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- Hård af Segerstad, Per, 1977, et al.
(författare)
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A micropolar theory for the finite elasticity of open-cell cellular solids
- 2009
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Ingår i: Proceedings of the Royal Society. Mathematical, Physical and Engineering Sciences. - : The Royal Society. - 1364-5021 .- 1471-2946. ; 465:2103, s. 843-865
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Tidskriftsartikel (refereegranskat)abstract
- A mechanistic model is presented for an open-cell cellular solid consisting of a threedimensional network of elastic struts. By considering the bending and torsion as well as stretching and buckling of the struts, we allow for length-scale effects in the macroscopic response. Constitutive equations are developed for the force and couple stress tensors, accounting for finite deformations and anisotropy. The consistent tangent stiffness operators are derived and the equations are fully implemented in a nonlinear twodimensional finite-element solution scheme for the coupled displacement/rotation problem. A boundary-value problem of a shear gap with prescribed boundary rotations is analysed, and the model is shown to predict the well-known gap size effect. The mechanistic model allows some detailed interpretation of the micropolar behaviour, such as the effects of strut slenderness, strut length and anisotropy.
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- Hård af Segerstad, Per, 1977, et al.
(författare)
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Computational modelling of dissipative open-cell cellular solids at finite deformations
- 2009
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Ingår i: International Journal of Plasticity. - : Elsevier BV. - 0749-6419 .- 1879-2154. ; 25:5, s. 802-821
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Tidskriftsartikel (refereegranskat)abstract
- This study concerns the constitutive modelling of dissipative open-cell structural cellular solids under primarily finite compressive deformations and the corresponding non-linear finite element implementation. A thermodynamically consistent, mechanistic approach presented in Hard of Segerstad et al. [Hard of Segerstad, P., Larsson, R., Toll, S., 2008. A constitutive equation for open-cell cellular solids, including viscoplasticity, damage and deformation induced anisotropy. International Journal of Plasticity. 24, 896-914.] is adopted for modelling the initial linear-elastic response and the subsequent plateau behaviour. In these regions the cellular solid is considered as a network of struts, where each strut connects two vertex points. A hypothesis is proposed that the vertex points move affinely in the finite strain regime, where the struts buckle plastically. The strut deformation is further assumed to be one-dimensional and depend directly on the macroscopic deformation; thus the description of the strut response requires only a scalar valued response function. Owing to this simple ansatz, the introduction of multiple non-linear mechanisms, such as hyperelasto-viscoplasticity and damage becomes feasible for large scale computations. An additional hyperelastic volumetric response, activated near the point-of-compaction, is introduced for two reasons, (i) to capture the stiffness recovery at high compressive volumetric deformations, where the struts come into contact, and (ii) to prevent numerical instability. The model is implemented as a user defined constitutive driver in the implicit version of the finite element code ABAQUS and tested experimentally for an open-cell aluminium alloy foam (Duocel 6101-0,40 ppi). All material parameters are determined by a simple compression test, and subsequently used to simulate the indentation of a rigid sphere into a foam cylinder. The model accurately captures the experimental load-displacement relation and the deformed geometry. (C) 2008 Elsevier Ltd. All rights reserved.
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- Hård af Segerstad, Per, 1977, et al.
(författare)
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Micro-mechanical model of a viscoplastic open-cell foam
- 2005
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Ingår i: Computational Plasticity VIII - Fundamentals and applications, D.R.J. Owen, E. Onate, and B. Suarez, CIMNE, Barcelona. ; , s. 755-758
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Konferensbidrag (refereegranskat)
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