Bracket design and natural frequency analysis of civil aircraft inertial reference unit

Abstract

The Inertial Reference Unit (IRU) is an important and indispensable airborne equipment for civil aircraft, which is used to provide information on aircraft attitude, heading, acceleration and so on. The design of its bracket will directly affect the signal accuracy of the equipment. In order to ensure the accuracy of the information of the measuring equipment, the stiffness design of the support has strict requirements to avoid the impact of vibration and elastic deformation on the accuracy of the output signal. Through theoretical formula derivation and finite element analysis, this paper summarizes the influence of different bracket structure forms on the natural frequency and obtains the scheme to improve the natural frequency of the bracket. By increasing the flange height, adjusting the lightening hole on the plane mounting plate of the bracket and making the plane mounting plate, frame and skin form a box-shaped structure, the torsional stiffness of the bracket is enhanced. The results show that the improved bracket meets the requirements of natural frequency which is greater than 110 Hz, which can provide a reference for the design and strength analysis of similar aircraft airborne equipment.