Diagnosis of Bolt Loosening Fault in Structures with a Novel Second-Order Output Spectrum based Method

2018 ◽  
Author(s):  
Quankun Li ◽  
Xingjian Jing
Keyword(s):  
Second Order ◽  
Output Spectrum ◽  
Bolt Loosening

A second-order output spectrum based method for detecting bolt-loosening fault in a satellite-like structure

2019 ◽  
Vol 26 (4) ◽  
pp. 157-165
Author(s):  
Quankun Li ◽  
Xingjian Jing
Keyword(s):  
Second Order ◽  
Bolted Joint ◽  
Output Spectrum ◽  
Engineering Structures ◽  
Local Tuning ◽  
Damage Indicator ◽  
Non Linear ◽  
Linear Behaviour ◽  
Novel Method ◽  
Bolt Loosening

Bolt-loosening faults frequently exist in industrial engineering structures since these bolted structures are often subjected to vibrations or the like in their service process. In this paper, a novel method based on the second-order output spectrum (SOOS) is proposed to detect potential bolt-loosening faults in a complex satellite-like structure. In this method, a general multi-degree-of-freedom (MDOF) model simulating bolt-loosening faults induced non-linearities and inherent boundary or material non-linearities by non-linear forces is built to describe the non-linear behaviour of the structure, and then a local damage indicator is derived for bolt-loosening fault detection through a local tuning approach (LTA) which tunes local structural properties. Results of experimental cases demonstrate that the state of bolted joint in the satellite-like structure with inherent non-linearities can be estimated by this novel SOOS based method effectively and reliably.

Fault diagnosis of bolt loosening in structures with a novel second-order output spectrum–based method

2019 ◽  
Vol 19 (1) ◽  
pp. 123-141 ◽  
Author(s):  
Quankun Li ◽  
Xingjian Jing
Keyword(s):  
Estimation Algorithm ◽  
Second Order ◽  
New Method ◽  
Spectrum Estimation ◽  
Output Spectrum ◽  
Damage Indicator ◽  
Restoring Forces ◽  
Bolt Loosening ◽  
A Chain ◽  
Detection And Localization

This article presents a novel second-order output spectrum–based method for detecting and localizing multiple bolt loosening faults in complex structures with a sensor chain. This new method is developed based on a recently developed nth-order output spectrum estimation algorithm using only proper data obtained from a chain of sensors. The properties of the second-order output spectrum transmissibility of the sensor chain along physical structures with bolts are studied systematically. In the new method, the noise effect on accuracy of the estimation of fault indicators is investigated as well. The new method also considers more general nonlinear restoring forces not only due to faults but also due to inherent nonlinearity in structure when deriving the properties of the second-order output spectrum transmissibility. Extensive simulation and experimental results demonstrate that the second-order output spectrum of the studied structure can be estimated efficiently, and the second-order output spectrum transmissibility can be used as an effective and reliable damage indicator for the detection and localization of multiple bolt loosening faults in complex bolted structures.

The second-order output spectrum-based method for fault localization in ring type structures

2019 ◽  
Vol 98 (3) ◽  
pp. 1935-1955 ◽  
Author(s):  
Quankun Li ◽  
Xingjian Jing ◽  
Yingqing Guo
Keyword(s):  
Fault Localization ◽  
Second Order ◽  
Output Spectrum ◽  
Ring Type

Disappearance Voltage Determinations Using a Convergent Beam

1971 ◽  
Vol 29 ◽  
pp. 184-185
Author(s):  
W. L. Bell
Keyword(s):  
Second Order ◽  
Objective Method ◽  
Uniform Thickness ◽  
Rocking Curve ◽  
Crystal Perfection ◽  
Kikuchi Line ◽  
Central Maximum ◽  
Diffraction Patterns ◽  
Convergent Beam ◽  
Beam Technique

Disappearance voltages for second order reflections can be determined experimentally in a variety of ways. The more subjective methods, such as Kikuchi line disappearance and bend contour imaging, involve comparing a series of diffraction patterns or micrographs taken at intervals throughout the disappearance range and selecting that voltage which gives the strongest disappearance effect. The estimated accuracies of these methods are both to within 10 kV, or about 2-4%, of the true disappearance voltage, which is quite sufficient for using these voltages in further calculations. However, it is the necessity of determining this information by comparisons of exposed plates rather than while operating the microscope that detracts from the immediate usefulness of these methods if there is reason to perform experiments at an unknown disappearance voltage.The convergent beam technique for determining the disappearance voltage has been found to be a highly objective method when it is applicable, i.e. when reasonable crystal perfection exists and an area of uniform thickness can be found. The criterion for determining this voltage is that the central maximum disappear from the rocking curve for the second order spot.

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