68th NIA CFD Seminar:
INTEGRATING THREE-DIMENSIONAL STRESS EVALUATION WITH ROTORCRAFT COMPREHENSIVE ANALYSIS
Olivier A. Bauchau, University of Maryland
November 19, 2015, 11:00 am, NIA, Rm 141
Abstract:
Rotorcraft comprehensive dynamic simulation is a basic tool in rotorcraft design, optimization, and performance evaluation. Comprehensive rotorcraft analysis implies that the simulation tool integrates the many relevant disciplines, such as aerodynamics, structural dynamics, and controls, but also involves sophisticated models of complex components such as engines or active and passive damping devices, to name just few. Because of computational cost constraints, rotor blade dynamic analysis is based on beam models, which can deal with the complex behavior of anisotropic composite materials. Over the past decade, CFD/CSD coupled simulations have ushered in a new era in comprehensive simulations by providing a quantum jump in the accuracy of aerodynamic loads predictions, although at a greatly increased computational cost. The coupled simulations predict time histories of stress resultants that are in good agreement with flight test measurements. But a truly comprehensive simulation requires the evaluation of three-dimensional stress distributions: blade detailed design, structural integrity, fatigue life, and their optimization all depend on the accurate knowledge of three-dimensional stress distributions. Three-dimensional finite element models could provide the desired level of accuracy but the associated computational cost is overwhelming. In industry, three-dimensional finite element models are used routinely to post-process the predictions of comprehensive analysis tools, but the assumptions inherent to this post-processing step might negate the improved accuracy gained by three-dimensional analysis.
This seminar will describe a general procedure for the dimensional reduction of complex structures made of advanced composite materials. The approach can be viewed as a Global/Local technique, and takes into account distributed (aerodynamic) loading and inertial (vibratory and centrifugal) effects. The three-dimensional state of stress can be recovered at any point in the rotor blade. Comparison with three-dimensional finite element results shows that very high accuracy is achieved, while keeping computational costs three to four orders of magnitude lower than those required by three-dimensional finite element analysis. Complex geometric configurations and material systems can be handled easily.
Speaker Bio: Dr. Bauchau earned his B.S. degree in engineering at the Université de Liège, Belgium, and M.S. and Ph.D. degrees from the Massachusetts Institute of Technology. He has been a faculty member of the Department of Mechanical Engineering, Aeronautical Engineering, and Mechanics at the Rensselaer Polytechnic Institute in Troy, New York (1983-1995), a faculty member of the Daniel Guggenheim School of Aerospace Engineering of the Georgia Institute of Technology in Atlanta, Georgia (1995-2010), a faculty member of the University of Michigan Shanghai Jiao Tong University Joint institute in Shanghai, China (2010-2015). He is now Igor Sikorsky Professor of Rotorcraft in the Department of Aerospace Engineering at the University of Maryland.
His fields of expertise include finite element methods for structural and multibody dynamics, rotorcraft and wind turbine comprehensive analysis, and flexible multibody dynamics. He is a Fellow of the American Society of Mechanical Engineers, senior member of the American Institute of Aeronautics and Astronautics, and member of the American Helicopter Society. His book entitled “Flexible Multibody Dynamics” has won the 2012 Textbook Excellence Award from the Text and Academic Authors Association. He is the 2015 recipient of the ASME d’Alembert award for lifelong contributions to the field of multibody system dynamics.
Additional information, including the webcast link, can be found
at the NIA CFD Seminar website, which is temporarily located at
http://www.hiroakinishikawa.com/niacfds/index.html