Deployable Structure Based On Bennett 4R Linkage

This dissertation presents a method of building deployable structures using an existing mechanism named Bennett 4R linkage, which is a famous overconstrained linkage and whose alternative form can fold and deploy completely. With the basic theory and geometric relationship of Bennett 4R linkage, the angle formulas of single linkage model which deploy completely into plane or curved face are both deduced, and by these angles the models are made quickly and simply instead of deducing the parameter relationship from its original form.A study into constructing the networks using Bennett 4R linkage as the basic element has been done. Three types of networks by the original form are put up, and rules of the angle between the axes are also deduced. Only obey these rules, the whole networks have a single degree of mobility. Meanwhile, a single layer structure has been extended to form multi-layer structures. In addition, according to the alternative form, a network of foldable model has been made.An idea of connecting the membrane with the linkage is proposed. With the altitude difference of the alternative linkage's four endpoints, membrane can be tensioned easily on the linkage to the hyperbolic paraboloid. In this way, the membrane folds and deploys with the linkage together. Furthermore, this dissertation also analyzes the geometrical compatibility between the membrane and the linkage.The final part of the dissertation is a research into the effect of the linkage's angle parameters on the structure. With the help of our own program and finite element program ANSYS, the form-finding and load analysis of membrane are studied. Considering the max stress and max displacement of membrane as the control parameters, the best angle group has been seek out. Meanwhile, after the load analysis of a single linkage and the network with four elements, a comparison of the two results has been done.