scholarly journals The analysis of nonlinear systems in the frequency domain using Nonlinear Output Frequency Response Functions

Automatica ◽  
2018 ◽  
Vol 94 ◽  
pp. 452-457 ◽  
Author(s):  
Rafael Suzuki Bayma ◽  
Yunpeng Zhu ◽  
Zi-Qiang Lang
Keyword(s):  
Nonlinear Systems ◽  
Frequency Response ◽  
Frequency Domain ◽  
Response Functions ◽  
Output Frequency ◽  
Frequency Response Functions

Analysis of Locally Nonlinear MDOF Systems Using Nonlinear Output Frequency Response Functions

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Z. K. Peng ◽  
Z. Q. Lang ◽  
S. A. Billings
Keyword(s):  
Nonlinear Systems ◽  
Frequency Response ◽  
Nonlinear Effects ◽  
Response Analysis ◽  
Response Functions ◽  
Output Frequency ◽  
Engineering Structures ◽  
Frequency Response Functions ◽  
Linear Characteristic ◽  
Mdof Systems

The analysis of multidegree-of-freedom (MDOF) nonlinear systems is studied using the concept of nonlinear output frequency response functions (NOFRFs), which are a series of one-dimensional functions of frequency recently proposed by the authors to facilitate the analysis of nonlinear systems in the frequency domain. By inspecting the relationships between the NOFRFs of two consecutive masses in the locally nonlinear MDOF systems, a series of properties about the NOFRFs of the nonlinear systems are obtained. These properties clearly reveal how the system linear characteristic parameters govern the distribution of nonlinear effects induced by the system nonlinear component within the whole systems. The results obtained in the present work are of significance to the frequency response analysis for nonlinear systems. One important potential application of these results is the detection and location of damages in engineering structures, which make the structures behave nonlinearly.

scholarly journals Dynamics Analysis of Active Variable Stiffness Vibration Isolator for Whole-Spacecraft Systems Based on Nonlinear Output Frequency Response Functions

2020 ◽  
Vol 33 (6) ◽  
pp. 731-743
Author(s):  
Kefan Xu ◽  
Yewei Zhang ◽  
Yunpeng Zhu ◽  
Jian Zang ◽  
Liqun Chen
Keyword(s):  
Frequency Response ◽  
Energy Absorption ◽  
Absorption Rate ◽  
Vibration Isolation ◽  
Variable Stiffness ◽  
Response Functions ◽  
Vibration Isolator ◽  
Output Frequency ◽  
Frequency Response Functions ◽  
Vibration Transmissibility

AbstractIn order to improve the harsh dynamic environment experienced by heavy rockets during different external excitations, this study presents a novel active variable stiffness vibration isolator (AVS-VI) used as the vibration isolation device to reduce excessive vibration of the whole-spacecraft isolation system. The AVS-VI is composed of horizontal stiffness spring, positive stiffness spring, parallelogram linkage mechanism, piezoelectric actuator, acceleration sensor, viscoelastic damping, and PID active controller. Based on the AVS-VI, the generalized vibration transmissibility determined by the nonlinear output frequency response functions and the energy absorption rate is applied to analyze the isolation performance of the whole-spacecraft system with AVS-VI. The AVS-VI can conduct adaptive vibration suppression with variable stiffness to the whole-spacecraft system, and the analysis results indicate that the AVS-VI is effective in reducing the extravagant vibration of the whole-spacecraft system, where the vibration isolation is decreased up to above 65% under different acceleration excitations. Finally, different parameters of AVS-VI are considered to optimize the whole-spacecraft system based on the generalized vibration transmissibility and the energy absorption rate.

The Nonlinear Output Frequency Response Functions of One-Dimensional Chain Type Structures

2009 ◽  
Vol 77 (1) ◽  
Author(s):  
Z. K. Peng ◽  
Z. Q. Lang
Keyword(s):  
Frequency Response ◽  
Type Systems ◽  
Practical Case ◽  
Dimensional Chain ◽  
Response Functions ◽  
Output Frequency ◽  
Frequency Response Functions ◽  
One Dimensional ◽  
Nonlinear Component ◽  
Chain Type

It is well-known that if one or a few components in a structure are of nonlinear properties, the whole structure will behave nonlinearly, and the nonlinear component is often the component where a fault or an abnormal condition occurs. Therefore it is of great significance to detect the position of nonlinear components in structures. Nonlinear output frequency response functions (NOFRFs) are a new concept proposed by the authors for the analysis of nonlinear systems in the frequency domain. The present study is concerned with investigating the NOFRFs of nonlinear one-dimensional chain type systems, which have been widely used to model many real life structures. A series of important properties of the NOFRFs of locally nonlinear one-dimensional chain type structures are revealed. These properties clearly describe the relationships between the NOFRFs of different masses in a one-dimensional chain type system, and allow effective methods to be developed for detecting the position of a nonlinear component in the system. The results are an extension of the authors’ previous research studies to a more general and practical case, and have considerable significance in fault diagnosis and location in engineering systems and structures.

Use of Time-Series Predictive Models for Piezoelectric Active-Sensing in Structural Health Monitoring Applications

2012 ◽  
Vol 134 (4) ◽  
Author(s):  
Eloi Figueiredo ◽  
Gyuhae Park ◽  
Kevin M. Farinholt ◽  
Charles R. Farrar ◽  
Jung-Ryul Lee
Keyword(s):  
Time Series ◽  
Structural Health Monitoring ◽  
Frequency Response ◽  
Frequency Domain ◽  
Health Monitoring ◽  
Active Sensing ◽  
Response Functions ◽  
Active Sensors ◽  
Frequency Response Functions ◽  
Structural Health

In this paper, time domain data from piezoelectric active-sensing techniques is utilized for structural health monitoring (SHM) applications. Piezoelectric transducers have been increasingly used in SHM because of their proven advantages. Especially, their ability to provide known repeatable inputs for active-sensing approaches to SHM makes the development of SHM signal processing algorithms more efficient and less susceptible to operational and environmental variability. However, to date, most of these techniques have been based on frequency domain analysis, such as impedance-based or high-frequency response functions-based SHM techniques. Even with Lamb wave propagations, most researchers adopt frequency domain or other analysis for damage-sensitive feature extraction. Therefore, this study investigates the use of a time-series predictive model which utilizes the data obtained from piezoelectric active-sensors. In particular, time series autoregressive models with exogenous inputs are implemented in order to extract damage-sensitive features from the measurements made by piezoelectric active-sensors. The test structure considered in this study is a composite plate, where several damage conditions were artificially imposed. The performance of this approach is compared to that of analysis based on frequency response functions and its capability for SHM is demonstrated.

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