P17341: Harris Near-Zero CTE Test Apparatus
/public/

Problem Definition

Table of Contents

Team Vision for Problem Definition Phase

Project Summary

Our team has been tasked with designing an improved coefficient of thermal expansion (CTE) tester for Harris Corporation. Harris' Precision Structures division utilizes advanced materials to design and fabricate stability-critical structures that operate on orbital satellites. Satellites are subjected to a wide range of temperatures while in orbit. Solar radiation provides large inward thermal flux on its day-facing side, while the satellite loses heat by radiation to the surrounding interstellar medium on its night-facing side. Stability of structures is critical to ensure that precision optics employed in geospatial imaging maintain focus and calibration, even across the wide range of temperatures the device must undergo while in orbit. Thus, it is crucial that the materials used on these orbital satellites must deform as little as possible under the influences of changes in temperature. This translates as possessing a near-zero CTE, and Harris develops and utilizes a variety of materials that fulfill this requirement.

Harris is interested in pursuing new technology to measure CTE on material samples here on the ground. Current methods of CTE measurement involve one of three main methods to accurately measure sample deformation under an applied range of temperature. These methods are: linear variable differential transformer (LVDT) technology, capacitive sensing, or laser interferometric sensing. However, the theoretical accuracy of these technologies is limited by errors and uncertainties inherent in the test setup. Mechanical error, introduced by the test fixturing, may deform the sample unduly or not allow it ample room to freely expand. Electrical error is introduced as uncertainty in the sensors themselves and noise in the data collection process. Environmental error is the final concern, referring to external factors interfering with the testing, such as vibrations, air currents, or unwanted temperature changes. Our team is working on a new type of fixturing that isolates the sample by magnetic levitation. The intention of this setup is to minimize error due to mechanical and environmental interference, while controlling electrical error as best we can.

We will investigate the feasibility of using magnetic levitation (maglev) to suspend a sample piece, and design and build a proof-of-concept test fixture to hold and measure the sample, even if the proof-of-concept piece is not necessarily a precision instrument the likes of those mentioned above. Our final design documents will include a comprehensive analysis of the errors and uncertainties in our design, including how expansion of individual subsystem components affects final measurements. Additionally, we intend to provide an engineering comparison to the legacy state-of-the-art test equipment currently in use at Harris and elsewhere.

Looking towards the future, there is still room for the project to grow after our team's involvement in Multidisciplinary Senior Design I&II is concluded. Harris intends to use our project documentation to draft a proposal for a precision build of a maglev tester. Harris also plans to patent the technology; the company will own the patent, but all team members and relevant parties will be credited in its authorship.

Stakeholders

Use Cases

The use of the maglev system is as follows:

Operator: Trained engineer/test technician

Use Case

Use Case

Project Goals and Key Deliverables

Communication with Harris has led to the development of following project deliverables to be present at the end of MSD II:
  1. Provide a proof-of-concept maglev system that stabilizes a sample coupon.
  2. Design custom maglev clamps for the sample coupon, possibly compatible with different size/shape samples.
  3. Choose an "off the shelf" chamber or design a chamber with appropriate dimensions for the system.
  4. Develop an error analysis for the maglev system.
  5. Provide documentation supporting our error analysis, as well as, design and functionality of the maglev technology.

Customer Requirements (Needs)

Customer Requirements

Customer Requirements

Outputs and Destination

To access the most recent copy of the Requirements & Testing document, which includes Customer Requirements, Engineering Requirements, and more, click here.

Engineering Requirements (Metrics & Specifications)

Engineering Requirements

Engineering Requirements

Constraints

House of Quality

House of Quality: CRs vs. ERs

House of Quality: CRs vs. ERs

Risk Management

Risk Assessment

Design Review Materials

Maglev Simulation demo: /public/Problem Definition Documents/Magnetic Levitation Response Demo.docx

Plans for next phase


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