Acoustic fatigue test booth for satellites
In collaboration with Marseille's Mechanics and Acoustics Laboratory, Le Mans Acoustique designed an acoustic fatigue test booth dedicated to satellites. Compared to existing test methods, the main advantage of the solution is its repeatability and the simplicity of the analysis, especially when a series of satellites of the same constellation need to be tested.The unit has been installed in ThalesAleniaSpace’s set-up plants in 2010 and has tested 40 satellites today in orbit.
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Once they are assembled, satellites must undergo an acoustic fatigue test to guarantee that they will support the very high noise levels generated during launch. More specifically, the aim is to test components that were not tested when assembled, and to verify that the assembly won’t be damaged during the launch.
Le Mans Acoustique designed a test booth that can generate a spatially homogeneous pressure field, overall greater than 143 dB. The booth is 40 m3 and is equipped with 95 electroacoustic sources placed on the walls.
This allows to generate an homogeneous acoustic field around the satellite.
The test booth is composed of a rigid ground, able to withstand the weight of the satellite, and walls fitted with 51 cubic boxes, each able to host 2 electroacoustic sources. The 2 “active” walls are slightly tilted so that there is no pair of parallel walls.
63 microphones are placed on a grid inserted between the external surface of the satellite and the internal walls of the booth: this grid therefore represents a 3D surface able to control the booth pressure.
The frequency range covered spans from 31Hz to 8kHz.
This test device could be used in sectors where the resistance of component assemblies to vibrations needs to be tested. Aeronautics, as well as the rail and automotive sectors are therefore of interest.
Innovations & Advantages
This non conventional and innovative solution originated from several requirements :
- Very high cost and time constraints
- Need to benefit from a test device placed inside the integration and test hall (cleanroom class 100 000)
- Need to benefit from a test device that is low-volume, dismantable, transportable and can meet frequency of use requirements (1 test per week), as well as other requiremenst such as operability, safety and maintenance.
This booth allows creating an acoustic environment close enough from classical means, both in terms of spatial homogeneity and spectrum. It is therefore considered a common referencial.
Compared to classical test methods, this method is highly repeatable and stable, an advantage when a series of satellites from the same constellation have to be tested. Moreover, these specificities greatly simplify the analysis job, allow to easily identify non-conventional behaviours and speed-up the test sequences.
Finally, almost no maintenance is required and a single operator is needed to carry on the test.
Current and Potential Domains of Application
The test booth is currently used for the testing of satellites component assemblies. It could be used in other sectors where the resistance of components assemblies to vibrations needs to be tested. Aeronautics, as well as the rail and automotive sectors are therefore of interest.