Manufacturing methods of net stiffeners

Patent metadata

Field	Value
Publication number	US-12384122-B2
Application number	US-202318365803-A
Country	US
Kind code	B2
Filing date	Aug 4, 2023
Priority date	Aug 9, 2022
Publication date	Aug 12, 2025
Grant date	Aug 12, 2025

Abstract

Method to make a T shaped stiffener form from a stiffener preform ( 100 ) having a foot ( 130 ) configured to be in contact with an aircraft panel, and a sole ( 120 ) with an edge ( 120 a ). The manufacturing method includes: obtaining laminates ( 110 a, 110 b ) formed of layers of composite material, folding the laminates ( 110 a, 110 b ) to be L shaped in cross section, joining the laminates to form a T shaped preform ( 100 ), molding the edge of the sole ( 120 a ) so that the edge is semicircular in cross section, applying to the edge ( 120 a ) a strip of semi-cured carbon fabric (L 1 ) and a fresh strip of prepreg fiberglass (L 2 ), and curing the preform ( 100 ) to obtain the stiffener.

First claim

The invention claimed is:

1. A manufacturing method to make a stiffener made of polymeric composite material reinforced with carbon fiber wherein the stiffer is T shaped in cross section and the stiffener is formed from a preform comprising a sole and a foot, the foot corresponds to a section of the stiffener configured to contact an aircraft panel, and the sole corresponds to a remaining part of the stiffener and includes an edge,
the manufacturing method comprises:
obtaining two laminates of the polymeric composite material each comprising a set of layers of the polymeric composite material;
shaping each of the two laminates of the polymeric composite material to be L shaped in cross section by applying a fold to each of the two laminates of polymeric composite material;
joining the two laminates of the polymeric composite material to form the preform with the T shaped cross section;
molding the edge of the sole of the preform to shape the edge to be semicircular in a cross section of the edge of the sole, wherein the molding the edge of the sole includes first molding the edge to obtain a wedge shaped cross section of the edge and second molding the edge with the wedge shaped cross section to form the semicircular cross section of the wedge;
applying to the edge of the sole a strip of semi-cured fiberglass and a fresh strip of prepreg fiberglass, and
curing the preform with the strip of the semi-cured fiberglass and the fresh strip of prepreg fiberglass to obtain the stiffener with the T shaped cross section.

2. The manufacturing method according to claim 1 , further comprising applying heat to the edge of the sole to soften a portion of the set of layers of the polymeric composite material.

3. The manufacturing method according to claim 1 , further comprising:
applying a flexible vacuum bag to the preform prior to the step of curing the preform; and
removing the flexible vacuum bag after the step of curing the preform.

4. A method comprising:
folding a first set of layers of a polymeric composite material reinforced with carbon fiber to form a first L shaped laminate including a first foot and a first sole joined to the first foot along a first fold wherein the first sole of the first L shape laminate includes a first back surface facing away from the first foot of the first L shaped laminate;
folding a second set of layers of a polymeric composite material reinforced with carbon fiber to form a second L shaped laminate including a second foot and a second sole joined to the second foot along a second fold wherein the second sole of the second L shape laminate includes a second back surface facing away from the second foot of the second L shaped laminate;
abutting the first back surface of the first L shaped laminate against the second back surface of the second L shaped laminate to form a stiffener preform that is T-shaped in cross section and includes a third foot formed of the first foot and the second foot and a third sole formed of the first sole and the second sole, wherein the third foot of the stiffener preform is configured to attach to a panel of an aircraft and the third sole of the stiffener preform has an edge opposite to the third foot of the stiffener preform;
molding the edge to form a molded edge of the third sole of the stiffener preform, wherein the molding includes shaping ends of the first set of layers and ends of the second set of layers at the edge of the third sole of the stiffener preform inward to close a gap between the ends of the first set of layers and the ends of the second set of layers, wherein the molding the edge of the third sole of the stiffener preform includes molding the edge to first form the edge into a wedge shaped cross section and then molding the edge to have a semicircular cross section;
applying to the molded edge of the third sole of the stiffener preform a strip of semi-cured fiberglass and a fresh strip of prepreg fiberglass, and
curing the stiffener preform with the strip of the semi-cured fiberglass and the fresh strip of prepreg fiberglass to form a stiffener having a T shaped cross section.

5. The method of claim 4 , wherein the ends of the first set of layers nearest a center plane of the third sole of the stiffener preform are shorter along a direction of the third sole than the ends of the first set of layers away from the center plane;
wherein the ends of the second set of layers are shorter nearest the center plane than the ends of the second set of layers away from the center plane; and
wherein the molding of the edge of the stiffener preform includes closing the gap such that at least one of the ends of the first set of layers and at least one of the ends of the second set of layers are bent towards the center plane.

6. The method of claim 4 , further comprising heating the edge of the third sole of the stiffener preform to soften the ends of the first set of layers and the ends of the second set of layers before or during the molding of the edge of the sole of the stiffener preform.

7. The method of claim 4 , further comprising:
applying a flexible vacuum bag to the stiffener preform prior to the curing of the stiffener preform; and
removing the flexible vacuum bag after the step of curing the preform.

8. A method comprising:
folding a first set of layers of a polymeric composite material reinforced with carbon fiber to form a first L shaped laminate including a first foot and a first sole joined to the first foot along a first fold wherein the first sole of the first L shape laminate includes a first back surface facing away from the first foot of the first L shaped laminate;
folding a second set of layers of a polymeric composite material reinforced with carbon fiber to form a second L shaped laminate including a second foot and a second sole joined to the second foot along a second fold wherein the second sole of the second L shape laminate includes a second back surface facing away from the second foot of the second L shaped laminate;
abutting the first back surface of the first L shaped laminate against the second back surface of the second L shaped laminate to form a stiffener preform that is T-shaped in cross section and includes a third foot formed of the first foot and the second foot and a third sole formed of the first sole and the second sole, wherein the third foot of the stiffener preform is configured to attach to a panel of an aircraft and the third sole of the stiffener preform has an edge opposite to the third foot of the stiffener preform;
molding the edge to form a molded edge of the third sole of the stiffener preform, wherein the molding includes shaping ends of the first set of layers and ends of the second set of layers at the edge of the third sole of the stiffener preform inward to close a gap between the ends of the first set of layers and the ends of the second set of layers, wherein the molding of the edge of the stiffener preform includes applying rollers to the edge to mold the edge to have a semi-circular cross section;
applying to the molded edge of the third sole of the stiffener preform a strip of semi-cured fiberglass and a fresh strip of prepreg fiberglass, and
curing the stiffener preform with the strip of the semi-cured fiberglass and the fresh strip of prepreg fiberglass to form a stiffener having a T shaped cross section.

Assignees

• Airbus Operations Slu

Inventors

• Miguez Charines Yolanda
• Colas Garcia Noelia
• Perez Pastor Augusto

Classifications

• B29K2105/0872

  Prepregs · CPC title

• B29K2307/04

  Carbon · CPC title

• B29L2031/003

  having a profiled transverse cross-section · CPC title

• Y02T50/40

  Weight reduction · CPC title

• B64C2001/0072

  from composite materials · CPC title