Generative 3D Shape Optimization With Fatigue Thickness Constraints

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Solution Overview

Problem

Current CAD software limitations in generative design for additive and subtractive manufacturing fail to effectively optimize 3D structures for fatigue resistance, particularly in ensuring minimum thickness and material efficiency under various load cases and materials, leading to potential catastrophic failures due to unmitigated fatigue damage.

Innovation Solution

A computer-aided design program iteratively modifies 3D shapes based on design criteria, including critical fatigue crack length, load cycles, and material specifications, using numerical simulations and shape change velocities to enforce minimum thickness and fatigue safety factors, ensuring damage tolerance through level-set representations and adaptive controllers like PID controllers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If generative design optimizes for minimum weight and material efficiency, then weight and material usage are reduced, but fatigue resistance and structural integrity deteriorate due to insufficient thickness

Engineering Contradiction:

ImproveweightVSAvoidfatigue resistance

Core Design Contradiction:

Weight of moving objectVSReliability

Solution Approach 1:

The patent introduces fatigue-based parameter constraints (minimum thickness, critical crack length, fatigue safety factors) into the generative design optimization process. These parameters dynamically adjust design variables to ensure fatigue resistance while minimizing weight, resolving the contradiction between weight reduction and fatigue reliability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback loops where fatigue analysis results (stress, strain, crack propagation) are continuously fed back into the generative design solver. This feedback mechanism allows the design to iteratively improve fatigue resistance while maintaining weight efficiency, addressing the contradiction between the two objectives.

Inventive Principle:

Principle #23Feedback

2Loss of substance

If generative design reduces material usage for weight optimization, then material efficiency improves, but manufacturing precision and minimum thickness constraints are violated

Engineering Contradiction:

Improvematerial efficiencyVSAvoidminimum thickness

Core Design Contradiction:

Loss of substanceVSManufacturing precision

Solution Approach 1:

The patent enforces minimum thickness constraints as hard parameters in the generative design optimization. These constraints prevent the solver from generating geometries thinner than manufacturable limits, ensuring manufacturing precision is maintained while still achieving material efficiency through optimized topology and distribution.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If traditional CAD software generates 3D geometry without fatigue constraints, then design flexibility and generative capability are maximized, but catastrophic fatigue failures occur due to unmitigated damage

Engineering Contradiction:

Improvedesign flexibilityVSAvoiddamage tolerance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary fatigue-based design constraints (fatigue safety factors, critical crack length limits, minimum thickness requirements) before the generative design process begins. These pre-established constraints guide the optimization to produce designs that are both flexible and inherently tolerant to fatigue damage, preventing catastrophic failures.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces preliminary anti-actions by constraining design variables to prevent geometries that would lead to fatigue failure. By pre-establishing fatigue safety factors and critical crack length limits, the design process actively counteracts potential fatigue damage before it can occur in the final structure.

Inventive Principle:

Principle #9Preliminary anti-action

4Strength

If generative design iteratively modifies shape for optimal performance, then structural efficiency improves, but computational complexity and solution time increase

Engineering Contradiction:

Improvestructural efficiencyVSAvoidcomputational complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent employs partial action by implementing adaptive fatigue constraints that are applied only where critical stress concentrations occur, rather than uniformly across the entire structure. This selective approach maintains structural efficiency while reducing the overall computational complexity of the iterative optimization process.

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentUS20230145217A1Generative design shape optimization with size limited fatigue damage for computer aided design and manufacturing

Publication Date: 2023.05.11 AUTODESK INC

AI summary

Methods, systems, and apparatus, including medium-encoded computer program products, for computer aided design of physical structures using generative design processes, A method includes obtaining, by a computer aided design program, a design space for a modeled object, one or more design criteria for the modeled object, one or more in-use load cases, and a critical fatigue crack length for a material from which A physical structure will be manufactured; iteratively modifying a generatively designed three dimensional shape of the modeled object in the design space in accordance with the critical fatigue crack length for the material, wherein the iteratively modifying comprises enforcing a design criterion that limits a minimum thickness of the generatively designed three dimensional shape, the minimum thickness being based on the critical fatigue crack length for the material.