Numerical investigation of subtle feature of geometry effects on magneto-active elastomer cylindrical actuators

Magneto-active elastomers (MAEs) are smart composite materials capable of undergoing large deformation when subjected to external magnetic fields, making them attractive for soft actuation and adaptive structures. In this study, a nonlinear finite element framework is developed to investigate the magnetically induced deformation behaviour of cylindrical MAE actuators subjected to radial magnetic loading. The magneto-mechanical response of the material is described using a continuum magneto-elastic constitutive model implemented through a user-defined material subroutine (VUMAT) within the ABAQUS/Explicit environment. The developed numerical model is used to examine the influence of the dimensionless geometric parameters α and β, representing the diameter-to-length and thickness-to-length ratios, on the deformation and stress distribution of the actuator. Parametric studies reveal that increasing these geometric aspect-ratio parameters significantly enhances circumferential deformation while producing localized circumferential stress concentration near the fixed boundary, which is identified as a critical region for failure initiation in practical actuator designs. The results further demonstrate a nonlinear interaction between actuator geometry and magnetic loading that strongly influences actuator performance. The findings provide insight into the role of geometry in magnetically driven soft actuators and offer useful guidelines for the design and optimization of MAE-based cylindrical actuation systems.