This thread will track of the version history of the following download:
Shafts - Natural Frequencies.xls

Thanks Roy -

I think though that for examples 2 3 and 4 the Freq needs to refer to mass and not Area as it does?

Also I think that to get the frequencies correct you need to use metres and not mm? The problem is that the square root of mm isnt the same as the sqrt of m.

Certainly when I use metres I get the same results you would expect using

n= pi/2 * sqrt(EI/ML^3)


Do you agree?

DRT wrote:
Also I think that to get the frequencies correct you need to use metres and not mm? The problem is that the square root of mm isnt the same as the sqrt of m.

Certainly when I use metres I get the same results you would expect using

n= pi/2 * sqrt(EI/ML^3)


Do you agree?

I think its becasue tehre is a factor of 1000 missing in the SQRT term which accounts for acceleration being 9.81ms-2 and NOT 9.81mms-2.

If using mm terms you need to multiply the top term in the SQRT by 1000 to account for gravity being 9810mms-2??

Hello

I created this calculation sheet . I am sorry for not replying earlier I have just been away on holiday.

Thanks DRT for your comment. I have quickly checked my worksheet and you are of course correct. I shall modify the spreadsheet within 24 hours ( when I have spend a little more time reviewing the calc.)

My initial intention is to simply convert the length units
to m. (from mm) this should then allow for the fact that a kg mass has
an accelaration of 1m/s when a force of 1 N is applied and not 1mm/s
as implied by the calc.

I am sorry for this error.