The preparation of CAD models for numerical analysis often represents up to 80% of the total time devoted to simulation projects. The automatic removal of fillets and chamfers constitutes a critical step in this process, particularly for non-parametric models where the absence of construction history significantly complicates simplification operations. These geometric elements, although essential for manufacturing, generate unnecessarily complex meshes that dramatically slow down calculations without improving the accuracy of results. Analysis engineers find themselves confronted with a permanent dilemma: maintain geometric fidelity or optimize calculation performance?
Table of contents
- The challenges of geometric preparation for simulation
- Specific issues with fillets and chamfers in simulation
- Fundamentals of automatic detection and removal
- CADfix DX: advanced automatic removal solution
- Optimized workflow for fillet removal
- Advanced features for simulation preparation
- Applications by simulation type (FEA, CFD, EM)
- Measurable benefits and return on investment
- Evolution perspectives and future technologies
The challenges of geometric preparation for simulation
The transition from a CAD model designed for manufacturing to an optimized model for numerical simulation constitutes a complex and often underestimated step. A standard CAD model typically contains a multitude of geometric details relevant for manufacturing but superfluous, even problematic, for numerical analysis. This transition involves several major challenges:
- Geometric simplification without compromising the physical validity of results
- Adaptation of the level of detail according to the type of analysis to be performed
- Processing of models from different CAD systems with various exchange formats
- Automation of the process to reduce time-consuming manual interventions
In the current industrial context, the diversity of CAD systems considerably complicates this step. A typical scenario involves designers using CATIA or NX, production engineers working on Pro/ENGINEER or SolidWorks, and analysis teams using proprietary formats specific to simulation software. This heterogeneity of digital environments creates significant barriers to the interoperability of technical data.
Geometric preparation becomes particularly critical for non-parametric models, often received as neutral formats such as STEP or IGES. The absence of a construction tree and parametric history makes it impossible to use the native defeaturing functionalities available in the original CAD systems.
Specific issues with fillets and chamfers in simulation
Fillets and chamfers represent the most problematic geometric features in the context of numerical simulation, for several fundamental reasons:
| Issue | Impact on simulation | Technical consequence |
|---|---|---|
| Excessive mesh densification | Exponential increase in the number of elements | Calculation times multiplied by 5 to 10 |
| High curvature geometry | Distorted or low-quality elements | Convergence problems in solvers |
| Multiple scales in the same model | Difficulties in respecting recommended aspect ratios | Compromise between local precision and global performance |
| High frequency in industrial models | Presence of thousands of fillets on a complex part | Impossible to process manually within reasonable timeframes |
On complex industrial models, the presence of fillets and chamfers can multiply model preparation time by 10 and calculation time by 5, without bringing significant additional precision to the results. For multi-physics simulations or parametric analyses requiring numerous iterations, this overhead becomes prohibitive.
The main difficulty lies in the automatic identification of these elements on non-parametric models. Without construction history, algorithms must analyze the raw geometry to detect the topological characteristics of fillets and chamfers: constant radii, tangential continuity, and transitions between adjacent surfaces.
Fundamentals of automatic detection and removal
The automatic removal of fillets and chamfers relies on sophisticated algorithms that combine geometric, topological, and heuristic analysis. The process breaks down into three main phases:
- Detection and classification: identification of candidate entities based on their geometric characteristics
- Contextual validation: analysis of the structural role of each entity in the global model
- Geometric reconstruction: replacement of removed entities with simplified geometry preserving model continuity
The most commonly used automatic detection criteria include:
- Constant or varying radius of curvature within a defined range
- Tangential continuity with adjacent surfaces
- Aspect ratio between the width of the fillet and its length
- Topological position (interior or exterior fillets)
- Relative volume compared to the overall model volume
The geometric reconstruction phase represents the most complex technical challenge. After removing a fillet, the algorithm must generate new geometry that correctly closes the model while preserving its topological validity. Several approaches exist:
- Extension of adjacent surfaces: prolongation of the main faces until their natural intersection
- Creation of substitute faces: generation of new analytical or procedural surfaces
- Reconstruction by meshing then conversion: hybrid approach using remeshing techniques
These methods must be applied with discernment according to the geometric context, as certain configurations can generate anomalies (self-intersections, degenerate edges) requiring additional interventions.
CADfix DX: advanced automatic removal solution
CADfix DX represents a specialized solution for preparing CAD models for numerical simulation. Unlike generic CAD tools, CADfix DX has been specifically designed to solve interoperability and geometric optimization issues for FEA, CFD, and electromagnetic analyses.
This solution distinguishes itself by its ability to process non-parametric models from various CAD systems exported in neutral formats (STEP, IGES, Parasolid, ACIS, etc.). Its architecture is centered on three functional pillars:
- Intelligent diagnosis: automatic analysis of models to identify potential problems
- Guided resolution: proposing solutions adapted to the specific context
- Optimized reuse: preparation of the model for the target application
In the specific context of fillet and chamfer removal, CADfix DX offers advanced features:
| Feature | Description | Technical advantage |
|---|---|---|
| Multi-criteria detection | Identification based on radius, position, and topology | Increased precision even on complex geometries |
| Selection by propagation | Automatic extension to adjacent and similar fillets | Drastic reduction of manual interventions |
| Modification preview | Interactive preview before applying changes | Control of the result during the process |
| Adaptive reconstruction | Specific algorithms according to the geometric context | Optimal preservation of model integrity |
CADfix DX's extended compatibility with common CAD formats constitutes a major asset. According to the technical documentation, the solution supports formats from CATIA V4/V5, NX, CREO/Pro-ENGINEER, SolidWorks, SolidEdge, Inventor, as well as neutral standards such as STEP (AP203, AP214, AP242), IGES, and JT.
Optimized workflow for fillet removal
The process of automatic fillet removal with CADfix DX follows a workflow structured in five main steps, designed to minimize manual interventions while maximizing the quality of the result:
- Import and initial diagnosis: loading the model and preliminary analysis of geometric characteristics
- Setting detection criteria: definition of recognition thresholds (minimum/maximum radius, continuity)
- Identification and selection: visual spotting of candidate entities with intelligent propagation
- Removal and reconstruction: application of defeaturing algorithms and surface regeneration
- Validation and export: verification of model integrity and preparation for downstream systems
The CADfix Wizard guides the user through this process with an intuitive interface that clearly presents detected problems and available solutions. Geometric entities are visualized with a color code indicating their status (detected fillet, removal candidate, potential problem).
CADfix DX's methodology adapts to the user's level of expertise:
- For novice users: step-by-step guided workflow with predefined parameters
- For intermediate users: adjustment of detection criteria and reconstruction options
- For experts: access to advanced parameters and possibility of targeted manual intervention
This gradual process allows for quickly obtaining satisfactory results while offering the flexibility necessary to handle complex cases requiring special attention.
Advanced features for simulation preparation
Beyond the removal of fillets and chamfers, CADfix DX offers a comprehensive set of advanced features to optimize models for numerical simulation:
- Complex zone parameterization: specific treatment of narrow surfaces problematic for automatic meshers
- Quadratic splitting: intelligent division of complex surfaces to improve mesh quality
- Hex-Skin partitioning: optimized preparation for hybrid hexahedral meshes
- Detection and removal of internal features: identification of cavities, holes, and pockets irrelevant for analysis
- Correction of geometric imperfections: repair of continuity problems, degenerate edges, or inconsistent faces
These features are based on proprietary technologies developed over more than 25 years of expertise in the field of CAD-CAE interoperability. CADfix DX's integrated approach allows for addressing all preparation issues in a single environment, avoiding back-and-forth between different software.
Among the differentiating capabilities, the treatment of "small faces" deserves particular attention. These geometric entities of reduced size but large in number often constitute a major challenge for automatic meshers. CADfix DX offers several treatment strategies:
- Merging with adjacent surfaces when continuity conditions allow
- Reconstruction based on surrounding topological constraints
- Controlled simplification preserving essential characteristics
These operations significantly optimize mesh quality and improve solver convergence, particularly for geometry-sensitive simulations such as acoustic or aerodynamic analyses.
Applications by simulation type (FEA, CFD, EM)
Geometric preparation requirements vary considerably depending on the type of simulation considered. CADfix DX offers specific approaches adapted to the main families of numerical analyses:
| Simulation type | Specific requirements | Dedicated features |
|---|---|---|
| Finite Element Analysis (FEA) | Watertight volume models, simplification of non-structural details | Targeted removal of non-load bearing fillets, preservation of critical areas (stress concentrations) |
| Computational Fluid Dynamics (CFD) | Precise extraction of fluid volume, definition of boundary layers | Extraction of external envelope, specific treatment of fluid-structure interfaces |
| Electromagnetism (EM) | Preservation of geometric details impacting wave propagation | Selective simplification based on analysis wavelength |
| Multiphysics analyses | Compatibility between different types of meshes and physical models | Generation of coherent geometric representations for different solvers |
For each type of analysis, the optimal level of simplification differs. In structural FEA, fillet removal can be aggressive in low-stress areas but must be more conservative in critical regions. In CFD, exterior fillets can significantly impact flow and require a more nuanced approach.
CADfix DX allows adaptation of the defeaturing level according to the analysis context:
- Preliminary analyses: maximum simplification to quickly obtain general trends
- Detailed studies: selective approach preserving characteristics influencing the phenomena being studied
- Validation simulations: intermediate level of detail optimizing the precision/performance compromise
This flexibility allows for adapting the preparation methodology to the specific objectives of each phase of the product development process.
Measurable benefits and return on investment
The implementation of an automated solution for fillet and chamfer removal like CADfix DX generates quantifiable benefits at several levels:
- Reduction in preparation time: 50% to 90% decrease in time devoted to model simplification
- Acceleration of calculations: reduction in mesh size resulting in analysis times divided by 3 to 10
- Improvement in result quality: better solver convergence and reduction of numerical artifacts
- Standardization of processes: reproducible methodology limiting variability related to manual interventions
These gains translate into tangible return on investment. According to experience feedback cited in the technical documentation:
"By using CADfix, model rework time has been reduced by approximately 90% and total model setup time reduced by approximately 50%." - David Merrit, Senior Engineer at Dana Glacier Vandervell, international supplier of engine bearings.
The optimization of the preparation process also allows for exploring more design variants in the same time interval, contributing to an overall improvement in the quality of developed products.
Indirect benefits include:
- Better collaboration between design and analysis teams
- Increased capacity to process complex models from different CAD systems
- Reduction of cognitive load for engineers who can focus on analyzing results rather than preparing models
- Elimination of bottlenecks in the product development process
These advantages position automatic fillet removal as a major efficiency lever in the digital transformation of product development processes.
Evolution perspectives and future technologies
The field of geometric simplification for simulation is experiencing rapid evolution, driven by several major technological trends:
- Artificial intelligence and machine learning: algorithms capable of identifying complex geometric patterns and learning user preferences
- Semantics-based approaches: recognition of the functional role of geometric entities to guide simplification
- Intelligent adaptive meshes: complementarity between geometric simplification and local mesh refinement
- Multi-fidelity digital twins: coordinated management of representations at different levels of detail according to the context of use
These advances will allow for further automation of the model preparation process while improving the relevance of the simplifications performed. The ultimate goal is to create a fully automated workflow where the system intelligently determines which geometric elements to preserve or simplify based on the physical phenomenon being studied.
For users of solutions like CADfix DX, these evolutions will translate into:
- More advanced automation requiring fewer manual interventions
- Contextual recommendations based on analysis of design intent
- Smoother integration into multiphysics simulation environments
- Predictive tools estimating the impact of simplifications on the accuracy of results
These emerging technologies will contribute to further reducing the gap between design and simulation, allowing for a more integrated approach to product development where numerical analysis becomes a daily tool rather than a specialized and separate step.
The evolution of exchange standards (such as STEP AP242) and the growing adoption of formats supporting metadata associated with geometric entities will also facilitate the intelligent identification and management of fillets and chamfers, even on imported models.
