STP-H5-Structural Health Monitoring (STP-H5 SHM) - 12.13.17

Overview | Description | Applications | Operations | Results | Publications | Imagery

ISS Science for Everyone

Science Objectives for Everyone
Satellites and space cargo are subjected to intense shaking and extreme temperatures during launch and arrival in low-Earth orbit, and commercial off-the-shelf equipment is not designed to withstand these physical challenges. The Space Test Program-H5-Spacecraft Structural Health Monitoring investigation (STP-H5 SHM) captures how the fasteners, glue and mechanical parts on the Space Test Program equipment change from its assembly, testing and arrival in orbit. Results provide new methods for determining various ways in which equipment fails, from bolts that have jostled loose to debris impacts.
Science Results for Everyone
Information Pending

The following content was provided by Derek Doyle, and is maintained in a database by the ISS Program Science Office.
Experiment Details

OpNom:

Principal Investigator(s)
Derek Doyle, Air Force Research Laboratory, Space Vehicles Directorate, Kirtland AFB, NM, United States

Co-Investigator(s)/Collaborator(s)
Information Pending

Developer(s)
Air Force Research Laboratory (Kirtland AFB), Albuquerque, NM, United States
JSC Engineering Directorate (ES), Houston, TX, United States
METIS Design Corporation, Boston, MA, United States

Sponsoring Space Agency
National Aeronautics and Space Administration (NASA)

Sponsoring Organization
Technology Demonstration Office (TDO)

Research Benefits
Scientific Discovery, Space Exploration

ISS Expedition Duration
September 2016 - February 2018

Expeditions Assigned
49/50,51/52,53/54

Previous Missions
None.

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Experiment Description

Research Overview

  • The research provides Air Force Research Laboratory (AFRL) a metric for the utility of Space Test Program-H5-Spacecraft Structural Health Monitoring investigation (STP-H5 SHM) to track change on a relevant spacecraft through a real integration procedure and degradation of the hardware in a relevant environment.
  • Logistical and performance metrics are identified into the true impact of integrating an SHM setup onto a spacecraft and the level of detail possible for inspection given a minimum number of sensors. Commercial-off-the-shelf (COTS) hardware are assessed for reliability in a harsh operating environment for long term performance changes that may impact scientific results. AFRL is working towards making all measured data available to academic partners for evaluating various SHM techniques.
  • Spacecraft Structural Health Monitoring (SHM) may prove to provide a higher level of detail for anomaly resolution based on mechanical issues (loose bolts, bad thermal interfaces, poor adhesive bonds, etc.) that may occur during the assembly, integration and testing operations to on-orbit missions. The ability to compare changed states with a known 'healthy' baseline may give technicians added assurance to the quality of the overall system from a structural perspective. For example, when a spacecraft is hit by orbital debris, the difference in electrical charges of the two bodies may cause some electrical upset to some subsystem. Ground personnel may have to put the system in a safe mode to diagnose all systems to ensure safe operational parameters. SHM, if operational at the time may be able to detect the impact event or if turned on after the impact, can detect the location of the impact on the structure allowing ground support to quickly isolate the source of the event that caused the anomally and save weeks of diagnostic exercises.

Description
The principal objective of the Space Test Program-H5-Spacecraft Structural Health Monitoring investigation (STP-H5 SHM) is to demonstrate SHM utility on a spacecraft prior/during/after system launch. All data is collected and inventoried in such a way that distribution is possible to SHM collaborators to investigate alternative approaches. Of specific interest with this experiment is collection of guided wave measurements as structural mates are made and preload applied to the monitored plates (base and bunker walls). Changes are tracked and monitored for detection resolution and reliability. Additionally, final assembly health is checked during environmental testing to capture changes to the loading profile on the plates. Once on orbit, the boundary conditions of the spacecraft are regularly inspected for deviations under space environmental loading and hardware reliability is tracked. The hardware uses piezoelectric wafer active sensors (PWAS) to serve as the SHM transducers. Each PWAS transfers electrical signals to mechanical displacements (and vice versa) to create guided ultrasonic waves. These waves reflect features in the structure and the wave information is used to track changes. Additionally 3 tri-axial accelerometers are used to monitor low level dynamics of the payload at its mounted position on ISS.

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Applications

Space Applications
This investigation’s main goal is to demonstrate the usefulness of monitoring a spacecraft’s structural health before, during and after launch. Studying physical changes at every stage can help engineers determine how and where equipment fails, and how to prevent future failures that can jeopardize a spacecraft’s health. This information can also identify structural changes that happen over time or are related to a catastrophic event, such as a debris impact or extreme temperature variation.

Earth Applications
Engineers can use structural health monitoring techniques to study sensitive equipment throughout the assembly, integration and testing processes, and detect changes in a structure at any stage of development. This benefits a wide range of technologies used on Earth, from computer processors to robotics to medical devices.

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Operations

Operational Requirements and Protocols

The STP-H5 hardware complement is installed with the Space Station Remote Manipulator System (SSRMS) and activated via ground based commands. Instrument health, status and operational data are downlinked via standard ISS 1553 communications protocols.

Measurement setups can be provided to the Principal Investigator to setup and execute. Parameters of interest for Guided Wave tests include frequency, steps, step size, measured time, averaging, gain, chirp setup. Accelerometer measurements can be varied by the sampling rate and number of measurement points recorded per interval.

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Decadal Survey Recommendations

Information Pending

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Results/More Information

Information Pending

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Related Websites

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Imagery

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NASA Image: ISS050E052652 - Space Test Program-H5 (STP-H5). Photo taken during Expedition 50.

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