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.

Strip Rolling Mill Random Vibration Analysis Based on Pseudo-Excitation Method

2011 ◽  
Vol 143-144 ◽  
pp. 250-254
Author(s):  
Bao Yu Xu ◽  
Xu Dong Wang ◽  
Yi Lun Liu ◽  
Hai Chao Feng
Keyword(s):  
Spectral Density ◽  
Power Spectral Density ◽  
Stochastic Dynamics ◽  
Rolling Force ◽  
Rolled Strip ◽  
Strip Rolling ◽  
Pseudo Excitation Method ◽  
Power Spectral ◽  
Pseudo Excitation ◽  
Excitation Method

The five-octave mill stochastic dynamics model was established, and then constructed the virtual rolling force excitation, converted random excitation into the rolling force deterministic harmonic excitation by taking advantage of pseudo-excitation method, finally the variance and power spectral density dynamic random changes in the roll gap was Obtained . The results show that the emergence degree of rolled-strip oscillation marks is proportional to random rolling force power spectral density, and in over the five-octave frequency, the roll gap’s dynamic variance no longer change.

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.

Random Vibration Analysis for a Building under Evolutionary Random Excitations

2013 ◽  
Vol 376 ◽  
pp. 262-266
Author(s):  
Zuo Yu Sun ◽  
Hui Wang ◽  
Yong Shan Zhang ◽  
Le Wei Yan
Keyword(s):  
Wavelet Transform ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Continuous Wavelet Transform ◽  
Vibration Analysis ◽  
Random Vibration ◽  
Continuous Wavelet ◽  
Power Spectral ◽  
Random Vibration Analysis ◽  
Excitation Method

For a building under evolutionary random excitations, a new random vibration analysis based on equivalent excitation method is presented, in which, the equivalent excitation is constructed by using continuous wavelet transform. When the input power spectral density of a seismic excitation is modulated by a time varying function, the continuous wavelet coefficients are calculated firstly by using scales and the evolutionary power spectral density, then the equivalent excitation is constructed by inverse continuous wavelet transform, finally the random vibration analysis is carried out following the procedures of the equivalent excitation method. An example is given to show the whole procedure, in which the special ability of the method for dealing with the evolutionary random excitation is discussed in detail.

scholarly journals Analysing Random Vibration of KLT Box during Transporting by Finite Element Method

10.29007/b1th ◽  
2022 ◽  
Author(s):  
Cong Hoa Vu ◽  
Ngoc Thien Ban Dang
Keyword(s):  
Finite Element ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Automotive Industry ◽  
Random Vibration ◽  
Element Model ◽  
Vibration Testing ◽  
Time Data ◽  
Power Spectral ◽  
The Impact

Today, freight is an extremely important industry for the world we are living. Fast transportation, large volume...will optimize the cost, time and effort. Besides, ensuring the products safety is a matter of concern. During transporting, it is inevitable that the vibration caused by the engine, rough road surface...the cargo inside can be damaged. Automobile industries have prime importance to vibration testing. Sine vibration testing is performed when we have been given with only one frequency at given time instant. Trend to perform random vibration testing has been increased in recent times. As random vibration considers all excited frequencies in defined spectrum at known interval of time, it gives real-time data of vibration severities. The vibration severity is expressed in terms of Power Spectral Density (PSD). KLT box is an industrial stacking container conforming to the VDA 4500 standard that was defined by German Association of the Automotive Industry (VDA) for the automotive industry. The aim of this paper is study about random vibration and power spectral density analysis, how it can be used to predict the impact of hash road to the KLT box on container / truck during transportation. Finite element model is developed in ANSYS, modal analysis and random vibration analysis were done.

scholarly journals Optimum Resolution Bandwidth for Spectral Analysis of Stationary Random Vibration Data

1993 ◽  
Vol 1 (1) ◽  
pp. 33-43 ◽  
Author(s):  
Allan G. Piersol
Keyword(s):  
Spectral Analysis ◽  
Spectral Density ◽  
Power Spectral Density ◽  
Random Vibration ◽  
Damping Ratio ◽  
Frequency Resolution ◽  
Power Spectral ◽  
Averaging Time ◽  
Resolution Bandwidth

This article presents a methodology for selecting the frequency resolution bandwidth for the spectral analysis of stationary random vibration signals in an optimum manner. Specifically, the resolution bandwidth that will produce power spectral density estimates with a minimum mean square error is determined for any given measurement duration (averaging time), and methods of approximating the optimum bandwidth using practical spectral analysis procedures are detailed. The determination of the optimum resolution bandwidth requires an estimate for the damping ratio of the vibrating structure that produced the measured vibration signal and the analysis averaging time. It is shown that the optimum resolution bandwidth varies approximately with the 0.8 power of the damping ratio and the bandwidth center frequency, and the −0.2 power of the averaging time. Also, any resolution bandwidth within ±50% of the optimum bandwidth will produce power spectral density (PSD) estimates with an error that is no more than 25% above the minimum achievable error. If a damping ratio of about 5% for structural resonances is assumed, a constant percentage resolution bandwidth of 1/12 octave, but no less than 2.5 Hz, will provide a near optimum PSD analysis for an averaging time of 2 seconds over the frequency range from 20 to 2000 Hz. A simple scaling formula allows the determination of appropriate bandwidths for other damping ratios and averaging times.

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.

Application of Power Spectral Density Method to Fatigue Life Estimation of the Axle Structure

2014 ◽  
Vol 487 ◽  
pp. 272-275
Author(s):  
Rui Feng Guo ◽  
Peng Li Wang
Keyword(s):  
Fatigue Life ◽  
Spectral Density ◽  
Density Function ◽  
Power Spectral Density ◽  
Random Vibration ◽  
Spectral Density Function ◽  
Power Spectral Density Function ◽  
Life Estimation ◽  
Power Spectral ◽  
Fatigue Life Estimation

Based on the random vibration theory, fatigue strength theory and Miner cumulative damage theory, the formulas for estimation of fatigue life which can be coped with narrowband and broadband random vibration was derived by the peak distribution function. The power spectral density function of axle structure is deduced after the power spectral density of standard road and the vibration model of wheel had studying. Combined the power spectral density function with broadband random vibration fatigue life estimation formula, the fatigue life of axle structure was obtained. This method is simple and has a strong engineering practicality.

Sign in / Sign up

Export Citation Format

Share Document