IM fiber in 787/A350?

[RPstress]

Does anyone have any idea how much of the carbon in the new generation of airliners is IM as opposed to the "usual" HS/HT/standard modulus?

We're looking for candidate materials for a civil test program and aren't sure how much emphasis to put on each fiber type.

 

[Compositepro]

I'm not aware of any significant amount of Intermediate Modulus fiber used on commercial aircraft. F-22 and F-35 use mainly IM7 fiber from Hexcel.

 

[RPstress]

Hm. Interesting, 'Pro.

Our estimates show that an upper wing skin/lower tailplane could see between 5 and 10% wt save in IM just from modulus. There are still a few questions over bearing strength and CAI. The tension skin might also have a small advantage (depends on permissable tension cutoff).

Some CAI data show a small advantage to IM; this seems a little odd, as whenever we do simple impact tests IM laminates see higher impact forces due simply to the higher stiffness and generally see more damage. However, we've never been able to afford a decent BVID CAI trial.

(BVID CAI is where you have to do visible-ish damage, irrespective of impact energy (subject to cutoff), typ. 50 thou dent depth. Some stuff, like C/PEEK, resists high impacts very well, but by the time you've done inspectable damage it loses a lot of the advantage.)

I'm not aware of any advantage for fuse in IM, but I'm not that familiar with fuse requirements.

 

[SWComposites]

Wing, fuselage, empennage primary structures on 787 all use IM class fiber (Toray T800). Same fiber used on 777 floor beams and empennage main boxes. Don't have any specific info for A350, but would suspect they are using IM type fiber in both wing and fuselage.

 

[RPstress]

Thanks SW. I was aware that Mr B. used a lot of T800/3900 prepreg, but I didn't know it was that much.

Anyone got any idea what the advantage of IM in a fuse is?

As an a minor aside, does anyone know of any aerospace use of Torayca T1000 IM? I'm aware of some use in racing cars.