The nonlinear computational analysis of the vibration of a whole-engine model with squeeze-film damper bearings Time Domain Approach

The direct study of real engine structures with nonlinear bearings has been severely limited by the fact that current nonlinear computational techniques are not well-suited for large-order systems. This paper introduces a novel implicit "Impulsive Receptance Method" (IRM) for the time domain analysis of such structures. The IRM's computational efficiency is largely immune to the number of modes used and dependent only on the number of nonlinear elements. This means that, apart from retaining numerical accuracy, a much more physically accurate solution is achievable within a short timeframe. Simulation tests on a realistically sized representative twin-spool engine showed that the new method was around 40 times faster than a conventional implicit integration scheme. Preliminary results revealed the varying degree of lift, journal orbit size and shape at the example engine's squeeze-film damper bearings for a given unbalance distribution. © IMechE 2008.