Reduced order modeling of helicopter substructures for dynamic analysis

Download

index.pdf

Date

2018

Author

Hayırlı, Uğur

Metadata

Show full item record

Item Usage Stats

320
views

769
downloads

Dynamic analysis of a structure is generally conducted by the finite element method in aerospace structures. The models usually contain large number of elements to be able to obtain more accurate results. Although the most computers are capable of solving the large and complex problems, the analysis problems such as dynamic optimization, aeroelastic, frequency and time response may take long time due to involving iterative and multi-step processes. In this study, various model reduction methods are described in order to achieve faster solutions by decreasing the size of the finite element model and preserving the dynamic behavior of the structure. The reduction techniques are categorized under three different approaches namely reduction of system matrices, component mode synthesis and stick model development. In this study, the techniques used to create the reduced models are reviewed in detail and the capability of the methods to reflect the dynamic behavior of the global structure is investigated. A simple cantilever plate and a typical helicopter tail finite element models are utilized to perform the reduction procedure and to verify the presented methodologies. The results of the normal modes, frequency and time response analyses are compared with the full/global finite element models to demonstrate the efficiency of the reduction techniques.

Subject Keywords

Helicopters, Finite element method., Helicopters

URI

http://etd.lib.metu.edu.tr/upload/12622159/index.pdf
https://hdl.handle.net/11511/27345

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

A normalized set of force and permeance data for doubly-salient magnetic geometries Mahariq, İbrahim; Ertan, Hulusi Bülent; Department of Electrical and Electronics Engineering (2009) In this study, a model is developed to represent doubly-salient magnetic circuits and to fit finite element analysis for the aim of obtaining a set of normalized normal force, tangential force, and permeance variation data. To obtain the desired data FE field solution method is used. The reliability of finite element results have been verified by three steps; first, comparing the numerical results with analytically calculated permeance, second, by solving two switch reluctance motors and comparing the resul...
Comparative study of finite element analysis and geometrically exact beam analysis of a composite helicopter blade Ataç, Meryem Nisa; Kayran, Altan; Department of Aerospace Engineering (2018) In this master thesis, comparative study of the finite element analysis and geometrically exact beam analysis of a composite helicopter blade is performed. The objective of this study is to investigate the applicability of the geometrically exact beam analysis of the composite helicopter blade in predicting the structural response of the composite blade. To evaluate the structural response determined by the geometrically exact beam analysis of the composite blade, detailed finite element model of the blade ...
Physical subspace identification for helicopters Avcıoğlu, Sevil; Kutay, Ali Türker; Department of Aerospace Engineering (2019) Subspace identification is a powerful tool due to its well-understood techniques based on linear algebra (orthogonal projections and intersections of subspaces) and numerical methods like QR and singular value decomposition. However, the state space model matrices which are obtained from conventional subspace identification algorithms are not necessarily associated with the physical states. This can be an important deficiency when physical parameter estimation is essential. This holds for the area of helico...
Modeling of the nonlinear behavior of steel framed structures with semi rigid connections Sarıtaş, Afşin; Özel, Halil Fırat (null; 2015-07-21) A mixed formulation frame finite element with internal semi-rigid connections is presented for the nonlinear analysis of steel structures. Proposed element provides accurate responses for spread of inelasticity along element length by monitoring the nonlinear responses of several crosssections, where spread of inelasticity over each section is captured with fiber discretization. Each material point on the section considers inelastic coupling between normal stress and shear stress. The formulation of the ele...
FORCED HARMONIC RESPONSE ANALYSIS OF NONLINEAR STRUCTURES USING DESCRIBING FUNCTIONS TANRIKULU, O; KURAN, B; Özgüven, Hasan Nevzat; IMREGUN, M (1993-07-01) The dynamic response of multiple-degree-of-freedom nonlinear structures is usually determined by numerical integration of the equations of motion, an approach which is computationally very expensive for steady-state response analysis of large structures. In this paper, an alternative semianalytical quasilinear method based on the describing function formulation is proposed for the harmonic response analysis of structures with symmetrical nonlinearities. The equations of motion are converted to a set of nonl...

Citation Formats

U. Hayırlı, “Reduced order modeling of helicopter substructures for dynamic analysis,” M.S. - Master of Science, Middle East Technical University, 2018.