Numerical Analysis of Dynamic Properties of an Auxetic Structure with Rotating Squares with Holes (original) (raw)
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1M. Tech-Mechanical Engineering (Design) Student, Vishwakarma Institute of Technology, Pune, India. 2Professor, Department of Mechanical Engineering, Vishwakarma Institute of Technology, Pune, India. -------------------------------------------------------------------------***-----------------------------------------------------------------Abstract – Auxetic structures are class of nonconventional structures having negative Poisson’s ratio. They expand laterally when axially stretched and laterally contract when axially compressed which is different from conventional structures. Light weight, high strength, impact damping capabilities and stiffness offers potential applications in the field of aerospace, automobile, military protection equipment, textile, suspension mount. Although different auxetic structures are studied and analyzed because of their strength to weight ratio and negative Poisson’s ratio, there is need of development of new structures to improve these properties. The...
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Poisson’s ratio, one of the important mechanical properties of materials and structures, is positive for almost all of the known materials and structures. However, auxetic materials or structures has negative Poisson’s ratios. Characteristics of the auxetic structures are very important to be used in design of a new structure. Computational or experimental studies on auxetic structures have been increasing in literature. In this study, a new auxetic lattice structure with different Poisson’s ratios was designed and studied by finite element analysis. Mechanical properties of the newly designed auxetic lattice structures were analyzed with different lattice inner thickness. Results showed that change in inner thickness affects the Poisson’s ratio, mass, volume and surface area of the newly designed Auxetic lattice structures.
Cellular plates with auxetic rectangular perforations
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The work describes a cellular structure configuration with a rectangular perforation topology exhibiting auxetic (negative Poisson's ratio) in-plane behaviour. The rectangular voids used in this structure produce a rigid rotating squares effect. Changes in the sizing parameters of aspect ratio, intercell spacing, and number of unit cells are made through non-dimensional modeling. The effects on the key properties of in-plane Poisson's ratio, Young's modulus and shear modulus are investigated. Through numerical modeling and experimental testing the auxetic behaviour is confirmed, with increased negative Poisson's ratio values in comparison to rhomboidal patterns of perforations available in open literature
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A preliminary study of the mechanical properties of auxetic cellular material consisting of re-entrant hexagonal honeycombs is presented. For different scales of the honeycombs, the finite element method (FEM) and experimental models are used to perform a parametric analysis on the effects of the Poisson's ratio (cell angle) and the relative density (cell thickness) of honeycombs on bearing capacity and dynamic performance of the auxetic material. The analysis demonstrates that the ultimate bearing capacity of the presented auxetic cellular material is scale-independent when the Poisson's ratio and the relative density are kept constant. The relationship between the geometric parameters and vibration level difference of the honeycombs is also revealed, which can be divided into two converse parts around the Poisson's ratio v = −1.5. When v is smaller than −1.5, increasing the cell thickness leads to an increase in the vibration level difference of the honeycombs. Moreover, the dynamic performance of thin-walled honeycombs is greatly influenced by the scale of the honeycombs, especially for the ones with small Poisson's ratio. These conclusions are verified by a frequency response test and a good agreement between the numerical results and experimental data is achieved.