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Squeeze Film - (-)BETAD value from a modal projection analysis

Thread starter DanJordy
Start date Aug 22, 2005

Status: Not open for further replies.

Aug 22, 2005

DanJordy

Mechanical

I'm running a squeeze film analysis to determine the damping parameters (ALPHAD & BETAD) for a clamped-clamped, non-perforated beam with Pressure = 0 BC at the open sides only (no specified pressure BC for the FLUID136 elements on the fixed sides). I have been following the example in Chapter 16 of the help manual, but they used perforations, and have Pressure = 0 on all sides. I've noticed that when the length:width ratio of my structure goes above 2:1, the BETAD value returned is negative.

Does anyone know why I keep getting a negative number?

Thanks in advanced

Dan