Othman
Well-Known Member
I need a sanity check on wing skin to spar interface, so I'm looking for some second opinions.
The attached figure shows the upper end of a cross-section of the main spar at the wing root. The spar is built-up from a thin web with aluminum bar chords (caps) on either side of the web. Since it is impossible to attach the skin to the spar as it is, I've attached a couple of additional formed angles to connect the spar to the skin, sort of like having a bent flange in the web. SInce I want the skin to have a butt joint, I used two angles instead of one.
Part of me says that this is an acceptable method to transfer the loads provided that the angles are sized to take the spanwise shear flow... and bending stress since they are at the extremities of the beam (I hope not have them carry much bending by making them discontinuous along the span... although I need to verify the relative stiffness between the main load bearing part of the spar and the added angles to avoid introducing stress concentrations).
When I look at the torsion side of things, I get the feeling that this arrangement may be less than adequate, depending on the stiffness of the back-to-back angles. Then again the ribs should transfer the torsional loads.
Thanks in advance to anyone who can share some insite on this matter.
Ashraf
The attached figure shows the upper end of a cross-section of the main spar at the wing root. The spar is built-up from a thin web with aluminum bar chords (caps) on either side of the web. Since it is impossible to attach the skin to the spar as it is, I've attached a couple of additional formed angles to connect the spar to the skin, sort of like having a bent flange in the web. SInce I want the skin to have a butt joint, I used two angles instead of one.
Part of me says that this is an acceptable method to transfer the loads provided that the angles are sized to take the spanwise shear flow... and bending stress since they are at the extremities of the beam (I hope not have them carry much bending by making them discontinuous along the span... although I need to verify the relative stiffness between the main load bearing part of the spar and the added angles to avoid introducing stress concentrations).
When I look at the torsion side of things, I get the feeling that this arrangement may be less than adequate, depending on the stiffness of the back-to-back angles. Then again the ribs should transfer the torsional loads.
Thanks in advance to anyone who can share some insite on this matter.
Ashraf
