Influence of the subtended angle on the behavior of folded tape springs

Conference paper (2018)

Authors

W.W.P.J. van de Sande Mechatronic Systems Design - Mechanical, Maritime and Materials Engineering
J.L. Herder Mechatronic Systems Design - Mechanical, Maritime and Materials Engineering , Precision and Microsystems Engineering
Research Group
Mechatronic Systems Design (Mechanical, Maritime and Materials Engineering) (TU Delft)
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Published Date

2018

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Precision and Microsystems Engineering

Research Group

Mechatronic Systems Design

Abstract

Tape springs are thin-walled structures with zero longitudinal and constant transverse curvature. Folding them twice and connecting both ends creates a tape loop which acts as a linear guide. When using a tape spring with a non-constant cross-section, a force generator can be created. At this time there is insufficient understanding of the influence of the tape spring’s cross-section on its behavior. This study investigates the influence of the subtended angle on the tape spring’s behavior, especially the energy distribution and the fold radius. A tape spring is once folded in a finite element model. By performing a curvature analysis of this folded geometry, the different regions within a tape spring are identified. This information is used to identify the amount of strain energy of each region. Finally, the fold radius and fold angle are determined by analyzing the geometry of the bent region. The analysis showed that the energy within the transition regions cannot be neglected. The energy within these regions as ratio of the total energy and the length of the transition regions both increase with the subtended angle. It is also shown that the fold radius is not constant when the subtended angle is small. Therefore, when designing a force generator using tape loops, the energy within the transition regions should be taken into account. The subtended angle should not be small to ensure a constant radius.