-dimensional Taylor Network is introduced firstly. The Multi-dimensional Taylor Network provides a new method to predict the nonlinear time series. The prediction model based on the Multi-dimensional Taylor Network can realize the prediction of the nonlinear time series just with input-output data without the system mechanism, and it can describe the dynamic characteristics of the system. Finally, the new prediction method is applied in the structural vibration response prediction. Results indicate the validity and the better prediction accuracy of this method.

Finite volume analysis of adaptive beams with piezoelectric sensors and actuators

This paper presents a finite volume (FV) formulation for the free vibration analysis and active vibration control of the smart beams with piezoelectric sensors and actuators. The governing equations based on Timoshenko beam theory are discretized using the finite volume method. For the purpose of forced vibration control of beam structures, the negative velocity feedback controller is designed for the single-input, single-output system. To achieve the best effect, the piezoelectric sensors and actuators are coupled with the host structure in different positions and then the performance of the designed control system is evaluated for each position. In the test examples, first the shear locking free feature of the present formulation is demonstrated. This has been performed by doing static and natural frequency analysis of some reference models. Then, the capability of the proposed method for the prediction of uncontrolled forced vibration response and active vibration control of a beam structure is studied.

Prediction of Vortex-Induced Vibration Response of a Pipeline Span by Coupling a Viscous Flow Solver and a Beam Finite Element Solver

This paper describes a fluid-structure interaction (FSI) modeling approach to predict the vortex-induced vibration response of a pipeline span by coupling a three-dimensional viscous incompressible Navier–Stokes solver with a beam finite element solver in time domain. The pipeline span is modeled as an Euler–Bernoulli beam subject to instantaneous flow-induced forces and solved using finite element basis functions in space and an unconditionally stable Newmark-type discretization scheme in time. At each time step, the instantaneous incremental displacement is fed back to the fluid flow solver, where the position of the pipeline is updated to compute the resulting instantaneous flow field and associated flow-induced forces. Numerical predictions from the FSI model are compared to current tank experimental measurements of a pipeline span subject to uniform free-stream currents.