Attachment of aircraft ribs to spars having variable geometry

1. For use in an aircraft wing, a joint for attaching a rib to a tubular spar, the tubular spar having a cross sectional shape that deforms during flight, the joint comprising:

a ring substantially surrounding and attached to the tubular spar, wherein the ring extends around and engages substantially an entire circumference of the tubular spar; and

pivot pins extending substantially parallel to the tubular spar, connecting the ring with the rib, and allowing relative movement between the rib and the tubular spar as a cross-sectional shape of the tubular spar deforms, wherein the rib includes upper and lower gaps into which the ring and the tubular spar deform.

2. The joint of claim 1 , wherein the ring is compliant and is radially loaded against the tubular spar.

3. The joint of claim 1 , wherein the ring has a radial stiffness that is less than a radial stiffness of the tubular spar.

4. The joint of claim 1 , wherein:

the rib includes a forward portion and a rear portion, and

the pivot pins include a first pair of pivot pins pivotally connecting the ring with the forward portion of the rib, and a second pair of pivot pins pivotally connecting the ring with the rear portion of the rib.

5. The joint of claim 1 , wherein the ring includes:

first and second halves, and

splice joints joining the first and second halves together.

6. The joint of claim 1 , wherein:

the cross sectional shape deforms about points of inflection along a curvature of the tubular spar where the curvature changes, and

the pivot pins are respectively located substantially at the points of inflection.

7. The joint of claim 1 , wherein the ring includes:

first portions having a substantially U-shaped cross section, and

second portions having a substantially flat cross sectional shape.

8. The joint of claim 1 , wherein the ring is formed of a fiber reinforced polymer laminate.

9. A joint between a substantially non-deformable structure and a tubular member having a cross sectional shape that deforms about points of inflection along a curvature of the tubular member, comprising:

a ring extending substantially around a circumference of and attached to the tubular member, wherein the ring extends around and engages substantially an entirety of the circumference of the tubular member; and

pivot pins extending substantially parallel to the tubular member and connecting the ring with the non-deformable structure respectively at the points of inflection, wherein the tubular member includes upper and lower gaps into which the ring and the tubular member deform.

10. The joint of claim 9 , wherein:

the ring is compliant and is radially loaded against the tubular member substantially around the entirety of the circumference of the tubular member, and

the ring is configured to remain compliant to the tubular member as the tubular member deforms.

11. The joint of claim 9 , wherein the ring includes:

a first portion having a substantially U-shaped cross section, and

a second portion includes a substantially flat strap.

12. The joint of claim 9 , further comprising:

webs on the non-deformable structure, and

wherein the pivot pins are respectively attached to the webs.

13. The joint of claim 9 , wherein the ring is formed from a fiber reinforced polymer laminate.

14. The joint of claim 9 , wherein:

the ring is in tension and is loaded against the tubular member by the tension, and

the ring is sufficiently compliant to change shape as the cross sectional shape of the tubular member deforms.

15. A method of attaching an aircraft wing rib to a tubular spar having a cross sectional shape that deforms during flight, comprising:

placing a ring around the tubular spar, wherein the ring extends around and engages substantially an entire circumference of the tubular spar;

loading the ring against the tubular spar; and

pivotally connecting the ring to the rib, wherein pivotally connecting the ring to the rib includes locating pivotal pins in the rib and the tubular spar such that the pivotal pins extend substantially parallel to the tubular spar, and wherein the rib includes upper and lower gaps into which the ring and the tubular spar deform.

16. The method of claim 15 , wherein loading of the ring against the tubular spar includes tensioning the ring.

17. The method of claim 15 , wherein pivotally connecting the ring to the rib includes locating the pivotal pins between the rib and the tubular spar at points of inflection along a curvature of the tubular spar.

18. The method of claim 15 , wherein placing the ring around the tubular spar includes:

placing two ring halves around the tubular spar, and

splicing the ring halves together.

19. The method of claim 15 , further comprising:

placing webs on the rib, and

wherein pivotally connecting the ring to the rib is performed by pivotally connecting the ring to each of the webs.