Inflated-beam soft robots, such as tip-everting vine robots, can control
curvature by contracting one beam side via pneumatic actuation. This work
develops a general finite element modeling approach to characterize their
bending. The model is validated across four pneumatic actuator types (series,
compression, embedded, and fabric pneumatic artificial muscles), and can be
extended to other designs. These actuators employ two bending mechanisms:
geometry-based contraction and material-based contraction. The model accounts
for intricate nonlinear effects of buckling and anisotropy. Experimental
validation includes three working pressures (10, 20, and 30 kPa) for each
actuator type. Geometry-based contraction yields significant deformation (92.1%
accuracy) once the buckling pattern forms, reducing slightly to 80.7% accuracy
at lower pressures due to stress singularities during buckling. Material-based
contraction achieves smaller bending angles but remains at least 96.7%
accurate. The open source models available at http://www.vinerobots.org support
designing inflated-beam robots like tip-everting vine robots, contributing to
waste reduction by optimizing designs based on material properties and stress
distribution for effective bending and stress management