Effective stiffness and effective compressive yield strength for unit-cell model of complex truss
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Effective stiffness and effective compressive yield strength for unit-cell model of complex truss Jeongho Choi · Tae-Soo Chae
Received: 21 November 2013 / Accepted: 10 June 2014 © Springer Science+Business Media Dordrecht 2014
Abstract In this study, the objective was to find the effective stiffness and effective strength for an intricate truss model. The model integrates three different types of unit-cell models: a microlattice truss, crossed tetrahedron truss, and regular hexahedron truss. The ideal solutions for the relative density, relative Young’s modulus, and relative compressive yield strength were derived. These were compared with the simulated results of computational models based on aspect ratios (ARs) of 0.2, 0.4, and 0.8 when either the truss diameter or truss length was constant. Commercial software was used for modeling, and the material properties of type 304 stainless steel were applied. The effective stiffness of the unit-cell model of the intricate truss was found to be proportionally correlated with the relative density; the effective strength was correlated with the relative density by a power law of 3/2, which means an open-cell model. Keywords Cellular solids · Open cell · Periodic unit cell · Prismatic structure List of Symbols AR Aspect ratio
J. Choi (&) · T.-S. Chae Research Institute, Samjung E&W Co. Ltd., Changwon City, Gyeongsangnamdo, Republic of Korea e-mail: [email protected] T.-S. Chae e-mail: [email protected]
FE FEA FEM d l ρ* ρs V* Vs E* Es σ* σs R2
Finite element Finite element analysis Finite element method Truss diameter Truss length Density of foam itself Density of the applied material Volume of foam itself Volume of applied material Elastic modulus of foam itself Elastic modulus of applied material Volume of foam itself Volume of applied material Measure of goodness of fit of trendline to data
1 Introduction Many researchers have studied the application of lightweight structures in various fields; these include the aerospace, automotive, shipbuilding, and medical industries. Recently, Schaedler et al. (2011) reported on ultralight metallic microlattices. This structure is based on a periodic truss comprising a hollow-tube microlattice and can be applied to sandwich core parts. Gibson and Ashby (1997) reported that the ideal solution of the structure can be matched with a prismatic open-cell structure because the relative elasticity of the microlattices can be correlated with the relative density. Thus, this model has been extended to material applications in the aerospace and airplane industries.
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The microlattice structure is a cellular solid. Deshpande et al. (2001a, b) showed that these solids can be mechanically characterized as deformable by bending or dominated tension. They showed that these solids can be used in structural applications because of their efficient weight, and they tested pin-jointed models including fixed struts. Rehme (2010) and Deshpande et al. (2001a, b) examined the microlattice structure of an octet-truss model e
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