Eigenanalysis and continuum modelling of pre-twisted repetitive beam-like structures

Stephen, N.G. and Zhang, Y. (2006) Eigenanalysis and continuum modelling of pre-twisted repetitive beam-like structures International Journal of Solids and Structures, 43, (13), pp. 3832-3855. (doi:10.1016/j.ijsolstr.2005.05.023).


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A repetitive pin-jointed, pre-twisted structure is analysed using a state variable transfer matrix technique. Within a global coordinate system the transfer matrix is periodic, but introduction of a local coordinate system rotating with nodal cross-sections results in an autonomous transfer matrix for this Floquet system. Eigenanalysis reveals four real unity eigenvalues, indicating tension–torsion coupling, and equivalent continuum properties such as Poisson’s ratio, cross-sectional area, torsion constant and the tension–torsion coupling coefficient are determined. A variety of real and complex near diagonal Jordan decompositions are possible for the multiple (eight) complex unity eigenvalues and these are discussed in some detail. Analysis of the associated principal vectors shows that a bending moment produces curvature in the plane of the moment, together with shear deformation in the perpendicular plane, but no bending–bending coupling; the choice of a structure having an equilateral triangular cross-section is thought responsible for this unexpected behaviour, as the equivalent continuum second moments of area are equal about all cross-sectional axes. In addition, an asymmetric stiffness matrix is obtained for bending moment and shearing force coupling, and possible causes are discussed.

Item Type: Article
Digital Object Identifier (DOI): doi:10.1016/j.ijsolstr.2005.05.023
ISSNs: 0020-7683 (print)
Keywords: pre-twist, repetitive, floquet, jordan canonical forms, eigenproblem, tension–torsion, bending–shear, continuum, homogenisation, properties
ePrint ID: 23694
Date :
Date Event
May 2006Published
Date Deposited: 21 Mar 2006
Last Modified: 16 Apr 2017 22:44
Further Information:Google Scholar
URI: http://eprints.soton.ac.uk/id/eprint/23694

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