Al-CFRP UD deformation

[JustinJin]

I am working on Al(1.0mm) + CFRP (UD or Weave) (1.0mm) laminaton project.
The panel size is 1 X 1 meter (1m2) and the requirement is as flat as possible during - 20 and + 60 C temp variations.
It is impossible to keep it flat with this temp ranges but we should achieve it.
One idea is to use "Soft Glue" for the lamination of those two panels and make them flow a little.
We triedhard glue first and as expected it deformed a lot during that temp chanegs.

Also for other project I would like to have data for CTE (Thermal expansion) for Glass fiber UD and Carbon Fiber UD.

Thanks a lot in advance. !!!

 

[blakmax]

Purely on the mathematics of a laminated composite, and treating the aluminium sheet as a layer of composite, what you propose is impossible to achieve. The CTE for aluminium is about 23 x 10-6 /C and carbon is roughly 3 x 10-6/C. No matter what you do with the adhesive, the end product will always distort with temperature.

Regards

Blakmax

 

[RPstress]

Agree with blakmax about problematicness. On a 1 m panel your 'soft glue' will have to accommodate movement of the Al of about 0.5 mm at the ends. Assuming a soft glue thickness of maybe 0.5 mm that's a shear strain of 1 needed with very little shear stress...Maybe 2 mm thick peanut butter would work (non-crunchy type).

UD IM-carbon/epoxy maybe +0.25 microstrain/K along fibres and +30 microstrain/K across fibres.

UD E-glass/epoxy maybe +10 microstrain/K along fibres and +40 microstrain/K across fibres.

All values (very) approx. NB: blakmax's +3 good for woven or roughly QI mixed-direction UD carbon laminate.

 

[blakmax]

Correct for the material type, RP. Also note my values were for SI units (C), not those "furlongs per fortnight" type old units.