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Finding the fundamental longitudinal eigenfrequency of disc

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Hi,

I'm trying to figure out the fundamental longitudinal eigenfrequency of a circular disc (thin cylinder). I'm using the eigenfrequency study from the Structural Mechanics physics. When I put the 2 disc faces as fixed BC, COMSOL gives me a very large list of random eigenfrequencies which I'm sure that includes both the lateral and longitudinal eigenfrequencies.

I'm only interested in the through-thickness frequency. For that, I produced mass-factored (weighted) eigenfrequencies and plotted the square of mpf1.mEffLX, mpf1.mEffLY and mpf1.mEffLZ. And then assigned the eigenfrequency with highest mpf1.mEffLZ as my fundamental longitudinal node.

Is my process sound and how can I make sure? Is there another way for searching for fundamental nodes?

Many thanks in advance and regards, Hamad


1 Reply Last Post May 12, 2020, 10:12 p.m. EDT
Dave Greve Certified Consultant

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Posted: 4 years ago May 12, 2020, 10:12 p.m. EDT

If it were me I would just look at the modes. Since your are after the lowest mode of a particular type you will not need to look at many of them.

If it were me I would just look at the modes. Since your are after the lowest mode of a particular type you will not need to look at many of them.

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