Finite Element Analysis On Mechanical Properties And Actuation Of Bi-stable Shell Structures

Bi-stable structure can be stable in both its extended state and coiled state without external force.It shows a broad application prospects in the field of aerospace and electronic communications,etc.In this paper,the mechanical properties and its actuation of isotropic bi-stable cylindrical shell are studied by theoretical derivation and finite element simulation methods.The contents and results of the dissertation are presented below.Based on the general theory and constitutive relation of the elastic isotropic cylindrical shell,the expression of strain energy in the deformation process of cylindrical shell was presented by using Two Parameter Method.The conditions for bi-stability are established by means of the principle of local minimum energy.The results show that cylindrical shell with certain initial stress has bi-stable characteristics,and theoretical value of the second stable rolled-up radius is obtained.In this paper,a new actuation method is proposed.A rigid indenter is used to flatten the shell partially to achieve the stable state conversion of bi-stable structure.The second stable rolled-up radius of different prestress is obtained by numerical simulation,which was in good agreement with the theoretical results.The influences of loading position and structure sizes(initial center angle and longitudinal length)on bi-stable mechanical behaviors of the shell are discussed through single factor analysis,including the second stable rolled-up radius,driving force and the maximum Mises equivalent stress.The ideal elastic-plastic mechanical model was established and the formation process of residual stress is briefly outlined.ABAQUS is used to simulate the forming process and loading process.The results show that the stable rolled-up radius obtained by theoretical,experiment and numerical simulation are consistent with each other;the load increases almost linearly with the displacement,and rapidly decreases to zero after reaching the peak;the shells with same geometrical properties have the similar slope of fitting.The work and results of this paper are intended to provide theoretical assistance for the design of isotropic bi-stable cylindrical shell structures and their actuation methods.