System and method for designing composite laminates using lamination parameters

• US 10,140,388 B1
• Filed: 11/16/2014
• Issued: 11/27/2018
• Est. Priority Date: 11/16/2014
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: Rassaian, Mostafa, Balabanov, Vladimir, Wu, Yuan-Jye, Tat, Hong, Weckner, Olaf
• Primary Examiner(s): Craig, Dwin M
• Application Number:
  US14/542,626
• Time in Patent Office: 1,472 Days
• Field of Search: 703 1
• CPC Class Codes: G06F 2113/26 Composites
• CPC Class Codes: G06F 30/23 using finite element methods [FEM] or finite difference methods [FDM]

Abstract

A method of generating an optimized design model for a composite laminate may include computing a normalized set of lamination parameters and laminate stiffness matrices of an initial laminate design, and determining, using an optimizer operating on a finite element model, optimum values for the lamination parameters and the laminate thickness. The method may further include adjusting the optimum value of the laminate thickness, and performing an inversion process extracting multiple solutions from the lamination parameters, each solution including a unique set of individual fiber angles for each ply and representing an optimized design model of the composite laminate.

Claims

1. A method of manufacturing a composite laminate, comprising:

performing steps (a) through (h) in a finite element analysis program executed by a processor of a computer;

a) computing a normalized set of lamination parameters and laminate stiffness matrices of an initial laminate design of the composite laminate based on an initial laminate thickness;

b) generating a finite element model of the composite laminate;

c) determining optimum values for the laminate thickness and corresponding optimum values of the lamination parameters based on the normalized set of lamination parameters and laminate stiffness matrices and the initial laminate thickness, and based on at least one of strength constraints and stiffness constraints associated with a loading condition applied to the finite element model when determining the optimum values for the laminate thickness and the corresponding optimum values of the lamination parameters;

d) adjusting an optimum value of the laminate thickness;

e) performing an inversion process extracting multiple solutions from the optimum values of the lamination parameters, each solution representing an optimized design model of the composite laminate at an adjusted laminate thickness and including a unique set of individual fiber angles for each ply of the optimized design model of the composite laminate;

f) selecting from the multiple solutions a preferred solution for the optimized design model of the composite laminate based on lamination layup criteria;

g) performing a design verification of the preferred solution to determine if margin of safety requirements are met;

h) repeating steps (c) through (g) until an optimized design model is obtained that meets the margin of safety requirements; and

laying up the composite laminate in an optimum laminate thickness and with optimum fiber angles according to the optimized design model.

2. The method of claim 1, wherein:

the initial laminate design is a traditional laminate.

3. The method of claim 1, wherein

the initial laminate design is a non-traditional laminate.

4. The method of claim 1, wherein

the initial laminate design is a steered fiber laminate.

5. The method of claim 1, wherein:

the steps (c) and (d) of determining values for the lamination parameters are performed with the lamination parameters being the same for each finite element in the finite element model;

the step (e) of performing the inversion process includes extracting solutions wherein the individual fiber angles are constant within each ply; and

each one of the solutions defining a traditional laminate.

6. The method of claim 1, wherein:

the steps (c) and (d) of determining values for the lamination parameters are performed with the lamination parameters being the same for each finite element in the finite element model;

the step (e) of performing the inversion process includes extracting solutions wherein the individual fiber angles are constant within each ply; and

each one of the solutions defining a non-traditional laminate.

7. The method of claim 1, wherein:

the steps (c) and (d) of determining values for the lamination parameters are performed with the lamination parameters being independent of one another for each finite element in the finite element model;

the step (e) of performing the inversion process includes extracting solutions wherein the individual fiber angles vary within the plane of each ply according to the lamination parameters of each finite element; and

each one of the solutions defining a steered fiber laminate.

8. The method of claim 1, wherein the initial laminate design has a balanced symmetric configuration for which the lamination parameters V₂ and V₄ are 0, and wherein:

step (a) includes determining the normalized set of lamination parameters V₁ and V₃ and a normalized A matrix of the laminate stiffness matrices of the initial laminate design; and

step (c) includes determining optimum values for V₁ and V₃ and a reduced laminate thickness associated with the optimum values for V₁ and V₃.

9. The method of claim 1, wherein:

the step (d) of adjusting the optimum value of the laminate thickness further includes setting to 0 any lamination parameter optimum value that is 1×

10<sup>−

4</sup> or less.

10. The method of claim 1, wherein the step of determining optimum values for the set of lamination parameters is based on at least one of the following:

strength constraints;

stiffness constraints;

buckling constraints; and

lamination parameter constraints.

11. The method of claim 1, wherein the step of determining optimum values for the lamination parameters is based on at least one of the following design rules or manufacturing constraints:

at least ten percent of the fibers in the composite laminate are oriented in a direction of every fiber angle prescribed in each solution;

the composite laminate is symmetric and/or balanced; and

a difference in the fiber angle of any two adjacent plies is no greater than 45 degrees.

12. A method of manufacturing a composite laminate, comprising:

performing steps (a) through (h) in a finite element analysis program executed by a processor of a computer;

a) computing a normalized set of lamination parameters and laminate stiffness matrices of an initial laminate design of a composite laminate configured as a non-traditional laminate having an initial laminate thickness;

b) generating a finite element model of the composite laminate for analysis in a finite element analysis application;

c) determining optimum values for the laminate thickness and corresponding optimum values of the lamination parameters based on the normalized set of lamination parameters and laminate stiffness matrices and the initial laminate thickness, the lamination parameters being independent of one another for each finite element in the finite element model

d) adjusting the optimum value of the laminate thickness until a total ply quantity is an integer;

e) performing an inversion process extracting multiple solutions from the lamination parameters, each solution representing an optimized design model of a steered fiber laminate at an adjusted laminate thickness and including a unique set of individual fiber angles that vary within a plane of each ply of the optimized design model of the steered fiber laminate;

f) selecting from the multiple solutions a preferred solution for the optimized design model of the steered fiber laminate based on lamination layup criteria;

g) performing a design verification of the preferred solution of the optimized design model to determine if margin of safety requirements are met;

h) repeating steps (c) through (g) until an optimized design model of the steered fiber laminate is obtained that meets the margin of safety requirements; and

laying up the steered fiber laminate in an optimum laminate thickness and with optimum fiber angles according to the optimized design model.

13. A processor-based system for manufacturing a composite laminate, comprising:

a processor;

a memory communicatively coupled to the processor and storing instructions of a finite element analysis program that, when executed by the processor, cause the processor-based system to perform as;

a normalizer configured to compute a normalized set of lamination parameters and laminate stiffness matrices of an initial laminate design of the composite laminate at an initial laminate thickness;

a finite element model generator configured to generate a finite element model of the composite laminate for analysis in a finite element analysis application;

an optimizer configured to determine optimum values for the laminate thickness and corresponding optimum values of the lamination parameters based on the normalized set of lamination parameters and laminate stiffness matrices and the initial laminate thickness;

a laminate thickness adjuster configured to adjust the optimum value of the laminate thickness;

a matrix inverter configured to perform an inversion process extracting multiple solutions from the lamination parameters, each solution representing an optimized design model of the composite laminate at an adjusted laminate thickness and including a unique set of individual fiber angles for each ply of the optimized design model of the composite laminate;

a solution selector configured to select from the multiple solutions a preferred solution for the optimized design model based on lamination layup criteria;

a design verifier configured to perform a design verification of the optimized design model to determine if margin of safety requirements are met;

an output file generator configured to generate an output file representing the optimized design model of the composite laminate;

wherein the normalizer, the finite element model generator, the optimizer, the laminate thickness adjuster, the matrix inverter, the solution selector, the design verifier, and the output file generator are embedded in the finite element analysis program which optimizes the lamination parameters in an iterative manner until converging on the optimized design model; and

a machine configured to execute the output file and lay up the composite laminate in an optimum laminate thickness and with optimum fiber angles according to the optimized design model.

14. The processor-based system of claim 13, wherein:

the optimizer and the laminate thickness adjuster are configured to determine values for the lamination parameters that are the same for each finite element in the finite element model; and

the matrix inverter is configured to extract solutions for a non-traditional laminate wherein the individual fiber angles are constant within each ply according to the same lamination parameters for each finite element.

15. The processor-based system of claim 13, wherein:

the optimizer and the laminate thickness adjuster are configured to determine values for the lamination parameters that are independent of one another for each finite element in the finite element model; and

the matrix inverter is configured to extract solutions for a steered fiber laminate wherein the individual fiber angles vary within a plane of each ply according to the lamination parameters of each finite element.

16. The processor-based system of claim 13, wherein:

the normalizer is configured to compute a normalized set of lamination parameters and laminate stiffness matrices of a traditional laminate as the initial laminate design.

17. The processor-based system of claim 13, wherein

the normalizer is configured to compute a normalized set of lamination parameters and laminate stiffness matrices of a non-traditional laminate as the initial laminate design.

18. The processor-based system of claim 13, wherein the initial laminate design has a balanced symmetric configuration for which the lamination parameters V₂ and V₄ are 0, and wherein:

the normalizer is configured to determine the normalized set of lamination parameters V₁ and V₃ and a normalized A matrix of the laminate stiffness matrices of the initial laminate design; and

the optimizer is configured to determine optimum values for V₁ and V₃ and a reduced laminate thickness associated with the optimum values for V₁ and V₃.

19. The processor-based system of claim 13, wherein the optimizer is configured to determine optimum values for the lamination parameters based on at least one of the following:

strength constraints;

stiffness constraints;

buckling constraints; and

lamination parameter constraints.

20. The processor-based system of claim 13, wherein the optimizer is configured to determine optimum values for the lamination parameters based on at least one of the following design rules or manufacturing constraints:

at least ten percent of the fibers in the composite laminate are oriented in a direction of every fiber angle prescribed in each solution;

the composite laminate is symmetric and/or balanced; and

a difference in the fiber angle of any two adjacent plies is no greater than 45 degrees.