A new thin-wall beam modal testing method based on single point laser continuous plane scanning vibration measurement

2013 ◽  
Author(s):  
Jigang Wu ◽  
Bin Qin ◽  
Xuejun Li ◽  
Qiancheng Zhao
Keyword(s):  
Single Point ◽  
Modal Testing ◽  
Vibration Measurement ◽  
Thin Wall ◽  
Testing Method ◽  
Plane Scanning

Identification of rotating asymmetry in rotating machines by using reverse directional frequency response functions

2001 ◽  
Vol 215 (9) ◽  
pp. 1053-1061
Author(s):  
C-W Lee ◽  
K-S Kwon
Keyword(s):  
Frequency Response ◽  
Frequency Response Function ◽  
Modal Testing ◽  
Vibration Sensor ◽  
Vibration Measurement ◽  
Response Functions ◽  
Physical Realization ◽  
Rotating Machines ◽  
Frequency Response Functions ◽  
Testing Method

A quick and easy but comprehensive identification method for rotating asymmetry in rotating machines is proposed, based on the complex modal testing method. In this work it is shown that the reverse directional frequency response function (reverse dFRF), which indicates the degree of asymmetry, can be identified with a simple testing method requiring only a single vibration sensor and a single exciter. To clarify physical realization associated with estimation of the reverse dFRF, its relation to the conventional frequency response functions, which are defined by the real input (excitation) and output (vibration measurement), are discussed extensively.

Identification of Rotating Asymmetry in Rotating Machines by Using Reverse dFRF

1999 ◽  
Author(s):  
Chong-Won Lee ◽  
Kye-Si Kwon
Keyword(s):  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Modal Testing ◽  
Vibration Sensor ◽  
Response Functions ◽  
Physical Realization ◽  
Simple Method ◽  
Testing Method ◽  
Asymmetric Rotor

Abstract A quick and easy but comprehensive identification method for asymmetry in an asymmetric rotor is proposed based on complex modal testing method. In this work, it is shown that the reverse directional frequency response function (reverse dFRF), which indicates the degree of asymmetry, can be identified with a simple method requiring only one vibration sensor and one exciter. To clarify physical realization associated with estimation of the reverse dFRF, its relation to the conventional frequency response functions, which are defined by the real input (exciter) and output (vibration sensor), are extensively discussed.

Research on Flow Characteristics of Aerostatic Circular Thrust Bearing with a Cone Cavity

2011 ◽  
Vol 308-310 ◽  
pp. 189-192
Author(s):  
Long Xing Chen ◽  
Wen Qi Ma ◽  
He Chun Yu ◽  
Hai Yan Liu ◽  
Hong Wang Du
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Thrust Bearing ◽  
Single Point ◽  
Flow Characteristics ◽  
Simulation Method ◽  
Flow Passage ◽  
Testing Method ◽  
Measurement Results ◽  
Simulation And Experiment

The aerostatic circular thrust bearing was taken as a study subject. The numerical simulation method was used to calculate the flow passage. Meanwhile, the single-point testing method was used to test the pressure distribution. The simulation and experiment measurement results were compared and analyzed. The results show that: The single-point testing method is effective to capture the change of flow characteristics. The overall results of simulation and testing coincide with each other well. In the range of cone cavity, the flow pattern for the gas is turbulent flow, and the flow field should be divided into different zones for simulation.

A New Imaging Method for Arterial Tubes Based on Vibration Measurement

2003 ◽  
Author(s):  
Xiaoming Zhang ◽  
Mostafa Fatemi ◽  
James F. Greenleaf
Keyword(s):  
Focal Point ◽  
Single Point ◽  
Vibration Measurement ◽  
Ultrasound Transducer ◽  
Imaging Method ◽  
Large Artery ◽  
Large Radius ◽  
Modal Shape ◽  
Measured Velocity ◽  
Gel Phantom

A new method for imaging and detecting modal shapes of vessels is introduced. Theory is developed that predicts the measured velocity is proportional to the value of the mode shape at the focal point of the ultrasound beam. Experimental a cylindrical gel phantom of large radius. This model simulates approximately a large artery and the surrounding body. The fundamental frequency was measured 83 Hz for the tube-phantom system. At this frequency the ultrasound transducer was scanned across the vessel plane with velocity measurement at one single point on the vessel and on the phantom by laser. The images obtained show clearly the interior tube and the modal shape of the tube.

Vibration Modal Testing Method of Thin-Walled Components Based on Curvature Scale Space Corner Detecting and Matching

2017 ◽  
Vol 54 (8) ◽  
pp. 081001
Author(s):  
伍济钢 Wu Jigang ◽  
张双健 Zhang Shuangjian ◽  
蒋勉 Jiang Mian ◽  
王刚 Wang Gang
Keyword(s):  
Scale Space ◽  
Modal Testing ◽  
Testing Method ◽  
Curvature Scale Space ◽  
Thin Walled ◽  
Vibration Modal

Interface Properties Due to Microslip From Vibration Measurement

1999 ◽  
Vol 123 (1) ◽  
pp. 230-233 ◽  
Author(s):  
H. A. Sherif ◽  
T. M. Abu Omar
Keyword(s):  
Contact Stiffness ◽  
Single Point ◽  
Peak Frequency ◽  
Vibration Measurement ◽  
Interface Properties ◽  
Flat Surfaces ◽  
Dry Contact ◽  
Impulse Excitation ◽  
Interface Parameters ◽  
Two Degree Of Freedom

A method of measuring contact stiffness and friction damping at interacting plane surfaces of a mechanical system comprised of two sub-structures in dry contact is presented. The method is based on the measurement of displacement ratio of the contacting sub-structures as a function of frequency due to light impulse excitation at a single point on any of the two sub-structures. The theoretical analysis depends on a very simple model of a two-degree-of-freedom system with elastic coupling. The effects of applied normal loads, and contact configuration on the interface parameters are shown. The theoretical and experimental analyses show that the interface properties for the flat-on-flat surfaces of the two contacting sub-structures can be determined from the measured peak amplitude and peak frequency of the microslip in the frequency domain.

Noncontacting Excitation and Measurement of Light Structures

2003 ◽  
Vol 125 (1) ◽  
pp. 114-119 ◽  
Author(s):  
Yacine M. Amraoui ◽  
Nick A. J. Lieven
Keyword(s):  
Frequency Response ◽  
Modal Testing ◽  
New Method ◽  
Vibration Measurement ◽  
Design Parameters ◽  
Primary Concern ◽  
Testing Procedures ◽  
Response Data ◽  
Loading Effects

This paper demonstrates a new method of conducting a noncontacting vibration measurement on light structures. Although laser vibrometry provides a routine method of acquiring response data, the method of achieving noncontacting point excitation of structures remains problematic. This is the primary concern of the paper. There is understandable motivation to develop a viable noncontacting excitation method as exciting methods involve contact thereby altering the structure’s in-situ properties. The method demonstrated in the paper explores the use of focused acoustic excitation. An ellipsoid cavity has been constructed which is designed to emit focused plane wave excitation over an area of 1 in. diameter, thus approximating to point excitation. The paper outlines the design and construction of the ellipsoid shell and discusses the design parameters in relation to the frequency response and footprint of the excitation. The results presented compare measurements acquired via this new method and the corresponding Frequency Response Functions obtained by the electrodynamic excitation. Significant differences are observable, largely arising from the mass loading effects associated with the standard modal testing procedures.

Complex Modal Testing Methods for Rotating Machinery

1991 ◽  
Author(s):  
Chong-Won Lee ◽  
Young-Don Joh
Keyword(s):  
Frequency Response ◽  
Rotating Machinery ◽  
Modal Testing ◽  
Response Functions ◽  
Testing Methods ◽  
Complex Signals ◽  
Indirect Assessment ◽  
Testing Method ◽  
Effective Use ◽  
Complex Modal

Abstract Various modal testing methods are proposed for the effective use of complex modal testing for rotating machinery, focusing on excitations and measurements. The proposed methods are developed, based on the input/output relationships for complex signals, for the direct or indirect assessment of frequency response and coherence functions between complex inputs and outputs. The proposed testing methods and the classical modal testing method are compared in consideration of required number of frequency response functions (FRFs) and testing efforts.

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