On the vibration transfer path analysis of aero-engines using bond graph theory

Abstract

Due to increases in fossil fuel prices worldwide, aero-engine manufacturers in the aerospace industry are introducing innovative designs that emphasize mass reduction, improving efficiency and lowering operating costs. However, this phenomenon has increased the exposure of aero-engines to vibration transfer, due to internal excitation loadings produced by issues such as rotor system unbalance. Due to these circumstances and the general advancement of aero-engine design technology, the demand for reductions in interior fuselage noise and vibration has increased. In this research, bond graph transfer path analysis (TPA) is extended to apply to aero-engines, with the goal of analyzing vibration propagation through the aero-engine's structural pathways. Bond graph TPA is a reliable and valuable method that can be utilized to efficiently diagnose and minimize noise and vibration problems during the design phase, prior to prototyping. One of the main advantages of bond graph TPA is its analytical algorithm, which attempts to circumvent the empirical limitations imposed by previously available TPA models such as operational path analysis and operational path analysis with exogenous inputs. The result is superior time efficiency when analyzing vibration propagation in structures such as aero-engines, especially as compared to earlier TPA methods which demand vast and extensive amount of experimental measurements which could be an inefficient approach at times In this study, the bond graph transfer path analysis methodology is explored and implemented on a reduced lumped model of an aero-engine in order to demonstrate this novel transmissibility analysis approach. Using this unique process, the concepts of global and direct transmissibility and path contribution in aero-engines were investigated based on the TPA methodology, and vibration reduction strategies proposed that will help to minimize vibration transfer to aircraft fuselages that originates from rotor's unbalanced forces.