Thesis Type: Doctorate
Institution Of The Thesis: Middle East Technical University, Faculty of Engineering, Department of Mechanical Engineering, Turkey
Approval Date: 2004
Thesis Language: English
Student: Canan Yılmazel
Supervisor: YAVUZ SAMİM ÜNLÜSOYAbstract:
Statistical Energy Analysis (SEA) is one of the methods in literature to estimate high frequency vibrations. The inputs required for the SEA power balance equations are damping and coupling loss factors, input powers to the subsystems. In this study, the coupling loss factors are derived for two and three plates joined with a stiffener system. Simple formulas given in the literature for coupling loss factors of basic junctions are not used and the factors are calculated from the expressions derived in this study. The stiffener is modelled as line mass, Euler beam, and open section channel having double and triple coupling. Plate is modelled as Kirchoff plate. In the classical SEA approach the joint beam is modelled as another subsystem. In this study, the beam is not a separate subsystem but is used as the characteristics of the joint and to calculate the coupling loss factor between coupled plates. Sensitivity of coupling loss factors to system parameters is studied for different beam approaches. The derived coupling loss factors and input powers are used to calculate the subsystem energies by SEA. The last plate is joined to the first one to simulate the fuselage structure. A plate representing floor structure and acoustic volume are also added. The different modelling types are assessed by applying pressure wave excitation. It is shown that deriving the parameters as given in this study increases the efficiency of the SEA method.