GNSS-aided accelerometer frequency domain integration approach to monitor structural dynamic displacements

2021 ◽  
pp. 1-14
Author(s):  
Xu Liu ◽  
Jian Wang ◽  
Jie Zhen ◽  
Houzeng Han ◽  
Craig Hancock
Keyword(s):  
Frequency Domain ◽  
Structural Dynamic ◽  
Integration Approach ◽  
Domain Integration

Modelling of Seabed Interaction in Frequency Domain Analysis of Mooring Cables

2003 ◽  
Author(s):  
Paul P. A. Ong ◽  
Sergio Pellegrino
Keyword(s):  
Frequency Domain ◽  
Equations Of Motion ◽  
Time Integration ◽  
Domain Analysis ◽  
Frequency Domain Analysis ◽  
Wave Loading ◽  
Computational Overhead ◽  
Spring System ◽  
Seabed Interaction ◽  
Domain Integration

Mooring cables under wave loading interact dynamically with the seabed; this interaction is nonlinear and can be modelled in full only by performing lengthy time integration of the equations of motion. However, time domain integration is far too computationally expensive to be carried out for all load cases. A new method of modelling the interaction between a cable and the seabed in the frequency domain, but without considering frictional effects and impact, is therefore proposed. The section of cable interacting with the seabed is truncated and replaced with a system of coupled linear springs, with stiffnesses linearised from static catenary equations. These springs would model the behaviour of the truncated cable and hence the time-varying boundary condition at the touchdown. The entire cable-spring system is then analysed in the frequency domain with a centred finite difference scheme. The proposed method has shown to increase the accuracy of frequency domain analysis in certain cases with affordable computational overhead.

scholarly journals Operational Modal Identification of Time-Varying Structures via a Vector Multistage Recursive Approach in Hybrid Time and Frequency Domain

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Si-Da Zhou ◽  
Li Liu ◽  
Wu Yang ◽  
Zhi-Sai Ma
Keyword(s):  
Parameter Estimation ◽  
Frequency Domain ◽  
Real Time ◽  
Time Estimation ◽  
Recursive Estimation ◽  
Modal Parameters ◽  
Time Varying ◽  
Modal Parameter ◽  
Structural Dynamic ◽  
Modal Parameter Estimation

Real-time estimation of modal parameters of time-varying structures can conduct an obvious contribution to some specific applications in structural dynamic area, such as health monitoring, damage detection, and vibration control; the recursive algorithm of modal parameter estimation supplies one of fundamentals for acquiring modal parameters in real-time. This paper presents a vector multistage recursive method of modal parameter estimation for time-varying structures in hybrid time and frequency domain, including stages of recursive estimation of time-dependent power spectra, frozen-time modal parameter estimation, recursive modal validation, and continuous-time estimation of modal parameters. An experimental example validates the proposed method finally.

scholarly journals Optimization Acceleration Integral Method Based on Power Spectrum Estimation

2018 ◽  
Vol 176 ◽  
pp. 03012 ◽  
Author(s):  
Ruijie Guo ◽  
Shengbo Ye ◽  
Yicai Ji
Keyword(s):  
Power Spectrum ◽  
Frequency Domain ◽  
Low Frequency ◽  
Power Spectrum Density ◽  
Frequency Noise ◽  
Spectrum Estimation ◽  
Integration Algorithm ◽  
Acceleration Signal ◽  
Spectrum Density ◽  
Domain Integration

Due to the excellent performance of the frequency domain integration method, it is widely used for acceleration integral calculations. However, the frequency-domain integration needs to select the effective integration frequency band to achieve its optimal integration performance. This paper proposes the method with power spectrum density (PSD) estimation to realize the optimization integral of the acceleration signal. By analysing the power spectrum density of the acceleration signal, the optimal low frequency cut-off frequency is obtained. Combined with frequency domain integration algorithm, it can effectively remove low-frequency noise and improve integral accuracy. Then, the novel algorithm tested by an experiment platform with a vibration bench. Experiment results show that this algorithm can adaptively select the low-frequency cut-off frequency and realize frequency domain integration optimization and the integration error is controlled within ±0.2mm.

An Improved Mixed-Radix FFT Technique and its Application in Frequency Spectral Analysis

2012 ◽  
Vol 226-228 ◽  
pp. 560-567
Author(s):  
Jian Bo Li ◽  
Ji Dong Wang ◽  
Bing Fu ◽  
Gao Lin
Keyword(s):  
Spectral Analysis ◽  
Frequency Domain ◽  
Time Domain ◽  
Engineering Application ◽  
Time History ◽  
Seismic Evaluation ◽  
Structural Dynamic ◽  
Unique Role ◽  
Discrete Frequency ◽  
Coefficient Method

Numerical analysis methods in time-domain and frequency-domain are commonly considers as two important ways for seismic evaluation of structure responses. FFT plays a unique role in building the equivalent expression between the structural dynamic signals in time domain and frequency domain, such as computing frequency spectrum values at discrete frequency points for time history data. On the basis of radix-4 and radix-2 FFT techniques, an improved district fast Fourier transfer FFT is presented in this paper to improve the transform efficiency, in which radix-4 transform is applied in most iterative steps, besides radix-2 transform used in the last one iterative step. As compared to the traditional radix-2 FFT, the new mixed-radix FFT leads to distinct reducing in computing amount, while the equivalent precision and the same discrete frequency points remain. Also by taking the trigonometric coefficient method as theoretical results, it’s numerically validated through some examples that the new improved FFT transform technique suits the engineering application of the fast numerical transform in the time and frequency domain for structural frequency spectral analysis.

Acceleration Signal Processing Based on EMD Adaptive Filtering and Frequency Domain Integration

2015 ◽  
Vol 719-720 ◽  
pp. 1038-1042
Author(s):  
Ping An Shi ◽  
Lei Wu
Keyword(s):  
Time Series ◽  
Signal Processing ◽  
Frequency Domain ◽  
Adaptive Filtering ◽  
High Frequency ◽  
Processing Method ◽  
Acceleration Signal ◽  
Signal Processing Method ◽  
Domain Integration ◽  
Better Than

In order to improve the accuracy of the phase and amplitude of acceleration integration results, a new method to transform acceleration signal into displacement was presented which combines Empirical Modal Decomposition (EMD) adaptive filtering with FFT based frequency domain integration. The acceleration signal is decomposed by EMD into n IMF, and by certain rules, the number of IMF pertaining high frequency (h) is determined, and the h IMF are adaptively filtered to cancel noises. After that, the FFT transform is applied to the n processed IMF, frequency domain integration is done, and finally the displacements time series is obtained by IFFT. Simulation shows that this acceleration signal processing method is better than the pure frequency domain integration transformation.

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