B-Rep Face Trajectory Swept Volume Design
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Solution Overview
Problem
Current CAD systems using B-Rep modeling face challenges in complex design operations due to the 'eraser side effect,' where details are unintentionally deleted, requiring cumbersome tests and long design times, especially when performing operations involving multiple faces or large distances.
Innovation Solution
A computer-implemented method for designing 3D modeled objects that allows users to select groups of faces, define trajectories, compute swept volumes, and assign material labels, updating the B-Rep model to minimize the eraser side effect by refining updates and respecting user intent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a user performs complex design operations by selecting one face at a time in existing B-Rep modeling systems, then the design can be completed, but the design time becomes excessively long and the process becomes cumbersome
Solution Approach 1:
The patent merges multiple face selection and modification operations into a single unified operation. Users can select multiple faces simultaneously and apply transformations to all selected faces in one action, rather than performing separate operations for each face. This combining of operations directly addresses the productivity issue by reducing the number of steps required for complex design tasks.
Solution Approach 2:
The system performs preliminary actions by maintaining a history of previous face positions and transformations. Before executing a transformation, the system prepares by storing the original state information, allowing users to revert or adjust operations. This preliminary preparation enables more efficient design iterations without requiring users to start from scratch or perform multiple test operations.
2Ease of manufacture
If a user pulls a face in B-Rep modeling to modify the solid shape, then the solid updates according to the new face position, but the eraser side effect causes details to be unintentionally deleted and not restored by reverse operations
Solution Approach 1:
The system implements beforehand cushioning by maintaining a history buffer that stores the original positions and states of faces before transformations are applied. When a user pulls or moves a face, the system prepares by recording the previous state, creating a protective buffer that prevents permanent loss of design details. This allows users to reverse operations or recover accidentally deleted details without permanent damage to the model.
Solution Approach 2:
The system provides feedback by monitoring and tracking face transformations, automatically detecting when details might be affected by eraser side effects. The history mechanism provides continuous feedback about previous states, allowing the system to warn users or automatically prevent transformations that would cause irreversible detail loss. This feedback loop ensures reliability by keeping users informed about the consequences of their design actions.
3Manufacturing precision
If existing CAD systems require many cumbersome tests and experiments before design operations can be used, then design accuracy can be achieved, but the design time and complexity increase significantly
Solution Approach 1:
The system performs preliminary actions by pre-calculating and storing the effects of potential transformations before they are fully applied. The history mechanism prepares by recording intermediate states, allowing users to preview or undo operations without actually committing to potentially erroneous changes. This preliminary preparation eliminates the need for multiple test operations, as users can confidently apply transformations knowing they can revert if needed.
Solution Approach 2:
The system provides self-service by automatically managing the history and state tracking without requiring user intervention for each test operation. The history mechanism autonomously records and manages design states, freeing users from the burden of manually testing and experimenting. This self-managing system maintains design accuracy while eliminating time-consuming manual verification steps.
Data Source
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AI summary
The invention notably relates to a computer implemented method for designing a 3D modeled object that represents a mechanical part. The method comprises selecting a group of faces of the B-Rep, defining a trajectory for each respective face of the group of faces, computing, for each face of the group of faces, a respective swept volume, the swept volume corresponding to the volume swept by the respective face with respect to the trajectory, assigning a material removal label or a material adding label to each swept volume, according to the position of the swept volume at the respective face with respect to the interior of the 3D modeled object, and updating the B-Rep with a material removal volume and then a material adding volume. The method improves the design of a 3D modeled object.