Construction And Deformation Properties Of Glass Fiber/Hydrogel Soft Actuator

Environment responsive hydrogel actuators are widely used as driving materials for intelligent soft robots due to their excellent flexibility and deformability,good stimulus responsiveness and biocompatibility.The complex deformation behaviors（such as bending,twisting,grasping,jumping,etc.）generated by the driving of hydrogels should be realized by constructing asymmetric structures.Layered structures are the most commonly used and most promising asymmetric structures,but there are problems such as weak interlayer connections and easy layering.In order to prepare and study the layered hydrogel actuator with good deformation effect,this paper introduced the glass fiber fabric（GF）as the passive layer,which was compounded with the solvent responsive calcium alginate/acrylamide（CA/PAAm）hydrogel for preparation.The change of the structure of the GF will lead to the uneven distribution of the internal stress of the actuator,thus producing complex deformation effects and improving the diversity of the drive.Compared with other fabrics,GF is soft and easy to deform,and are not easy to absorb water,which will not affect the water absorption and release performance of hydrogels.In addition,the warp and weft yarns of the GF are bent and crossed,and there are a lot of gaps that can allow the hydrogel to penetrate into the fabric.The main component of the GF is silicon dioxide（Si O₂）,which can form hydrogen bonds with the hydrogel to strengthen the connection.The high modulus of GF can further improve the mechanical properties of composite actuators.It is a good material used to enhance the interface performance of double-layer hydrogel actuators.This paper mainly studies the deformation effect of the software actuator,the factors that affect the deformation effect,and the interface performance of the actuator,build and verify the simulation model of the actuator,and further explore its deformation performance.（1）Fabrication and deformation performance of actuatorIn this paper,a double-layer asymmetric soft actuator of glass fiber fabric/calcium alginate/acrylamide（GF/CA/PAAm）was prepared by one-step molding.The layered heterogeneous structure of the actuator was determined by SEM.The interface connection is proved by the cycle experiment and peeling experiment.The hydrogel layer is used as the active layer for deformation based on its solvent response characteristics.In deionized water（DI）,the volume expansion of hydrogel water absorption makes the actuator bend to the side of the fabric layer;In organic solvents（for example,acetone,ethanol）,osmotic pressure makes the hydrogel layer release water and make the hydrogel volume shrink,thus bending to the side of the hydrogel layer.By changing the length width ratio of the actuator,the thickness ratio of the double-layer structure and other parameters,the influence of the size on the driving effect is explored.The results show that the larger the aspect ratio is,the greater the bending angle of the actuator is;With the increase of the thickness of hydrogel layer,the deformation degree decreases.In addition,by changing the structure of GF and the arrangement density of warp and weft yarns,the double-layer asymmetric structure actuator can produce more complex and diverse deformation effects.Taking advantage of the tailor ability of fabric and hydrogel,the actuator was cut into the shape of a hexagonal gripper,it can grab object in both DI water and acetone.（2）Simulation and research on driving effect of software actuator based on Finite Element SimulationAccording to the appearance size and physical performance of the actual actuator,the model is constructed.In this paper,the thermodynamic analysis method is used to simulate the process of water absorption expansion and water release contraction of the hydrogel.The steady-state thermal analysis module system in the simulation software is used to construct the double-layer asymmetric structure of the software actuator and endow it with physical properties,and then the model is further meshing and boundary processing.Through the simulation of single-layer material deformation,double-layer actuator deformation,actuator deformation with different aspect ratios,and different hydrogel layer thickness,the results show that the simulation and actual deformation effects are consistent,and can reach an absolute bending angle of 360°,which verifies the rationality of the model and the correctness of the simulation method.In the model,the shape of the actuator,the pattern of the hydrogel layer,the thickness of the fabric layer and the physical properties of the material are changed,and the deformation effect and internal strain of the actuator under different parameters are deeply explored.The influence of the structure and performance of the actuator on its deformation effect is clarified through simulation,which provides a theoretical basis for the optimal preparation and research of the hydrogel actuator.