Modeling of positive and negative pressure in soft Pneu-net actuator subjected to airflow volume changes in rectangular chambers

It is an essential design requirement to understand the method to represent the pressure deformation of elastomers as a crucial aspect of pneumatic actuator behavior. Most research focus on the motion of positive pressure kinematics and ignore the contribution of negative pressure to soft actuators in free space. This study presents an analytical model for soft pneumatic networks (Pneu-net) at both positive and negative pressures. The analytical model, based on finite strain membrane and hyperelastic material models, describes the relationship between pressures and volume change in the actuator’s chamber, and predicts the Pneu-net’s deformation and tip force under both positive and negative pressures. Experimental validation shows that the model can accurately predict the Pneu-net’s deformation behavior under low pressure (−20 to 20 kPa) with an error band of less than 15%. The model’s accuracy decreases beyond ±20 kPa due to material nonlinearity. This model addresses a gap in the research of Pneu-net kinematics at negative pressure, which will put forward the optimal design of Pneu-net and its potential applications in soft robotics such as soft grippers and biomimetics at both positive and negative pressure.