Flex Representation CAD Spline Envelope Geometry
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Solution Overview
Problem
Current CAD representation methods, such as BREP models, face challenges in producing high-quality hexahedral meshes due to mathematical limitations, leading to dirty geometry and increased time and cost in simulation preparation, while traditional immersed finite element methods lack flexibility and accuracy in capturing complex geometries.
Innovation Solution
The Flex Representation Method leverages smooth splines to create an envelope CAD domain, allowing for flexible and accurate simulation modeling by using U-splines and Bézier projection to fit the CAD geometry, enabling high-fidelity spline models and efficient mesh generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If BREP models are used to represent CAD geometry, then the representation can handle complex shapes with splines, but the models suffer from dirty geometry artifacts (gaps, overlaps, sliver surfaces) that negatively impact downstream simulation applications
Solution Approach 1:
The patent introduces an intermediary processing step between BREP model creation and simulation that automatically detects and repairs dirty geometry artifacts. This intermediary repair process meditates between the complex shape representation capability of BREPs and the watertight geometry requirement for simulation, allowing both needs to be satisfied without manually replacing the BREP with a mesh.
2Reliability
If the entire BREP model is replaced with a mesh to fix dirty geometry, then watertight representation is achieved, but the process becomes tedious, manual, time-consuming, expensive, and error-prone
Solution Approach 1:
The patent implements a self-service automated repair system that detects and fixes dirty geometry artifacts in BREP models without requiring manual intervention. The system automatically identifies gaps, overlaps, and sliver surfaces, then applies appropriate repair operations to achieve watertight geometry, eliminating the need for time-consuming manual mesh replacement while maintaining reliability.
Solution Approach 2:
The patent changes the state of the geometry representation by introducing parameterized repair operations that automatically adjust geometric parameters to eliminate artifacts. Instead of manual mesh replacement, the system modifies BREP parameters (such as surface continuity, intersection curve precision, and trimming boundaries) to achieve watertight geometry automatically.
3Adaptability or versatility
If standard fillet features are applied to CAD models, then design completeness is improved, but the resulting spline surfaces become geometrically imprecise with boundaries not conducive to decomposition
Solution Approach 1:
The patent applies preliminary action by performing geometry repair and decomposition optimization before the simulation process begins. The system proactively identifies and corrects geometric imprecision issues caused by fillet features, and pre-decomposes complex surfaces into simulation-friendly subdomains, avoiding downstream problems without requiring design changes.
Solution Approach 2:
The patent applies local quality by selectively repairing and decomposing only the affected regions around fillet features rather than processing the entire model. The system identifies local geometric imprecision caused by fillets and applies targeted repair operations to those specific areas, maintaining design completeness while improving local geometric precision where it matters most.
Data Source
AI summary
Embodiments are presented for Flex Representation in Computer Aided Design (CAD) and Computer Aided Engineering (CAE). The Flex Representation Method (FRM) leverages unique computational advantages of splines to address limitations in the process of building CAE simulation models from CAD geometric models. Central to the approach is the envelope CAD domain that encapsulates a CAD model. An envelope CAD domain can be of arbitrary topological and geometric complexity. Envelope domains are constructed from spline representations, like U-splines, that are analysis-suitable. The envelope CAD domain can be used to approximate none, some, or all of the features in a CAD model. This yields additional simulation modeling options that simplify the model-building process while leveraging the properties of splines to control the accuracy and robustness of computed solutions. The potential of the method is illustrated through several carefully selected benchmark problems.