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A number of pneumatic soft robots are made of hyperelastic silicone rubber. The dynamic modeling and control of the soft robot require the establishment of a constitutive model of the silicone rubber. The Neo-Hookean constitutive model was established according to the material properties of silicone rubber. In this study, using the optimization module of COMSOL Multiphysics, we fitted uniaxial and equibiaxial measured data against the Neo-Hookean constitutive model. We obtained the stretch-stress relationship of the silicone rubber material from the uniaxial tension test. For the uniaxial and equibiaxial measured data, different weights are assigned to improve fitting accuracy. For silicone rubber with a large range of stretch factor, the measured data are fitted piecewise against the Neo-Hookean model. The Neo-Hookean material model fits both test data quite well for the case of different weight and piecewise fitting for uniaxial and equibiaxial data set.

The technology of reducing yarn hairiness using air-jet nozzle on the winder (JetWind) is a combination of the ring spinning and air-jet (vortex) spinning technologies. A dynamic model for the coupling between the ramie yarn hair and the airflow field inside the hairiness-reducing nozzle on the winder is developed in this research. Based on the model, computer simulation of the dynamics of the hair in the nozzle is performed and the hairiness-reducing principle is theoretically investigated. The high-speed photography technology is used to capture experimentally the dynamics of the hair in the nozzle to verify the simulation result. The dynamics of the hair in the nozzle is obtained through the computer simulation which indicates the principle of reducing ramie yarn hairiness using air-jet nozzle on the winder is to make the hair wrap onto the yarn body with the action of the swirling airflow. The high-speed photography validates the simulation result.