Study of cumulative fatigue damage detection for used parts with nonlinear output frequency response functions based on NARMAX modelling

2017 ◽  
Vol 411 ◽  
pp. 75-87 ◽  
Author(s):  
Honglan Huang ◽  
Hanying Mao ◽  
Hanling Mao ◽  
Weixue Zheng ◽  
Zhenfeng Huang ◽  
...  
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Fatigue Damage ◽  
Response Functions ◽  
Output Frequency ◽  
Frequency Response Functions ◽  
Cumulative Fatigue Damage

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.

Model updating–based damage detection of a concrete beam utilizing experimental damped frequency response functions

2018 ◽  
Vol 22 (4) ◽  
pp. 935-947 ◽  
Author(s):  
Qianhui Pu ◽  
Yu Hong ◽  
Liangjun Chen ◽  
Shili Yang ◽  
Xikun Xu
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Frequency Response Function ◽  
Concrete Beam ◽  
Model Updating ◽  
Response Functions ◽  
Experimental Frequency ◽  
Frequency Response Functions ◽  
Function Formulation ◽  
Analytical Frequency

This article evaluates the use of experimental frequency response functions for damage detection and quantification of a concrete beam with the help of model updating theory. The approach is formulated as an optimization problem that intends to adjust the analytical frequency response functions from a benchmark finite element model to match with the experimental frequency response functions from the damaged structure. Neither model expansion nor reduction is needed because the individual analytical frequency response function formulation is derived. Unlike the commonly used approaches that assume zero damping or viscous damping for simplicity, a more realistic hysteretic damping model is considered in the analytical frequency response function formulation. The accuracy and anti-noise ability of the proposed approach are first verified by the numerical simulations. Next, a laboratory reinforced concrete beam with different levels of damage is utilized to investigate the applicability in an actual test. The results show successful damage quantification and damping updating of the beam by matching the analytical frequency response functions with the experimental frequency response functions in each damage scenario.

A novel analysis method for fault diagnosis of hydro-turbine governing system

2017 ◽  
Vol 231 (2) ◽  
pp. 164-171 ◽  
Author(s):  
Xin Xia ◽  
Wei Ni ◽  
Yingjun Sang
Keyword(s):  
Fault Diagnosis ◽  
Frequency Response ◽  
Experimental Studies ◽  
Response Functions ◽  
Output Frequency ◽  
Frequency Response Functions ◽  
Hydro Turbine ◽  
Identification Method ◽  
Governing System ◽  
Diagnosis Method

The fault diagnosis of hydro-turbine governing system is important to the operation of the hydropower station and the stability of the power grid. In order to improve the diagnostic accuracy and efficiency, a novel fault diagnosis method based on nonlinear output frequency response functions and a novel identification method of nonlinear output frequency response functions have been proposed and applied to the problem of hydro-turbine governing system fault diagnostics. First, the nonlinear model of hydro-turbine governing system is built. And the fault diagnosis principles based on nonlinear output frequency response functions are also introduced. Then, the disadvantages of the traditional identification method are discussed, and a novel identification method is proposed for nonlinear output frequency response functions according to the operation characteristic of hydro-turbine governing system. Finally, simulation verification and experimental studies have been presented to demonstrate the accuracy and efficiency of the proposed fault diagnosis method. The results indicate that the proposed method is simple and practical for fault diagnosis of hydro-turbine governing system.

Detection of Local Damage of Flexural Member Using Measured Frequency Response Functions

2018 ◽  
Vol 23 (No 3, September 2018) ◽  
pp. 314-320
Author(s):  
Eun-Taik Lee ◽  
Hee-Chang Eun
Keyword(s):  
Damage Detection ◽  
Frequency Response ◽  
Damage Index ◽  
External Noise ◽  
Local Damage ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Measured Frequency ◽  
Measured Frequency Response ◽  
Proper Orthogonal

Measurements by sensors provide inaccurate information, including external noises. This study considers a method to reduce the influence of the external noise, and it presents a method to detect local damage transforming the measured frequency response functions (FRFs) to reduce the influence of the external noise. This study is conducted by collecting the FRFs in the first resonance frequency range from the responses in the frequency domain, taking the mean values at two adjacent nodes, and transforming the results to the proper orthogonal decomposition (POD). A damage detection method is provided. The curvature of the proper orthogonal mode (POM) corresponding to the first proper orthogonal value (POV) is utilized as the damage index to indicate the damage region. A numerical experiment and a floor test of truss bridge illustrate the validity of the proposed method for damage detection.

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