Numerical modeling of a 3D printed soft pneumatic actuator

Purpose This study aims to develop and validate a finite element method (FEM) model for predicting the behavior of fused filament fabrication (FFF) 3D-printed soft pneumatic actuators (SPAs). The study focuses on improving the accuracy of numerical simulations by optimizing the constitutive material model used to describe the anisotropic behavior of thermoplastic polyurethane (TPU). Design/methodology/approach A FEM model was developed to simulate the planar bending behavior of a bellow-type SPA under pneumatic pressure. The model was used to evaluate bending angles and generated forces for different design parameters, including wall thickness, number of bellow segments and operating pressure. TPU-based actuators were manufactured using FFF and experimentally tested to measure bending angles and forces. Simulations were performed in Ansys 2019 using a second-order Ogden hyper elastic model, and material parameters were optimized through fitting to experimental data. Findings The optimized material parameters improved the prediction of the actuator bending behavior by 12% compared with literature-based values. Further optimization based on fitting multiple points of the bending curve at different pressure levels reduced the prediction error by an additional 9.7%. The validated model provides a more accurate representation of the mechanical response of FFF-printed TPU SPAs. Originality/value This work proposes an experimentally validated methodology for calibrating FEM material models of FFF-printed TPU SPAs. The approach improves simulation accuracy and provides a useful tool for the design and optimization of 3D-printed SPAs, supporting researchers and engineers working in soft robotics and additive manufacturing.