Hybrid characterization of engine isolator and its application to cabin noise studies.

Abstract

Aircraft companies typically build a global acoustic model of the aircraft, engines, and engine attachments, which would allow for prediction of cabin noise related to engine operating conditions up to 500 Hz. The objective of the hybrid characterization method is to provide a matrix of stiffness (or mobility) for an isolator over a broad frequency range which is suited for use in the global model. The method is called “hybrid” because it aims at aligning viscoelastic material test data, isolator shaker testing, and a detailed finite element model. The result is a six degrees of freedom matrix of translational, rotational, and cross coupling terms for the engine attachment. This paper covers a case study showing how this method was used for the engine attachments on a business jet aircraft.