Perform In-house DFAN Test for Customer Flight Hardware

30 Neutrons™, 10x3 configuration on a 14.5' internal diameter

Tight Schedule and Challenges with Reverberant Chamber Lead Customer to ARS

Challenge

The customer has a very high 149dB OASPL profile with demanding 1/3Oct band requirements, the object is a little small and instrumentation, hardware installation and data acquisition are required.

Approach

To maximize system output capability, Neutrons™ configured in tightly packed arrangement. This increases the acoustic power density and enables higher OASPL capability while still utilizing uncorrelated drives to maintain acoustic uniformity. The full-range Direct Field Acoustic Testing (DFAN) capability of the Neutron ensures that all frequencies are properly represented and the system is driven in a fully optimized fashion. Bare chamber testing is performed to ensure that field uniformity meets or exceeds all customer requirements at the 0dB test level. Full level maintained for 60 seconds with no degradation in system performance or damage to the acoustic test system. Due to Neutron’s purpose-built construction, the legacy requirement from testing with line array systems of a 6′ distance from the sound generation source to the unit under test has been reduced, and test configuration could be built much more efficiently and tightly to ensure maximum SPL and uniformity around the unit under test. ARS provided four tri-axis accelerometers and 17 single-axis accelerometers to meet the customer’s test requirements. ARS staff technicians performed the installation, tap checks, and de-installation of all sensors under direct supervision of the customer. The acoustic test controller and data acquisition system came from ARS’s in-house inventory. We provided 12 acoustic outputs, 16 channels of inputs for microphones in the acoustic field, and 29 channels of inputs for customer sensors. All test information was recorded to a single system, and both ARS and customer analysts were provided with complete time history files for all inputs, with microphones and accelerometers all synchronized due to the use of a single combined test control + data acquisition system. ARS provided office space and working areas for customer representatives, and analysts were able to process data onsite in parallel with ARS to minimize the time between test runs and maximize opportunities to review and validate the test data between both the customer and ARS.

Results

The test ran successfully and met or exceeded all the customer’s requirements for both test articles provided. The test was completed ahead of schedule, and the customer saved significant time over their planned schedule that would have utilized a reverberant chamber. ARS’s in-house test technicians supported the installation of the test fixture, flight hardware, instrumentation, and the de-installation and packing of the units after testing was complete. ARS’s data analysis team provided complete time histories for all sensors, as well as our own set of highly detailed plots for validating the uniformity and diffusivity of the acoustic field.

Specifications

Neutron configuration

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