Measurement of SEA damping loss factor for complex structures

2008 ◽  
Vol 123 (5) ◽  
pp. 3060-3060 ◽  
Author(s):  
Maxime Bolduc ◽  
Noureddine Atalla
Keyword(s):  
Loss Factor ◽  
Complex Structures ◽  
Damping Loss Factor

Measurement of SEA Damping Loss Factor for Complex Structures

2005 ◽  
Author(s):  
Maxime Bolduc ◽  
Nourddine Atalla ◽  
Andrew Wareing
Keyword(s):  
Loss Factor ◽  
Complex Structures ◽  
Damping Loss Factor

A New Methodology for the Accurate and Consistent Identification of Modal Parameters Using Multi-FRF Analysis

1995 ◽  
Author(s):  
R. M. Lin ◽  
S.-F. Ling
Keyword(s):  
Eigenvalue Problem ◽  
Loss Factor ◽  
Frequency Response Function ◽  
Natural Frequencies ◽  
Identification Problem ◽  
Modal Parameters ◽  
Frequency Range ◽  
Case Examples ◽  
Measured Frequency Response ◽  
Damping Loss Factor

Abstract A new method for the estimation of modal parameters is presented in this paper. Unlike the majority of the existing methods which involve complicated curve fitting and interpolative procedures, the proposed method calculates the modal parameters by solving eigenvalue problem of an equivalent eigensystem derived from measured frequency response function (FRF) data. It is developed based on the practical assumption that only one incomplete column of the FRF matrix of the test structure has been measured in a frequency range of interest. All the measured FRFs are used simultaneously to construct the equivalent eigensystem matrices from which natural frequencies, damping loss factor and modeshape vectors of interest can be directly solved. Since the identification problem is reduced to an eigenvalue problem of an equivalent system, natural frequencies and damping loss factors identified are consistent. Further procedures for normalizing the identified eigenvectors so that they become mass-normalized are developed. Numerical case examples are given to demonstrate the practicality of the proposed method and results obtained are indeed very promising. It is believed that with the availability of such identification method, modal analysts’ dream of intelligent and full automatic modal analysis will become a reality.

The Backing Design in the Free Damping Cylindrical Shell Damping Test

2013 ◽  
Vol 437 ◽  
pp. 475-480
Author(s):  
Bang Hui Yin ◽  
Min Qing Wang
Keyword(s):  
Cylindrical Shell ◽  
Energy Method ◽  
Design Problem ◽  
Loss Factor ◽  
Cylindrical Shells ◽  
Harmonic Response ◽  
Different Types ◽  
Damping Loss Factor

The ANSYS harmonic response results are post-processed with the energy method to obtain the damping loss factor (DLF) of different types of free damping structures. Firstly, the DLF of free damping cylindrical shell in air is compared with DLF of free damping plate in air. Secondly, the DLF of free damping cylindrical shell with stiffened ribs in air is compared with that without stiffened ribs in air. Thirdly, the DLF of free damping cylindrical shell in water is compared with the DLF of free damping plate in water. Fourthly, the DLF of free damping cylindrical shell with stiffened ribs in water is compared with that without stiffened ribs in water. In the end, based on the above analysis, the backing design problem in air and water are discussed. Studies have shown that: DLF of free damping cylindrical shell is close to that of free damping plate in air; DLF of free damping cylindrical shell with stiffened ring ribs is close to that without stiffened ring ribs in air; When testing free damping cylindrical shells DLF in air, plate with the same thickness can be used as the backing; DLF of free damping plate is close to that of free damping cylindrical shell in water; DLF of free damping cylindrical shell with stiffened ring ribs is close to that without stiffened ring ribs in water; When testing free damping cylindrical shells DLF in water, plate with the same thickness can be used as the backing.

Experimental Determination of the Damping Loss Factor of Highly Damped Ribbed-Stiffened Panels

2008 ◽  
Author(s):  
Jesús Ortiz Martinez ◽  
Márcio Calçada ◽  
Roberto Jordan ◽  
Samir N. Y. Gerges
Keyword(s):  
Experimental Determination ◽  
Loss Factor ◽  
Stiffened Panels ◽  
Damping Loss Factor

A Robust Testing Method for Determination of the Damping Loss Factor of Composites

1992 ◽  
Vol 14 (2) ◽  
pp. 70
Author(s):  
WS Johnson ◽  
JE Masters ◽  
TK O'Brien ◽  
RM Crane ◽  
JW Gillespie
Keyword(s):  
Loss Factor ◽  
Testing Method ◽  
Robust Testing ◽  
Damping Loss Factor

Optimization Design on Vibration and Noise Reduction of Damping Sandwich Circular Saw

2012 ◽  
Vol 215-216 ◽  
pp. 433-437
Author(s):  
Ting Wang ◽  
Tao Yao ◽  
Guo Lin Duan
Keyword(s):  
Noise Reduction ◽  
Loss Factor ◽  
Optimization Design ◽  
Design Method ◽  
Optimal Thickness ◽  
Damping Effect ◽  
Circular Saw ◽  
Damping Material ◽  
Material Element ◽  
Damping Loss Factor

In view of the study of topology optimization design method on vibration and noise reduction of damping sandwich circular saw, the optimal thickness and layout of damping material were obtained. The optimization model of circular saw was established by using the coupling method, the optimum thickness of damping layer was found. By using ESO method, deleting elements method and modal loss factor sensitivity calculation method were obtained. Making use of modal loss factor sensitivity, ineffective elements were deleted by judging the whole structure damping effect on each damping material element, optimal configuration of damping sandwich circular saw structure under the stiffness condition was obtained, which reduced the vibration and noise and reached a certain stiffness requirements. By contrasting the damping loss factor of three different circular saw models, the results show that optimized circular saw structure has the best damping effect.

Effects of Mesh Density on Static Load Performance of Metal Mesh Gas Foil Bearings

2011 ◽  
Author(s):  
Yong-Bok Lee ◽  
Chang Ho Kim ◽  
Tae Ho Kim ◽  
Tae Young Kim
Keyword(s):  
Test Data ◽  
Loss Factor ◽  
Static Load ◽  
Stiffness Coefficient ◽  
Metal Mesh ◽  
Rotor Spinning ◽  
Foil Bearings ◽  
Mesh Density ◽  
Damping Loss Factor ◽  
Mesh Structures

Metal mesh materials have been used successfully in vibration isolators and bearing dampers due to their superior friction or hysteresis damping mechanism. These materials are formed to metal mesh (or wire mesh) structures in ring-shape by compressing a weave of metal wires, in general. Recently, oil-free rotating machinery implement metal mesh structures into hydrodynamic gas foil bearings by replacing bump strip layers with them, to increase its bearing structural damping. A metal mesh foil bearing (MMFB) consists of a top foil and support elastic metal mesh pads installed between a rotating shaft and a housing. The present research presents load capacity tests of a MMFB at rotor rest (0 rpm) and 30 krpm for three metal mesh densities of 13.1%, 23.2%, and 31.6%. The metal mesh pad of test MMFB is made using a stainless steel wire with a diameter of 0.15 mm. Test rig comprises a rigid rotor with a diameter of 60 mm supported on two ball bearings at both ends and test MMFB with an axial length of 50 mm floats on the rotor. Static loads is provided with a mechanical loading device on test MMFB and a strain gauge type load cell measures the applied static loads. A series of static load versus deflection tests were conducted for selected metal mesh densities at rest (0 rpm). Test data are compared to further test results of static load versus journal eccentricity recorded at the rotor speed of 30 krpm. Test data show a strong nonlinearity of bearing deflection (journal eccentricity) with static load, independent of rotor spinning. Observed hysteresis loops imply significant structural damping of test MMFB. Measured journal deflections at 0 rpm are in similar trend to recorded journal eccentricities at the finite rotor speed, thus implying that the MMFB performance depends mainly on the metal mesh structures. The paper also estimates linearlized stiffness coefficient and damping loss factor of test MMFB using the measured static load versus deflection test data at 0 rpm and 30 krpm. The results show that the highest mesh density of 31.6% produces highest linearlized stiffness coefficient and damping loss factor. With rotor spinning at 30 krpm, the linearlized stiffness coefficient and damping loss factor decrease slightly, independent of metal mesh densities. The present test data will serve as a database for benchmarking MMFB predictive models.

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