Page 42 - ASME AM3D/IDETC/CIE 2015 Program
P. 42
IDETC/CIE KEYNOTE & PLENARY LECTURES
a century’s practical experience in a range of industrial applications. Advisory Board (STAB) for the CleanSky Programme from 2010-
2014.
Background: Vibration in structures, machines and vehicles remains
one of the major performance-limiting features, particularly so for the His research has focused on two main areas—Modal Testing and
critical applications in the advanced aerospace, defense and power Vibrations in Turbomachinery, in the latter case, working closely with
industries. As a result, designers of such engineering products Rolls-Royce with whom he set up the Vibration UTC at Imperial in
demand techniques which enable them to eliminate or control any 1990. Current research priorities seek to ensure that the dynamics of
undesirable behavior such as excessive vibration, and to do so at the engineering structures can be controlled by: (a) routinely including
design stage. Increasingly, they turn to computer models to provide models of the joints that hold structures together, (b) accepting that
such a capability and at the same time raise their expectations of just all structures are non-linear to a degree, and (c) ensuring that
how much can be done to remove vibration from the list of concerns. modeling, prediction and measurement are fully integrated in the
From a different perspective, customers and regulatory authorities teaching, research and practice of structural dynamics.
expect evidence that the products they are being delivered will, He is a Fellow of the Royal Society and of the Royal Academy of
indeed, be free from all the side effects that are associated with Engineering, and of the Indian National Academy of Engineering.
vibration. This means that tests must be done to provide such
evidence and, here again, expectations and demands are raised in
this process. Modern structural dynamics provides the technology Wednesday, August 5
required to meet these demands. It comprises three main skills—the-
oretical modelling, numerical analysis and experimental measure- SESSION: VIB-17-3
ment—and the overarching theme of this lecture is the need for these 11:40AM – 12:40PM
three basic tools to be balanced and integrated. In effect, this means Location: Room 305, Level 3
that as simulation techniques (modelling plus computation) improve
—often dramatically because of great strides in computation—it is
necessary for experimental techniques to keep step, not the least Maurizio Porfiri
because the final stage in any product is the pass-off or certification
test. In practice, and especially for the critical structures of advanced 2015 C.D. Mote, Jr. Early Career Award Recipient
high-performance machinery, vehicles and plant, the ideal simula- Polytechnic School of Engineering, New York
tion-test integration comes when tests can complement and inform University
modelling activities and, equally, when advanced models can inform
the design and conduct of the expensive pass-off tests. In both of MODELING FINITE AMPLITUDE VIBRATIONS OF
these major endeavors (constructing a model than can be used with FLEXIBLE BEAMS IN VISCOUS FLUIDS
confidence to be used to design, and carrying out tests which Abstract: The analysis of mechanical vibrations of flexible slender
convincingly demonstrate the predicted functionality across the structures immersed in viscous fluids is of fundamental importance in
operating spectrum) the underlying concern is to reduce uncertain- many technical fields, across a wide range of length and force scales,
ties to an acceptable level. This, in turn, means ensuring that the from atomic force microscopy to naval engineering. One of the main
levels of vibration experienced in service are such that the structural challenges in this class of problems involves the prediction of the
performance meets its designed levels of life, reliability and distur- forces exerted on the oscillating structure by the fluid. In this talk, I will
bance. The lecture will emphasise how today’s state-of-the-art present a comprehensive modeling framework to interpret and
structural dynamics needs to be focused on the ‘bottom line’ in all predict the steady-state response of flexible beams oscillating in
vibration problems encountered in practice: managing vibration viscous fluids. We will depart from unsteady Stokes hydrodynamics
response levels across the structure and throughout its service life in to consider finite-amplitude structural vibrations, for which vorticity
order to satisfy the structural performance demands as well as those generation and transport modulate the fluid-structure interaction. To
of functional performance. illustrate the methodology, I will focus on harmonic bending vibrations
of a thin cantilever beam in an unbounded fluid. Theoretical results will
be validated against direct three-dimensional fluid dynamics
Biography: David J. Ewins has spent the past 50 years studying and simulations and experiments on centimeter-size beams undergoing
measuring vibration in a range of application areas—mostly in low frequency and finite amplitude underwater vibrations. Then, I will
aerospace, defense and other hi-tech industries. Having studied at briefly touch on torsional vibrations and discuss the role of finite beam
Imperial College London and Cambridge University, he has been thickness, interactions with side walls, polychromatic excitations, and
based at Imperial as Professor of Vibration Engineering since 1983, application to biomimetic propulsion and energy harvesting. I will
with periods as Visiting Professor overseas in the USA, France, conclude with a series of open questions and possible research
Switzerland and Singapore. Following partial ‘retirement’ in 2005, directions.
he spends part of his time at Imperial and part at Bristol University as
Professor of Vibration Engineering. He sits on a number of advisory
Boards and was Chairman of the Scientific and Technological Biography: Maurizio Porfiri was born in Rome, Italy in 1976. He
42
a century’s practical experience in a range of industrial applications. Advisory Board (STAB) for the CleanSky Programme from 2010-
2014.
Background: Vibration in structures, machines and vehicles remains
one of the major performance-limiting features, particularly so for the His research has focused on two main areas—Modal Testing and
critical applications in the advanced aerospace, defense and power Vibrations in Turbomachinery, in the latter case, working closely with
industries. As a result, designers of such engineering products Rolls-Royce with whom he set up the Vibration UTC at Imperial in
demand techniques which enable them to eliminate or control any 1990. Current research priorities seek to ensure that the dynamics of
undesirable behavior such as excessive vibration, and to do so at the engineering structures can be controlled by: (a) routinely including
design stage. Increasingly, they turn to computer models to provide models of the joints that hold structures together, (b) accepting that
such a capability and at the same time raise their expectations of just all structures are non-linear to a degree, and (c) ensuring that
how much can be done to remove vibration from the list of concerns. modeling, prediction and measurement are fully integrated in the
From a different perspective, customers and regulatory authorities teaching, research and practice of structural dynamics.
expect evidence that the products they are being delivered will, He is a Fellow of the Royal Society and of the Royal Academy of
indeed, be free from all the side effects that are associated with Engineering, and of the Indian National Academy of Engineering.
vibration. This means that tests must be done to provide such
evidence and, here again, expectations and demands are raised in
this process. Modern structural dynamics provides the technology Wednesday, August 5
required to meet these demands. It comprises three main skills—the-
oretical modelling, numerical analysis and experimental measure- SESSION: VIB-17-3
ment—and the overarching theme of this lecture is the need for these 11:40AM – 12:40PM
three basic tools to be balanced and integrated. In effect, this means Location: Room 305, Level 3
that as simulation techniques (modelling plus computation) improve
—often dramatically because of great strides in computation—it is
necessary for experimental techniques to keep step, not the least Maurizio Porfiri
because the final stage in any product is the pass-off or certification
test. In practice, and especially for the critical structures of advanced 2015 C.D. Mote, Jr. Early Career Award Recipient
high-performance machinery, vehicles and plant, the ideal simula- Polytechnic School of Engineering, New York
tion-test integration comes when tests can complement and inform University
modelling activities and, equally, when advanced models can inform
the design and conduct of the expensive pass-off tests. In both of MODELING FINITE AMPLITUDE VIBRATIONS OF
these major endeavors (constructing a model than can be used with FLEXIBLE BEAMS IN VISCOUS FLUIDS
confidence to be used to design, and carrying out tests which Abstract: The analysis of mechanical vibrations of flexible slender
convincingly demonstrate the predicted functionality across the structures immersed in viscous fluids is of fundamental importance in
operating spectrum) the underlying concern is to reduce uncertain- many technical fields, across a wide range of length and force scales,
ties to an acceptable level. This, in turn, means ensuring that the from atomic force microscopy to naval engineering. One of the main
levels of vibration experienced in service are such that the structural challenges in this class of problems involves the prediction of the
performance meets its designed levels of life, reliability and distur- forces exerted on the oscillating structure by the fluid. In this talk, I will
bance. The lecture will emphasise how today’s state-of-the-art present a comprehensive modeling framework to interpret and
structural dynamics needs to be focused on the ‘bottom line’ in all predict the steady-state response of flexible beams oscillating in
vibration problems encountered in practice: managing vibration viscous fluids. We will depart from unsteady Stokes hydrodynamics
response levels across the structure and throughout its service life in to consider finite-amplitude structural vibrations, for which vorticity
order to satisfy the structural performance demands as well as those generation and transport modulate the fluid-structure interaction. To
of functional performance. illustrate the methodology, I will focus on harmonic bending vibrations
of a thin cantilever beam in an unbounded fluid. Theoretical results will
be validated against direct three-dimensional fluid dynamics
Biography: David J. Ewins has spent the past 50 years studying and simulations and experiments on centimeter-size beams undergoing
measuring vibration in a range of application areas—mostly in low frequency and finite amplitude underwater vibrations. Then, I will
aerospace, defense and other hi-tech industries. Having studied at briefly touch on torsional vibrations and discuss the role of finite beam
Imperial College London and Cambridge University, he has been thickness, interactions with side walls, polychromatic excitations, and
based at Imperial as Professor of Vibration Engineering since 1983, application to biomimetic propulsion and energy harvesting. I will
with periods as Visiting Professor overseas in the USA, France, conclude with a series of open questions and possible research
Switzerland and Singapore. Following partial ‘retirement’ in 2005, directions.
he spends part of his time at Imperial and part at Bristol University as
Professor of Vibration Engineering. He sits on a number of advisory
Boards and was Chairman of the Scientific and Technological Biography: Maurizio Porfiri was born in Rome, Italy in 1976. He
42
