Random Vibration Study of Structures under Multi-Component Seismic Excitations

2002 ◽  
Vol 5 (3) ◽  
pp. 185-192 ◽  
Author(s):  
S. D. Xue ◽  
Z. Cao ◽  
X. S. Wang
Keyword(s):  
Random Vibration ◽  
Seismic Analysis ◽  
Ground Motions ◽  
Coupled Vibration ◽  
Seismic Excitations ◽  
Pseudo Excitation Method ◽  
Significant Difference ◽  
Lattice Shell ◽  
Pseudo Excitation ◽  
Excitation Method

A random vibration study of structures under multi-component seismic excitations is presented in this paper. The pseudo excitation method proposed by J. H. Lin is employed and is further developed, from which a multi-component pseudo excitation method is formulated. Then, the random model and correlation for multiple ground motions are investigated. Based on the method, a computer program is developed and a random vibration study is performed for a double-layer spherical lattice shell to investigate its seismic performance under multi-component seismic excitations. It is found that a significant difference may occur between single and multi-component seismic excitations. The present study has shown that the developed method is a highly efficient and accurate CQC algorithm, in which all the cross-correlation terms between both participant modes and seismic excitations are involved. This method can easily be used for multi-component seismic analysis of structures that have closely spaced natural frequencies and coupled vibration modes.

Random Vibration Analysis for Centrifugal Compressor Impellers With Unsteady Aerodynamic Excitations

2016 ◽  
Author(s):  
Yuefang Wang ◽  
Yan Liu ◽  
Xuejun Wang ◽  
Hongkun Li ◽  
Daren Jiang
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Centrifugal Compressor ◽  
Random Vibration ◽  
Pressure Field ◽  
Pseudo Excitation Method ◽  
Vibration Problem ◽  
Power Spectral ◽  
Pseudo Excitation ◽  
Excitation Method

Dynamic response of impeller of centrifugal compressor is studied considering pulsating pressure field on blades due to unsteady flow conditions. The aerodynamic forces on the blades are modeled as random load whose spectral characteristics are determined through computational fluid dynamic simulations in the time domain. The dynamical response in the unsteady case is solved as a random vibration problem in the frequency domain which provides useful power spectral density displacement and stress for early stage of impeller design. A semi-open impeller mounted with 19 blades is modeled using three dimensional solid finite elements. The random vibration problem of the impeller is solved through the Pseudo-Excitation Method considering spatial variance of the pressure field. A user-defined module is developed based on harmonic analysis to generate the auto power spectral density and variance of displacement and stress at 200 nodes. It is demonstrated that solving a random vibration problem through the Pseudo-Excitation Method is faster than the commonly adopted multiple-step transient analysis. It is concluded that evaluating the structural integrity of impeller solids in the regime of random vibration is a feasible and efficient approach at the early design stage of compressors.

Random Vibration Analysis for Impellers of Centrifugal Compressors Through the Pseudo-Excitation Method

2015 ◽  
Vol 12 (04) ◽  
pp. 1540002 ◽  
Author(s):  
Yuefang Wang ◽  
Sujing Wang ◽  
Lihua Huang
Keyword(s):  
Time Domain ◽  
Random Vibration ◽  
Structural Integrity ◽  
Centrifugal Compressors ◽  
Pseudo Excitation Method ◽  
Transient Stress ◽  
Aerodynamic Pressure ◽  
Pseudo Excitation ◽  
Excitation Method ◽  
Stress Analyses

Impellers of centrifugal compressors are generally loaded by fluctuating aerodynamic pressure in operations. Excessive vibration of the impellers can be induced by unsteady airflows and lead to severe fatigue failures. Traditional transient stress analyses implemented in time domain generally require multiple load-step, very time-consuming computations using input of temporal pneumatic force previously obtained from Computational fluid dynamics (CFD) analyses. For quick evaluation of structural integrity of impellers, it is necessary to develop random vibration models and solution approaches defined in frequency domain. In this paper, the Pseudo-Excitation Method (PEM) is used to obtain power spectral density of three-dimensional, dynamic displacement and stress of impellers. A finite element model of an unshrouded impeller of a centrifugal compressor is generated based on the result of unsteady CFD analysis. Compared with the direct transient stress analyses in time domain, the pseudo-excitation method provides accurate and fast estimation of dynamic response of the impeller, making it an applicable and efficient method for analyzing random vibration of impellers.

Random Vibration Analysis of Heavy-Duty Truck Based on Pseudo Excitation

2011 ◽  
Vol 299-300 ◽  
pp. 1244-1247
Author(s):  
Yu Ying Qin ◽  
Jing Qian Wang ◽  
Guo Hong Tian
Keyword(s):  
Random Vibration ◽  
Statistical Characteristics ◽  
Heavy Duty ◽  
Pseudo Excitation Method ◽  
Heavy Duty Truck ◽  
Power Spectral ◽  
Vibration Model ◽  
Vibration Responses ◽  
Pseudo Excitation ◽  
Excitation Method

This paper discusses pseudo excitation method and constructs pseudo six-wheel pseudo excitation. For the complexity of heavy-duty truck, construction of vibration model is difficult for real structures; thirteen-degree-of-freedom full model is constructed for heavy-duty truck. Taken frequency response function as a bridge, pseudo excitation method is applied and a new method is gained for statistical characteristics of heavy-duty truck. The result shows that the method for random vibration of heavy-duty truck is feasible and convenient by constructing six-wheel road pseudo excitation and obtaining power spectral densities of vibration responses.

Dynamic Reliability Evaluation by First-Order Reliability Method Integrated with Stochastic Pseudo Excitation Method

2020 ◽  
pp. 2150024
Author(s):  
Siyu Zhu ◽  
Tianyu Xiang
Keyword(s):  
Random Variable ◽  
Random Excitation ◽  
Pseudo Excitation Method ◽  
First Order Reliability Method ◽  
Dynamic Reliability ◽  
First Order ◽  
Reliability Method ◽  
Uncertain Structure ◽  
Pseudo Excitation ◽  
Excitation Method

The stochastic pseudo excitation method (SPEM), which is based on the principle of pseudo excitation method (PEM), is introduced to represent the randomness of dynamic input in which the amplitude of excitation is adopted as a random variable. Based on the mathematic definition of power spectral density, a physical interpolation of the SPEM is discussed. Even if one random variable is involved in calculation, the effects of the uncertainties are required to be investigated. The SPEM offers a simple but quite effective way to solve the dynamic reliability problem. Through integrating the new algorithm into first-order reliability method (FORM), the dynamic reliability of uncertain structure subjected to random excitation is studied. A linear oscillator with three types of white noise is adopted to verify the SPEM for dynamic reliability of linear random vibration analysis. Also, the accuracy and efficiency of SPEM to handle the multi-degree-of-freedom structure is investigated in this paper.

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