6781 Fiberglass

Aeronautics & Space Engineering general discussion Aircraft
#1

QUESTION
Does anyone have a decent spec sheet for this material that includes the shear Modulus or Modulus of elasticity? It is using a phenolic resin.

REPLIES

compositepro
6781 is an 8 harness satin weave of S-2 glass fiber. As a dry fabric it has no shear modulus. As a composite the shear modulus would be determined mainly by the resin properties.

6781 is the identical to 7781 except for the use of S2-glass rather than E-glass (most just call it S-glass but the original S-glass, which was qualified to a number of defense and ballistic missile programs, is no longer made. S2 is made to commercial specifications rather than military, just like E-glass. You can easily find information through a google search.

As for phenolic resin, you need to know the exact proprietary product formulation for properties. Resin properties can be all over the map and depends on the exact formulation and processing. You can generally only get that from the manufacturer. SC-1008 is one of the most common phenolics used in aerospce composites. This resin can be used straight out of the drum or with additives.

SOURCE
https://www.eng-tips.com/viewthread.cfm?qid=421168
Above is a snippet.

#2

@compositepro, Thank you for the informative reply. It lays out a good view of the job ahead, and where the original poster needs to focus their energies.

#3

A comparison between style 6781 and the more common 7781:

Style	Weave		Count	Count
					Warp	Fill      Warp Yarn		Fill Yarn
6781 	8H Satin  	57 		54 		SCG  75 1/0 	SCG  75 1/0 	
7781 	8H Satin   	57 		54 		ECDE 75 1/0 	ECDE 75 1/0 	

			Weight				Thickness 		Strength  
Style		(oz/yd2) (g/m2)		(mils) (mm)	(lbf/in) 	(lbf/in)	
6781 		8.94 	303 		9.6 	0.24 	568 		454 
7781 		8.87 	301 		8.6 	0.22 	501 		408

Overall they do seem similar. My guess is the 6781 will be a little harder to work with, being thicker, but maybe not noticeable given its use of the same yarn and weave.

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