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A study of symbolic processing and computational aspects in helicopter dynamics

Ravichandran, S and Gaonkar, G and Nagabhushanam, J and Reddy, TSR (1990) A study of symbolic processing and computational aspects in helicopter dynamics. In: Journal of Sound and Vibration, 137 (3). pp. 495-507.

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Official URL: http://dx.doi.org/10.1016/0022-460X(90)90814-G


Even research models of helicopter dynamics often lead to a large number of equations of motion with periodic coefficients; and Floquet theory is a widely used mathematical tool for dynamic analysis. Presently, three approaches are used in generating the equations of motion. These are (1) general-purpose symbolic processors such as REDUCE and MACSYMA, (2) a special-purpose symbolic processor, DEHIM (Dynamic Equations for Helicopter Interpretive Models), and (3) completely numerical approaches. In this paper, comparative aspects of the first two purely algebraic approaches are studied by applying REDUCE and DEHIM to the same set of problems. These problems range from a linear model with one degree of freedom to a mildly non-linear multi-bladed rotor model with several degrees of freedom. Further, computational issues in applying Floquet theory are also studied, which refer to (1) the equilibrium solution for periodic forced response together with the transition matrix for perturbations about that response and (2) a small number of eigenvalues and eigenvectors of the unsymmetric transition matrix. The study showed the following: (1) compared to REDUCE, DEHIM is far more portable and economical, but it is also less user-friendly, particularly during learning phases; (2) the problems of finding the periodic response and eigenvalues are well conditioned.

Item Type: Journal Article
Publication: Journal of Sound and Vibration
Publisher: Elsevier Science
Additional Information: Copyright of this article belongs to Elsevier Science.
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited: 07 Jan 2011 11:43
Last Modified: 07 Jan 2011 11:43
URI: http://eprints.iisc.ac.in/id/eprint/34891

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