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Message ID: 3207     Entry time: Tue Jul 13 14:59:04 2010
Author: Gopal 
Type: Update 
Category: Optic Stacks 
Subject: Eigenfrequency Analysis of Single Stack Complete 

Via reconfiguration of Viton parameters (previously posted), I managed to debug the COMSOL run time errors and null pointer exceptions. Listed are the resultant eigenfrequencies obtained through structural analysis testing. For all tests, the bottom of the Viton springs are constrained from motion, and all other parts are free to oscillate. Notice that color variations signify displacement from the equilibrium position. Also note that different initial conditions produce different eigenmodes:

No initial displacement:

Eigenmode_Stack_4.png


0.01 m x-displacement:

Eigenmode_Stack_4_xdisp.png


0.01 m y-displacement:

Eigenmode_Stack_4_ydisp.png


 0.01 m z-displacement:

 Eigenmode_Stack_4_zdisp.png


Clearly, the plate has its first harmonic between 210-215 Hz, which is much greater than seismic noises (which never exceed the 10-Hz range). This suggests a highly attenuating transfer function. Since the remaining three plates have been designed to resonate similarly, it is likely that the entire stack system will also function very well.

Next steps:

1) Extend the eigenfrequency analysis to obtain a transfer function for the single-plate system

2) Expand the CAD model to include all four stack layers, and perhaps a base

 

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