complex young's modulus?

[flyinghorse21]

when considering structural loss in vibration problems, young's modulus E is a complex,E=E1(1+i*sigma).I want to know the value of sigma for aluminium.who can help me? Thanks!

 

[GregLocock]

You'll get about 0.2% damping in a welded aluminium structure. How you turn that into your E* parameter is left as an exercise.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[flyinghorse21]

thank you for your reply, Greg Locock.From some information i got recently,i know the sigma for steel is about 0.03.So i use 0.03 for aluminium in my computation.Can you tell me where(books or websites) i can find the value for aluminium.Thanks!

 

[MikeyP]

The internal loss factor for the material is not usually the dominant form of damping in a real structure. I seem to remember than Beranek quotes 1E-2 to 1E-3 for aluminium. That's a pretty broad range though.

M

--
Dr Michael F Platten