Applied Research in Dynamics and Vibration

Some of the applied research areas are wind energy, torsional pendulum vibration absorbers, biolocomotion, among other interesting areas.  Descriptions are below.

Wind Energy--Towards Improved Wind-Turbine Reliability

As wind turbines continue to get larger and larger, maintenance becomes more expensive, and reliability more uncertain.  For example, bearings in gearboxes may too often fail prematurely.  A conclusion of the National Renewable Energy Laboratory's Gearbox Reliability Collaborative is that there exist loading conditions that are not well understood.  In this research, we examine resonances and stability of blade vibration, and examine how its inertial loading affects the gearbox.  Loadings on the blades are quite complicated, making this a rich dynamical systems problem.  We have derived blade models that accommodate somewhat large deflections, along with gravitational and aerodynamic loadings.  The single-mode in-plane model is complicated enough.  It has elements of a forced Mathieu equation, which can undergo superharmonic resonances, even in the linear case.  This is bad news, since wind turbines operate at frequencies below the rotating undamped natural frequency.  Our research continues by adding complexity to the analyzed system.   The graduate student, V. Ramakrishnan, has spent some internships with Romax, and worked on gear contact and gearbox housing issues.

Support: National Science Foundation CBET-0933292 (any opinions, findings, conclusions, and recommendations are those of the authors, and do not necessarily reflect the views of the NSF), and Romax Technologies with software support.

Publications

• V. Ramakrishnan and B. F. Feeny, 2012, "Resonances of the forced Mathieu equation with reference to wind turbine blades," Journal of Vibration and Acoustics, to appear. Preprint.
  
• V. Ramakrishnan and B. F. Feeny, 2011, "In-plane nonlinear dynamic analysis of wind turbine blades," ASME International Design Engineering Technical Conferences, 23rd Biennial Conference on Vibration and Noise, Washington, August 28-31, paper no. DETC2011-48219, on CD-ROM.  Preprint.
• A. Crowther, V. Ramakrishnan, N. A. Zaidi, C. Halse, 2011, "Sources of time varying contact stress and misalignments in wind turbine planetary sets," Wind Energy 14 (5), 637-651.

Centrifugal Pendulum Vibration Absorbers--For a More Fuel Efficient Fleet

It is imperative that automotive fuel efficiency continue to improve.  Reduction of torsional vibrations in drive shafts can improve fuel efficiency in several ways:  removal of vibrations when lugging an engine, improving torque converter lockup and thereby reducing losses, and removal of shake when operating in reduced cylinder modes.  This work, headed by Steve Shaw, addresses the reduction of torsionals by employing torsional vibration absorbers.  Current research issues include understanding the effects of gravity, tuning absorbers for multiple orders of excitation, and effects of damping.

Support: National Science Foundation CMMI-0700307 (S. Shaw, A. Haddow, B. Feeny, B. Geist of Chrysler), and CMMI-1100260 (S. Shaw, B. Feeny, B. Geist); any opinions, findings, conclusions, and recommendations are those of the authors, and do not necessarily reflect the views of the NSF.  Also Chrysler Group (Shaw, Feeny) and the Ford Motor Company (Shaw, Feeny).

Publications

• B. J. Vidmar, B. F. Feeny, S. W. Shaw, A. G. Haddow, B. K. Geist, and N. J. Verhanovitz, 2012, "Effects of Coulomb damping on the performance of centrifugal pendulum vibration absorbers," Nonlinear Dynamics, accepted and published on-line. (preprint)
  
• T. Theisen, 2011, Gravity's Effect on Centrifugal Pendulum Vibration Absorbers, MS Thesis, East Lansing, MI.

Bio-Locomotion

This is a nice application of the complex orthogonal decomposition tool for extracting wave modes from measured oscillations.  We've applied it to the nematode C. elegans in collaboration with the Sternberg Lab at Caltech.  Studies on this worm are important because it is the first critter to have its genome sequenced, and is has a quick life cycle, making the worm very useful in studying genetics.  The movement patterns are influenced by genetics, and thus quantifying the movement patterns helps studying mechanisms of genetics that are not just relevant to the worms, but to all species, including humans, with implications to aging, development, genetic therapies, and many other things.  We have also looked at the motions of fish, by analyzing the swimming patterns recorded in a seminal paper by Sir James Gray, yielding new information from Gray's historical work.  The modal description of fish can help fluid flow simulations, which is important to studying the amazing efficiency of undulatory caudal-fin swimming, which in turn is useful in developing undersea robots, and is satisfying simply in understanding the beauty of nature.   Finally, with Tammy Reid-Bush, we have examined human walking and running in terms of complex modes.  Complex modes accommodate and quantify the nonsynchronicity in the movements of the legs.

Publications

• B. F. Feeny, P. W. Sternberg, and C. Cronin, 2009, "Complex modal decomposition of nematode posturing," ASME International Design Engineering Technical Conferences, San Diego, August 28 to September 1, on CD-ROM. (preprint)
• B. F. Feeny and A. K. Feeny, 2011, "Complex modal analysis of the swimming motion of a whiting," ASME International Design Engineering Technical Conferences, 23rd Biennial Conference on Vibration and Noise, Washington, August 28-31, paper no. DETC2011-48204, on CD-ROM. (preprint)
• B. Rutledge, K. Friederichs, T. Reid-Bush, and B. F.  Feeny, 2010, "Complex modal analysis of human walking and running," 16th US National Congress of Theoretical and Applied Mechanics, June 27-July 2, State College, on CD ROM number USNCTAM2010-1322.

Animated vibration absorbers, by Thomas Theisen.	Animation of Gray's series of photos of a healthy swimming whiting.  Photos from J. Gray, Journal of Experimental Biology 10, pp. 391-402 (1933).  Animation by A. K. Feeny.