Mechanical Behavior of Pressurized Rods: 3D Shape Transformations of Rod Networks via Local Curvature Control

Abstract

The analysis of material shape transformations is highly valuable in areas including soft robotics, space system design, or medicine. As the elastic rods with anisotropic cross sections discussed in the report can act as bending actuators upon pressurization, an interconnected network of such rods could show promising transformation properties. The project seeks to analyze the mechanical behavior of the pressurized rods through computational finite element simulations and theoretical modelling. A three-dimensional finite element model for the mechanics of single rod configurations and the results of its application are presented in an attempt to showcase the qualitative consistency between the computations and experiments. As the complete 3D simulations proved to be extremely demanding in terms of computational resources, a reduced one-dimensional model is proposed. The primary motivation for the development of the reduced-order model is to maximize the efficiency and accuracy of the rod network simulations, such that the 3D shape transformations can be obtained as a function of the applied pressure differential. Analytical arguments within the theory of rod mechanics are demonstrated and utilized to construct a comprehensive description of the kinematics of a soft robotic arm comprised of the rods analyzed in the project. The mathematically explicit analytical model is also superimposed against the results of the reduced-order numerical scheme, whenever applicable, so as to validate the proposed computational framework.