L Bracket joining 2 carbon composite panels 4

[Kakalip]

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.

 

[Kakalip]

Another picture of L bracket attached joining composite panels
Please do let me know your views.

 

[rb1957]

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.

 

[Kakalip]

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.

 

[rb1957]

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.

 

[bf109g]

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

 

[SWComposites]

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)

 

[clivesinger]

You might find this interesting:

http://www.mathiverse.com/forum

 

[RPstress]

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.

 

[WKTaylor]

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

 

[Kakalip]

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.

 

[SWComposites]

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.

 

[Kakalip]

Please find one of internal load for STA 1281

 

[Kakalip]

Please find one of internal load for STA 1257

 

[Kakalip]

Please find one of internal load for STA 1305

 

[Kakalip]

Please find one of internal load for STA 1233

 

[SWComposites]

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

 

[Kakalip]

This is how the cross section looks like fitted at bottom with pressure deck and L section attached to skin on sides.Yet to scan Freebody diagram for same.

 

[Kakalip]

Critical pressure deck fitting loads are as attached

 

[Kakalip]

Free Body of L Section