Biomimetic Artificial Joints Based on Multi-Material Pneumatic Actuators Developed for Soft Robotic Finger Application

To precisely achieve a series of daily finger bending motions, a soft robotic finger corresponding to the anatomical range of each joint was designed in this study with multi-material pneumatic actuators. The actuator as a biomimetic artificial joint was developed on the basis of two composite materials of different shear modules, and the pneumatic bellows as expansion parts was restricted by frame that made from polydimethylsiloxane (PDMS). A simplified mathematical model was used for the bending mechanism description and provides guidance for the multi-material pneumatic actuator fabrication (e.g., stiffness and thickness) and structural design (e.g., cross length and chamber radius), as well as the control parameter optimization (e.g., the air pressure supply). An actuation pressure of over 70 kPa is required by the developed soft robotic finger to provide a full motion range (MCP = 36°, PIP = 114°, and DIP = 75°) for finger action mimicking. In conclusion, a multi-material pneumatic actuator was designed and developed for soft robotic finger application and theoretically and experimentally demonstrated its feasibility in finger action mimicking. This study explored the mechanical properties of the actuator and could provide evidence-based technical parameters for pneumatic robotic finger design and precise control of its dynamic air pressure dosages in mimicking actions. Thereby, the conclusion was supported by the results theoretically and experimentally, which also aligns with our aim to design and develop a multi-material pneumatic actuator as a biomimetic artificial joint for soft robotic finger application.

Band Bending Mechanism in CdO/Arsenene Heterostructure: A Potential Direct Z-scheme Photocatalyst

For the few years, two-dimensional (2D) materials have aroused general focus. In order to expand the properties and application range of 2D materials, two different layered materials are usually combined into heterostructure through van der Waals (vdW) interaction. In this research, based on first-principles simulation, we propose CdO/Arsenene (CdO/As) vdW heterostructure as a semiconductor possessing a direct bandgap by 2.179 eV. Besides, the CdO/As vdW heterostructure presents type-II band alignment, which can be used as a remarkable photocatalyst. Importantly, the CdO/As heterostructure demonstrates a direct Z-type principle photocatalyst by exploring the band bending mechanism in the heterostructure. Furthermore, we calculated the light absorption characteristics of CdO/As vdW heterostructure by optical absorption spectrum and conversion efficiency of a novel solar-to-hydrogen efficiency (ηSTH) about 11.67%, which is much higher than that of other 2D photocatalysts. Our work can provide a theoretical guidance for the designing of Z-scheme photocatalyst.

An isogeometric scaled boundary plate formulation for the analysis of ionic electroactive paper

In recent years, electroactive paper emerged as a new alternative in the field of smart actuators. It is based on a cellulose material which is able to bend under the influence of an external electric field similarly as ionic polymer metal composites. The bending mechanism is mainly attributed to the migration of ionic charges over the thickness of a thin sheet of paper. The present contribution proposes a numerical framework for the simulation of electroactive paper. It is based on a scaled boundary plate formulation for isogeometric analysis. In contrast to the standard scaled boundary plate approach, the scaling direction is solved numerically by a B-Spline approximation. This allows to render nonlinear effects over the plate thickness as well as displacement fields of higher continuity. The model is applicable to very thin structures such as electroactive paper, and it also captures the nonlinear ionic charge distribution which is coupled to the bending mechanism of the actuator.

Ethylene Acts as a Negative Regulator of the Stem-Bending Mechanism of Different Cut Snapdragon Cultivars

This study investigated whether ethylene is involved in the stem-bending mechanism of three different snapdragon cultivars ‘Asrit Red’, ‘Asrit Yellow’, and ‘Merryred Pink’, by treating their cut stems with an ethylene-releasing compound (ethephon), an ethylene-action inhibitor [silver thiosulfate (STS)], and distilled water (as the control). Ethephon completely prevented stem bending in all cultivars, whereas STS exhibited a higher bending rate compared with the control. The bending rates were influenced by several factors, such as the degree of stem curvature, relative shoot elongation, ethylene production, and lignin content, indicating their involvement in the stem-bending mechanism of the cultivars. The analysis of the expression of genes involved in the ethylene and lignin biosynthetic pathways also supported the importance of lignin and ethylene in the stem-bending mechanism. Taken together, as ethephon completely prevented stem bending of the three snapdragon cultivars, this study suggested that ethylene acts as a negative regulator of the stem-bending mechanism of snapdragon cultivars, and the information will be valuable for the prevention of stem bending in other commercially important ornamental flowers.

Design of Manual Pipe Bending Mechanism

Rotary draw bending an ongoing process. It’s an at-hand service proffered within the current market. However, each draw bender features a divergent mechanism with its pros and cons, thanks to its main advantages; the rotary draw bender was selected. Pipe bending machines have progressed many enhancements and augmentations over the amount. The sort of pipe bending plays a critical role in industries, instruments, and transporting of fluids. The first concern is that the required bend angle that this pipe will bend on. The following report will include an outline of the accessibility of this machine. The crucial variables that ought to be accounted for within the pipe bending is bend radius bend angle, pipe diameter, and thickness. The concept of press bending is employed to hold out the operation; thus, the specified force is administered with the help of a hydraulic jack. Also, other important variables are accounted for, like the bending force, bending torque, simulation outcomes about the work piece analysis, and eventually the machine design. Moreover, a prototype that satisfies the specified constraints is manufactured and assembled. Being a manual bending machine means no use of electricity is required, leading to no power consumption. Additionally, this machine is favorable, feasible, affordable, low maintenance, and higher accuracy.

Effect of Stirrup Spacing and Polypropylene Fiber Ratio on Behavior of Reinforced Concrete Beams

In this study, the effect of the change of stirrup ratio and polypropylene (PP) fiber ratio on the behavior of reinforced concrete beams was investigated. The variables of this study consisting of without stirrup, spacing up to 20 %, 40 % and 80 % of beam depth as stirrup spacing and 0.125 % and 0.500 % of the weight of reinforced concrete beam were used as PP fiber ratios. In the context of experimental study, 1/2 scaled 12 reinforced concrete beams were tested with 4-point bending mechanism. In the light of the obtained data, the load-displacement, stiffness and energy absorption graphs were plotted. The results were interpreted comparatively. According to the results, it is observed that the PP fiber additive significantly changed the behavior of the reinforced concrete beams, and the fiber effect decreased in proportion to the increase of the stirrup rate. It has been observed that the cracks spread more to the beam surfaces with the increase of PP fibers. In addition, the increase in the fiber ratio especially in the non-stirrup beams increases the bending capacity.