Operational Vibration Testing: The Development of a Test Setup for Operational Vibration Testing

Kurzfassung

Aerospace systems are subjected to environmental conditions with broad range of characteristics in terms of vibration. To ensure that launcher systems operate reliably throughout the mission, it is important to test them in representative environments prior to flight. All launcher systems undergo a series of tests to expose them to different elements of the operational environment, such as thermal and vibration tests which are prescribed by industry standards.

To simulate the launch conditions as accurately as possible, it has become of interest to test systems in controlled vibration environments. Commonly, systems are tested to verify their survivability for external vibrations. However, launcher systems need to both survive and operate in the vibration environment. To predict the behavior of the System Under Test (SUT) an operational vibration test campaign can be conducted for which a dedicated setup needs to be developed. During testing, it is required to characterize the response of the setup to predict the vibrational environment that the SUT will experience, given a vibration excitation to the setup.

This thesis describes the design, development, and verification of a novel test setup for vibration testing. The setup is developed for the Institute of Space Systems at the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt, DLR).

The setup needs to ensure a controlled environment to the SUT without distortions to prevent under- or overtesting of the SUT. As a result, the setup has to ensure a transmissibility close to unity of vibration from the shaker to the SUT. The setup was assembled and a vibration test campaign was carried out during which the frequency response of the setup was determined. The design of the setup evolved over three prototypes in an attempt to comply with stringent requirements regarding the transmissibility of vibration.

The operational vibration testing capabilities are a valuable asset for DLR’s Institute of Space Systems, regarding the development of future products. The methodologies, test procedures, and data analyses described in this thesis function as an example and can be carried for further testing and setup development.