The Analysis Of Three Bars Tensegrity Structure Twist Angle And Topology

Tensegrity is a spatial structure that re-attracts scholars at home and abroad to study in recent years.Owing to its characters of light quality,beautiful appearance,high mass stiffness ratio,being deployable,tensegrity structure has many applications.Such as tensegrity robot,cable dome that is deducted and developed from tensegrity,spatial extension arm and deployable satellite.At present,the study about tensegrity mainly includes configuration analysis,optimization,topology and application.And analysis of form-finding as fundamental theory sill does not form a unified theory.This paper analyzes 3-bar tensegrity fundamental structure from the aspect of statics form-finding about the consistence of twist angle when structure is stable,and the problem of twist angle change as form-finding change.The concrete analysis process is as follows.Firstly,component space vector relationship can be gained by node coordinates that acquired by Cartesian coordinate system.Then 3-bar tensegrity can be analyzed by using static density method.The twist angle result gained according to the method above is discrete state meets the information that is from references.Also,in the process of force analysis,it is necessary to add a component if twist angle is consistent when structure is stable.So,3 plans are raised to satisfy the demand: 1,additional cable is added in node.2,additional cable is added in component.3,additional bar is added in node.3 plans have 3 forms respectively,also 3 kinds of twist angle ranges can be gained.Secondly,verify the result according to single node above by SVD decomposition of equilibrium matrix,and contrast rigidity by nonlinear finite element method.The scope of twist angle above is right by equilibrium matrix.In addition,the rigidity result can't be straightly gained by the method above,but the deformation amount can be used.The smaller deformation amount is,the bigger rigidity is;vice versa.Thirdly,the analysis of topology interface about 2-layers' 3-bar tensegrity.Define the twist angle between two units.In this way,we do not consider other scopes.According to the methods chapter 2 and 3,stable twist angle scope can be gained in every twist angle between two units.Then,the maximum scope and the minimum scope can be acquired.Lastly,the test and analysis of twist angle relationship between two adjacent units.The twist angle relationship can be gained by rigidity analysis when deformation amount is smallest.Finally,according to interface mode,we conclude characters and laws.And acquire the possibility of N-layers topology along the Z axial.To conclude is that the condition for the existence of structural twist angle stability is obtained by analysis.Then gaining all kinds of the relationship from structure by referring documents and comparing two plans.Finally concluding characters and laws,achieving the possibility of N-layers topology.