Bracket System Dynamic Modification and Vibration Isolation Design

In the process of civil aircraft development, the design requirements for the vibration tolerance of onboard equipment are higher than the standard values, while in fact, the input spectrum of the supplier's environmental test is smaller than the standard spectrum in the specification. In order to meet the vibration environmental test requirements, appropriate vibration isolation design need to be taken before the mounting of the bracket. Taking a certain type of bracket as the research object, this paper conducts modal model correction based on the sweep test data. The corrected modal frequencies and peak residuals are within 5%. Then, the vibration isolation design is carried out by adding isolators and sticking damping layers at the connection between the bracket and the fuselage, which proves that the vibration isolation measures are effective, as the simulated random response after isolation is lower than the standard spectrum by 20dB.