Stress Analysis and Operational Limits of an SLA-Printed Soft Antagonistic Actuator Using a Yeoh-Calibrated Finite Element Model

Soft robotics has emerged as a promising approach for safe human–machine interaction, adaptive manipulation, and bioinspired motion, yet its progress relies on accurate material characterization and structural analysis of actuators. This study presents the mechanical behavior and stress analysis of a stereolithography-printed pneumatic actuator with antagonistic architecture, fabricated using Elastic 50A resin V2. Uniaxial tensile tests were performed according to ASTM D412 to derive material parameters, which were fitted to hyperelastic constitutive models. The Yeoh model was identified as the most accurate and implemented in finite element simulations to predict actuator deformation under multiple pressurization modes. Results revealed critical stress zones and established operational pressure limits of 110–130 kPa, beyond which the material approaches its tensile strength. Experimental testing with a controlled pneumatic system validated the numerical predictions, confirming both bending and multidirectional actuation as well as structural failure thresholds. The integration of material characterization, numerical modeling, and experimental validation provides a robust workflow for the design of SLA-fabricated antagonistic actuators. These findings highlight the advantages of combining digital fabrication with antagonistic actuation and material modeling to expand the understanding of soft robots’ behavior.