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STRINGER RUN-OUT

IP.com Disclosure Number: IPCOM000244548D
Publication Date: 2015-Dec-21
Document File: 5 page(s) / 272K

Publishing Venue

The IP.com Prior Art Database

Abstract

This disclosure relates to improve in the design of the Stringer Run-Outs (SRO) in the composite wing boxes.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 61% of the total text.

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STRINGER RUN-OUT

This disclosure relates to improve in the design of the Stringer Run-Outs (SRO) in the composite wing boxes.

Stringer Run-Out is a great design challenge in the composite wing box structures due to higher loads and the associated failure at the run-out due to high shear and peel off stress. The typical stress distributions and deformations are shown in the figure below.

Fig 1: Shear Stress Distribution

Fig 2: Peel Off Stress Distribution


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Fig 3: Deformation at the run-out; Shear & Peel Off Stress acting together (Mode I & II together)

Additionally there is web cracking phenomena happening due to bending and buckling of the web at the run-out. To reduce the above effects due to stress concentrations at the run-out, various design configurations have been advised in the prior literatures. Some of them are outlined below.

Fig 4: Ply Drop-Off in stringer foot and web


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Fig 5: Stringer Run-Out shape with Finger Plate

Fig 6: Addition of bolted run-out to reduce bending (peel off) load at the run-out


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Fig 7: Peel Off loads transferred by bolts; the bonding edge shifted to minimum bending moment location (US 20110164918 A1)

Fig 8: Ply substitution at SRO (Local stiffness reduction by reduction of 0 deg ply in stringer run- out) (US 20120308770 A1)

This idea is a similar addition to the prior inventions to reduce the stress concentration at the run-out. However, it locally changes the stress/load path in the wing skin a...