Ply blending and stacking sequence

• US 10,315,783 B2
• Filed: 08/26/2015
• Issued: 06/11/2019
• Est. Priority Date: 08/26/2015
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Blom, Adriana Willempje, Kang, Laura Sumi, Epton, Michael Andrew
• Primary Examiner(s): Nguyen, Vanthu T
• Application Number:
  US14/836,333
• Publication Number:
  US 20170057666A1
• Time in Patent Office: 1,385 Days
• CPC Class Codes: B64F 5/10 Manufacturing or assembling aircraft, e.g. jigs therefor
• CPC Class Codes: G06F 2113/26 Composites
• CPC Class Codes: G06F 2113/28 Fuselage, exterior or interior
• CPC Class Codes: G06F 30/15 Vehicle, aircraft or watercraft design
• CPC Class Codes: Y02T 90/00 Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation

Abstract

A method and apparatus for ply blending. A desired thickness and a desired stiffness distribution for a composite structure are received. A model of the composite structure is split into a plurality of panels. Lamination parameters and a quantity of plies for each panel of the plurality of panels are determined using the desired thickness and the desired stiffness distribution for the composite structure. Ply shapes for each ply of the plurality of panels are determined using an objective function. A fiber angle is determined for each ply of the plurality of panels. Each ply of a first half of a panel of the plurality of panels has a different fiber angle value than each other ply of the first half of the panel.

Claims

1. A method of manufacturing a composite structure, wherein the composite structure is a non-traditional laminate structure having a stiffness equal to a desired stiffness of a traditional composite laminate part, wherein the non-traditional laminate structure has at least one ply with a fiber angle other than 0°

, 90°

or ±

45°

, the method comprising;

receiving a desired thickness and a desired stiffness distribution for the composite structure;

splitting a model of the composite structure into a plurality of panels;

determining a set of lamination parameters and a quantity of plies for each panel of the plurality of panels using the desired thickness and the desired stiffness distribution for the composite structure, wherein the lamination parameters are non-dimensional parameters that together with the desired thickness and material invariants describe a laminate stiffness matrix independent of the quantity of plies;

determining ply shapes for each ply of the plurality of panels using an objective function;

determining a fiber angle for the each ply of the plurality of panels, such that the model of the composite structure has a stiffness equal to the desired stiffness distribution; and

laying up composite material according to the model with determined ply shapes and determined fiber angles to form the composite structure, wherein the composite structure has the stiffness equal to the desired stiffness distribution.

2. The method of claim 1, wherein each ply of a first half of a panel of the plurality of panels has a different fiber angle value than each other ply of the first half of the panel.

3. The method of claim 1 further comprising:

arranging the plies according to stacking sequence rules to form a ply arrangement.

4. The method of claim 3, wherein the stacking sequence rules include at least one of symmetry, separation of the plies with fiber angles with more than a 45 degree difference, or avoidance of ply clusters.

5. The method of claim 1 further comprising:

grouping panels of the plurality of panels with a same quantity of plies and a same set of lamination parameters to form a plurality of groups, wherein each panel of a group of the plurality of groups has a same layup.

6. The method of claim 5 further comprising:

creating a plurality of ply sequences for the plurality of groups, wherein each of the plurality of ply sequences represents at least one ply in the composite structure.

7. The method of claim 6, wherein determining ply shapes for the each ply of the plurality of panels comprises minimizing a total length of a ply boundary over all of the plurality of groups.

8. The method of claim 6, wherein determining a fiber angle for the each ply of the plurality of panels comprises:

generating equations for the set of lamination parameters for each group of the plurality of groups;

combining the equations for the each group of the plurality of groups into a system; and

solving for a plurality of angle variables in the system.

9. The method of claim 8, wherein the system is underdetermined and multiple solutions are possible, further comprising:

selecting one of the multiple solutions based on at least one of a desirable stacking sequence or matching fiber angles with the ply shapes.

10. The method of claim 8, wherein a quantity of the plurality of ply sequences is equal to at least a quantity of the plurality of groups times a quantity of lamination parameters in the set of lamination parameters.

11. The method of claim 8, wherein a quantity of the plurality of ply sequences is chosen such that for any two groups in the plurality of groups with a thickness difference of fewer plies than a quantity of lamination parameters in the set of lamination parameters, there are at least a quantity of ply sequences equal to the quantity of lamination parameters in the set of lamination parameters in which the two groups have different ply present or absent states.

12. The method of claim 1, wherein determining ply shapes for the each ply of the plurality of panels comprises:

maximizing a connection quantity over all of the plurality of panels, wherein a connection is a common ply between two adjacent panels of the plurality of panels, and wherein a connection quantity is a sum of connections.

13. The method of claim 1, wherein determining ply shapes for the each ply of the plurality of panels comprises:

limiting a quantity of plies with a same geometry to less than a quantity of lamination parameters.

14. The method of claim 1, wherein a first panel and a second panel of the plurality of panels have a different number of plies.

24. The method of claim 1, wherein the set of lamination parameters comprises twelve lamination parameters:

(V_1A, V_2A, V_3A, V_4A), (V_1B, V_2B, V_3B, V_4B), and (V_1D, V_2D, V_3D, V_4D) which are defined by equations;

25. The method of claim 1, wherein (U₁, U₂, U₃, U₄, and U₅) are the material invariants that depend only on ply material properties and are defined as follows:

U₁=(3*Q₁₁+3*Q₂₂+2Q₁₂+4Q₆₆)/8

U₂=(Q₁₁−

Q₂₂)/2

U₃=(Q₁₁+Q₂₂−

2Q₁₂−

4Q₆₆)/8

U₄=(Q₁₁+Q₂₂+6Q₁₂−

4Q₆₆)/8

U₅=(Q₁₁+Q₂₂−

2Q₁₂+⁴Q₆₆)/8

26. The method of claim 1, wherein a relationship between normalized lamination parameters, thickness, and stiffness matrices A, B, D is given by equations:

15. A method of manufacturing a composite structure, wherein the composite structure is a non-traditional laminate structure having a stiffness equal to a desired stiffness of a traditional composite laminate part, wherein the non-traditional laminate structure has at least one ply with a fiber angle other than 0°

, 90°

or ±

45°

, the method comprising;

receiving a desired thickness and a desired stiffness distribution for the composite structure;

splitting a model of the composite structure into a plurality of panels;

determining a set of lamination parameters and a quantity of plies for each panel of the plurality of panels using the desired thickness and the desired stiffness distribution for the composite structure;

determining ply shapes for each ply of the plurality of panels using an objective function, wherein determining the ply shapes for each ply of the plurality of panels using the objective function comprises;

grouping panels of the plurality of panels with a same quantity of plies and same set of lamination parameters to form a plurality of groups, wherein each panel of a group of the plurality of groups has a same layup; and

creating a plurality of ply sequences for the plurality of groups, wherein each of the plurality of ply sequences represents at least one ply for at least one panel in the plurality of panels;

determining a fiber angle for each ply of the plurality of panels, wherein determining a fiber angle for each ply of the plurality of panels comprises;

generating equations for the set of lamination parameters for each group of the plurality of groups;

combining the equations for each group of the plurality of groups into a system; and

solving for a plurality of angle variables in the system; and

laying up composite material to form each of the plurality of panels having a determined quantity of plies and determined fiber angle, wherein forming each of the plurality of panels forms the composite structure, wherein the composite structure has the stiffness equal to the desired stiffness distribution.

16. The method of claim 15, wherein a quantity of the plurality of ply sequences is equal to at least a quantity of the plurality of groups times a quantity of lamination parameters in the set of lamination parameters.

17. The method of claim 16, wherein a quantity of the plurality of ply sequences is chosen such that for any two groups in the plurality of groups with a thickness difference of fewer plies than a quantity of lamination parameters in the set of lamination parameters, there are at least a quantity of ply sequences equal to a quantity of lamination parameters in the set of lamination parameters in which the two groups have different ply present or absent states.

18. The method of claim 15, wherein the system is underdetermined and multiple solutions are possible, further comprising:

selecting one of the multiple solutions based on at least one of a desirable stacking sequence or matching fiber angles with the ply shapes.

19. The method of claim 15, wherein determining ply shapes for the each ply of the plurality of panels comprises:

maximizing a connection quantity over all of the plurality of groups, wherein a connection is a common ply between two adjacent panels of the plurality of panels, and wherein a connection quantity is a sum of connections.

20. The method of claim 15, wherein determining ply shapes for the each ply of the plurality of panels comprises:

limiting a quantity of plies with a same geometry to less than a quantity of lamination parameters.

21. A method for forming a composite structure, wherein the composite structure is a non-traditional laminate structure having a stiffness equal to a desired stiffness of a traditional composite laminate part, wherein the non-traditional laminate structure has at least one ply with a fiber angle other than 0°

, 90°

or ±

45°

, the method comprising;

receiving a desired thickness and a desired stiffness distribution for the composite structure;

splitting a model of the composite structure into a plurality of panels;

determining a set of lamination parameters and a quantity of plies for each panel of the plurality of panels using the desired thickness and the desired stiffness distribution for the composite structure, wherein the lamination parameters are non-dimensional parameters that together with the desired thickness and material invariants describe a laminate stiffness matrix independent of the quantity of plies;

determining ply shapes for each ply of the plurality of panels using an objective function;

determining a fiber angle for each ply of the plurality of panels;

arranging the plies according to stacking sequence rules to form a ply arrangement, wherein the stacking sequence rules include at least one of symmetry, separation of plies with fiber angles with more than a 45 degrees difference, or avoidance of ply clusters; and

laying up composite material according to the ply arrangement to form the composite structure, wherein the composite structure has the stiffness equal to the desired stiffness distribution.

22. The method of claim 21, wherein determining ply shapes for the each ply of the plurality of panels using an objective function comprises:

grouping panels of the plurality of panels with a same quantity of plies and same set of lamination parameters to form a plurality of groups, wherein each panel of a group of the plurality of groups has a same layup;

creating a plurality of ply sequences for the plurality of groups, wherein each of the plurality of ply sequences represents at least one ply in the plurality of panels; and

determining a ply shape for each ply of the plurality of ply sequences.

23. The method of claim 22, wherein determining the fiber angle for the each ply of the plurality of panels comprises:

generating equations for the set of lamination parameters for each group of the plurality of groups;

combining the equations for the each group of the plurality of groups into a system; and

solving for a plurality of angle variables in the system.