• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.1320-1323
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• 2003

In this study, the micro-FE analyses were carried out for the plastic behaviour of vertebral trabecular bones. Many researchers have investigated the elastic behaviour of trabecular bones by using the micro-finite element models based on the micro-CT images. However, there was no micro-FE model to account for the plastic behaviour of trabecular bones. Ulrich et at. reported that best results at coarser model were obtained when using 'compensated hexahedron models' with the same relative density. This study indicates that, for the elastic and plastic analysis, 'the compensated hexahedron FE model' is likely to be limited to about 63$\mu\textrm{m}$ image resolution in the vertebra trabecular bones.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.181-182
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• 2006

Cylindrical specimens with different levels of density have been submitted to uniaxial compression tests with loading and unloading cycles. The analysis of the elastic loadings shows a non linear elasticity which can be mathematically represented by means of a potential law. Results are explained by assuming that the total elastic strain is the contribution of two terms one deriving from the hertzian deformation of the contacts among particles and another that takes into account the linear elastic deformation of the powder skeleton. A simple model based in an one pore unit cell is presented to support the mathematical model.

• Steel and Composite Structures
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• v.13 no.4
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• pp.343-365
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• 2012

Steel suspension members subjected to tension and bending offer an economical and efficient alternative for many structural problems. This paper is concerned with the elastic and elastic-plastic behaviour of suspension members with bending stiffness subjected to vertical point and uniformly distributed loads. An experimental study is described which focuses on the response of three suspension members with various T-shaped steel hot rolled sections and geometric configurations. The tests enable direct assessment of the influence of a key parameter such as the sag-to-span ratio on the response of suspension members. Detailed nonlinear finite-element models are generated to provide a tool for theoretical analyses and to facilitate further understanding of the behaviour. Results demonstrate that experimentally obtained responses can generally be closely predicted numerically because there are relatively good agreements between finite element and tests results. The results and observations of subsequent numerical parametric studies offer an insight into the key factors that govern the behaviour of suspension members with bending stiffness in the elastic-plastic range.

• Structural Engineering and Mechanics
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• v.51 no.1
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• pp.131-140
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• 2014

This study focuses on seismic behaviour of tall piers characterized by high slender ratio. Two analysis models were developed based on elastic-plastic hinged beam element and elastic-plastic fiber beam element, respectively. The effect of the division density of elastic-plastic hinged beam element on seismic demand was discussed firstly to seek a rational analysis model for tall piers. Then structural seismic behaviour such as the formation of plastic hinges, the development of plastic zone, and the displacement at the top of the tall piers were investigated through incremental dynamic analysis. It showed that the seismic behaviour of a tall pier was quite different from that of a lower pier due to higher modes contributions. In a tall pier, an additional plastic zone may occur at the middle height of the pier with the increase of seismic excitation. Moreover, the maximum curvature reaction at the bottom section and maximum lateral displacement at the top turned out to be seriously out of phase for a tall pier due to the higher modes effect, and thus pushover analysis can not appropriately predict the local displacement capacity.

• Structural Engineering and Mechanics
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• v.44 no.4
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• pp.449-463
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• 2012

For buildings subjected to blast loading, structural failure can be categorized into local failure (direct blast effects) and progressive collapse (consequential effects). In direct blast effects, the intensive blast pressures create localized failure of structural elements such as exterior columns and walls. Columns, and their behaviour, play a key role in these situations. Therefore investigating the behaviour of columns under blast loading is very important to estimate the strength, safety and reliability of the whole structure. When a building is subjected to blast loading, it experiences huge loading pressures and undergoes great displacement and plastic behaviour. In order to study the behaviour of an element under blast loading, in addition to elastic properties of materials, plastic and elastic-plastic properties of materials and sections are needed. In this paper, using analytical studies and nonlinear time-history analysis by Ansys software, the effects of shape of column sections and boundary conditions, on behaviour and local failure of steel columns under blast load are studied. This study identifies the importance of elastic-plastic properties of sections and proposes criteria for choosing the best section and boundary conditions for columns to resist blast loading.

• Coupled systems mechanics
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• v.6 no.4
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• pp.465-485
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• 2017

In this paper, free vibration and static response of magneto-electro-elastic (MEE) beams has been investigated. To this end, a 3D finite element formulation has been derived by minimization the total potential energy and linear constitutive equation. The coupling between elastic, electric and magnetic fields can have a significant influence on the stiffness and in turn on the static behaviour of MEE beam. Further, different Barium Titanate ($BaTiO_3$) and Cobalt Ferric oxide ($CoFe_2O_4$) volume fractions results in indifferent coupled response. Therefore, through the numerical examples the influence of volume fractions and boundary conditions on the natural frequencies of MEE beam is illustrated. The study is extended to evaluate the static response of MEE beam under various forms of mechanical loading. It is seen from the numerical evaluation that the volume fractions, loading and boundary conditions have a significant effect on the structural behaviour of MEE structures. The observations made here may serve as benchmark solutions in the optimum design of MEE structures.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1992.10a
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• pp.52-57
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• 1992

The purpose of this study is that to develop computer program, which is about to analy size nonlinear behaviour of elastic framed structures include to geometric & material nonlineality, and to formulate between stress-strain relationship. In order to examplity the efficiency of this program, a few analytical results have been obtained on : (1) nonlinear behaviour of beam which is subject to vertical force (2) nonlinear behaviour of portal frame which is subject to vertical & horizontal force.

• Steel and Composite Structures
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• v.23 no.5
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• pp.517-527
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• 2017

In this paper, the effect of active confinement on the compressive behaviour of circular steel tube-confined concrete (STCC) and concrete-filled steel tube (CFST) columns is investigated. In STCC columns the axial load is only applied to the concrete core, while in CFST columns the load is carried by the whole composite section. A new method is introduced to apply confining pressure on fresh concrete by laterally prestressing steel tubes. In order to achieve different prestressing levels, short-term and long-term pressures are applied to the fresh concrete. Three groups of STCC and CFST specimens (passive, S-active and L-active groups) are tested under axial loads. The results including stress-strain relationships of composite column components, secant modulus of elasticity, and volumetric strain are presented and discussed. Based on the elastic-plastic theory, the behaviour of the steel tube is also analyzed during elastic, yielding, and strain hardening stages. The results show that using the proposed prestressing method can considerably improve the compressive behaviour of both STCC and CFST specimens, while increasing the prestressing level has insignificant effects. By applying prestressing, the linear range in the stress-strain curve of STCC specimens increases by almost twice as much, while the improvement is negligible in CFST specimens.

• Structural Engineering and Mechanics
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• v.62 no.5
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• pp.643-649
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• 2017

Masonry walls are amongst the oldest building systems. A large portion of the research on these structures focuses on the load-bearing walls. Numerical methods have been generally used in modelling load-bearing walls during recent years. In this context, macro and micro modelling techniques emerge as widely accepted techniques. Micro modelling is used to investigate the local behaviour of load-bearing walls in detail whereas macro modelling is used to investigate the general behaviour of masonry buildings. The main objective of this study is to investigate the elastic behaviour of the load- bearing walls in masonry buildings by using micro modelling technique. In order to do this the brick and mortar units of the masonry walls are modelled by the combination of plane truss elements and plane frame elements with no shear deformations. The model used in this study has fewer unknowns then the models encountered in the references. In this study the vertical frame elements have equivalent elasticity modulus and moment of inertia which are calculated by the developed software. Under in-plane static loads the elastic displacements of the masonry walls, which are encountered in literature, are calculated by the developed software, where brick units are modelled by plane frame elements, horizontal joints are modelled by vertical frame elements and vertical joints are modelled by horizontal plane truss elements. The calculated results are compatible with those given in the references.

• Korea-Australia Rheology Journal
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• v.17 no.4
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• pp.181-190
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• 2005

Rheological characterisation of flocculated kaolinite pulps has been undertaken to elucidate particle interactions underpinning the dewatering behaviour induced by flocculation with polyethylene oxide (PEO), anionic polyacrylamide (PAM A) and their blends. Shear yield stress $(\tau_y)$ analysis indicated that polymer mediated particle interactions were markedly amplified upon shear of PEG based pulps. In contrast, PAM A based pulps showed a significant decrease in yield values upon shear. Steady stress measurements analysed using a modified Ellis model indicated subtle differences between the respective linear viscoelastic plateaus of the pulps. Furthermore, modified shear thinning behaviour was evident in PEG based pulps. Estimation of elastic and viscous moduli (G', G') was made using dynamic stress analysis for comparison with values determined from vane measurements. Despite a noticeable difference in the magnitude of G' between the two methods, similar trends indicating sheared PEG-based pulps to be more elastic than PAM based pulps, were observed. Floc microstructural observations obtained in support of rheological properties indicate that PEG flocculant induces significantly more compact particle aggregation within the clay pulps under shear consistent with the yield stress data, in contrast to PAM A, or indeed unsheared PEG based pulps. Consequentially, sheared PEG based pulps show significantly improved dewatering behaviour. The implications of the results, potential benefits and drawbacks of flocculation with PEG and PAM A are discussed with respect to improvements in current dewatering processes used in the minerals industry.