Design Of A Spreadable Mechanism With A Fixed Section Based On The Two-bar Tensegrity Structure

With the development of the aerospace industry in recent years,the expandable mechanism has become a new direction of development.The spreadable mechanism takes up little space in the closed state,is easy to transport and has a certain loadbearing capacity;in the unfolded state it can be expanded from the closed state to the required working form,which can effectively cope with the problem of limited storage space for launch vehicles,and is therefore widely used in the aerospace field.To overcome this problem,tensioned monolithic structures have been introduced.The tensioned monolithic structure is a new type of structure that has been widely used in recent years.Its self-balancing,self-stabilisation and rapid recovery characteristics complement the disadvantages of the spreadable mechanism,enabling the rapid unfolding of the spreadable mechanism from a closed state,while ensuring that the unfolding process mechanism has high stability and a certain load-bearing capacity.Firstly,through the analysis of the output characteristics of the plane four-bar mechanism,the analysis of the existing spreadable mechanism at home and abroad,the summary of its closing and unfolding change characteristics,and then combined with the structural analysis about the existing space extension arm at home and abroad,to form a preliminary understanding of the mechanism model.Secondly,based on the theoretical system of the two-bar tensioning monolithic structure,an innovative tensioning monolithic structure is obtained by combining the previous analyses of the planar four-bar mechanism,the spreadable mechanism and the extension arm mechanism,and by improving the two-bar tensioning monolithic structure.The characteristics of the innovative two-bar tensioning monolithic structure are determined based on the study of the characteristics of the tensioning monolithic structure,and the feasibility of the new structure as a spreading unit for the spreadable mechanism is then determined.The stability analysis of the tensionable unit is carried out using the 3D drawing software Solidworks to draw a 3D model of the mechanism and to carry out numerical analysis of its velocity,acceleration and displacement.The three-dimensional model of the mechanism unit is imported into Adams for dynamics simulation analysis,and the dynamics simulation data of velocity,acceleration and displacement are obtained and compared with the data in Solidworks to establish the model of the trigonometric extension arm.Finally,by 3D printing technology,the rigid components of the structure are printed and then combined with the tension spring structure to build the solid prototype.