Topology optimization of pneumatic soft actuators based on porohyperelasticity

This paper introduces a new nonlinear topology optimization framework which employs porohyperelasticity for providing computational design of pneumatic soft actuators. Density-based topology optimization is used with the objective of maximizing the bending response in a soft actuator made of an elastomer, for given actuation pressure and external resistance. Pressurization of interconnected cavities is modeled via an extension of the Darcy flow theory that is valid for large deformations. Essential for the good performance of the framework is a carefully chosen interpolation scheme for the permeability between void and solid regions, as well as a suitable definition of a drainage term in the solid regions. Results are shown for a variety of actuation pressures and maximum allowable strain energy density levels, covering a wide range of system responses from small to rather large deformations.