Shape of the power spectral density matrix components: Influence on fatigue damage

2019 ◽  
Vol 42 (4) ◽  
pp. 972-987 ◽  
Author(s):  
Sabrina Vantadori ◽  
Giovanni Fortese ◽  
Andrea Carpinteri
Keyword(s):  
Density Matrix ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Fatigue Damage ◽  
Spectral Density Matrix ◽  
Power Spectral ◽  
Matrix Components

scholarly journals Spline-Interpolation-Based FFT Approach to Fast Simulation of Multivariate Stochastic Processes

2011 ◽  
Vol 2011 ◽  
pp. 1-24 ◽  
Author(s):  
Jinhua Li ◽  
Chunxiang Li ◽  
Shuisheng Chen
Keyword(s):  
Density Matrix ◽  
Spectral Density ◽  
Stochastic Processes ◽  
Power Spectral Density ◽  
Spline Interpolation ◽  
Spectral Density Matrix ◽  
Power Spectral ◽  
Computational Speed ◽  
Interpolation Technique ◽  
Spline Interpolation Technique

The spline-interpolation-based fast Fourier transform (FFT) algorithm, designated as the SFFT algorithm, is proposed in the present paper to further enhance the computational speed of simulating the multivariate stochastic processes. The proposed SFFT algorithm first introduces the spline interpolation technique to reduce the number of the Cholesky decomposition of a spectral density matrix and subsequently uses the FFT algorithm to further enhance the computational speed. In order to highlight the superiority of the SFFT algorithm, the simulations of the multivariate stationary longitudinal wind velocity fluctuations have been carried out, respectively, with resorting to the SFFT-based and FFT-based spectral representation SR methods, taking into consideration that the elements of cross-power spectral density matrix are the complex values. The numerical simulation results show that though introducing the spline interpolation approximation in decomposing the cross-power spectral density matrix, the SFFT algorithm can achieve the results without a loss of precision with reference to the FFT algorithm. In comparison with the FFT algorithm, the SFFT algorithm provides much higher computational efficiency. Likewise, the superiority of the SFFT algorithm is becoming more remarkable with the dividing number of frequency, the number of samples, and the time length of samples going up.

scholarly journals Fretting Fatigue Damage Nucleation and Propagation Lifetime Using a Central Point Movement of Power Spectral Density

2020 ◽  
Vol 2020 ◽  
pp. 1-16 ◽  
Author(s):  
Thanh Q. Nguyen ◽  
Hieu C. Doan ◽  
Luan C. Vuong ◽  
H. Nguyen-Xuan ◽  
Nhi K. Ngo
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Fatigue Damage ◽  
Fretting Fatigue ◽  
Central Point ◽  
Reference Source ◽  
Forced Circulation ◽  
New Approach ◽  
Power Spectral ◽  
Different Levels

This paper presents a new perception in evaluating fretting fatigue damage nucleation and propagation lifetime under periodically forced circulation. A new approach, which is proposed in this paper, is to measure the change of the central point of power spectral density (CP-PSD) in different structural stiffness degradation stages. A notable aspect of this study lies in the combination between vibration amplitude and forced frequency of the fatigue-causing factors in beam structures. Additionally, it is found that randomization of the first phase from 0 to 2π yields more accurate modelling of the fatigue phenomenon. Results show that the CP-PSD parameter is significantly more sensitive compared to the regularly damage-evaluating parameters such as natural frequency, eigenvalues, or stress value. This reflects different levels of fatigue cycle effect on the structure in the experiment. At the same time, CP-PSD also categorizes the degradation level on different points on the structure under the periodically forced circulation. In addition, this paper also quantifies the relation between the changes of CP-PSD and each fatigue state. Results of this research will be a reference source to evaluate the lifespan of the structure by experimental methods.

scholarly journals Numerical study of the relation between chosen statistical parameters of input stresses and cumulative fatigue damage provided rainflow decomposition

2019 ◽  
Vol 254 ◽  
pp. 02006
Author(s):  
Milan Sága ◽  
Ondrej Štalmach ◽  
Mária Blatnická ◽  
Marian Handrik ◽  
Zuzana Ságová
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Fatigue Damage ◽  
Numerical Study ◽  
Statistical Moments ◽  
Statistical Parameters ◽  
Material Parameters ◽  
Numerical Tests ◽  
Power Spectral ◽  
Cumulative Fatigue Damage

The aim of the article is to present a series of numerical tests of the cumulative fatigue damage solution under assumption of random stress input. It is realised study of the influence of the statistical moments or power spectral density on the cumulative fatigue damage using well-known rainflow method. The distribution of the cumulative fatigue damage is determined for pre-defined material parameters.

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