Modares Mechanical Engineering

Modares Mechanical Engineering

Determination of Mechanical Properties of a Micro-Cellular Auxetic Structure Using Modified Strain Gradient Theory

Document Type : Original Research

Authors
Seyed Mohammad Akhavan Alavi
Rahmatollah Ghajar
Department of Mechanical Engineering, K. N. Toosi University of Technology
10.22034/MME.24.1.11
Abstract
In this article, the determination of the mechanical properties of a micro-cellular auxetic structure is investigated. This lattice structure consists of hexagonal cells, whose cell-wall dimensions are on a micro-scale. First, using modified strain gradient theory (MSGT) and energy method, the mechanical properties of the micro-cellular auxetic structure are analytically obtained. Then for validation, Young's modulus of a micro-cellular auxetic structure is derived by tensile test and compared with theoretical results. The comparison of analytical and experimental results shows good agreement. A nanosecond laser cutting machine is used to fabricate the microcellular auxetic structure, and the ISO 6892-1 standard is used to perform tensile tests. The results show that the modified strain gradient theory plays an important role in determining the mechanical properties of micro-cellular auxetic structures. In some cases, the results of this theory are more than 100% different from the classical theory. In addition, it can be seen that by changing the dimensional parameters of the micro-cells, the mechanical properties of the auxetic structure can be tunable. For example, by reducing the magnitude of the angle of the cell wall, Young's modulus in the X 1 direction increases, and Young's modulus in the X 2 direction and the shear modulus of the structure decrease
Keywords
Auxetic
Micro-Cellular Structure
Micro Beam
MSGT

Subjects

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Modares Mechanical Engineering
Volume 24, Issue 1
December 2023
Pages 11-20