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Coupled vibration and flexural axis of an open section beam.

Hemingway, Neil G. (1971) Coupled vibration and flexural axis of an open section beam. Doctoral thesis, University of Surrey (United Kingdom)..

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The object of this investigation was to examine an assumption, commonly used when analysing the coupled vibrations of asymmetric turbine blades and structural members, that the specimen cross-section displacements can be represented by a translation of, and a rotation about, the centre-of-flexure. The specimen examined comprised a cantilever with monosymmetric, thin-walled section of circular arc open profile. By applying a theory of Argyris, which considered the higher order effects of specimen mid-wall shear strain contributions due to non-uniform warping, it was evident that the specimen need not rotate about its centre-of-flexure when subject to torsion moments due to inertia effects during torsional vibration. This led to a comparison being made between two coupled vibration theories. A lower order theory of Gere & Lin and a higher order theory of Tso which was similar to that of Argyris. The differential equations of motion of both theories were solved numerically using a transformation technique and a finite difference method to determine the first: three coupled normal mode frequencies and shapes. The mode frequencies were compared with experimental results while the theoretical modal shapes were used to establish centre-of-rotation axes for each mode, The results indicated that the centre-of-rotation axis did not always coincide with the centre-of-flexure axis but diverged from it in regions of non-uniform warping along the specimen. However, it is not desirable to utilise this curved reference axis in an analysis and it was concluded that a centre-of-flexure axis be taken as the reference axis, providing, the true displacements relative to that axis are known. This is achieved by utilising a higher order theory which takes into account the specimen mid-wall shear strain contributions during non-uniform warping.

Item Type: Thesis (Doctoral)
Divisions : Theses
Authors :
Hemingway, Neil G.
Date : 1971
Contributors :
Additional Information : Thesis (M.Phil.)--University of Surrey (United Kingdom), 1971.
Depositing User : EPrints Services
Date Deposited : 22 Jun 2018 13:01
Last Modified : 06 Nov 2018 16:52

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