Vibration Qualification Test of an Aircraft Piccolo Tube Using Multiple-Input-Multiple-Output Control Technology

摘要

Wing Anti-Icing Systems (WAIS) are integral part of a wing design. Their presence ensures safety in all-weather conditions. In standard designs, the WAIS are fitted in the slat internal structure and runs throughout its span in between the ribs. Given its critical function, such a system has to pass qualification test. The test specification is dictated by international standards. In the case discussed in this article, the standard adopted is the RTCA DO-160G "Environmental Conditions and Test Procedures for Airborne Equipment". In particular, the work presented here concerns with the Vibration environmental test. The standard prescribes a number of dynamic tests to be carried out on the AIS: random, shock and sine excitation tests have to be performed in order to study their effect on the parts composing the Anti-Icing System. The standard prescribes vibration levels at the attachment locations of the AIS to the wings' ribs. However, one issue specific to the anti-icing system is its dimension. As previously said, this runs the wing span which makes it a very slender body (length than cross-section area). Each part of the system is long over 3m. At the same time it has a very light weight. Such a flexible structure becomes very cumbersome to excite with a single shaker setup. And even bigger problem is to ensure a uniform excitation level at the attachment points. In order to overcome such difficulties, it is shown here that it is possible to test this system using Multiple-Output-Multiple-Input technology to ensure that each excitation point is appropriately excited. In this case five exciters (shakers) have been mounted at the 5 locations where the loads are transmitted to the structure (through the wings' ribs). The amplitude levels are maintained at the prescribed levels using a state-of-the-art MIMO closed loop control technology. The results show that the system has been exposed to the right level of vibration at each location reducing drastically the uncertainties related to its operational exposure to both ordinary (e.g. Ground-Air-Ground) and extra-ordinary (e.g. FBO) vibratory loads.