Methods and systems of engineering analysis using a hybrid approach with FEM and adaptive SPH

• US 20090228246A1
• Filed: 03/05/2008
• Published: 09/10/2009
• Est. Priority Date: 03/05/2008
• Status: Active Grant

• Current Assignee: Ansys Incorporated
• Original Assignee: Livermore Software Technology Corporation
• Inventors: Lacome, Jean Luc
• Granted Patent: US 8,423,327 B2
• Time in Patent Office: Days
• US Class Current: 703/2
• CPC Class Codes: G01N 2203/0067 Fracture or rupture
• CPC Class Codes: G01N 2203/0087 Resistance to crushing
• CPC Class Codes: G01N 2203/0216 Finite elements
• CPC Class Codes: G01N 3/48 by performing impressions under impulsive load by indentors, e.g. falling ball G01N3/54 takes precedence
• CPC Class Codes: G06F 2111/10 Numerical modelling

Abstract

Systems and methods of computer aided engineering analysis using hybrid approach of finite element method (FEM) and adaptive smoothed particle hydrodynamics (SPH) are described. According to one aspect, a computer-aided engineering analysis is performed to simulate an impact event between structures. A FEM grid model is created to represent the structures using a plurality of solid elements which represents geometry and material properties. Once a contact between two structures resulted into a material or structural failure according to predefined material constitutive equation, solid elements representing the failed portion of the structure are removed. Each failed solid element is then replaced by a plurality of particles to be analyzed using the SPH analysis. The particles replacing the failed element inherit all of the states and properties of the failed element, such as location, mass, velocity, acceleration, etc. The replacement is conducted according to the principles of mass, momentum and energy conservation.

Claims

1. A method of engineering analysis using a hybrid approach of finite element method (FEM) and adaptive smoothed particle hydrodynamics (SPH), the method comprises:

(a) defining a FEM grid model representing a plurality of structures in an impact event, the FEM grid model includes a plurality of solid elements;

(b) defining a group of first particles representing debris resulting from the impact event, the group of first particles is empty at onset;

(c) starting a time domain simulation of the engineering analysis of the impact event using the FEM in an initial solution cycle;

(d) determining whether there has been at least one solid element failed in the FEM according to a set of structural failure criteria;

(e) converting each of the at least one failed solid element into a plurality of second particles, which inherits states of said each of the at least one failed solid element and merging the plurality of second particles into the group of first particles if required;

(f) incrementing time in the time domain simulation to a next solution cycle;

(g) performing the engineering analysis of the non-empty group of first particles using the adaptive SPH and performing the engineering analysis of the FEM grid model with remaining elements using the FEM in the next solution cycle; and

(h) repeating (d)-(g) until the time domain simulation ends.

2. The method of claim 1, wherein each of the plurality of structures comprises a material property that is defined in the FEM model.

3. The method of claim 2, wherein the material property is used for defining the set of structural failure criteria in form of a stress-strain relationship.

4. The method of claim 1, wherein the impact event comprises at least two of the plurality of structures contacting with each other.

5. The method of claim 1, wherein the states of said each of the at least one failed solid element include location, mass, moment and energy.

6. The method of claim 1, wherein said converting said each of the at least one failed solid element into the plurality of second particles further comprises partitioning said each of the at least one failed solid element to a plurality of portions in accordance with an adaptivity rule, wherein each of the plurality of second particles corresponds to respective one of the plurality of portions.

7. The method of claim 6, further comprising maintaining conservation of mass, moment and energy between said each of the at least one failed solid element and the plurality of second particles.

8. The method of claim 6, wherein the adaptivity rule ensures that the plurality of second particles is best suitable to represent the failed element as the debris in the impact event.

9. The method of claim 1, wherein the time domain simulation ends when a predefined total simulation time has reached.

10. The method of claim 1, wherein the plurality of solid elements comprises hexahedral elements.

11. The method of claim 1, wherein the plurality of solid elements comprises pentahedral elements.

12. A system for performing engineering analysis using a hybrid approach of finite element method (FEM) and adaptive smoothed particle hydrodynamics (SPH), the system comprises;

an input/output (I/O) interface;

a memory for storing computer readable code for an application module;

at least one processor coupled to the memory, said at least one processor executing the computer readable code in the memory to cause the application module to perform operations of;

(a) defining a FEM grid model representing a plurality of structures in an impact event, the FEM grid model includes a plurality of solid elements;

(b) defining a group of first particles representing debris resulting from the impact event, the group of first particles is empty at onset;

(c) starting a time domain simulation of the engineering analysis of the impact event using the FEM in an initial solution cycle;

(d) determining whether there has been at least one solid element failed in the FEM according to a set of structural failure criteria;

(e) converting each of the at least one failed solid element into a plurality of second particles, which inherits states of said each of the at least one failed solid element and merging the plurality of second particles into the group of first particles if required;

(f) incrementing time in the time domain simulation to a next solution cycle;

(g) performing the engineering analysis of the no-empty group of first particles using the adaptive SPH and performing the engineering analysis of the FEM grid model with remaining elements using the FEM in the next solution cycle; and

(h) repeating (d)-(g) until the time domain simulation ends.

13. The system of claim 12, wherein said converting said each of the at least one failed solid element into the plurality of second particles further comprises partitioning said each of the at least one failed solid element to a plurality of portions in accordance with an adaptivity rule, wherein each of the plurality of second particles corresponds to respective one of the plurality of portions.

14. The system of claim 13, further comprising maintaining conservation of mass, moment and energy between said each of the at least one failed solid element and the plurality of second particles.

15. The system of claim 13, wherein the adaptivity rule ensures that the plurality of second particles is best suitable to represent the failed element as the debris in the impact event.

16. A computer usable medium having computer a readable medium stored thereon to perform a method of engineering analysis using a hybrid approach of finite element method (FEM) and adaptive smoothed particle hydrodynamics (SPH) comprising:

(a) computer readable code for defining a FEM grid model representing a plurality of structures in an impact event, the FEM grid model includes a plurality of solid elements;

(b) computer readable code for defining a group of first particles representing debris resulting from the impact event, the group of first particles is empty at onset;

(c) computer readable code for starting a time domain simulation of the engineering analysis of the impact event using the FEM in an initial solution cycle;

(d) computer readable code for determining whether there has been at least one solid element failed in the FEM according to a set of structural failure criteria;

(e) computer readable code for converting each of the at least one failed solid element into a plurality of second particles, which inherits states of said each of the at least one failed solid element and merging the plurality of second particles into the group of first particles if required;

(f) computer readable code for incrementing time in the time domain simulation to a next solution cycle;

(g) computer readable code for performing the engineering analysis of the no-empty group of first particles using the adaptive SPH and performing the engineering analysis of the FEM grid model with remaining elements using the FEM in the next solution cycle; and

(h) computer readable code for repeating (d)-(g) until the time domain simulation ends.

17. The computer usable medium of claim 16, wherein said computer readable code for converting said each of the at least one failed solid element into the plurality of second particles further comprises computer readable code for partitioning said each of the at least one failed solid element to a plurality of portions in accordance with an adaptivity rule, wherein each of the plurality of second particles corresponds to respective one of the plurality of portions.

18. The computer usable medium of claim 16, further comprising computer readable code for maintaining conservation of mass, moment and energy between said each of the at least one failed solid element and the plurality of second particles.