Innovation in Spacecraft Testing: Direct Field Acoustic Testing (DFAT) Explained
MSI - DFAT SERVICES, LLC
The portable acoustic test facility for the space industry.
Time for a pop quiz! How many decibels (dB) is a rocket launch????
The external noise environment of a rocket launch can easily exceed 220 dB. That is an extremely harsh, high-intensity, violent noise environment!????????????
Sound energy at this level is not only hazardous, but it creates an unstable environment in which to launch expensive and mission-critical rockets and payloads. That is precisely what rocket scientists prefer to avoid at all costs!????????
Think about it… should any satellites, rovers, telescopes, space stations, or landers be launched without verifying that they can hold up to these kinds of extreme noise environments??
Definitely not!??
Even at much lower noise levels, workmanship testing is used in order to ensure that structural and electronic components can withstand the noise and vibrations during the launch journey. At higher levels, it is a mission-critical qualification requirement. Acoustic testing is thus mandated by the space agencies and launch authorities.?
Payloads are commonly placed at the top of the rocket, housed in a “protective” fairing. However, this housing is not enough to guarantee total protection of the delicate structural and electronic components from the harsh launch conditions. Engineers are therefore required to perform extensive vibroacoustic testing prior to launch to understand if the payload can survive the vibroacoustic loads.?
Until recently, traditional methods of acoustic testing, such as Reverberant Field Acoustic Noise (RFAN), have long been the gold standard. However, these traditional methods come with hefty price tags and inefficient logistical challenges. For example, as acoustic qualification tests are infrequently conducted, these expensive rooms often sit unused and idle, representing wasted investment and operational cost for the building owner, and increased cost of testing to the customer.??
While these rooms provide very reliable acoustic testing results, they are extremely expensive to build, operate, and maintain. If a company does not have these facilities, they must move the spacecraft to an available reverb chamber - in some cases even to a competitor’s location! - which adds to the cost, complicates the logistics, and increases the chances of damage to the spacecraft or payload.?
Enter Direct Field Acoustic Testing (DFAT) - a revolutionary acoustic testing method that offers a cost-effective alternative with impressive results, in a mere fraction of the time.?
Direct Field Acoustic Testing, as invented and pioneered by MSI DFAT, involves subjecting spacecraft and their components to the direct sound field of loudspeakers. This method simulates the intense acoustic environments experienced during rocket launches, providing invaluable insights into a payload's resilience. DFAT is much more cost-effective and time-efficient than any other acoustic testing method.??
The Business Case for Direct Field Acoustic Testing
Cost-effectiveness: Unlike traditional reverberant chamber testing, DFAT can be conducted in ordinary rooms, using specially-designed state-of-the-art loudspeakers and amplifiers.??
It is important to note that no special facilities are required, but commercial-off-the-shelf loudspeakers cannot be used. This is because COTS loudspeakers cannot meet the frequency ranges and loudness required to successfully replicate rocket launch environment conditions experienced inside of the fairing.??
DFAT translates to significant cost savings for companies, eliminating the need for expensive testing facilities. Take for example, transporting a satellite from Colorado to traditional reverberant chamber facilities located far away in Ohio or Washington. This distance is thousands of miles and represents significant wasted cost and wasted time in a qualification testing program.?
Portability and Convenience: DFAT setups are highly portable, allowing for flexibility in spacecraft scheduling and testing locations. With the ability to truck speakers and audio equipment to different sites, companies can streamline their testing processes without compromising on accuracy.?
Precise Noise Control: Modern Direct Field noise testing methods utilize a closed-loop Multiple Input Multiple Output (MIMO) random control algorithm to ensure the accuracy and uniformity of the acoustic environment. This precise control mechanism, coupled with advanced simulation tools like Siemens Simcenter 3D, ESI VAOne, or Dassault Systems Wave6, optimizes testing parameters and minimizes the risk of structural damage. In other words, a digital twin of the entire DFAN test can be conducted prior to running the real-world experiment.?
Versatility: Beyond spacecraft testing, DFAT can also be applied to assess the acoustic resilience of various systems, from high-performance aircraft payloads to internal material bays subjected to jet noise. Its adaptability makes it a valuable tool across multiple industries from space, to aircraft, or defense applications.?
?Key Considerations Prior to Conducting DFAT?
While Direct Field Acoustic Testing offers numerous benefits, its effective implementation requires addressing key challenges, which can only be accomplished by leveraging teams of highly skilled, knowledgeable and experienced engineers. Fortunately, to date, MSI DFAT has successfully qualified over 200 spacecraft and satellites!??
Think about the considerations that go into setting up and running such an experiment:?
?? How many speakers are required??
?? How should the speakers be configured??
?? How many control microphones are required??
?? Where should the microphones be placed??
?? How can the noise profile be safely generated and controlled??
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?? How can the responses be accurately measured and interpreted??
If these are not answered before testing begins, engineers may discover that there is not enough acoustic energy due to too few speakers. Alternatively, they may find out that they invested time and budget into too many speakers.???????
DFAT-as-a-Service ??
DFAN can also be a costly endeavor, particularly since it is not a system that most companies will use every day. Therefore, it is often safer and more cost-efficient to procure DFAN testing as a service. DFAT-as-a-service frees up valuable engineering time for space companies. It spares companies the cost of investing time and budget into a DFAN system.?
As part of this DFAT-as-a-service offering, MSI DFAT Services provides:?
??All aspects of speaker array set up and tear down, including configuration pre-check and rigging, utilizing our state-of-the-art designed and manufactured loudspeaker and amplifier systems?
??DFAT-experienced personnel ready to support different system configurations and test requirements?
??A state-of-the-art true narrowband MIMO random control system (acoustic noise control module)?
??Increased test efficiency and safety (risk mitigation) based upon numerical pre-test analysis?
??Collection of pressure, accelerometer and/or strain gauge responses?
??Hardware and software safety shutdowns for UUT protection?
??Real-time onsite concurrent data processing and analysis of both time history and frequency data?
??Thousands of channels of data acquisition hardware and transducers??
??Insights into the dynamics of the UUT by performing operational modal analysis (OMA)?
DFAT Equipment System Sales & Maintenance
Alternatively, some companies may prefer to invest in developing their in-house capabilities, knowledge, and resources for conducting acoustic testing and analysis internally. In this case, MSI DFAT also designs, manufactures and supplies state-of-the-art Noise Generation (NGS) and Control (NCS) systems to customers for outfitting their environmental testing lab facilities.??
MSI DFAT also provides expert consulting and training services and masterclass education sessions so that engineers can learn how to safely and effectively perform their own Direct Field Acoustic Experiment (DFAX).?
Numerical Pre-test Analysis for Optimal Test Setup Configuration?
Using Siemens Simcenter 3D, Dassault Systems Wave 6, or ESI VAOne, simulation experts can determine the appropriate speaker and microphone configurations to meet Unit Under Test (UUT) acoustic loading requirements. This includes the speaker arrangement, position of the test item, and reflectors as needed. Pre-test analysis helps improve the uniformity of the acoustic field.??
Setting this up in simulation reduces the number of iterations that would need to be done through physical testing, which significantly reduces the time and cost of DFATing. Determining the ideal number and configuration of loudspeakers and microphones is crucial for achieving uniform field distribution.?
Simulation tools aid in pre-test analysis, guiding engineers in optimizing test setups and mitigating risks. Understanding the influence of room acoustics on the generated sound field is essential for accurate testing. Advanced simulations can also help predict room effects, ensuring test environments meet desired specifications.??
Finally, to de-risk tests and predict performance accurately, digital twins of DFAT setups can be created using simulation software. These virtual models enable engineers to anticipate structural responses and ensure test success.?
Looking Ahead
As the space industry continues to evolve, DFAT stands at the forefront of innovative testing methodologies. To delve deeper into this groundbreaking technology, industry professionals can participate in upcoming DFAT masterclasses, where leading experts provide insights and practical demonstrations.?
We invite you to join us for the 1st ever DFAT Masterclass in the USA on October 29-31 2024 at Dayton T. Brown, Inc. in Long Island, NY, USA! ??????
Register at https://resources.sw.siemens.com/en-US/aerospace-defense-direct-field-acoustic-testing-2024???
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Launching things into space??
?? Contact us for assistance at [email protected]?
?Dr. Alex Carrella?& Bradley Hope?
Business Development?
MSI DFAT Services, LLC?
4900 Wetheredsville Rd., Baltimore, MD 21207?
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Program Manager at CEB metaSystems
4 个月It’s also important to highlight that performing DFAT testing on-site reduces risk by eliminating the need to transport the satellite/hardware, thereby minimizing potential damage and logistical challenges associated with moving delicate equipment.