Predicting the elastic properties of lattice materials, a geometrically nonlinear approach

Master thesis (2022)

Authors

D. van Megen Mechanical Engineering

Contributors

C. Ayas Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering (mentor)
A. van Keulen Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering (graduation committee member)
J.M. van der Zwet Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering (graduation committee member)
Faculty
Mechanical Engineering, Mechanical Engineering
Copyright: © 2022 Demi van Megen
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Published Date

03-03-2022

Language

English

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Faculty

Mechanical Engineering

Abstract

In recent studies, selection criteria for lattice materials suitable for active shape-morphing have been composed. These criteria have directly resulted in the proposal of a lattice that is able to compete with the Kagome lattice, which in the literature is identified as a lattice material with optimal in-plane stiffness and shape-morphing capabilities. The selection of suitable lattice materials is mostly related to the properties of the lattice before shape-morphing. Naturally the question 'What is the effect of morphing on the macroscopic properties of the lattice material?' arises.

This research investigates the relationship between kinematic properties of the pin-jointed Kagome truss and elastic macroscopic properties of the welded-jointed Kagome lattice during deformation. The kinematic properties of the Kagome truss are explored at all possible collapse configurations. The same collapse configurations of the pin-jointed truss are then used to determine the elastic response of the welded-jointed twisted lattice with the use of the commercial finite element program ABAQUS.

The results show that only the pin-jointed initial configuration of the Kagome truss can support all macroscopic loads without inducing a collapse of the truss, no other pin-jointed configuration shares this property. Indicating different elastic responses of the initial welded-jointed lattice and the twisted lattices. The results of the finite element analysis support this finding, as it can be shown that the type of deformation of the initial configuration of a welded-jointed lattice differs from the deformation of any other twisted configuration. A stark difference between Young's modulus is observed between the initial configuration and the twisted configurations. The deformation induced by single member actuation creates a weak layer in the lattice. Therefore the attractive properties of the Kagome lattice are not preserved during shape-morphing.

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