F2 - Nonlinear structural dynamics
in turbomachines

Organizer: M. Legrand & L. Salles

Mathias Legrand is an Assistant Professor in the Department of Mechanical Engineering at McGill University. His current research activity spans non-smooth modal analysis, unilateral contact dynamics, vibration analysis of large-scale bladed-disk assemblies, and modelling of abradable coating removal through close industrial collaboration with jet engine manufacturers like Safran Group and Pratt & Whitney Canada.

Loic Salles is a Research Fellow in the Department of Mechanical Engineering at Imperial College London. He extensively works on nonlinear vibration in turbomachinery and the way to minimize it using friction damper devices. He is in the charge of the development of a numerical tool used by Rolls-Royce for predicting level of vibration in aircraft engine.


Modern turbomachines should reach an optimal trade-off between performance and operating costs. For aircraft applications, such requirements shall be partly met through (1) designs which minimize operating clearances between stationary and rotating components, (2) lighter and thus more flexible blades, and (3) fewer compressor stages with comparable compression rates. Overall, modern designs enjoy improved energy efficiency and lower greenhouse signature but shall also give rise to harmful side effects involving possibly catastrophic unilateral contact and friction occurrences between blades and surrounding casings, for instance.
Currently, such complexities are not adequately addressed even though the proper understanding of the corresponding nonlinear dynamics is a primary concern to ensure reliable and safe operating conditions. In the same line, subsequent vibratory phenomena and associated resonances should be accurately predicted since excessive vibration in structures can cause high-cycle fatigue and fracture.
Starting from these considerations, the forum targets all possible manifestations of structural nonlinearities in turbomachines with emphasis placed on (1) prediction tools based on analytical and numerical techniques, (2) experimental set-ups and investigations devoted to the characterization of nonlinear phenomena, and (3) realistic large-scale engineering applications and multi-physics modelling.

Non-exhaustive list of suggested Topics:

- Full three-dimensional and/or reduced-order models

- Large strain and large displacement formulations for blades

- Nonlinear dynamics within bearings

- Blade-tip/casing interactions through unilateral contact and friction

- Time-marching techniques

- Nonlinear modal analysis

- Abradable coating removal and surface conditioning for low friction and wear

- Advance signal processing techniques, fault identification, and condition monitoring

- Mass imbalance, forced responses and whirl/whip occurrences