Multi-scale mesh modeling software products and controllers

Patent metadata

Field	Value
Publication number	US-10664560-B2
Application number	US-201415105683-A
Country	US
Kind code	B2
Filing date	Dec 19, 2014
Priority date	Dec 19, 2013
Publication date	May 26, 2020
Grant date	May 26, 2020

Abstract

Simulation systems, manufacturing systems, software products and controllers are provided with multi-scale modeling in which a coarse mesh and a fine mesh that models a stimulus are decoupled. The fine mesh can be moved within the coarse mesh with a cut and paste operation. The coarse mesh is updated by sparsely propagated effects through the coarse mesh. Simulations of the invention can be conducted in real-time, and be used as controllers in manufacturing systems, such as additive manufacturing systems. A number of efficient methods are provided for solving meshing determinations that arise from movement of a stimulus modeled within a fine mesh.

First claim

The invention claimed is:

1. A modeling and simulation software product in a control system for an additive manufacturing process, comprising code stored on a non-transient medium, the product comprising code for:
generating a coarse scale mesh to model coarse scale changes to at least a portion of a material substrate upon application of a stimulus for manufacturing an article;
performing multi-scale refinement or de-refinement operations for an area within boundaries of the coarse scale mesh in response to movement or changes of the stimulus, the multi-scale refinement or de-refinement operations comprising:
identifying the area within the boundaries of the coarse scale mesh where the stimulus has an effect on the article within the boundaries of the coarse scale mesh,
generating a fine scale mesh for the area within the boundaries of the coarse scale mesh, the fine scale mesh configured to model changes that are finer in scale than the coarse scale changes, the changes that are finer in scale being attributed to the application of the stimulus on the article, wherein the fine scale mesh is based on a different fine scale mesh generated at a different time point, and
replacing a portion of the coarse scale mesh corresponding to the area within the boundaries of the coarse scale mesh with the fine scale mesh wherein a nodal connectivity between the fine scale mesh and a separate portion of the coarse scale mesh is determined based on one or more stiffness matrices computed for the different fine scale mesh generated at the different time point; and

generating, based on the multi-scale refinement or de-refinement operations, a simulated output representing the stimulus having the effect on the article.

2. The product of claim 1 , wherein the changes that are finer in scale than the coarse scale changes comprise changes to at least one of geometry, internal features and microstructures of the article.

3. The product of claim 1 , comprising code for solving directional finite element problems to determine an effect of the stimulus on the article within the boundaries of the coarse scale mesh using a numerical technique for dimensional reduction of physical field variable/tensor problems by computing Eigenmodes of a transformed non-dispersive stiffness matrix.

4. The product of claim 3 , wherein the transformed non-dispersive stiffness matrix comprises a functional form of a B −1 A equation where B indicates a first stiffness matrix of the one or more stiffness matrices between successive planes perpendicular to the direction in which the stimulus has been applied and A indicates an in-plane stiffness matrix of the corresponding plane.

5. The product of claim 4 , comprising code for conducting multiscale homogenization of the coarse scale and fine scale meshes using periodic and higher order boundary conditions (PHOBC) at scale of the fine mesh based on dominant Eigenmodes computed at scale of the coarse mesh.

6. The product of claim 3 , comprising code for conducting multiscale homogenization of the coarse scale and fine scale meshes using periodic and higher order boundary conditions (PHOBC) at scale of the fine mesh based on dominant Eigenmodes computed at scale of the coarse mesh.

7. The product of claim 6 , wherein the PHOBCs are calculated from a Taylor expansion of dominant Eigenmodes.

8. The product of claim 7 , further comprising computing a homogenized thermomechanical constitutive model computed from the PHOBCs.

9. The product of claim 8 , wherein the constitutive model is used to iteratively determine the effect of the stimulus on the coarse scale mesh to model macroscopic Eigenmodes for multi-scale and/or non-linear phenomena.

10. The product of claim 1 , wherein said performing multi-scale refinement or de-refinement operations further comprises solving simultaneous equations by:
calculating a stiffness matrix for initial material properties of the article;
assigning an initial value of a tolerance based on existing values in the stiffness matrix;
calculating an E matrix, in a Cholesky decomposition, using different criteria to compute each successive value in the Cholesky matrix such that the E matrix has information of which entities corresponding to a lower triangular matrix of the Cholesky matrix are to be computed;
determining a number of iterations for the value of the tolerance;
updating the tolerance by iteratively adjusting the tolerance until an error is within a predetermined acceptable limit; and
subsequently using the E matrix for a next iteration for the same or a different stiffness matrix for the same coarse scale mesh with different material properties in case of any nonlinearity.

11. A manufacturing system including the product of claim 1 , wherein the manufacturing system includes a tool to apply the stimulus, and a controller controlled by the product of claim 1 to move and/or modify output of the tool.

12. The system of claim 11 , wherein the system is an additive manufacturing system, and the tool is a laser.

13. The system of claim 12 , wherein the fine scale mesh characterizes a melt pool region of the article.

14. The system of claim 13 , comprising Eigensolvers that predict thermo-mechanical variables away from the melt pool region.

15. The system of claim 14 , wherein the Eigensolvers further predict areas where thermomechanical gradients are lower than within an area of stimulus.

16. The system of claim 14 , comprising a banded vectorization that truncates a neighborhood of any nodal point used for computation of thermomechanical fields by extracting a lower triangular matrix from a stiffness matrix such that row-wise multiplication of any two lower triangular matrix vectors is less than a predetermined threshold then an entity corresponding to the lower triangular matrix is assumed to be zero and is not computed.

17. A material or space modeling system for modeling material or space subjected to an additive manufacturing process that uses a stimulus upon the material or space, the system comprising:
a memory storing instructions; and
one or more processors coupled to the memory that execute the instructions to
obtain physical property data about the material or space; and
generate a coarse scale mesh to model coarse scale changes to at least a portion of the material or space upon application of the stimulus on the material or space; and
perform multi-scale refinement or de-refinement operations for an area within the boundaries of the coarse scale mesh in response to movement or changes of the stimulus on the material or space, the multi-scale refinement or de-refinement operations comprising:
identifying the area within the boundaries of the coarse scale mesh where the stimulus has an effect on the material or space within the boundaries of the coarse scale mesh,
generating a fine scale mesh for the area within the boundaries of the coarse scale mesh, the fine scale mesh configured to model changes that are finer in scale than the coarse scale changes, the changes that are finer in scale being attributed to the application of the stimulus on the material or space, wherein the fine scale mesh is based on a different fine scale mesh generated at a different time point, and
replacing a portion of the coarse scale mesh corresponding to the within the boundaries of the coarse scale mesh area with the fine scale mesh wherein a nodal connectivity between the fine scale mesh and a separate portion of the coarse scale mesh is determined based on one or more stiffness matrices computed for the different fine scale mesh generated at

Assignees

• Univ Louisville Res Found Inc

Inventors

• Pal Deepankar
• Patil Nachiket
• Stucker Brent

Classifications

• G06F2119/18

  Manufacturability analysis or optimisation for manufacturability · CPC title

• G05B2219/49007

  Making, forming 3-D object, model, surface · CPC title

• G06F30/23

  using finite element methods [FEM] or finite difference methods [FDM] · CPC title

• G05B2219/35134

  3-D cad-cam · CPC title

• G06F2111/10

  Numerical modelling · CPC title