Design And Fabrication Of Soft Pneumatic Actuators Programmed By Microstructures

Soft materials may deform significantly under external physical fields,in form of stretching,bending,twisting and their combinations,lending themselves for use as soft actuators.Microstructure-based metamaterials have mechanical properties that are difficult to achieve by traditional materials,such as tunable Young’s modulus,negative Poisson’s ratio,light weight and high stiffness.The combination of microstructures and soft materials opens up an avenue for innovative design of soft actuators and robots embodied with complex motion behaviors.However,due to the complex interplay among structure geometry,multiple materials and actuation under large deformation,systematic design theory and method are still lacking.In this thesis,we propose an integrated modeling and analysis method for design synthesis of soft pneumatic actuators programmed by microstructures.Through the parametrization and optimization of spatial-varying lattice microstructures,new soft pneumatic bending actuators and twisting actuators are realized.We construct a geometric modeling platform,by using beam element to describe the microstructures,and by using shell element to describe the chamber which shares the same nodes of the microstructures.The coupled model is evaluated by nonlinear large deformation analysis,with good convergence quality and at acceptable computation cost.Based on the integrated modeling and analysis method,new bending actuators based on positive and negative Poisson’s ratio microstructures and twisting actuators based on chiral microstructures are proposed.The design is further improved by dimensionless analysis and parameter optimization.The bending deformation of 0.43 °/mm and the twisting deformation of 1.43 °/mm are achieved.