Abstract
Bolted preload flange joints are present in many forms in aero-engine assembly components and can be found everywhere. The nonlinearities introduced by flange contacts greatly impact on the dynamic characteristics of these assemblies subjected to external excitation loads. The matter now is that the mechanisms by which nonlinearity affects dynamics are not analyzed from a deep microscopic point of view, making it difficult to effectively use or weaken nonlinear properties to control vibration. In this paper, two analytical models are developed to carry out the study: an assembly of two plates with bolted preload flange joints for analyzing the effect of contact nonlinearity introduced by bolted connections on the vibration characteristics between two plates, and a complex whole-engine casing-plate model for applying and validating the findings of this paper. Moreover, a novel vibrational energy flow analysis method is applied to this paper to study essentially the effect of propagation of vibration. Also the phase plane method combines two macroscopic variables (displacements and velocities) to characterize the changes in the state of motion of the system. Combining those two methods, the differences in vibrational energy flow transmission behaviors were analyzed in detail when the external sinusoidal excitation force was loading in two opposite directions. A set of equilibrium equations for vibrational energy transmission has been skillfully established to correlate the macroscopic vibration characteristics with the microscopic vibrational energy transfer characteristics. Finally, the conclusions drawn in this paper based on that plate assembly model are validated numerically and experimentally by a complex whole-engine casing-support model, which provides a methodological basis for nonlinear vibration characterization and control of aero-engine bolted preloaded casing assemblies.
