scholarly journals Non-linear joint parameter identification using the frequency response function of the linear substructure

2004 ◽  
Vol 218 (9) ◽  
pp. 947-955 ◽  
Author(s):  
W-J Kim ◽  
B-Y Lee ◽  
Y-S Park
Keyword(s):  
Parameter Identification ◽  
Frequency Response ◽  
Frequency Domain ◽  
Response Function ◽  
Frequency Response Function ◽  
Excitation Amplitude ◽  
The Finite Element Method ◽  
Unknown Parameters ◽  
Identification Process ◽  
Non Linear

A method based on frequency domain approaches is presented for the non-linear parameter identification of a structure having non-linear joints. The frequency response function (FRF) of the linear substructure, which can be calculated from the finite element method or measured by an experimental method, is used to calculate its FRFs needed in the parameter identification process. This method is easily applicable to a complex real structure having non-linear joints since it uses the FRF of the substructure. Since this method is performed in the frequency domain, the number of equations can be easily increased to as many as required to identify unknown parameters, not only by just varying the excitation amplitude but also by selecting the excitation frequencies. The validity of this method was tested numerically and experimentally with a cantilever beam having a non-linear element. It was verified through examples that the proposed method is useful to identify the non-linear joint parameters of a structure having arbitrary boundaries.

scholarly journals Parameter Identification of Weakly Nonlinear Vibration System in Frequency Domain

2004 ◽  
Vol 11 (5-6) ◽  
pp. 685-692 ◽  
Author(s):  
Jiehua Peng ◽  
Jiashi Tang ◽  
Zili Chen
Keyword(s):  
Parameter Identification ◽  
Frequency Response ◽  
Nonlinear Vibration ◽  
Frequency Domain ◽  
Response Function ◽  
Frequency Response Function ◽  
Physical Parameters ◽  
Vibration System ◽  
Weakly Nonlinear ◽  
Nonlinear Vibration System

A new method of identifying parameters of nonlinearly vibrating system in frequency domain is presented in this paper. The problems of parameter identification of the nonlinear dynamic system with nonlinear elastic force or nonlinear damping force are discussed. In the method, the mathematic model of parameter identification is frequency response function. Firstly, by means of perturbation method the frequency response function of weakly nonlinear vibration system is derived. Next, a parameter transformation is made and the frequency response function becomes a linear function of the new parameters. Then, based on this function and with the least square method, physical parameters of the system are identified. Finally, the applicability of the proposed technique is confirmed by numerical simulation.

Frequency response function-based parameter identification from short data sequences

2004 ◽  
Vol 18 (5) ◽  
pp. 1097-1116 ◽  
Author(s):  
B. Cauberghe ◽  
P. Guillaume ◽  
P. Verboven ◽  
S. Vanlanduit ◽  
E. Parloo
Keyword(s):  
Parameter Identification ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function

Modal Testing and Parameter Identification of Active Magnetic Bearing System

1995 ◽  
Author(s):  
Chong-Won Lee ◽  
Young-Ho Ha ◽  
Cheol-Soon Kim ◽  
Chee-Young Joh
Keyword(s):  
Parameter Identification ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Magnetic Bearing ◽  
Experimental Results ◽  
Active Magnetic Bearing ◽  
Modal Testing ◽  
Modal Parameters ◽  
Bearing System

Abstract Complex modal testing is employed for parameter identification of a four-axis active magnetic bearing system. In the test, magnetic bearings are used as exciters while the system is in operation. The experimental results show that the directional frequency response function, which is properly defined in the complex domain, is a powerful tool for identification of bearing as well as modal parameters.

Relationship between harmonic balance method and non-linear output frequency response function approach

2007 ◽  
Vol 221 (12) ◽  
pp. 1533-1543 ◽  
Author(s):  
Z K Peng ◽  
Z Q Lang
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Harmonic Balance ◽  
Frequency Response Function ◽  
Harmonic Balance Method ◽  
Balance Method ◽  
Output Frequency ◽  
Non Linear ◽  
Harmonic Components ◽  
The Relationship

The current paper is concerned with the investigation of the relationship between the harmonic balance method (HBM) and the non-linear output frequency response function (NOFRF) approach in the analysis of non-linear systems. Both are applied to the Duffing's oscillator to demonstrate their relationships. The results reveal that, if the Volterra series representation of a non-linear system is convergent, the harmonic components calculated by the NOFRFs are a solution of the HBM. Moreover, the simulation studies show that, in the convergent cases, the NOFRF method can give more accurate results for the higher-harmonic components than the HBM. The relationship investigated in the current study between the two methods should help researchers and engineers to understand the HBM and the NOFRF methods.

Investigation and Modification of Frequency Response Function Using Digital Fourier Analysis for High Speed Dynamic Testing Facility

2009 ◽  
Author(s):  
Chandrashekhar K. Thorbole ◽  
Keshavanarayana S. Raju
Keyword(s):  
Frequency Response ◽  
Frequency Domain ◽  
Response Function ◽  
Time Domain ◽  
Frequency Response Function ◽  
Detection System ◽  
Structural Response ◽  
Wave Form ◽  
Data Set ◽  
Load Detection

The increasing application of composites in the aviation and automobile industry demands a better understanding of composite material behavior under high loading rate. This shall provide a better insight of actual loads on occupants while preserving livable crashworthy structure. In this study, a high stroke rate MTS servo-hydraulic testing machine is used to characterize the behavior of composite materials at high strain rates. At higher stroke rates, the output of the load detection system acquired by the load cell deviates from the true load-time wave form of the specimen. This is due to the convolution of the structural response of the detection system with the true characteristic of the specimen. To identify the true nature of the specimen load-time behavior, the de-convolution of the detection system response is necessary to restore the specimen characteristic wave form closer to its true behavior. The convolution of data set in the time domain is a time consuming process which explains the benefit of using the frequency domain; as the convolution in time domain corresponds to multiplication in the frequency domain. This process requires the transformation of the time domain data to frequency domain data via Fast Fourier Transform (FFT). In the frequency domain the complex division of the Fourier transfer of the detection system output with frequency response function of the detection system shall provide the true complex input characteristic. This paper elaborates the methodology utilized for obtaining the Frequency Response Function (FRF) of the load detection system using digital Fourier analysis with a single input/output data set. This also emphasizes precautions and guidelines for improving results with FFT to obtain true FRF measurements of the load detection system. The FRF obtained is successfully used to identify the actual specimen wave form characteristic. This is achieved by extracting the structural response of the load detection system from the load cell output.

Sign in / Sign up

Export Citation Format

Share Document