Composite Scarf Repairs Theory
Composite Scarf Repairs Theory
(OP)
Hi everybody,
I study on composite-composite scarf repairs and need theory of this repair type to understand better this application. Could you give me some references, please.
Thanks
I study on composite-composite scarf repairs and need theory of this repair type to understand better this application. Could you give me some references, please.
Thanks





RE: Composite Scarf Repairs Theory
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RE: Composite Scarf Repairs Theory
RE: Composite Scarf Repairs Theory
type: composite scarf repair
search returns lots of results
RE: Composite Scarf Repairs Theory
The theory behind scarf repairs is that if the scarf angle is sharp enough (about 1 in 30) the nasty "stress concentrations" represented by the shear stress peaks at the ends of a lap-joint could be virtually eliminated, giving a nearly uniform shear stress distribution. In practice, to avoid creep, the joint shear stress must be kept below the elastic limit. Given that such a large proportion of adhesive strength is derived from plastic behaviour, keeping the shear stress below the elastic limit for creep reasons means that the joint is not achieving full performance.
A further concern with scarf repairs is that the 1/30 scarf results in removal of substantial amounts of perfectly good structural material. If the structure was 0.5 inches thick, the repair would be 30 inches in diameter plus the size of the damage. You may want to grind out 30 inches of a structure but I certainly would not.
For thin composites, a lap repair can actually be stronger than the material. Hence the only reasons I would use a scarf repair would be 1. asthetics, 2. aerodynamic or clearance requirements on repair thickness or 3. stiffness restoration for stiffness critical structure.
RE: Composite Scarf Repairs Theory
RE: Composite Scarf Repairs Theory
That a well done splice at 25:1 or 27:1 is going to be better than a poorly done 50:1 splice.
Lately on thin skin carbon fiber structures SR Ms have done away with scarf joints in favor of a technique loosely translated as (Hammer scarfing)where the foam core of a wing skin is deformed to allow a lap joint repair without creating a bulge in a laminar wing profile.
B.E.
RE: Composite Scarf Repairs Theory
RE: Composite Scarf Repairs Theory