Expansion rate of Carbon Fiber vs Steel

[Valhalla14]

I am a lisc. Auto body tech, and I have a customer who wants a Carbon Fiber roof on a Volkwagen bug, I can fabricate a inner frame, and bonding will not be an issue, (according to paint rep)

The hard part is I want to do a flush seem and have paint blend into carbon fiber. I will "butt" match it, and have it bonded on the back side where I can strengthen the bond, and on the outside I will do the standard procedure as a quarter panel

If the expansion rate is different I will experience cracking, maybe ghosting from the seam.

Is this something I could figure out, or just run from the Idea

 

[edgepflow]

Yes, you could figure this out with the coefficients of thermal expansion of both materials:

Net Growth = (coeff exp metal - coeff exp carbon fiber) X Temperature Difference X Original Length

The temperature difference would be the maximum or minimum temperature in the area minus the temperature during assembly.

After you figure the expansion, you may be able to put a groove feature or something to accommodate this expansion.