Composite stiffener

Patent metadata

Field	Value
Publication number	US-11241851-B2
Application number	US-202016798860-A
Country	US
Kind code	B2
Filing date	Feb 24, 2020
Priority date	Mar 1, 2019
Publication date	Feb 8, 2022
Grant date	Feb 8, 2022

Abstract

A composite stiffener for a stiffener reinforced panel is disclosed. The stiffener has a longitudinal direction and a run-out region which terminates at an end of the stiffener. The stiffener also has a constant section region inboard of the run-out region in the longitudinal direction and having a constant cross section transverse to the longitudinal direction with a crown between adjacent foot portions. The run-out region has a changing cross section transverse to the longitudinal direction with a crown between adjacent foot portions and the crown reduces in height towards the end of the stiffener forming a ramp. The composite stiffener includes a number of blankets of non-crimp fabric layers.

First claim

The invention claimed is:

1. A composite stiffener for a stiffener reinforced panel, wherein the stiffener has a longitudinal direction and a run-out region which terminates at an end of the stiffener, and a constant section region inboard of the run-out region in the longitudinal direction and having a constant cross section transverse to the longitudinal direction with a crown between adjacent foot portions,
wherein the run-out region has a changing cross section transverse to the longitudinal direction with a crown between adjacent foot portions and the crown reduces in height towards the end of the stiffener forming a ramp,
the composite stiffener comprises a plurality of blankets of non-crimp fabric layers, and a transition region between the constant section region and the run-out region, wherein the constant section region has a plurality of blankets of non-crimp fabric layers sandwiched between woven fabric layers, and at least one of the blankets of non-crimp fabric layers is terminated in the transition region.

2. A composite stiffener according to claim 1 , wherein the run-out region comprises one or more woven fabric layers.

3. A composite stiffener according to claim 2 , wherein the one or more woven fabric layers extends from a top of the ramp to a bottom of the ramp.

4. A stiffener according to claim 1 , wherein all of the blankets of non-crimp fabric layers in the constant section region are terminated in the transition region.

5. A stiffener according to claim 1 , wherein the run-out region includes the woven fabric layers and no non-crimp fabric blankets.

6. A stiffener according to claim 1 , wherein the run-out region has a ramped portion including the ramp, and a substantially planar toe portion between the ramp and the end of the stiffener.

7. A stiffener according to claim 1 , wherein each of the blankets of non-crimp fabric layers include a first layer having a 0 degree fibre orientation aligned with the stiffener longitudinal direction and a second layer having a fibre orientation not aligned with the stiffener longitudinal direction.

8. A stiffener according to claim 1 , wherein the run-out region includes one or more of the non-crimp fabric blankets.

9. A stiffener according to claim 8 , wherein the blanket has a dart cut out and overlaps itself in the run-out region.

10. A stiffener according to claim 1 , wherein the constant section region has an omega section.

11. A stiffener according to claim 1 , wherein the constant section region has a cross section with continuous layers extending through the crown and the adjacent foot portions.

12. A stiffener according to claim 1 , comprising carbon fibre composite material.

13. An aircraft structure including a panel reinforced with a composite stringer having a longitudinal direction and a run-out region which terminates at an end of the stringer, and a constant section region inboard of the run-out region in the longitudinal direction and having a constant cross section transverse to the longitudinal direction with a crown between adjacent foot portions,
wherein the run-out region has a changing cross section transverse to the longitudinal direction with a crown between adjacent foot portions and the crown reduces in height towards the end of the stringer forming a ramp,
wherein the stringer comprises a plurality of blankets of non-crimp fabric layers, and a transition region between the constant section region and the run-out region, wherein the constant section region has a plurality of blankets of non-crimp fabric layers sandwiched between woven fabric layers, and at least one of the blankets of non-crimp fabric layers is terminated in the transition region.

14. A method of manufacturing a stiffener, wherein the stiffener has a longitudinal direction with a run-out region at an end of the stiffener, a constant section region inboard of the end in the longitudinal direction and having a cross section with a crown between adjacent foot portions, wherein the run-out region has a changing cross section with a crown between adjacent foot portions and the crown reduces in height towards the end of the stiffener forming a ramp, and a transition region between the constant section region and the run-out region, wherein the method comprises laying up a plurality of blankets of non-crimp fabric layers and a plurality of woven fabric layers as dry fabrics on a mould tool, wherein the plurality of blankets of non-crimp fabric layers are sandwiched between woven fabric layers in the constant section region, cutting at least one of the blankets of non-crimp fabric layers so that the blanket is terminated in the transition region, and co-infusing the dry fabrics with resin followed by co-curing to form the stiffener.

15. A method according to claim 14 , further comprising cutting all of the blankets of non-crimp fabric layers so that all of the blankets are terminated in the transition region.

16. A method according to claim 14 , wherein the run-out region includes the woven fabric layers and no non-crimp fabric blankets.

17. A method according to claim 14 , further comprising laying up the plurality of woven fabric layers on a portion of the mould tool to define the shape of the ramp in the run-out region followed by the co-curing step without an intermediate step of cutting the woven fabric layers laid up on the mould tool.

Assignees

• Airbus Operations Ltd

Inventors

• Zhang Junwei
• Gaitonde Martin
• Bonaventura Joshua
• Woolcock John Norman

Classifications

• B29C70/207 Primary

  arranged in parallel planes of fibres crossing at substantial angles · CPC title

• B29C70/302

  Details of the edges of fibre composites, e.g. edge finishing or means to avoid delamination · CPC title

• B29D99/001

  Producing wall or panel-like structures, e.g. for hulls, fuselages, or buildings (articles with hollow walls B29D24/00) · CPC title

• B64C3/182

  Stringers, longerons · CPC title

• B29C70/085

  the structure being deformed in a three dimensional configuration (B29C53/805 takes precedence) · CPC title