A fuzzy finite element procedure for the calculation of uncertain frequency response functions of damped structures: Part 2—Numerical case studies

2005 ◽  
Vol 288 (3) ◽  
pp. 463-486 ◽  
Author(s):  
Hilde De Gersem ◽  
David Moens ◽  
Wim Desmet ◽  
Dirk Vandepitte
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Case Studies ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Finite Element Procedure ◽  
Fuzzy Finite Element

Change of modal parameters due to crack growth in a tripod tower platform

1993 ◽  
Vol 20 (5) ◽  
pp. 801-813 ◽  
Author(s):  
Yin Chen ◽  
A. S. J. Swamidas
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Response Function ◽  
Frequency Response Function ◽  
Experimental Results ◽  
Modal Testing ◽  
Modal Parameters ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Strain Frequency

Strain gauges, along with an accelerometer and a linear variable displacement transducer, were used in the modal testing to detect a crack in a tripod tower platform structure model. The experimental results showed that the frequency response function of the strain gauge located near the crack had the most sensitivity to cracking. It was observed that the amplitude of the strain frequency response function at resonant points had large changes (around 60% when the crack became a through-thickness crack) when the crack grew in size. By monitoring the change of modal parameters, especially the amplitude of the strain frequency response function near the critical area, it would be very easy to detect the damage that occurs in offshore structures. A numerical computation of the frequency response functions using finite element method was also performed and compared with the experimental results. A good consistency between these two sets of results has been found. All the calculations required for the experimental modal parameters and the finite element analysis were carried out using the computer program SDRC-IDEAS. Key words: modal testing, cracking, strain–displacement–acceleration frequency response functions, frequency–damping–amplitude changes.

scholarly journals Analyzing the Dynamic Characteristics of Milling Tool Using Finite Element Method and Receptance Coupling Method

2019 ◽  
Vol 9 (2) ◽  
pp. 3918-3923
Author(s):  
J. P. Hung ◽  
W. Z. Lin ◽  
K. D. Wu ◽  
W. C. Shih
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Dynamic Characteristics ◽  
Coupling Method ◽  
Response Functions ◽  
Original Design ◽  
Frequency Response Functions ◽  
Feeding Mechanism ◽  
Receptance Coupling ◽  
Milling Tool

This study aims to investigate the dynamic characteristics of a milling machine with different head stocks by using finite element (FE) method and receptance coupling analysis (RCA). For this purpose, five full finite element machine models, including vertical column, reformed head stock and feeding mechanism were created. With these models, the tool point frequency response functions were directly predicted. Another approach was the application of the receptance coupling method, in which the frequency response of the assembly milling tool was calculated from the receptance components of the individual substructures through the coupling operation with the interfaces of the feeding mechanism. Results show that a whole machine model with reformed stock has superior dynamic behavior when compared with the original design, by an increment of 10% in the dynamic stiffness. The receptance coupling method was verified to show an accurate prediction of the frequency response functions of the spindle tool when compared with the results obtained from the full FE models. Overall, the proposed methodology can help the designer to efficiently and accurately develop the machine tool structure with excellent mechanical performance.

Squeeze Oil-Film Fluid-Structure Interaction Analysis by the Finite Element Method

2013 ◽  
Vol 401-403 ◽  
pp. 446-449
Author(s):  
Jie Chen ◽  
Neng Xi ◽  
Jia Jun Yang ◽  
Mei Ling Zhao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Frequency Response ◽  
Fluid Structure Interaction ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Fluid Structure ◽  
Oil Film ◽  
Structure Interaction ◽  
Element Method

The squeeze oil-film dampers have been applied to damp out vibration in linear guideway systems of CNC machine tools. An accurate estimate of squeeze oil-film damping effects is significant to predict the dynamic performance of rolling guidance systems. This paper presents a finite element method to solve the fluid-structure interaction problem of squeeze oil-film dampers. Three-node Mindlin plate element is used in the structure domain model. The oil-film behavior is provided by the Reynolds equation of lubrication theory. Both the structural domain and fluid domains are discretized by finite element method. The frequency response functions of coupled systems are derived by considering the oil-film pressures and the structure displacements on the boundary as the coupling conditions. The validity of the frequency response functions is verified by a simple example. It shows that the oil-film thickness has significant influence on the frequency response.

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