Techniques for performing cross-sectional stress analysis for three-dimensional objects

Patent metadata

Field	Value
Publication number	US-10434715-B2
Application number	US-201414544156-A
Country	US
Kind code	B2
Filing date	Dec 2, 2014
Priority date	Dec 3, 2013
Publication date	Oct 8, 2019
Grant date	Oct 8, 2019

Abstract

In one embodiment of the present invention, a stress analysis engine efficiently computes stresses for an arbitrarily shaped three-dimension (3D) model. In operation, the stress analysis engine slices the 3D model into layers of cross-sections. The stress analysis engine then groups the cross-sections into virtual cross-sections. For each virtual cross-section, the stress analysis engine applies bending moment equilibrium-based equations to determine a corresponding structural stress for the 3D model. The efficiency of this stress analysis process enables real-time feedback of stresses to an interactive design tool that facilitates a trial-and-error design process. Using this trial-and-error process reduces the guesswork and/or over-engineering associated with conventional approaches based on finite element methods that are typically too slow for interactive feedback. Consequently, the disclosed cross-sectional stress analysis techniques enable efficient design of 3D models that produce structural robust 3D objects when manufactured by a 3D printer.

First claim

What is claimed is:

1. A computer-implemented method for performing a structural stress analysis for a three-dimensional model of an object, the method comprising:
slicing the three-dimensional model to produce one or more layers of two-dimensional cross-sections;
grouping a plurality of disjoint two-dimensional cross sections included in a first layer into a first virtual cross-section based on a connectivity of the three-dimensional model; and
computing a structural stress associated with the first virtual cross-section based on bending moment equilibrium.

2. The method of claim 1 , wherein computing the structural stress comprises applying an Euler-Bernoulli assumption to the first virtual cross-section.

3. The method of claim 1 , wherein grouping comprises clustering cross-sections that collectively influence the distribution of an external force applied to the three-dimensional model when the three-dimensional object is fixed at a first location.

4. The method of claim 3 , wherein clustering cross-sections comprises:
constructing an adjacency graph representing the connected triangles of the 3D model and a connectivity graph representing the geometric distribution of the cross-sections across the 3D model;
assigning a first cross-section included in a first layer to a first group;
based on the analyzing the adjacency graph in conjunction with the connectivity graph, identifying a second cross-section that is accessible from both sides of the plane of the first layer via paths of triangles that do not cross other cross-sections; and
adding the second cross-section to the first group.

5. The method of claim 1 , wherein computing the structural stress associated with each virtual cross-section comprises:
selecting a neutral axis based on the plurality of disjoint cross-sections included in the virtual cross-section; and
applying bending moment equilibrium to the virtual cross-section in conjunction with the neutral axis.

6. The method of claim 1 , further comprising identifying a time constraint, and wherein slicing the three-dimensional model comprises:
selecting a thickness based on the time constraint; and
partitioning the three-dimensional model at intervals of the selected thickness.

7. The method of claim 1 , further comprising:
grouping a plurality of disjoint two-dimensional cross-sections included in the first layer into a second virtual cross-section based on the connectivity of the three-dimensional model;
computing a structural stress associated with the second virtual cross-section based on bending moment equilibrium;
calculating a maximum stress for the three-dimensional model based on the structural stress associated with the first virtual cross-section and the structural stress associated with the second virtual cross-section.

8. The method of claim 1 , further comprising:
computing a structural stress associated with an independent cross-section, wherein the independent cross-section is included in the first layer but is not included in the first virtual cross-section; and
calculating a maximum stress for the three-dimensional model based on the structural stress associated with the first virtual cross-section and the structural stress associated with the independent cross-section.

9. The method of claim 1 , further comprising:
determining a value corresponding to the computed structural stress associated with the first virtual cross-section;
enhancing an image of the three-dimensional model displayed on a device to reflect the value;
receiving an updated three-dimensional model;
slicing the updated three-dimensional model to produce one or more new layers of two-dimensional cross-sections;
grouping a plurality of disjoint two-dimensional cross sections included in a second layer into a second virtual cross-section based on the connectivity of the updated three-dimensional model;
computing a structural stress associated with the second virtual cross-section based on bending moment equilibrium;
determining a value corresponding to the computed structural stress associated with the second virtual cross-section; and
updating the image to reflect the value associated with the second virtual cross-section.

10. One or more non-transitory computer-readable storage media including instructions that, when executed by one or more processing units, cause the one or more processing units to analyze the structural stress for a three-dimensional model of an object by performing the steps of:
slicing the three-dimensional model to produce one or more layers of two-dimensional cross-sections;
grouping a plurality of disjoint two-dimensional cross sections included in a first layer into a first virtual cross-section based on a connectivity of the three-dimensional model; and
computing a structural stress associated with the first virtual cross-section based on bending moment equilibrium.

11. The one or more computer-readable storage media of claim 10 , wherein computing the structural stress comprises applying an Euler-Bernoulli assumption to the first virtual cross-section.

12. The one or more computer-readable storage media of claim 10 , wherein grouping comprises clustering cross-sections that collectively influence the distribution of an external force applied to the three-dimensional model when the three-dimensional model is fixed at a first location.

13. The one or more computer-readable storage media of claim 12 , wherein clustering cross-sections comprises:
constructing an adjacency graph representing the connected triangles of the 3D model and a connectivity graph representing the geometric distribution of the cross-sections across the 3D model;
assigning a first cross-section included in a first layer to a first group;
based on the analyzing the adjacency graph in conjunction with the connectivity graph, identifying a second cross-section that is accessible from both sides of plane of the first layer via paths of triangles that do not cross other cross-sections; and
adding the second cross-section to the first group.

14. The one or more computer-readable storage media of claim 10 , wherein computing the structural stress associated with each virtual cross-section comprises:
selecting a neutral axis based on the plurality of disjoint cross-sections included in the virtual cross-section; and
applying bending moment equilibrium to the virtual cross-section in conjunction with the neutral axis.

15. The one or more computer-readable storage media of claim 14 , wherein selecting the neutral axis comprises determining an axis that is both perpendicular to the virtual cross-section and passes through the centroid of the plurality of disjoint cross-sections included in the virtual cross-section.

16. The one or more computer-readable storage media of claim 14 , wherein selecting the neutral axis comprises identifying a medial axis of the plurality of disjoint cross-sections included in the virtual cross-section.

17. The one or more computer-readable storage media of claim 10 , further comprising identifying an accuracy constraint, and wherein slicing the three-dimensional model comprises:
selecting a thickness based on the accuracy constraint; and
partitioning the three-dimensional model at intervals of the selected thickness.

18. The one or more computer-readable storage media of claim 10 , further comprising:
determining a value corresponding to the computed structural stress associated with the first virtual cross-section;
enhancing an image of the three-dimensional model displayed on a device to r

Assignees

• Autodesk Inc

Inventors

• Umetani Nobuyuki
• Schmidt Ryan Michael

Classifications

• G06F2119/18

  Manufacturability analysis or optimisation for manufacturability · CPC title

• G06F30/00

  Computer-aided design [CAD] · CPC title

• B29C64/40

  Structures for supporting 3D objects during manufacture and intended to be sacrificed after completion thereof · CPC title

• G05B2219/49038

  Support help, grid between support and prototype, separate easily · CPC title

• G05B19/4099

  Surface or curve machining, making three-dimensional [3D] objects, e.g. desktop manufacturing · CPC title