Problem Statement:Individual Project 1
Design Objective:
A FEM study has been made to determine internal loads
for an aircraft design subjected to specified design loads.
A lumped-mass estimate was made of the loads
on stringer-skin segments on the wing upper surface.
The critical stiffened panel is indicated in the
sketch above.
The stringers carry through the ribs but are
firmly attached with fasteners to the rib chords
The skin, too is fastened to the ribs.
The 3 concepts for stringers, sketched above,
have been presented for study.
Weight reduction and assembly effort are of primary importance.
No skin wrinkling is allowed
Design Requirements:
Design the critical stiffened panel concept assigned to you for
- rivet (center-to-center) spacing along stringer
- distance between ribs
- shape and dimensions of stringer
Fixed Constraints:
- Design (ultimate) span-wise load on stringer-skin segment = 30.2 kip
- Design (ultimate) shear load chordwise on skin between stringers = 1.94 kip
- Lumped skin/stringer area = 1.205 sq. in.
- Stringer thickness = .096 in.
- Skin thickness = .160 in.
- Stringer (center-to-center) spacing 5.0 inches
- Stringers: formed from 7075-T6-T3 aluminum alloy sheet
- Rivets: 2017-T3 aluminum, 100 degree flush-head, solid, machine-countersunk
- Skin: 2024-T3 aluminum alloy sheet