Topology-Optimized Vibration Test Fixture Design

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Solution Overview

Problem

Existing vibration test fixtures are often oversized, leading to logistical challenges and potential interference with vibration responses due to added weight, and may cause resonances that complicate identifying the test article's resonance frequencies.

Innovation Solution

A method using finite element analysis with boundary conditions such as g-load parameters, natural frequencies, and material strength to optimize the topology of the test fixture, ensuring it is lightweight, stiff enough for test loads, and avoids resonances with the test article's frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a larger test fixture is used to securely hold the test article, then the holding strength is improved, but the weight increases making logistics difficult and requiring a larger slip table

Engineering Contradiction:

Improveholding strengthVSAvoidfixture weight

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The fixture is divided into multiple members (first member, second member, third member) that can be individually optimized for strength and weight. This segmentation allows each component to be sized appropriately for its specific function rather than designing a single large monolithic structure, resolving the contradiction between holding strength and weight.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different portions of the fixture are designed with different properties - the first member has a first natural frequency while the second member has a second natural frequency, allowing each region to be optimized for its specific requirements. This local optimization enables the fixture to provide sufficient holding strength in critical areas while minimizing weight in less critical areas.

Inventive Principle:

Principle #3Local quality

2Strength

If a larger test fixture is used to securely hold the test article, then the holding strength is improved, but the slip table size must increase to accommodate the added weight

Engineering Contradiction:

Improveholding strengthVSAvoidslip table size

Core Design Contradiction:

StrengthVSArea of stationary object

Solution Approach 1:

By segmenting the fixture into multiple members, the overall weight is reduced compared to a single large fixture. This weight reduction allows the slip table to remain smaller while still supporting the fixture and test article, resolving the contradiction between holding strength and slip table size.

Inventive Principle:

Principle #1Segmentation

3Ease of manufacture

If a non-optimized test fixture is used, then the design process is simpler, but the natural frequency causes resonances that make it difficult to identify test article resonances

Engineering Contradiction:

Improvedesign simplicityVSAvoidresonance identification accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The design process involves changing the natural frequency parameters of the fixture members. By ensuring the first member has a first natural frequency and the second member has a second natural frequency that differs from the test article's resonance frequencies, the fixture is optimized to avoid masking the test article's resonances. This parameter optimization resolves the contradiction between design simplicity and measurement precision.

Inventive Principle:

Principle #35Parameter changes

4Stability of the object's composition

If a heavier test fixture is used, then the structural stability is improved, but it inadvertently affects the vibration response of the test article

Engineering Contradiction:

Improvestructural stabilityVSAvoidvibration response interference

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

Segmenting the fixture into multiple members allows the total weight to be reduced while maintaining structural stability through proper distribution of structural functions. Each member provides stability in its specific region without adding excessive weight that would interfere with the test article's vibration response.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different members are designed with different natural frequencies and structural properties appropriate to their specific locations and functions. This local optimization ensures each member provides necessary structural stability while minimizing the overall impact on the test article's vibration characteristics.

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS11774319B2Method of designing a fixture for a vibration testing system and a vibration testing system having the test fixture

Publication Date: 2023.10.03 THE BOEING CO

AI summary

A method of designing a test fixture configured to mount to a vibration slip table and fix a test article to the vibration slip table during a vibration test includes performing finite element analysis using one or more boundary conditions determined from parameters of the vibration slip table, the test article, or the vibration test to optimize a topology of the test fixture, and outputting a geometric model of the test fixture having the optimized topology. Another method of designing a test fixture includes inputting the one or more boundary conditions into a topology optimizing solver. A vibration test system includes a test fixture designed according to the method.