Session: MR-04-02 Origami-Based Engineering Design

Paper Number: 68904

Start Time: August 18, 11:10 AM

68904 - Towards a Synthesis Method of Kresling Tower Used as a Compliant Building Block 

In this paper, the use of the Kresling tower origami to design compliant mechanisms is considered. The general objective is to use this specific origami as a compliant structure with a kinematic behavior equivalent to the helical joint, interesting for building block design approaches.

Origami has several interesting mechanical properties such as deployability, advantageous ratio between stiffness and weight, reconfiguration capabilities and, for some origami structures, bistability. The Kresling tower offers all these properties, as outlined in this article. Several works have been consequently devoted to the synthesis of the Kresling tower pattern, in order to fulfil requirements in terms of location of stable configuration or energy to actuate the structure and switch between stable configurations. The limits of previous works on the topic are outlined in a first step, with the absence of models to determine the origami pattern starting from design inputs which are the location of stable configurations and possibly the lead angle of the helical joint that can model the origami kinematics.

In a second step, the first contribution which is a synthesis method to design the origami pattern is presented. Analytical relationships are derived which can be used to select the four parameters that define the origami pattern. The validity of the models is verified by prototyping different Kresling towers. The accuracy in the determination of the stable configurations and the lead angle value is characterized. Discrepancies do not exceed of a few percent for both characteristics. It is observed the accuracy is degraded when the tower is submitted to the highest compression, so a refinement of the models in the vicinity of these configurations is discussed as future work.

In a third step, the second contribution is presented which is the introduction of a local modification of fold line geometry. The goal is to tune the stiffness of the origami, and hence the actuation requirements when used as a mechanical component, without modifying the kinematics of the tower. The local modification consists in a suppression of material at the centre of the fold, where the highest mechanical stress in the fold lines is observed. The approach is experimentally evaluated using several prototypes. The large impact on the maximum force necessary to switch between stable configurations is observed, with a division by a factor of 4 when suppressing 40% of the effective length of the folds. In parallel, a direct measurement of the location of stable configurations shows that these locations are only slightly affected with relative variations in the order of 5%. This constitutes encouraging results, and it motivates future work to go toward a complete design method of Kresling tower to be used as a compliant building block. One of the next steps will be in particular to build the model between the level of fold modification and the structure effective stiffness.

Presenting Author: John Berre ICube

Authors:

John Berre ICube
François Geiskopf INSA - CNRS - University of Strasbourg
Lennart Rubbert INSA - CNRS - University of Strasbourg
Pierre Renaud INSA - CNRS - University of Strasbourg