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Vibration Data (vibration + data)

Distribution by Scientific Domains

Engineering	100%

Selected Abstracts

A Wavelet-Based Approach to Identifying Structural Modal Parameters from Seismic Response and Free Vibration Data

COMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 6 2005
C. S. Huang
The wavelet transform with orthonormal wavelets is applied to the measured acceleration responses of a structural system, and to reconstruct the discrete equations of motion in various wavelet subspaces. The accuracy of this procedure is numerically confirmed; the effects of mother wavelet functions and noise on the ability to accurately estimate the dynamic characteristics are also investigated. The feasibility of the present procedure to elucidate real structures is demonstrated through processing the measured responses of steel frames in shaking table tests and the free vibration responses of a five-span arch bridge with a total length of 440 m. [source]

Damage identification of structures with uncertain frequency and mode shape data

EARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2002
Yong Xia
Abstract A statistical method with combined uncertain frequency and mode shape data for structural damage identification is proposed. By comparing the measured vibration data before damage or analytical finite element model of the intact structure with those measured after damage, the finite element model is updated so that its vibration characteristic changes are equal to the changes in the measured data as closely as possible. The effects of uncertainties in both the measured vibration data and finite element model are considered as random variables in model updating. The statistical variations of the updated finite element model are derived with perturbation method and Monte Carlo technique. The probabilities of damage existence in the structural members are then defined. The proposed method is applied to a laboratory tested steel cantilever beam and frame structure. The results show that all the damages are identified correctly with high probabilities of damage existence. Discussions are also made on the applicability of the method when no measurement data of intact structure are available. Copyright © 2002 John Wiley & Sons, Ltd. [source]

On the influence of trigger level in distribution vibration surveys

PACKAGING TECHNOLOGY AND SCIENCE, Issue 4 2009
Vincent Rouillard
Abstract This paper follows on from recently published research that examined the effects of recording parameters on the outcomes of distribution vibration surveys. Whereas the previous research focused on the effects of the sampling period at which sub-records of the process are captured, this paper deals with another often-used recording parameter, namely, the vibration level trigger. The paper describes the development of a software tool that was designed specifically to study the influence of various sampling parameters on continuously recorded vibration data. This software tool was used to undertake a thorough statistical analysis on a vibration record set consisting of continuously sampled data measured from a wide variety of vehicle types and routes. The paper shows that the outcomes of vibration surveys are very sensitive to the trigger level and can produce highly distorted results by introducing a bias that nearly always overestimates the overall vibration levels. This is reflected in estimates of common descriptors of random vibration processes such as the average power spectral density (PSD), the peak-hold PSD and the overall root-mean-square values. The main outcome of this analysis is the formulation of a correction method based on relationships between the true mean and peak-hold PSDs and estimates from sampled data. The effect and significance of the proposed correction procedure is demonstrated, especially in the context of laboratory simulation of distribution vibrations. The paper concludes by making specific recommendations for configuring high-capacity field data recorders and applying correction strategies to ensure that vibration surveys yield statistically sound results. Copyright © 2009 John Wiley & Sons, Ltd. [source]

The use of intrinsic mode functions to characterize shock and vibration in the distribution environment

PACKAGING TECHNOLOGY AND SCIENCE, Issue 1 2005
Vincent Rouillard
Abstract This paper describes an innovative approach, based on the instrinsic mode functions (IMFs), to characterize the nature of mechanical vibration encountered in transport vehicles. The paper highlights the importance of understanding the nature of transport vibration and shows that their accurate characterization is essential for the optimization of protective packaging. Although there have been numerous studies aimed at characterizing random vibration during transport, the majority of those have been limited to applying relatively conventional signal analysis techniques, such as the average power spectral density (PSD). This paper investigates the benefits offered by the recently introduced Hilbert,Huang transform when characterizing non-stationary random vibration in comparison with more traditional Fourier analysis-based techniques. The paper describes the operation of the Hilbert,Huang transform, which was developed to assist in the analysis of non-Gaussian and non-stationary random data. The Hilbert,Huang transform is based on the empirical mode decomposition (EMD) technique used to produce a finite number of IMFs, which, as a set, provide a complete description of the process. It is shown how these IMFs are well suited to the application of the Hilbert,Huang transform to determine the magnitude and instantaneous frequency of each IMF. The technique is applied to various records of random vibration data collected from transport vehicles in order to illustrate the benefits of the method in characterizing the nature of non-stationarities present in transport vibration. Copyright © 2004 John Wiley & Sons, Ltd. [source]