It was noted that it's difficult ( referred to DIY structures of course... not for a commercial aircraft where it's common) to layup UD in the shear web... not in spar caps, where it would be preferable ( for the reasons explained above).
Also for homebuilts to check for buckling is mandatory...
I think that the use of ud tape for caps is more appropriate than fabric. Uni- has no kinks as happens with warp and weft of fabric, so more alligned fiber, better fiber volume fraction and higher strenght.
The value of E1=70 GPa that you cite, if referred to fabrics , seems too high. Anyway...
Maybe I will misunderstand again, but are you saying that the caps ( that is the section of the beam wich resists tension and compression), are made with woven fabric oriented at 0/90 along the spar axis ?
The fact that you have different moduli in two direction doesn't explain why the cap's...
L.L = limit load
U.L. = ultimate load = 1.5*L.L
For composite construction additional safety factors must be taken in account based on surfaces color, and in case of static tests executed or not at high temperature. Therefore 150% could not be the ultimte load.
It sounds strange that upper...
For a one-seat homebuilt, designed according to EAA,ASTM-LSA, BCAR, or LTF rules ( I strongly suggest you to take a look at them..), you will find that a conservative design ( from shear strenght viewpoint at ultimate load) for shear web of a wing supposed cantilever type, will give you 4 layers...
Hi,
although your final application is not clear ( rc model, homebuilt airplane,...??) , SWcomposites's advice holds in general.
Your spar web will be loaded in shear ( then +-45° fabric) and spar caps ( located where..?) will be loaded in tension/ compression.
It's is good practice (...
Never change temperature during infusion, start the process at the temperature held possibily constant at the value prescribed by the technical sheet (generally T>15°C )
Slow down the resin flow close to vacuum line placing the vacuum tubing at 50-60 mm from the laminate edge ( dont' place it...
What's that Soric for ? Is it intended as flow media ? If yes ,remove it. 6 layer can be easily infused with a normal flow media meshe available in different size an permeability.Of course your resin is intended for infusion and not for hand layup
Then, starting from the mould:
- mold release
-...
SW,
- I didn't use the fem to determine G modulus;I used it only to check the angle of torsion; I compared this value with that obtained from two hand calculation where I used the G moduli obtained from a66 (G_membranal)first and b66 (G_bending) then.
-"you do not have a case of pure...
Hi Brian,
thank you for your quick reply.
I did the same, and I reached the same conclusion ( laminate is symmetric and balanced). After some hand calculation and some runs on ABD matrix, I run a simple case on fem; cross-checking all procedures I saw that, effectively, d66 terms influence G...
Hi all,
a response to the following general problem would be appreciated very much.
I have a rectangular plate made of n plies , its section is rectangular . Long edges aligned with x axis, short ones with y axis
It is constrained (built in) at its left edge, free on other edges; pure torque...
...."Can someone advice me on the subject."...
"Simple" request for a (very) difficult answer in one or more posts..!
Just to start ...look at NASA Reference Publication 1351 titled " Basic mechanics of laminated composite plates"; you find it on internet.
Hope it will be useful.
Cpinz
