B-Rep Mechanical Part Design for Protrusion and Depression Recognition

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Solution Overview

Problem

Existing methods for recognizing and selecting protrusions or depressions in mechanical parts are inefficient and lack ergonomics, making it difficult to select all relevant faces in a B-rep representation.

Innovation Solution

A computer-implemented method that automatically recognizes a set of faces representing either a depression or protrusion feature in a B-rep, using a two-step approach to identify connected subsets of faces bounded by specific edge types, without requiring user interaction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If existing methods for protrusion or depression recognition are used, then the design process can proceed, but the efficiency and ergonomics are poor due to difficulty in selecting all relevant faces in complex B-rep

Engineering Contradiction:
Improvedesign efficiencyVSAvoidergonomics
Core Design Contradiction:
ProductivityVSEase of operation

Solution Approach 1:

The system performs automatic recognition of depression and protrusion features without requiring user interaction. The CAD system independently identifies relevant faces by analyzing geometric properties such as convexity/concavity of edges and connectivity relationships, eliminating the need for manual face selection and thereby improving both efficiency and ergonomics

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces manual mechanical selection operations with automated computational algorithms. Instead of requiring users to manually select faces through graphical interface operations, the system uses automated geometric analysis including edge type detection (convex/concave), face connectivity traversal, and feature classification algorithms to identify depression and protrusion features

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If manual selection of faces is required to identify depression or protrusion features, then user control is maintained, but the process becomes time-consuming and inefficient

Engineering Contradiction:
Improvefeature recognition speedVSAvoidtime for face selection
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system performs preliminary automated analysis of the B-rep structure by pre-identifying edge types (convex/concave) and establishing face connectivity relationships before feature recognition. This preliminary processing enables rapid automatic identification of depression and protrusion features without requiring time-consuming manual face selection operations

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The CAD system autonomously performs the entire feature recognition process including automatic traversal of connected faces, classification based on edge geometry, and identification of depression/protrusion features without user intervention, thereby eliminating time loss associated with manual selection

Inventive Principle:
Principle #25Self-service

3Ease of operation

If automatic recognition is implemented, then ergonomics improve, but the system must accurately handle complex geometric relationships including convex and concave edges

Engineering Contradiction:
Improveautomation levelVSAvoidgeometric feature detection accuracy
Core Design Contradiction:
Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The system applies different detection criteria to different local geometric contexts. It distinguishes between convex edges and concave edges, and uses these local geometric properties to determine face connectivity and classify features. The algorithm adapts its detection logic based on the local geometric characteristics of each face and edge encountered during traversal

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes geometric parameters such as edge convexity/concavity and face connectivity to identify different feature types. By analyzing these parameter variations, the system can automatically distinguish between depression features (characterized by convex edges) and protrusion features (characterized by concave edges), ensuring accurate detection despite geometric complexity

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3690682B1Designing a part featuring a protrusion or a depression
Publication Date: 2025.10.15 DASSAULT SYSTEMES SA
  • EP3690682B1 patent drawingFigure 1
  • EP3690682B1 patent drawingFigure 2
  • EP3690682B1 patent drawingFigure 3

AI summary

The invention notably relates to a computer-implemented method for designing, with a CAD system, a 3D modeled object representing a mechanical part. The method comprises providing a B-rep representing the mechanical part. The B-Rep has faces and edges. The method further comprises providing a first set of faces and a feature type. The feature type is either a depression feature type or a protrusion feature type. The method further comprises, automatically by the CAD system, recognizing a second set of faces within the first set of faces. The second set of faces represents a feature of the provided feature type. This constitutes an improved method for designing a mechanical part.