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Re: [Fwd: Vibration analysis]
On Wed, 12 Mar 2008, Tim Whitlatch wrote:
Dear all,
I have a small question, is this really a topic we need to worry about
now ?????
I really don't think so. I think we have to show that we are aware of this
issue and have plans to investigate it. Dan we have so much work at the
moment that it is really not a benefit to have a 100% totally designed FDC
but everything else is behind
cheers elke
> Date: Wed, 12 Mar 2008 11:16:41 -0400
> From: Tim Whitlatch <whitey@jlab.org>
> To: Daniel S. Carman <carman@jlab.org>
> Cc: Chuck Hutton <huttonc@jlab.org>, Ed Daly <eddaly@jlab.org>,
> halld-me@jlab.org
> Subject: Re: [Fwd: Vibration analysis]
>
> Hi Dan,
>
> Yes it was me that instructed Chuck not to spend time on this right now.
> As we discussed earlier, the most effective way to find the natural
> frequencies of the cathode plane would be to perform a test using the
> equipment that you said you have access to. This would involve setting
> up an acoustic driver at varying frequencies and observing the vibration
> of the cathode.
> One of the unknowns is the tension in the plane. This will directly
> affect the natural frequencies. A hand calculation can give some
> ballpark estimates of the natural frequency and subsequent modes. This
> again depends on the tension. Assuming the tension is very low (on the
> order of a 1 lb/foot of circumference), the1st natural frequency mode is
> in the single digits hz.
> If we want to get a better feel for the tension, a sag measurement under
> gravity alone can be made and the tension could be backed out.
> In my opinion, before any finite element model can be effective, these
> measurements should be made. Also, these measurement will be more
> accurate than an FEA model.
> I do not believe the natural frequencies will be a problem, and if it
> turns out to be, it can be easily solved.
> The first order frequencies we would need to avoid is 60hz and 120 hz.
>
> Cheers,
>
> Tim
>
> Chuck Hutton wrote:
> > I have been instructed not to worry about this right now and to focus
> > on more pressing issues.
> >
> > Chuck
> >
> > ------------------------------------------------------------------------
> >
> > Subject:
> > Vibration analysis
> > From:
> > "Daniel S. Carman" <carman@jlab.org>
> > Date:
> > Wed, 12 Mar 2008 07:46:59 -0400 (EDT)
> > To:
> > huttonc@jlab.org
> >
> > To:
> > huttonc@jlab.org
> >
> >
> > Chuck,
> >
> > The same day that you asked me to contact Ed Daly with the information
> > regarding the vibration analysis of the cathodes, I sent him a
> > write-up with the details (cc'ed to you as well). I have not heard
> > back from him. Can you check in with him today and give us an update
> > tomorrow at the FDC meeting on where this work stands? Let me know
> > if you have any questions.
> >
> >
> > Regards,
> >
> > Daniel
> >
> >
> > **********************************************************************
> > * *
> > * Dr. Daniel S. Carman e-mail : carman@jlab.org *
> > * Staff Scientist office : (757)-269-5586 *
> > * Jefferson Laboratory web: www.jlab.org/~carman *
> > * *
> > **********************************************************************
> >
> >
> >
>
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