Influence of wavy imperfections in cell walls on elastic stiffness of cellular solids

Grenestedt, Joachim L.

doi:10.1016/s0022-5096(97)00035-5

Cited by 186 publications

(85 citation statements)

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“…Studies on the effect of structural defects reveal that cell wall waviness and curvature play an important role in determining the yield surface. [10,[14][15][16] Gioux et al have included the effect of these imperfections and have predicted a yield surface that matches well with experimental data. [10] Our observations on the plastic strength, its dependence on density (Figure 4(a), Part I), and the role of constraint also underscore the significance of imperfections.…”

Section: A Backgroundmentioning

confidence: 75%

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Effect of Lateral Constraint on the Mechanical Properties of a Closed-Cell Al Foam: Part II. Strain-Hardening Models

Karthikeyan

Kolluri

Ramamurty

2007

Metall Mater Trans A

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Experimental results, presented in the companion article, show that the compressive deformation of a closed-cell Al foam under lateral constraint is characterized by significant strain hardening. This enhanced hardening is due to the change in stress state from uniaxial to triaxial, which additionally contributes to friction between the deforming foam and the walls of the constraining sleeve. Detailed analysis, employing two different types of deformation models, is presented in this article in order to rationalize the experimental observations. In the heterogeneous model, it is assumed that plastic deformation is similar with and without constraint and that it occurs via collective plastic collapse of cells. The bands, thus formed, elastically bear the lateral stresses and give rise to friction. In the homogeneous deformation model, it is assumed that the deformation mode is different under constraint and involves uniform densification, which leads to inherent hardening as well as additional friction. By comparing the model predictions with experimental observations, it is suggested that the plastic strain hardening of the metallic foam under constraint is due, in equal measure, to the triaxial state of stress and friction. Mechanistically, the material deforms principally by collective cell collapse, though there is some evidence of concurrent homogeneous deformation.

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Section: A Backgroundmentioning

confidence: 75%

“…For a foam of relative density 0.1, we obtain E b = 1223 MPa, E f = 526 MPa, and q 0 q f =q b ¼ 0:3 by fitting the experimental data to Eqs. [16] and [17]. Further measurements are underway to quantify these parameters as a function of initial foam density.…”

Section: A Heterogeneous Deformation Modelmentioning

confidence: 99%

Effect of Lateral Constraint on the Mechanical Properties of a Closed-Cell Al Foam: Part II. Strain-Hardening Models

Karthikeyan

Kolluri

Ramamurty

2007

Metall Mater Trans A

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“…The higher stiffness (K 3 ) noted in this last part during unloading is attributed to a structural effect combined with localized plasticity. This phenomenon has already been observed for cellular solids [11]. Dynamic response of samples is not representative of the dynamic behaviour of the complete structure; therefore the obtained results are only exploited to validate the proposed models and will be presented in section 5.2 for discussion.…”

Section: Tensile Testsmentioning

confidence: 90%

Simplified modelling of the behaviour of 3D-periodic structures such as aircraft heat exchangers

Rishmany¹,

Mabru²,

Chieragatti³

et al. 2008

International Journal of Mechanical Sciences

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. AbstractIn this paper, experimental, analytical and numerical analysis are used to study and model the mechanical behaviour of a heat exchanger core consisting of a 3D-periodic structure. The purpose of the present investigation is not only to acquire knowledge on the mechanical behaviour of a given heat exchanger core but also to propose a simplified approach to model this behaviour. An experimental study is carried out in order to get an insight on the mechanical behaviour of this structure. Global static characteristics are obtained via analytical and finite element analysis of a unit cell of the core. Dynamic behaviour is studied by means of finite element calculations based on the results of the static modelling.The proposed approach is validated by comparison with experimental tests results.

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“…Such correlation writes as follows for the elastic modulus = n Y E Cρ (1) where E Y is the modulus of elasticity, ρ is the relative density, i.e., density of the cellular materials over that of the dense material, C and n are constants to be determined. Some other contributions fed the concerned literature with series of studies describing the role of other structural features such as cell size distribution, defects, etc [2][3][4][5]. Size effects have also been described leading to several limitations for the generalisation of the effective properties of cellular materials [6].…”

Section: Introductionmentioning

confidence: 99%

Multiscale modelling and optimisation strategies for better under-standing of biopolymer mechanical properties: review of recent contributions

Guessasma

2009

Int. J. Simul. Multidisci. Des. Optim.

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-Some biopolymers are considered as interesting natural materials for the replacement of oil-based products. Others are known as complex food systems for which texture properties determine the sensory perception. For both applications, the need to understand the mechanical behavior of biopolymers is essential. Control of texture, improvement of mechanical performance are some of the issues for which a growing research interest is noticed. The understanding of the mechanical properties cannot be considered without valuable information about the microstructure. For such materials, structural heterogeneities, which affect the behavior, appear to be dependent on several interacting scales. It is the aim of this work to shed more light on the possibility to use optimization techniques to either identify or optimize the mechanical properties of starch-based materials at different scales. We take the example of the starch cellular material, which proved to be necessitating a multiscale approach. The context of the present study is related to the investigation of elasticity behavior of cellular materials.

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Influence of wavy imperfections in cell walls on elastic stiffness of cellular solids

Cited by 186 publications

References 5 publications

Effect of Lateral Constraint on the Mechanical Properties of a Closed-Cell Al Foam: Part II. Strain-Hardening Models

Effect of Lateral Constraint on the Mechanical Properties of a Closed-Cell Al Foam: Part II. Strain-Hardening Models

Simplified modelling of the behaviour of 3D-periodic structures such as aircraft heat exchangers

Multiscale modelling and optimisation strategies for better under-standing of biopolymer mechanical properties: review of recent contributions

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