An Octopus-Inspired Bionic Flexible Gripper for Apple Grasping

When an octopus grasps something, the rigidity of its tentacle can change greatly, which allowing for unlimited freedom, agility, and precision. Inspired by this, a three-finger flexible bionic robot gripper was designed for apple picking. First, a flexible chamber finger was designed to drive the gripper finger to elongate, shorten, and bend, which works through a process of inflating and deflating. Further, we proposed a three-finger mode to achieve two kinds of motion states: grasping and relaxing, by simulating the movement of an octopus grasping at something. In this paper, we evaluated the bending property of the designed flexible bionic gripper through an apple grasping experiment. The experimental results show that the 100.0 g bionic gripper can load an apple with a weight of 246.5~350.0 g and a diameter of 69.0~99.0 mm, and the grasping success rate is 100%. It has a good grasping performance. Compared to other soft grippers, the proposed bionic flexible gripper has the advantages of being lightweight, and having good cushioning, low driving air pressure, and a strong grasping force.

Evaluation of some physical performance properties of ultrasonic seaming, conventional seaming and sealing adhesive tape on waterproof polyester knitted fabrics with polyurethane

Ultrasonic seaming has become an important issue in recent years due to its various features. In this study, waterproof polyester knitted fabrics with polyurethane coating were used and the bursting strength, bending property and water permeability property of ultrasonic seaming were examined by changing various parameters. Besides, the ultrasonic seaming method was compared to conventional seaming and adhesive tape application. It is observed that there were high water permeability values generally in ultrasonic seaming and also fabrics with no water penetration were seen in this method, although, in some ultrasonic seaming parameters, values are lower than adhesive tape sealed ones. On the other hand, the bursting strength values of the ultrasonically sewn fabrics are found to be comparable to conventional seam and sealing adhesive tape when the optimum seaming parameters are determined. Also, it can be said that for the bending property according to increasing bending length values in this method compared with the others, ultrasonic seaming may find more usage areas where fabric stiffness is more advantageous. It has been observed that it is important to determine the fabric and ultrasonic sewing parameters according to the required performance property.

A strain gradient strategy to quantifying longitudinal compression behavior in slender fibrous assembly structures

Slender fibrous assembled structures can easily buckle under longitudinal compressive load. The limitation in characterizing the longitudinal compression behavior poses a significant challenge to the mechanics optimization of such structures. To address this challenge, we use one-dimensional yarns as a model system, and the yarns are deformed in bending to form a strain gradient, from tension to compression, along the radial direction of the yarns. The compression modulus as a function of compression strain is calculated based on bi-moduli elastic theory. The evolution of the fiber arrangement and the position of the neutral layer in the yarn is interpreted along with the change of compression modulus. Also, the local stress distribution in the bent yarn was determined by finite element simulation, and it is remarked that the bending property of yarns is sensitive to the compression modulus. The present study offers insights on the modeling and simulation of fabrics and garments in drape and bending deformation. Results from such investigations can provide effective guidance for the mechanical and structural design of textiles and textile-based composites.

Burnishing Characteristics of Sliding Burnishing Process With Active Rotary Tool Targeting Stainless Steel

This paper investigates the burnishing characteristics of a developed sliding burnishing method with active rotary tool targeting a martensitic stainless steel. Two types of martensitic stainless steel, annealing (AN) stainless steel and quenching and tempering (QT) stainless steel, were targeted. The burnishing characteristics evaluated included surface roughness, profile, microstructure, subsurface hardness, bending property, and corrosion resistance. A sufficiently smooth surface, approximately Ra = 0.1 μm and Ra = 0.025 μm in both materials, respectively, was obtained using the developed burnishing method; irregular profile smoothing occurred due to the material flow of the subsurface. The subsurface hardness increased at a depth of 40 μm or more when using the developed burnishing method on the AN material, but no effect was observed for the QT material. Moreover, the bending yield point and strength of the sheet shape workpiece increased by applying the burnishing process to the AN material. The influence of the burnishing process on the bending properties was also observed for the QT material. Corrosion resistance can be improved through the burnishing process.