Gap SHFE-HAB-01: What validated acoustic model can predict the effects of structures, materials, crew and equipment on the acoustic environment of a spacecraft or habitat? (CLOSED)
Last Published:  07/31/19 10:05:30 AM (Central)
Responsible Element: Space Human Factors and Habitability (SHFH)
Status: Closed
Closure Rationale

The NASA Human Research Program (HRP) Space Human Factors and Habitability Element (SHFH) manages a research portfolio related to characterizing and mitigating five human health risks, including the Risk of Incompatible Vehicle/Habitat Design (“HAB”). One of the identified research gaps for this risk, SHFE-HAB-01, reads: “SHFE-HAB-01: What validated acoustic model can predict the effects of structures, materials, crew and equipment on the acoustic environment of a spacecraft or habitat?”

This knowledge gap addresses the need to characterize the unique acoustic characteristics, and environmental systems which produce non-trivial levels of noise in spacecraft and habitats by using acoustic modeling.  Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and predict vehicle noise levels at various stages in vehicle development, first with estimates of noise sources, later with experimental data.

Data contained in the Flight Crew Integration (FCI) ISS Crew Comments Database indicate that ISS crews rely heavily on auditory information and warnings on-orbit which may be impacted by noise interference. While noise exposure is an aspect of all living and working environments, the continuous nature of noise exposure from constant sources such as air handling equipment results in a relatively higher noise dosage for crews. Crew health hazards of most concern are temporary or permanent hearing loss, though other effects can be significant.


The Acoustics Modeling Task completed all of its aims, contributing to closure of the HAB-01 acoustic model gap as written. A modeling methodology was developed that can be used to create quieter space vehicle environments for Orion as well as Commercial crewed vehicles, and the model was delivered to the Multi-Purpose Crew Vehicle (MPCV) Orion Cockpit Working Group (CWG) and Lockheed Martin Acoustics team.


The acoustic model used commercial-off-the -shelf modeling software, VA One from ESI Group, to demonstrate the development of spacecraft cabin Statistical Energy Analysis (SEA) acoustic models and validating the accuracy of the models in predicting Sound Pressure Levels (SPLs) using acoustic mockups (e.g., ISS US Lab and Orion Crew Module configuration 606c) with incrementally increasing model fidelity. The developed models were used to show:

  • the effect of source location on the accuracy of the model predictions with highly absorptive mockup interior
  • appropriately subdivided SEA cavities for modeling the SPL distribution in a large mockup with a highly absorptive interior
  • prediction of the effectiveness of noise control treatments, including sound absorption material for cabin SPL reduction and sound blocking material for sealing gap and preventing ECLSS noise leaking into cabin
  • various methods for modeling the effects of noise control treatments
  • the accuracy of SEA models in SPL predictions

Acoustic modeling was performed for Orion Crew Module version 606c, and jointly, along with Lockheed Martin, for versions 606g, and 606h. In addition, model validations were performed on an acoustic model of the Orion Acoustics Mockup, which was built by this project for the purpose of validating Orion acoustic models. Comparisons between the model and measurements inside the mockup were within 3 dB for many different configurations, validating the approach. Finally, acoustic materials testing, including absorption and transmission loss testing, was performed on various materials and used in both Orion and Acoustic Mockup models to predict effects of candidate noise treatments. Noise controls that were validated included the sealing of gaps around the Environmental Control and Life Support (ECLS) wall, and transmission loss through the ECLS wall with application of various absorptive treatments on various surfaces.


Based on the work performed, inputs were made to the Orion CWG and Lockheed Martin Acoustics team that was set up to investigate System Level noise treatments. Recommendations included sealing the gaps around the ECLS wall and with the use of absorbent acoustic blankets on portions of the ECLS wall, storage locker closeouts, and other areas in the Crew Module (CM). A presentation was made to this CM team regarding the acoustic modeling validation work, including validation of predicted Orion ECLS wall leakage sealing effects. Finally, acoustic requirements for space-vehicles were refined as part of this project. In particular, a requirement devised to protect voice communications was developed, demonstrated, and adopted as part of this project.


In addition to delivering the validated model and recommendations to the MPCV customer, presentations were also made at the 41st International Conference on Environmental Systems, Spacecraft and Launch Vehicle Dynamic Environments Workshop and the NASA Human Research Program Investigators' Workshop.


We believe this task fully addresses the original gap, SHFE-HAB-01, and closes it since it provided the information the stakeholder required/needed. However, structure-borne noise modeling and human acoustic modeling that was not within the scope of the original gap are still in need of development. In addition, there is a need to develop the HIDH Noise Control chapter, and Acoustic Noise Control Plan guidelines/template. These subsequent efforts will now be addressed, based on the SHFE research priorities and funding, under SHFE-HAB-03: “We need to understand how new aspects of the natural and induced environment (e.g., vehicle/habitat architecture, acoustics, vibration, and lighting) may impact performance, and need to be accommodated in internal vehicle/habitat design.”

References

1. Chu SR, Allen CS. "Spacecraft Cabin Acoustic Modeling and Validation with Mockups." 41st International Conference on Environmental Systems, Portland, Oregon, July 17-21, 2011. Paper AIAA-2011-5112. , Jul-2011

2. Dandaroy I, Chu SR. "Cabin Noise Studies for the Orion Spacecraft Crew Module." Presentation at the Spacecraft and Launch Vehicle Dynamic Environments Workshop, The Aerospace Corporation, El Segundo, Calif., June 7-9, 2011.

3. Chu SR, Allen CS. "Spacecraft Internal Acoustic Environment Modeling." Space Human Factors and Habitability Poster Session. NASA Human Research Program Investigators' Workshop, Houston, TX, February 3-5, 2010.


Description
Spacecraft and habitats possess unique acoustic characteristics, and environmental systems produce non-trivial levels of noise.  Acoustic modeling can be used to identify key noise sources, determine/analyze sub-allocated requirements, keep track of the accumulation of minor noise sources, and to predict vehicle noise levels at various stages in the development, first with estimates of noise sources, later with experimental data.  Bench testing of isolated systems alone is not sufficient as the installation effects are often not known.  Acoustic modeling can be used to assist with the development and implementation of spaceflight acoustic materials and to predict their effectiveness including sound containment, absorption and vibration isolation.


Target for Closure
No Target for Closure available.
Mappings
Risk Risk of an Incompatible Vehicle/Habitat Design
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