Finite element and experimental modal analysis of ultra-precision air bearing linear motion stage

2006 ◽  
Author(s):  
Zhang Ming ◽  
Zhu Yu ◽  
Ren Gexue ◽  
Duan Guanghong ◽  
Chen Yaying ◽  
...  
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Experimental Modal Analysis ◽  
Air Bearing ◽  
Linear Motion ◽  
Ultra Precision ◽  
Motion Stage

Finite Element and Experimental Analysis on Micro-Vibration of Ultra Precision Air Bearing Linear Motion Stage and Methods of Its Elimination

2007 ◽  
Author(s):  
Ming Zhang ◽  
Yu Zhu ◽  
Gexue Ren ◽  
Guanghong Duan ◽  
Guohua Gao
Keyword(s):  
Finite Element ◽  
Laminar Flow ◽  
Load Capacity ◽  
Air Bearing ◽  
Linear Motion ◽  
Turbulence Flow ◽  
Ultra Precision ◽  
Air Channel ◽  
Motion Stage ◽  
Micro Vibration

Air bearing linear motion stages with high speed and ultra high positioning performances are always used in steppers or scanners which are the most important equipments in microlithography process. Excellent air bearing design is one of the keys to archive those performances. Good load capacity and stiffness are always the main design objective for designers. But experiment shows that air bearing stage with high stiffness and load capacity may suffer from micro vibration. The micro vibration is not the “pneumatic hammer” which usually happens to air bearing due to poor restrictor design. Its amplitude ranges from tens to hundreds of nanometers and frequency from tens to thousands of Hz. For an ultra precision linear motion stage which positioning accuracy level is about ten nanometers, the vibration amplitude is obviously unacceptable. Further more, the micro-vibration seriously lower system’s dynamic characteristics. To find the reason of micro-vibration, finite element method is used to analyze the air flow in the air channel of air bearing. The result shows that the turbulence flow in the air channel will induce the micro-vibration. So the laminar flow in the air channel is the key way to eliminate the micro-vibration of air bearing stage. To turn the turbulence flow into laminar flow, the designer must consider the radius of the air channel, the number of air inlet and mass flow rate of air bearing comprehensively.

Modal Analysis of Externally Pressurized Air Bearing Workbench Based on Spring-Mass System Method

2011 ◽  
Vol 188 ◽  
pp. 602-607
Author(s):  
Bo Zhang ◽  
Ping Ma ◽  
J.J. Huang
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Nonlinear Modeling ◽  
Experimental Modal Analysis ◽  
Air Bearing ◽  
Mass System ◽  
System Method ◽  
Good Agreement

The stiffness of externally pressurized air bearing is nonlinear, so it is difficult for nonlinear modeling and modal analysis with Finite Element Modal Analysis(FEMA). In this paper, the spring-mass system method which use linear springs in place of nonlinear air bearing has been developed to make FEMA of externally pressurized air bearing workbench more easier and faster. The actual modes of the workbench have also been attained with Experimental Modal Analysis (EMA). The results of EMA have a good agreement with FEAM results ,which verifies the feasibility of spring-mass system method.

Structural Analysis of a Grinding Machine with Linear Motion Guide Applied

2013 ◽  
Vol 336-338 ◽  
pp. 1014-1019
Author(s):  
Seon Yeol Oh ◽  
Han Seok Bang ◽  
B. Y. Choi ◽  
Woo Chun Choi ◽  
S. J. Cho
Keyword(s):  
Finite Element ◽  
Structural Analysis ◽  
Structural Design ◽  
Element Model ◽  
Linear Motion ◽  
Precision Grinding ◽  
Base Side ◽  
Ultra Precision ◽  
Linear Motion Guide ◽  
Grinding Machine

A finite element model of an ultra-precision grinding machine that can have high precision and high stiffness is constructed and structural analysis is done with equivalent stiffnesses of linear motion guides by after structural design and the deformation of the grinding machine is obtained. In order to reduce the deformation of the grinding machine that causes bad influence, structural complement is conducted by adding ribs at the lower part of the column. Also, the straightness of the grinding machine is improved by lifting that the base side of the column.

scholarly journals Rayleigh Damping Coefficients of Laminated Rubber Bearing

2019 ◽  
Vol 8 (4) ◽  
pp. 12294-12300
Keyword(s):  
Finite Element ◽  
Modal Analysis ◽  
Natural Frequencies ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Ground Structure ◽  
Damping Coefficients ◽  
Rubber Bearing ◽  
Stability And Instability ◽  
Laminated Rubber Bearing

In isolating the ground structure and the above ground structure from seismic loads, a significant device called laminated rubber bearing is usually found in structure. The complexity of the material which is made up from a combination of rubber and steel shim plates in alternate layer, has made it difficult to measure damping value. Damping is a dissipation of energy or energy losses in the vibration of the structure. Measuring the accurate amount of damping is fundamental as damping plays a crucial role in fixing the borderline between stability and instability in structural systems. Therefore, to determine the damping value including dynamic properties in any materials, modal analysis can be used. Hence, the main objective of this research is to determine the Rayleigh’s damping coefficients α and β and to evaluate the performance of the laminated rubber bearing using finite element and experimental modal analysis. Finding shows that, the finite element modal analysis with the addition of Rayleigh’s damping coefficients α and β, shows a good agreement with the experimental modal analysis in term of natural frequencies and mode shapes. Findings show that, the values of natural frequencies reduced when precise Rayleigh’s damping coefficient added in the finite element modal analysis. It can be concluded that both finite element and experimental modal analysis method can be used to estimate the accurate values of damping ratio and to determine the Rayleigh’s damping coefficients α and β as well.

Improved Results in Structural Dynamic Calculations by Linking Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA)

1995 ◽  
Author(s):  
Ulrich Gabbert ◽  
Manfred Zehn ◽  
Friedrich Wahl
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Modal Analysis ◽  
Numerical Models ◽  
Mass Matrix ◽  
Computer Time ◽  
Experimental Modal Analysis ◽  
Mode Shapes ◽  
Element Analysis ◽  
Structural Dynamic

Abstract The paper deals with improvements of accuracy of structural dynamic calculations by using both the advantages of Finite Element Analysis (FEA) and Experimental Modal Analysis (EMA). The basis for such improvements are reasonable mechanical and numerical models and accurate frequency response measurements (eigenfrequencies and mode shapes). The paper deals first with reasons for and estimations of errors in numerical and experimental analysis. It can be shown by theory and experiment that neither FEA nor EMA models are unique, due to inevitable incompleteness of the mode shapes and eigenfrequencies from a vibration test. Verification and updating of FE models by linking FEA with EMA are discussed in the paper and mainly focussed on FE models with a large number of degrees of freedom. Hence an update method has been introduced, which leads to an improved model in a relatively small quantity of computer time. It can be shown, that based on measured eigenfrequencies and calculated eigenvectors, an updating of FE-models for real engineering problems, by changing the mass matrix only, is a very efficient procedure with a surprisingly good quality updated model.

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