69713 - MECHANICS OF MACHINES M

Learning outcomes

The course strengths the knowledge of the students on the understanding and problem solving in dynamic behaviour of real machines and mechanisms, with particular attention to structural dynamics, experimental approaches, diagnostics and substructuring.

The main point is to give the students the instruments to dialogue with other experts in multidisciplinary groups that work on the constructions of complex machines, such as turbo-machines and wind-turbines in energy production and harvesting, but also on the emerging electrical vehicles and environmental friendly or vibro-acoustically comfortable machines, from an air conditioning system to a dish-washer. From this stand point, the course wishes to provide means to act on the machine concept and design, which are from aerospace origin but find more and more application in advanced common products; the master students will gain skills to better interact in a team of experts, being able to understand the language of designers and to rightly follow the evolution and behaviour of complex machines

Course contents

Numerical kinematics and dynamics for planar rigid body mechanisms

• Equations of motion

• Constraints and external loads

• Time- and frequency- domain analysis

Structural dynamics of multi degree of freedom flexible linear systems

• Equations of motion

• Structural Matrices representation

• Modal base extraction, orthogonality and transforms

• Generalized damping in structural dynamics

• Applications & examples (Heartquake, vehicles, windturbines, general machinery)

Signal processing and dynamic measurements for structural characterization and diagnostics

• the measurement chain

• sensors for vibro-acoustics

• sampling and transforms

• Correlations, Spectra, Power spectral densities, Frequency Response Functions, Coherence

Diagnostics of mechanical components and machines:

• cracks, superficial faults and fatigue life predictions on the components with dynamic loadings
  

• bearings and gear mesh

• joints and couplings

• rotor dynamics and balancing for high speed spindles and axes

Experimental modal analysis as an identification approach for vibro-acoustic problems

• review of EMA approaches

• structural model updating and optimisation

• structural modifications

• vibro-acoustic similarities and applications

Substructuring in spatial and frequency domain

• approaches for a consistent dynamic reduction

• coupling and assembly of reduced models

• flexible multi-body systems for planar mechanisms

• vibro-acoustics experimental models and hybrid coupling
  

Readings/Bibliography

D.J. Ewins, Modal Testing, Theory, Practice and Application, ISBN-13: 978-0863802188
W. Heylen, S. Lammes, P. Sas, Modal Analysis Theory and Testing, PMA-KULEUVEN
J.S. Bendat, A.G. Piersol, Random data: analysis and measurement procedures, John Wiley & Sons, 2011
R.R. Craig, Structural dynamics: an introduction to computer methods,Wiley, Aug 19, 1981
A. Muszynska, Rotordynamics, May 20, 2005 by CRC Press, ISBN 9780824723996
E.J. Haug, Computer Aided Kinematics and Dynamics of Mechanical Systems, Volume I: Basic methods, Allyn & Bacon 1989

Teaching methods

Lessons in class and eventual coding

Assessment methods

Oral exam with discussion of eventual work

Teaching tools

Blackboard, beamer, computer, experimental equipment

Links to further information

http://diem1.ing.unibo.it/personale/zanarini/Zanarini_ricerca_EN.htm

Office hours

See the website of Alessandro Zanarini