|M.Sc Thesis||Department of Architecture and Town Planning|
|Supervisors:||Prof. Emeritus Burt Michael|
|Assoc. Prof. Rosenfeld Yehiel|
This work deals with kinematic scissor-link structures, focusing on geodesic types, and examining mainly their morphological behavior.
Scissor-link structures belong to the Class of kinematic structures characterized by rapid and easy deployment and collapse for reuse. They are built - of pairs of rod elements, pinned to each other at some points along their longitudial dimension.
At the collapsed state they create a straw-like bundle of straw - like near parallel rods, while at their deployed state they create a stable net work which encloses a defined space. These particular structures are advantageous for special uses, such as emergency shelters, exhibition and display structures, moving theaters, tents, skeletons for permanent structures, etc., all characterized by the need for rapid and easy comployment, convenient storage and transportation, and simple non-professional handling.
The purpose of the study was to investigate the behavior and the stability of these structures by mathematical formulation of their parameters and to propose a structured design method on the basis of the analysis. The major objective was to investigate the “clicking” phenomenon featuring scissor - link structures which do not behave as a perfect mechanism but ruther as a “pseudo-mechanism”.
This phenomenon allows to design the structure in a way that both extreme states- the folded arid the fully deployed - there are no internal stresses in the rods. Such stresses are only developed momentarily during the process of transformation between the states, due to geometric non-fit among the elements of the network.
Morphology was used in this study, first as a basic analytical tool, and later for the synthesis of a whole structure: The complete geodesic structure was divided into its basic components down to a triangle - based pyramid, and similarly, the basic unit of the scissor - link mechanism was also divided down - to “tri - scissors” - composed of three interconnected pairs of scissors. The spatial merge between these two basic kinematic arrays led to the creation of “periodic kinematic networks".
An important achievement of the study was the development of a calculation method for scissor- link networks according to the features of the desired structure. The output of the computer programs which were developed within this study are of similar importance as a database for future research and development.
The study concludes with different recommended directions of future work: In the morphologic aspects -it is possible to create more efficient divisions (frequencies) of the polyhedra in order to achieve more economical use; In the aspect of representative parameters - it is possible to develop more precise mathematical formulation of the "clicking” phenomenon; and, finally, in the technological aspect - there is a need to develop sophisticated connections for this family of structures and to incorporate them in a full scale prototype.