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L Bracket joining 2 carbon composite panels
4

L Bracket joining 2 carbon composite panels

L Bracket joining 2 carbon composite panels

(OP)
Just wanted to check what are the views of you guys who has experience of two composite panels in pressure deck area with L bracket which can be metallic or of composite.I wanted to check which will be more useful or valuable to the design and construction ?
I have attached picture for same.

Please do let me know your opinion.

RE: L Bracket joining 2 carbon composite panels

is the dark blue panel the pressure skin, and the light blue just an interior panel (with pressure on both sides) ?

a formed angle looks better at accomodating the rotation dispalcement expected if both panels are pressure skins. if the dark blue is the only pressure skin then there would tend to be more of a tension load on the angle (as the dark blue would displace away from the light blue) ... offset so a little bending introduced.

but (of course) the angles main job is to transfer shear from one panel to the other.

RE: L Bracket joining 2 carbon composite panels

(OP)
Yes,dark blue panel is the pressure skin and the light blue just an interior panel with pressure on both side.I was wondering whether using composite L section would be any better than metallic L bracket,though the cost to repair composite panel can be higher in future.
Please do let me know your thoughts.
 

RE: L Bracket joining 2 carbon composite panels

composite (carbon) would be easier with compatability issues, harder in designing the stiffness/lay-up properly ... i'd put longitudinal (0deg) plies on the outside surfaces, and 90deg plies on the inside.

Aluminium would be easier and cheaper to form, but would have to be isolated from the carbon.

RE: L Bracket joining 2 carbon composite panels

rb is right.  I'd just add a ply or two of fiberglass at the angle contact areas and form it from aluminum.

RE: L Bracket joining 2 carbon composite panels

The angle is likely to see moments in the radius.  Composites typically have crummy (low) interlaminar properties (strength and stiffness), and a moment will result in radial (interlaminar) tensile stresses.  Make the angle out of metal and design in the appropriate isolation (such as fiberglass plies on the composite surfaces)

RE: L Bracket joining 2 carbon composite panels

Concur with SW. Your can try for a composite angle, but it usually winds up heavier than an Al one (and more expensive). This is especially true if the angle has to be able to work after receiving an impact to the corner area. A sole exception might be if the angle only ever sees loading which tries to 'close' it, putting the corner into through-thickness compression.
 

RE: L Bracket joining 2 carbon composite panels

For the noted application ave You considered adhesive-bonded* titanium** [good strength, weight savings]; or adhesive bonded* PH CRES** [simplicity, possibly higher strength than Ti]?


* plus fasteners at metallic frames and fittings
**machined or formed, each has advantages

Regards, Wil Taylor

RE: L Bracket joining 2 carbon composite panels

(OP)
Hello ,
I am doing analysis for L Bracket connected to pressure deck at bottom(blue color) and T Section adjacent to it on pressure deck as L Bracket connected to skin on sideward.
Any idea of approach for this analysis I should focus on.
Please advise.Picture is in the first posting attached.

RE: L Bracket joining 2 carbon composite panels

Do you have the internal loads for the L bracket? If so, please post a free body diagram for each critical load case - then we can advise analysis approaches.

RE: L Bracket joining 2 carbon composite panels

Free
Body
Diagram
??

ie, a cross-section picture of the part with all loads for a given load case shown on it.

not a dump of numbers from a FEM

 

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