Deformation Analysis of Soft Actuator having a Bellows Structure Operated by Inner Pressure

抄録

The effects of bellows and inner pressure on the bending mechanism of a bending soft actuator, which has a rectangular cross-section divided into the upper and bottom pressure chambers in a beam structure, were investigated using a three-dimensional finite element method (3D-FEM) analysis considering large deflection. Because soft actuators are useful in fragile objects and living bodies, they have been developed and applied for many purposes. The mechanics, however, have not yet been understood because of the difficulties in predicting the 3D deformation that alters the rigidity of the actuator. In the present study, the deflection and generated force were calculated, and then the result was compared with empirical data. Consequently, the following results have been obtained: (1) the bellows structure shows a greater deflection angle than the straight structure probably because of the enhancement in the rigidity and (2) the analyzed deflection angles were consistent with the experimental result; however, the forces in the analysis did not agree well with those obtained in the experimental result. It has been suggested that the difference is caused by the Mullins effect showing hysteresis in the stress-strain curve of rubber materials, since the deflection angles were measured after the experimental data of generated force were obtained.