Rigid Origami And Networks Of Spherical Mechanisms

Rigid origami,which can be regarded as assembly of spherical linkages,are widely used in space technologies,architecture and metamaterials.In this thesis,the possibilities of constructing mobile networks based on spherical linkages are explored,1D and 2D mobile networks based on rigid origami are analyzed,the family of origami tubes is enlarged and a method to construct thick-panel origami tubes is proposed.First,an 1D open-loop helical structure of spherical 4R linkages is obtained,inspired by a rigid origami pattern.Eggbox-based chiral units are developed to construct homogeneous and heterogeneous chiral structures and demonstrate a theoretical approach to tune the chirality of these structures by modulating their geometrical parameters to realize the chirality switching through a mechanism bifurcation.Furthermore,by introducing a helical tessellation between the chiral units,hierarchical helical structures with a chirality transfer from the construction elements to the morphological level are designed and a novel helix with two zero-height configurations during the unwinding process is presented.Next,the 2D planar mobile networks based on rigid origami patterns are explored.A one-DOF network system of spherical 4R linkages is developed by replacing the unit facets of the planar eggbox pattern with volumetric tetrahedrons.The 4R configuration can be expanded to an arbitrary surface profile by inserting 6R and 8R linkages in the original network system.The above-mentioned surface is known as a morphing surface,and it can transform between two target surfaces through the implementation of suitable design parameters.Subsequently,an extended family of rigid origami tubes is presented.Using a mechanism construction process,I demonstrate that the existing origami tubes can be used as building blocks to form new tubes that are rigidly foldable with a single degreeof-freedom.A combination process is introduced,along with the option of inserting new facets in an existing tube.The approach can be applied to both single and multilayered tubes with a straight or curved profile.Finally,a method of constructing thick-panel origami tubes is proposed.Origami patterns are commonly created using a zero-thickness sheet;however,the panel thickness cannot be disregarded in real engineering applications.By replacing the spherical 4R linkages in the original rigid origami tube with overconstrained linkages such as Bennett and Bricard linkages,origami tubes of thick panels are obtained,which can be used to reproduce kinematic motions equivalent to those realized using zerothickness origami.This thesis provides theoretical basis for origami structures,robots and metamaterials.