Lateral torsional buckling in translational and rotational compliant joints to obtain zero-stiffness behaviour

Master thesis (2023)

Authors

M.A. Moerman Mechanical Engineering

Contributors

G. Radaelli Mechatronic Systems Design - Mechanical, Maritime and Materials Engineering (supervisor 1)
J.L. Herder Precision and Microsystems Engineering (supervisor 2)
A. Amoozandeh Mechatronic Systems Design - Mechanical, Maritime and Materials Engineering (coach)
J. Jovanova Transport Engineering and Logistics - Mechanical, Maritime and Materials Engineering (coach)
Faculty
Mechanical Engineering
Copyright: © 2023 Marco Moerman
Compliant mechanisms Lateral torsional buckling Zero-stiffness Translational joint Rotational joint
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Published Date

24-02-2023

Language

English

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Faculty

Mechanical Engineering

Abstract

Compliant mechanisms are a popular alternative to conventional mechanisms because of their advantages on mass reduction, friction, backlash and lubrication. However, the major drawback in the use of compliant mechanisms is the stiffness is the desired direction of motion. The advantages of conventional and compliant mechanisms can be combined if the stiffness can be reduced or ideally removed, resulting in a zero-stiffness compliant mechanism. In current designs of zero-stiffness mechanisms, a preload is applied in the stiffest (compression) direction of a flexible beam. This working principle is based on Euler buckling. In this work, compliant mechanisms with zero-stiffness behaviour are obtained using lateral torsional buckling as their working principle. For this purpose, two compliant joints are modelled in a FEA, a translational and a rotational joint. The results of the FEA are verified by experiments. Also, a sensitivity analysis is performed on the cross-sectional dimensions of the flexible beams to optimize the range of zero-stiffness. Both types of joints showed zero-stiffness behaviour for the optimal preload and a good agreement is found between simulations and experiments. From the sensitivity analysis is found that a rectangular cross-section results in the largest range of zero-stiffness.