Publications
198 results found
Saito D, Wadee MA, 2008, Post-buckling behaviour of prestressed steel stayed columns, ENG STRUCT, Vol: 30, Pages: 1224-1239, ISSN: 0141-0296
A steel column that is reinforced by prestressed stays generally has an increased strength in axial compression. A geometrically nonlinear model accounting for the post-buckling behaviour of the stayed column is formulated using the Rayleigh–Ritz method and then validated using the finite element method. It is found that the post-buckling behaviour is strongly linked to the level of the initial prestress. As the prestress is increased, the following different levels of the responses can be observed in sequence: initial Euler buckling that subsequently restabilizes strongly, the critical load increasing with a post-buckling path that is either stable or unstable, an upper limit for the critical load where the post-buckling is unstable after an initially rather flat response. These findings are important for designers aiming to achieve safer and more efficient designs for this structural component.
Yiatros S, Wadee MA, 2008, Advances in the analytical modelling of thin-walled tubes in pure flexure, Brisbane, Australia, ICTWS 2008: 5th International Conference on Thin-Walled Structures, Publisher: Queensland University of Technology, Pages: 1017-1024
Wadee MA, 2008, Nonlinear buckling in sandwich struts: Mode interaction and localization, Buckling and Postbuckling Structures: Experimental, Analytical and Numerical Studies, Editors: Falzon, Aliabadi, Singapore, Publisher: World Scientific, Pages: 335-374, ISBN: 9781860947940
Wadee MK, Wadee MA, Bassom AP, 2007, Effects of orthotropy and variation of Poisson's ratio on the behaviour of tubes in pure flexure, J MECH PHYS SOLIDS, Vol: 55, Pages: 1086-1102, ISSN: 0022-5096
The behaviour of tubes under conditions of pure bending is investigated for the cases where the material of which they are constructed is either orthotropic or of various Poisson's ratios. Large deflections and moderate nonlinear strains are considered and the modelling incorporates Timoshenko beam theory thereby allowing non-zero shear strains to develop. This in turn makes axially inhomogeneous deformation of the cross-section possible and, in particular, the compressed side can develop wrinkling. Numerical solutions are presented for various material types and tube dimensions and some interesting phenomena, such as mode interaction and jumping, are demonstrated. (C) 2006 Elsevier Ltd. All rights reserved.
Tsang CMN, Wadee MA, 2007, Research in structural engineering at Imperial College London, Publisher: IStructE
Kimura F, Hobbs RE, Wadee MA, 2007, Reliability assessment for the failure from the weld defects in pipelines considering the accuracy of flaw detection by AUT, Cupertino, California, USA, ISOPE 2007, Publisher: International Society of Offshore and Polar Engineers, Pages: 951-956
Wadee MA, Saito D, 2007, Zones of nonlinear buckling responses in prestressed stayed columns, Rotterdam, SEMC 2007: 3rd International Conference on Structural Engineering, Mechanics and Computation, Publisher: Millpress, Pages: 783-790
Yiatros S, Wadee MA, Hunt GR, 2007, The load bearing duct: Applying biomimicry principles in structural design, Proceedings of the Institution of Civil Engineers - Engineering Sustainability, Vol: 160, Pages: 179-188, ISSN: 1478-4637
The philosophical aspects of applying the principles of biomimicry are explored in a case study of structural design. Integrating structural engineering with services engineering can be regarded, to some extent, as taking principles from biological systems and applying them to large-scale conceptual design. The end-product discussed herein a so-called load-bearing duct, a functional naturally ventilated multi-storey office building that takes the applied loading efficiently both structurally and cost-effectively giving it the potential to be sustainable throughout its design life.
Wadee MA, Kaye NB, 2007, Buckling of thin-walled tubes under combined bending and pressure loading, Rotterdam, SEMC 2007: 3rd International Conference on Structural Engineering, Mechanics and Computation, Publisher: Millpress, Pages: 901-907
Wadee MA, 2007, Nonlinear mathematics in structural engineering, Mathematics Today, Vol: 43, Pages: 104-108, ISSN: 1361-2042
Wadee MK, Wadee MA, Bassom AP, et al., 2006, Longitudinally inhomogeneous deformation patterns in isotropic tubes under pure bending, Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, Vol: 462, Pages: 817-838
A variational model is formulated that accounts for the localization of deformation due to buckling under pure bending of thin-walled elastic tubes with circular cross-sections. Previous studies have successfully modelled the gradual process of ovalization of the cross-section with an accompanying progressive reduction in stiffness but these theories have had insufficient freedom to incorporate any longitudinal variation in the tube. Here, energy methods and small-strain nonlinear elastic theory are used to model the combined effects of cross-section deformation and localized longitudinal buckling. Results are compared with a number of case studies, including a nanotube, and it is found that the model gives rise to behaviours that correlate well with some published physical experiments and numerical studies.
Edmunds R, Hunt GW, Wadee MA, 2006, Parallel folding in multilayered structures, J MECH PHYS SOLIDS, Vol: 54, Pages: 384-400, ISSN: 0022-5096
A recent two-layer nonlinear model for parallel folding is extended to a full multilayer formulation for n identical layers. The general behaviour of the multilayer is characterized using a sinusoidal Galerkin approximation substituted into the linearized potential energy function and equations for the wavelength and critical load are found. Comparisons with experiments conducted on layers of paper constrained between two sheets of foam rubber show that the trend of the load-amplitude plots is in good agreement with that predicted. Excellent correlation is also achieved between the wavelengths calculated by the linearized buckling analysis and those seen experimentally. (c) 2005 Elsevier Ltd. All rights reserved.
Wadee MA, Wadee MK, Bassom AP, 2006, Analytical modelling of non-uniform deformation in thin-walled orthotropic tubes under pure bending, London, ISTS-11: 11th International Symposium and IIW International Conference on Tubular Structures, Publisher: Taylor & Francis, Pages: 195-202
Wadee MA, Wadee MK, Bassom AP, 2006, Analytical modelling of non-uniform deformation in thin-walled orthotropic tubes under pure bending, Welding in the World, Vol: 50, Pages: 179-186, ISSN: 0043-2288
An analytical model employing both large displacement and Timoshenko beam theories is presented for tubes with circular cross-sections under pure bending. The resulting equations are solved numerically to simulate the inhomogeneous buckling deformation and the moment--curvature relationships for various tubes constructed from orthotropic materials. Not only is this an advancement on classical Brazier buckling theory, but a significant modal interaction is identified that severely reduces the moment capacity of tubes with particular levels of the shear modulus.
Wadee MA, da Silva LAPS, 2005, Asymmetric secondary buckling in monosymmetric sandwich struts, J APPL MECH-T ASME, Vol: 72, Pages: 683-690, ISSN: 0021-8936
An interactive buckling model for sandwich struts accounting for buckle pattern localization is extended to cover such struts with differing face plate thicknesses. Although this does not affect the critical buckling characteristics of the structure, there is a significant change in the postbuckling behavior; formerly symmetric secondary buckling and imperfection sensitivity characteristics lose this quality as both become asymmetric.
Wadee MA, Edmunds R, 2005, Kink band propagation in layered structures, J MECH PHYS SOLIDS, Vol: 53, Pages: 2017-2035, ISSN: 0022-5096
Confined layered structures in layer-parallel compression exhibit kink band deformation that has an associated severe initial instability. However, once the first kink band forms the system restabilizes and the bands then propagate in two mechanisms: band broadening and band progression. Previous work on triggering the initial instability and band broadening is now extended to include band progression. A new model for this propagation mechanism that successfully accounts for the modulating restabilizing response is presented and quantitative comparisons with the physical experiments yield excellent results. (c) 2005 Elsevier Ltd. All rights reserved.
Edmunds R, Wadee MA, 2005, On kink banding in individual PPTA fibres, COMPOS SCI TECHNOL, Vol: 65, Pages: 1284-1298, ISSN: 0266-3538
Whilst having excellent tensile qualities, poly(p-phenylene terephthalamide) (PPTA) fibres perform poorly in compression often suffering from localized structural instabilities such as kink band deformation. A recent two-dimensional model for the initiation of kink bands in layered materials is adapted to examine the possibility of their appearance in PPTA fibres. Using models and experimental results from the literature, the crystalline and fibrillar structure, the elastic properties and the propensity for kink banding of the fibres are discussed. Ranges for the parameters for the kink band initiation model are then deduced and lead to predictions of band widths that compare favourably with those measured experimentally. © 2005 Elsevier Ltd. All rights reserved.
Wadee MK, Wadee MA, Bassom AP, 2005, Nonlinear bending in tubes, Aberdeen, UK, IMA Conference on Recent Advances in Nonlinear Mechanics, Publisher: IMA
Beardmore RE, Peletier MA, Budd CJ, et al., 2005, Bifurcations of periodic solutions satisfying the zero-Hamiltonian constraint in reversible differential equations, SIAM J MATH ANAL, Vol: 36, Pages: 1461-1488, ISSN: 0036-1410
This is a study of the existence of bifurcation branches for the problem of finding even, periodic solutions in fourth-order, reversible Hamiltonian systems such that the Hamiltonian evaluates to zero along each solution on the branch. The class considered here is a generalization of both the Swift - Hohenberg and extended Fisher - Kolmogorov equations that have been studied in several recent papers. We obtain the existence of local bifurcations from a trivial solution under mild restrictions on the nonlinearity and obtain existence and disjointness results regarding the global nature of the resulting bifurcating continua for the case where the Hamiltonian has a single-well potential.The local results rest on two abstract bifurcation theorems which also have applications to sixth-order problems and which show that the curves of zero-Hamiltonian solutions are contained within two-dimensional manifolds of solutions of both negative and positive Hamiltonian.
Wadee MA, Hunt GW, Peletier MA, 2004, Kink band instability in layered structures, J MECH PHYS SOLIDS, Vol: 52, Pages: 1071-1091, ISSN: 0022-5096
A recent two-dimensional prototype model for the initiation of kink banding in compressed layered structures is extended to embrace the two propagation mechanisms of band broadening and band progression. As well as interlayer friction, overburden pressure and layer bending energy, the characteristics of transverse layer compressibility and foundation stiffness are now included. Experiments on constrained layers of paper show good agreement with the predictions of angle of orientation, kink band width and post-kink load-deflection response obtained from the model. (C) 2003 Published by Elsevier Ltd.
Wadee MA, Edmunds R, 2004, Modelling kink band propagation in layered structures, Cantabria, Spain, Euromech Colloquium 464. Fibre-Reinforced Solids: Constitutive laws and instabilities, Publisher: Euromech, Pages: 47-48
Wadee MA, Hunt GW, Peletier MA, 2003, Simplified kink banding: A predictive model for localized failure in layered structures, New Orleans, USA, ICCE-10: 10th Annual International Conference on Composites/Nano Engineering, Publisher: International Community for Composites Engineering, Pages: 925-928
Wadee MA, 2002, Localized buckling in sandwich struts with pre-existing delaminations and geometrical imperfections, J MECH PHYS SOLIDS, Vol: 50, Pages: 1767-1787, ISSN: 0022-5096
A recent model for the nonlinear structural response of compression sandwich struts is developed further to account for pre-existing face-core delaminations and initial imperfections in the strut geometry. Whilst the pre-existing delaminations only take effect after the critical bifurcation for overall (Euler) buckling, it is found that the secondary instability associated with localized buckling occurs earlier than for the initially perfectly bonded strut. More severe instabilities can also be promoted by superimposing geometric imperfections. In combination with delamination, the practical structural response can be highly unstable. (C) 2002 Elsevier Science Ltd. All rights reserved.
Louca LA, Wadee MA, 2002, Simplified non-linear analysis of plates subjected to hydrocarbon explosions, J STRAIN ANAL ENG, Vol: 37, Pages: 301-311, ISSN: 0309-3247
An elastic Lagrangian formulation for an unstiffened plate subject to blast loading is presented. Building on a previous formulation, which accounted for membrane strains from purely out-of-plane displacement, the addition of in-plane stretching highlights the importance of membrane action. Numerical results of the resulting system of non-linear differential equations from the new model are compared with a non-linear finite element analysis package in terms of the various displacements and membrane strains, with good correlation.
Wadee MA, Hobbs RE, 2002, Localized instabilities in tyre cords, Tension Technology International, London
Wadee MA, Louca LA, 2002, A lagrangian model for offshore plated panels under hydrocarbon explosion modelling, Portugal, Proceedings of the 3rd international conference on steel structures (EUROSTEEL 2002), Coimbra, Portugal, 19 - 20 September 2002, Publisher: CMM, Pages: 551-559
Wadee MA, Daniel L, 2002, Kink banding in layered structures: a Maxwell stability approach, New Orleans, ICCE/9: 9th Annual International Conference on Composites Engineering, Publisher: International Community for Composites Engineering, Pages: 825-826
Wadee MA, 2002, Book review: 'Nonlinear analysis of thin-walled structures: statics, dynamics and stability'
Hunt GW, Wadee MA, Ord A, 2001, Length scale interactions in the folding of sandwich structures, TECTONOPHYSICS, Vol: 335, Pages: 111-120, ISSN: 0040-1951
Compressed sandwich structures, comprising thin stiff faces separated by a thick layer of a soft-core material exhibit behaviour analogous to the geological phenomenon of parasitic folding in multi-layered media. Earlier cross-fertilization of ideas from structural mechanics into structural geology is extended, by considering the interactions of folding on two different length scales - overall buckling comprising a single half wave over the length of the structure, combined with short wavelength local wrinkling of a single face or layer. A new theory for such interactions is briefly presented and reviewed in the geological context. In the present problem, we see folding on different length scales at the same moment in time, implying a coupling of the instabilities associated with overall and local bucking. (C) 2001 Elsevier Science B.V. All rights reserved.
Wadee MA, Blackmore A, 2001, Delamination from localized instabilities in compression sandwich panels, J MECH PHYS SOLIDS, Vol: 49, Pages: 1281-1299, ISSN: 0022-5096
Compressed sandwich structures, comprising two stiff face plates separated by a softer core material, while designed principally as efficient integral structures, can lose this quality when modes of overall (Euler) buckling and local buckling interact to produce buckle localization. Moreover, differing responses occur depending on the profile of the face plate buckling pattern relative to the core. An earlier variational formulation, leading to a system of nonlinear differential equations subject to boundary and integral constraints, has been adapted to account for an asymmetric response which manifests itself in delamination - the face plate coming apart from the core material. These are solved in a numerical continuation package, such that the response far into the unstable range can be portrayed. (C) 2001 Elsevier Science Ltd. All rights reserved.
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