CFRP Damping Ratio?

[sdpe]

I am looking for the damping ratios for CFRP composites. The exact ratio is contingent on the orientation and type of fibers but I am just looking for a ballpark number for a quasi-isotropic layup. Any help?

 

[franck]

Hi Sdpe,

I have used CFRP tubes for a space structure. For my analysis, I used (with fear since did not know what to expect) a Q of 25 (damping of 0.02) and this led me to conversative accelerations when I compared with the results from a sine test.

Best regards,

Franck

 

[GBor]

I've seen steel analyst use a damping ratio of 2%, so it doesn't suprise me that 2% would be conservative. I've seen thick balsa cored (3 to 6 inch) composites with as high as 6%. If I had to take a guess, assuming a carbon fiber of modulus 30e6 in an epoxy resin, I would say 3% would still be conservative. 4% may be close...but that's an educated guess (with a strong emphasis on GUESS.

Garland E. Borowski, PE

 

[vanstoja]

Try an internet search on "Material Damping of Vibration". When I did that some months ago I found that the majority of recent information involves damping of composite material.