CISM short course on Modal Analysis of Nonlinear Mechanical Systems, June 25-29, 2012

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A short course on ‘Modal Analysis of Nonlinear Mechanical Systems’ will be held at the International Centre for Mechanical Sciences (CISM) in Udine, Italy ( in the period June 25-29, 2012. You can download the flyer of this course here.
Content of the course:

Modal analysis and testing of linear structures has been developed over the past 40-50 years, and the techniques available today are really quite sophisticated and advanced. Because nonlinearity is a frequent occurrence in real-life applications, there is a need for efficient nonlinear modal analysis methods.  In this context, nonlinear normal modes (NNMs) offer a solid mathematical tool for interpreting a wide class of nonlinear dynamical phenomena, yet they have a clear conceptual relation to the classical linear normal modes (LNMs), with which structural engineers are familiar. However, for reasons that will be detailed during the course, most practicing engineers still view NNMs as a concept that is foreign to them, and they do not yet consider them as a practical tool. This course will first introduce the concept of NNMs and their definitions. The fundamental differences between LNMs and NNMs will be highlighted (e.g., the frequency-energy dependence, bifurcations and modal interactions of NNMs) and illustrated using simple examples. The pedagogical treatment of NNMs will be an important objective of the course so that the theory will be accessible to attendees coming from both academic and industrial areas. Different methods for computing NNMs from a mathematical model will be presented. Participants will be exposed to both advanced analytical and numerical methods. Particular attention will be devoted to the invariant manifold and normal form theories. We will also show that numerical algorithms pave the way for an efficient and practical computation of NNMs. Realizing that a large body of the literature deals with low-order lumped-mass models, omplex structures including rotorcraft blades and a full-scale aircraft will be examined. The course will also discuss experimental modal analysis, which amounts to extracting NNMs directly from experimental data. Two methods will be presented. The first method is based on the concept of slow flow and builds a model based on intrinsic modal oscillators. The second method relies on the generalization of the phase lag quadrature criterion to nonlinear systems. Advanced signal processing, including the wavelet transform and empirical mode decomposition will prove very useful for experimental NNM identification. Finally, the course will describe several important applications of the NNM theory, including model validation, model reduction, and vibration and acoustic mitigation.


Bruno Cochelin, Ecole Centrale de Marseille, France
Oleg Gendelman, Technion, Israel
Gaetan Kerschen, University of Liege, Belgium
Steve Shaw, Michigan State University, USA
Cyril Touze, Ecole Nationale Superieur de Techniques Avancees, France
Alexander Vakakis, University of Illinois at Urbana-Champaign, Urbana, USA

Symposium on System Identification and Condition Monitoring for Dynamics for Design, 1st ASME Biennial International Conference on Dynamics for Design (DFD), Chicago, IL, August 12-15, 2012

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The 1st Biennial International Conference on Dynamics for Design (DFD) will be held as part of the 2012 ASME International Design Engineering Technical Conferences & Computers and Information in Engineering Conference (IDETC/CIE) in Chicago, IL, August 12-15, 2012. The DFD conference is jointly organized by the ASME Technical Committee on Multibody Systems and Nonlinear Dynamics (TC-MSND) and the ASME Technical Committee on Vibration and Sound (TCVS), both within the Design Engineering Division. A Call for Papers for this Conference can be downloaded from here.

A topical symposium will be organized on System Identification and Condition Monitoring for DFD, jointly organized by Prof. D. Adams (Purdue University) and Prof. A.F. Vakakis (University of Illinois at Urbana – Champaign). Contributions are sought that emphasize system identification and condition/health monitoring methodologies and techniques grounded in DFD principles. System identification topics include but are not limited to, model updating and parameter estimation; nonlinear modal analysis; identification of non-smooth and strongly nonlinear effects such as clearances, vibro-impacts and dry friction; and identification of multi-physics and multi-scale dynamics.  Condition/health monitoring topics include but are not limited to, sensors and algorithms for damage detection and classification in materials and machines; physical models of damage mechanics for quantifying health and predicting damage evolution for damage prognosis; and applications emphasizing real-time evaluation of system health in the presence of exogenous perturbations. Contributions that document certifiable condition monitoring protocols for complex cyberphysical systems and experimental case studies in practical settings are particularly welcome.

For more detailed information about the conference, please see As per the online publication schedule, abstracts for initial review must be submitted by 5 pm EST on Monday, February 6, 2012, using the online submission system. In addition, and only if an abstract is submitted by the due date, a full length draft paper should be submitted for peer review by 5 pm EST on Monday, February 20, 2012.