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The Acoustic Modal Method
The Acoustic Modal Method
A next-generation solution that uses acoustic energy to excite the structure, no mechanical contact required, while seamlessly integrating with your existing in-situ acoustic test configuration.
What is the Acoustic Modal Method?
The Acoustic Modal Method is a state-of-the-art technique for performing full modal analysis on sensitive aerospace structures where mechanical contact or suspending modal shakers introduce unnecessary risk. The ARS Neutron’s unique capability to generate a uniform, uncorrelated acoustic field enables safe excitation of the structure and yields high-fidelity estimates of critical modal parameters.
This method reduces risk and complexity across hardware, schedule, and cost by eliminating mechanical interfaces and the need to ship the test article, removing the requirement for shaker installation or modifications to the acoustic test setup, and enabling the collection of high-fidelity modal parameters with minimal incremental cost.
Our Strategic Partnership
We are proud to introduce the Acoustic Modal Method in collaboration with our partner, ATA Engineering. This partnership brings proven expertise across modal pre-test analysis, test execution, and post-test parameter estimation – providing confidence that comes from working with established industry leaders in modal analysis.
Our Approach
Sierra Space / Shay SaldanaIn addition to providing a non-contact, uniform, and uncorrelated acoustic excitation field, the ARS Neutron™ offers the following advantages for modal testing:
Low-frequency capability: Acoustic excitation enabling modal parameter estimation down to 2 Hz.
Mode separation: Independent sources that allow resolution of closely spaced modes.
High-quality FRFs: Independent control voltage signals that serve as reference inputs for clean, well-conditioned FRF matrices.
Predictability: A high-fidelity source model that supports accurate pre-test simulation of the test article response and optimal accelerometer placement.
Key Benefits
Non-Contact Testing
In-situ acoustic modal testing significantly reduces hardware risk for sensitive aerospace structures. The test is performed at your production facility and requires no mechanical interfaces or physical contact with the test article.
Flexible Excitation
ARS Neutrons provide flexible acoustic excitation that enhances modal testing. Excitation levels can be varied to assess modal damping sensitivity, and spatial excitation patterns can be adjusted to preferentially excite fundamental modes of interest.
Cost-Effective Solutions
The Neutron™ system enables multiple dynamic tests to be performed in situ using a single test configuration. This integrated approach significantly reduces overall test campaign cost by eliminating the need to set up and execute multiple independent tests.
Seamless Integration
The Neutron™ system enables modal testing to be conducted concurrently with Direct Field Acoustic Noise (DFAN) testing, compressing overall test campaign schedules and minimizing disruption to production activities.
Key Differentiators
Sierra Space / Shay SaldanaFixed-Base Correction Methods
When access to a seismic mass is impractical, ATA Engineering’s Fixed-Base Correction (FBC) method can be incorporated into the modal test approach. The FBC method does not require direct contact with the test article. Instead, modal shakers excite the flexible base supporting the test article, and the resulting base motion is removed through post-processing. This produces experimental modal analysis results that are effectively “fixed-base,” enabling more direct comparison with numerical modal analysis. When acoustic excitation and the FBC method are employed in a modal test, the excitation mimics loads the test article will experience through the launch sequence.
Sierra Space / Shay SaldanaAcoustic Excitation
ARS’s innovative use of non-contact acoustic excitation differentiates it from traditional modal excitation methods that require mechanical contact with the test article.
Sierra Space / Shay SaldanaCapability to Excite Lower Frequencies
The Neutron™ acoustic device has demonstrated the ability to excite test article responses down to 2 Hz for modal parameter estimation. This unique low-frequency capability provides sufficient bandwidth to support experimental modal analysis for a wide range of aerospace test programs.
Sierra Space / Shay SaldanaExpert Collaboration with ATA Engineering
Our strategic partnership with ATA combines the modal analysis expertise of a respected industry leader with ARS’s innovative acoustic excitation capability. ATA’s deep experience in pre-test simulation, test execution, and post-test analysis provides high confidence in critical modal parameter estimates.
Have Questions?
Contact us today to discover how ARS elevates mission-assurance dynamic testing for your programs.
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