Systems and methods for stretch-forming multi-thickness composite skins

Patent metadata

Field	Value
Publication number	US-9370922-B1
Application number	US-201414218661-A
Country	US
Kind code	B1
Filing date	Mar 18, 2014
Priority date	Mar 18, 2014
Publication date	Jun 21, 2016
Grant date	Jun 21, 2016

Abstract

Systems and methods for stretch-forming multi-thickness composite skins are disclosed herein. The methods include locating a flexible support structure in a transition region that is defined by a charge of composite material and applying a vacuum to an interface between the charge of composite material and the flexible support structure to define a charge-support assembly. The methods also include separating the charge-support assembly from the layup surface and locating the charge-support assembly on a cure surface of a layup mandrel. The methods further include deforming the charge-support assembly on the cure surface to generate a conformed charge of composite material, releasing the vacuum, and separating the flexible support structure from conformed charge of composite material. The systems include systems that are configured to perform the methods.

First claim

The invention claimed is:

1. A method of forming a non-planar skin surface contour of a skin for a composite structure, wherein the skin for the composite structure is formed from a charge of composite material that is defined by a plurality of stacked plies of composite material, wherein the charge of composite material defines a first region that has a first number of stacked plies and a first thickness, and a second region that has a second number of stacked plies and a second thickness that is greater than the first thickness, and further wherein the first region and the second region define a transition region therebetween, the method comprising:
locating a flexible support structure in the transition region such that the charge of composite material extends between the flexible support structure and a layup surface that supports the charge of composite material, wherein the flexible support structure includes a support surface that defines a support surface profile, wherein, prior to the locating the flexible support structure, the charge of composite material defines an exposed surface that defines a non-planar exposed surface profile, wherein the support surface profile corresponds to the non-planar exposed surface profile, and further wherein the locating the flexible support structure includes locating such that the support surface conforms to the exposed surface;
applying a vacuum to an interface between the charge of composite material and the flexible support structure to temporarily define a charge-support assembly;
during the applying, separating the charge-support assembly from the layup surface;
locating the charge-support assembly on a cure surface of a layup mandrel, wherein the cure surface defines a non-planar cure surface contour;
deforming the charge-support assembly to conform the charge of composite material to the non-planar cure surface contour and generate a conformed charge of composite material that defines the non-planar skin surface contour;
releasing the vacuum; and
separating the flexible support structure from the conformed charge of composite material while retaining the conformed charge of composite material on the cure surface.

2. The method of claim 1 , wherein the method further includes locating a flexible vacuum chuck such that the flexible support structure extends between the flexible vacuum chuck and the charge of composite material, wherein the applying the vacuum includes applying the vacuum with the flexible vacuum chuck.

3. The method of claim 2 , wherein the flexible vacuum chuck includes a selective stiffening element, wherein the method includes engaging the selective stiffening element to resist deformation of the charge-support assembly prior to the locating, and further wherein the method includes disengaging the selective stiffening element to permit the deforming.

4. The method of claim 2 , wherein the deforming includes deforming the flexible vacuum chuck concurrently with deforming the charge-support assembly.

5. The method of claim 1 , wherein the method further includes laying up a plurality of plies of composite material on the layup surface to generate the plurality of stacked plies that defines the charge of composite material, wherein the laying up comprises:
defining the first region of the charge of composite material; and
defining the second region of the charge of composite material.

6. The method of claim 5 , wherein the layup surface is a substantially planar layup surface, and further wherein the laying up the plurality of plies of composite material includes laying up on the substantially planar layup surface.

7. The method of claim 5 , wherein the laying up includes laying up such that the charge of composite material includes a first plurality of plies of composite material that extends within both the first region and the second region and a second plurality of plies of composite material that extends within the second region but not within the first region.

8. The method of claim 7 , wherein the second plurality of plies of composite material includes a plurality of edges that defines the transition region.

9. The method of claim 1 , wherein the deforming includes maintaining, with the flexible support structure, the charge of composite material in tension in a direction that is parallel to an interface between a first stacked ply of the plurality of stacked plies and a second stacked ply of the plurality of stacked plies.

10. The method of claim 9 , wherein the maintaining includes locating the charge of composite material on a convex side of the charge-support assembly during the deforming.

11. The method of claim 9 , wherein the maintaining includes at least one of:
(i) maintaining the charge of composite material completely in tension;
(ii) maintaining the charge of composite material in tension across an entire thickness of the charge of composite material; and
(iii) maintaining at least a threshold fraction of a total volume of the charge of composite material in tension, wherein the threshold fraction of the total volume includes at least 80% of the total volume.

12. The method of claim 1 , wherein the deforming includes resisting, with the flexible support structure, a relative motion among the plurality of stacked plies in the direction that is parallel to the interface.

13. The method of claim 12 , wherein the resisting the relative motion includes at least one of pressing against the transition region with the flexible support structure during the deforming and compressing at least a portion of the transition region with the flexible support structure during the deforming.

14. The method of claim 1 , wherein the applying the vacuum includes applying the vacuum through the flexible support structure to the interface between the charge of composite material and the flexible support structure.

15. The method of claim 1 , wherein the method further includes curing the conformed charge of composite material to form the skin for the composite structure subsequent to the separating the flexible support structure from the conformed charge of composite material, and further wherein the method includes separating the skin of the composite structure from the cure surface.

16. A method of forming a non-planar skin surface contour of a skin for a composite structure, wherein the skin for the composite structure is formed from a charge of composite material that is defined by a plurality of stacked plies of composite material, wherein the charge of composite material defines a first region that has a first number of stacked plies and a first thickness, and a second region that has a second number of stacked plies and a second thickness that is greater than the first thickness, and further wherein the first region and the second region define a transition region therebetween, the method comprising:
locating a flexible support structure in the transition region such that the charge of composite material extends between the flexible support structure and a layup surface that supports the charge of composite material;
applying a vacuum to an interface between the charge of composite material and the flexible support structure to temporarily define a charge-support assembly;
during the applying, separating the charge-support assembly from the layup surface;
locating the charge-support assembly on a cure surface of a layup mandrel;
deforming the charge-support assembly to conform the charge of composite material to a non-planar cure surface contour and generate a conformed charge of composite material that defines the non-pl

Assignees

• Boeing Co

Inventors

• Metschan Stephen Lee
• Phillips Richard V
• Withrow Bryan Joseph
• Kroeger Lee Michael
• Stewart Samuel Ray

Classifications

• B29C70/44 Primary

  using isostatic pressure, e.g. pressure difference-moulding, vacuum bag-moulding, autoclave-moulding or expanding rubber-moulding · CPC title

• B32B37/18 Primary

  involving the assembly of discrete sheets or panels only · CPC title

• B29C70/541

  Positioning reinforcements in a mould, e.g. using clamping means for the reinforcement (positioning inserts in moulds B29C33/12; lay-up on a mould B29C70/30) · CPC title

• B29C70/543 Primary

  Fixing the position or configuration of fibrous reinforcements before or during moulding (for non-woven fabrics D04H3/08) · CPC title

• B29C70/38

  Automated lay-up, e.g. using robots, laying filaments according to predetermined patterns {(application heads for tyres B29D30/28)} · CPC title