Prediction of Acoustic Natural Frequencies for two dimensional simplified aircraft cabin by Impedance Mobility and Compact Matrix(IMCM) approach

Prediction of modal characteristics of acoustic cavities with irregular shapes is an important topic in vibro-acoustic analysis of systems. In this paper, proposed method of impedance and mobility compact matrix (IMCM) provided the approach of Integro Modal Method (IMM) in the matrix form for prediction of modal characteristics of acoustical cavities with irregular shape. This method, consists of discretizing the whole cavity into a series of sub cavities either regular or irregular cavities. Acoustic pressure in regular sub cavities has been decomposed over a modal basis and for irregular sub cavities over that of bounding surface. Continuity of both pressure and velocity between adjacent sub cavities is ensured using a membrane with zero mass and stiffness. This method aims to develop a physical basis rather than a numerical approach. Mathematical formulation of the method has been explained in detail. Coupling equations being in a matrix form, so, it is easily solved using numerical methods in computer. The current approach is demonstrated by considering two dimensional simplified aircraft cabin as an irregular cavity. Predicted natural frequencies of the simplified aircraft cabin based on the proposed method have been compared with the available results in the literature and are in good agreement.