Bending Angle Research Articles

Mimicking Symmetry‐Breaking Einstein Ring by Optical Lens

The celebrated theory of general relativity has inspired research on optical simulations using artificial microstructures to mimic curved space–times. The gravitational lensing that bends light close to large mass concentrations is one of the most fascinating predictions by general relativity. Herein, an optical lens is utilized to emulate the gravitational lensing effect and observe the Einstein ring (ER) patterns. The ER patterns and their spatial evolution with imaging distance, both experimentally and theoretically, are quantitatively studied. A profound example of the symmetry‐breaking ER, i.e., the Einstein cross, is observed utilizing a rotation‐symmetry‐breaking hemi‐ellipsoid lens. Based on the bending angle diagram, a series of deformed Einstein cross patterns induced by noncollinearly alignment of the light source–lens–observer are revealed. Inspired by the analogy between gravitational lensing and optical lens, a novel lens of nested concentric grooves is created and multi‐ER patterns are realized. The work provides an intriguing platform for exploring the unconventional gravitational lensing effect and may also find applications in optical ranging.

Investigation on multiple bending using laser forming of mild steel plate and its bend angle prediction

In manufacturing industries like shipbuilding, automotive, microelectronics, and aerospace, laser forming is a potential new technology. Laser forming is an intricate thermo-mechanical process in which the process mechanisms are determined by the temperature profile across the sheet thickness, which is influenced by laser power, scan speed, number of passes, laser beam diameter, and workpiece geometry. During the process, the material deforms because of compressive stress generated in the underneath region due to the thermal expansion of the irradiated region. This study focuses on the multiple bending and the effect of different process parameters on the laser bending of the sheet. Experiments were performed on 4 mm and 8 mm thick sheets of mild steel sheet of grade IS 2062 E250 using a 2-kW fiber laser with various influencing parameters such as power, scan speed, and laser spot diameter. Hardness and grain size measurements of laser-formed surfaces at different combinations of influencing parameters were performed and the features formed due to laser irradiation were analyzed. An artificial neural network (ANN) model is proposed to predict the bend angle value.

Inspired by the growth behavior of plants: biomimetic soft robots that just meet the requirements of use.

Soft robots are usually manufactured using the pouring method and can only be configured with a fixed execution area, which often faces the problem of insufficient or wasteful performance in real-world applications, and cannot be reused for other tasks. In order to overcome this limitation, we propose a simple and controllable rather than redesigned method inspired by the bionic growth behavior of plants, and prepare bionic soft robots that can just meet the requirements of use, and transform biological intelligence into mechanical intelligence. Based on finite element method, we establish a theoretical model of soft robot performance. and the experimental platform is designed to conduct experimental research on the prototype of the soft robot (Fashion2). Compared with the results obtained through the theoretical model, it is found out that the experimental bending angle and elongation are slightly smaller than the simulation results. The maximum prediction error of bending angle is 5.9%, and the maximum prediction error of elongation is 7.4%. However, the high consistence between our theoretical model and the experimental results shows that the theoretical model is applicable to accurately predict the performance of soft robots. It is worth pointing out that this design as proposed in this paper can be extended to the wider field of soft robotics as a generic one.&#xD.

Analysis of Mechanisms of Mandible Fractures by Lateral Impact: A Biomechanical Approach Using Finite Element Models

Background/Aim: The purpose of this study was to reproduce a lateral fall using a computer simulation model and to clarify the circumstances of mandible fracture caused by a lateral impact. Material and methods: Fall scenarios were reconstructed using a computer simulation with finite element models. The fall condition was set as a fall from the head direction, which would cause facial injuries. In each simulation, the effective plastic strain of the mandible and its site were determined. Analysis of variance was performed to determine which factors had a significant effect on the maximum effective plastic strain of the mandible. Results: Significant differences with p-values less than 0.001 were found for the following factors: pitch angle, lateral bending angle, impact object, combination of pitch angle and lateral bending angle, and combination of pitch angle and impact object. In most cases with higher values of effective plastic strain, which can cause mandibular fractures, the site was found at the condylar process or mandibular angle of the attacked side. Conclusion: If the patient falls laterally and their face makes contact with a protruding object, medical professionals can predict fractures of the upper part of the mandibular angle and the condyle of the affected side.

Design and calibration of a low-cost embedded system-based line laser sensor for measuring bending angle in industrial applications

Design and calibration of a low-cost embedded system-based line laser sensor for measuring bending angle in industrial applications

Design and experiments of a humanoid torso based on biological features.

Among the components of a humanoid robot, a humanoid torso plays a vital role in supporting a humanoid robot to complete the desired motions. In this paper, a new LARMbot torso is developed for obtaining better working performance based on biological features. Through analyzing the anatomy of a human torso and human spine, a parallel cable-driven is proposed to actuate the whole mechanism by using two servo motors and two pulleys. Analysis are conducted to evaluate the properties of the proposed parallel cable-driven mechanism. A closed-loop control system is applied to control the whole LARMbot torso. Experiments in three modes are conducted by using the manufactured prototype for evaluating the characterizations of the proposed design. Results show that the proposed LARMbot can complete the desired motions. For general bending at different directions,the maximum bending angle is 40 degree, the maximum cable tension is 0.68 N, and the maximum required power is 18.3 W. In full rotation motion, the maximum bending angle is 30 degree, the maximum cable tension is 0.75 N, and the maximum power required is 20.5 W. This design is more simple and lightly, its low energy consumption and flexible spatial motion performance meet the needs of the humanoid robot torso's application in complex scenarios and commercial requirements.&#xD.

Low-Temperature, Highly Sensitive Ammonia Sensors Based on Nanostructured Copper Iodide Layers

Chemiresistive ammonia gas sensors with a low limit of detection of 0.15 ppm and moisture-independent characteristics based on p-type copper iodide (CuI) semiconductor films have been developed. CuI films were deposited on glass and polyethylene terephthalate (PET) substrates using a Successive Ionic Layer Adsorption and Reaction method to fabricate CuI/glass and CuI/PET gas sensors, respectively. They have a nanoscale morphology, an excess iodine and sulfur impurity content, a zinc blende γ-CuI crystal structure with a grain size of ~34 nm and an optical band gap of about 2.95 eV. The high selective sensitivity of both sensors to NH3 is explained by the formation of the [Cu(NH3)2]+ complex. At 5 °C, the responses to 3 ppm ammonia in air in terms of the relative resistance change were 24.5 for the CuI/glass gas sensor and 28 for the CuI/PET gas sensor, with short response times of 50 s to 210 s and recovery times of 10–70 s. The sensors have a fast response–recovery and their performance was well maintained after long-term stability testing for 45 days. After 1000 repeated bends of the flexible CuI/PET gas sensor in different directions, with bending angles up to 180° and curvature radii up to 0.25 cm, the response changes were only 3%.

Machine Learning Models for Assistance from Soft Robotic Elbow Exoskeleton to Reduce Musculoskeletal Disorders

Musculoskeletal disorders are very common injuries among occupational and healthcare workers. These injuries are preventable in many scenarios using exoskeleton-based assistive technology. Soft robotics initiates an evolution in exoskeleton devices due to their safe human interactions, ergonomic design, and adaptive characteristics. Despite their enormous advantages, it is a challenging task to model and control soft robotic devices due to their inherent nonlinearity and hysteresis. Learning-based approaches are becoming more popular to overcome these limitations. This work proposes an approach to estimate the pressure input for a pneumatically actuated soft robotic elbow exoskeleton to assist occupational workers to avoid musculoskeletal disorders. An elbow exoskeleton design made up of modular pneumatic soft actuators is discussed, which helps to flex/extend an elbow joint. Machine learning (ML) approaches are used to develop a relationship between the air pressure, the bending angle of the elbow, and the percentage of the weight of the arm to be assisted by the exoskeleton. The most popular and widely used regression-based ML approaches are applied and compared in terms of accuracy and computation cost. Further, a modified KNN (K-Nearest Neighbor) approach is proposed, which outperforms the accuracy of other approaches.

Aerodynamic analysis of complex flapping motions based on free-flight biological data

The wings of birds contain complex morphing mechanisms that enable them to perform remarkable aerial maneuvers. Wing morphing is often described using five wingbeat motion parameters: flapping, bending, folding, sweeping, and twisting. However, the specific impact of these motions on the aerodynamic performance of wings throughout the wingbeat cycle, and their potential to inform engineering applications, remains insufficiently explored. To bridge this gap and better incorporate the properties of coupled motions into the design of biomimetic aircraft, we present a numerical investigation of four flapping-based coupled motions during different flight phases (i.e. take-off, level flight, and landing) using a pigeon-like airfoil model. The wingbeat motion data for these four coupled motions were based on real flying pigeons and divided into: flap-bending, flap-folding, flap-sweeping, and flap-twisting. We used computational fluid dynamic simulations to study the effects of these coupled motions on the flow field, generation of transient aerodynamic forces, and work done by different motions on flapping. It was found that, first, the flap-bending motion causes unstable changes in the effective angle of attack (AoA), which affects the attachment of the leading-edge vortex (LEV), thereby producing more lift at smaller bending angles. Next, the flap-folding motion causes the LEV to attach to the wing earlier and regulates the detachment of vortices. Significant changes in the folding angle are used to influence lift generation and the flap-sweeping motion has minimal effect on the flow field structure across the three flight phases. Finally, flap-twisting motion leads to notable changes in the effective AoA, allowing for dynamic adjustments to control aerodynamics at different stroke stages, resulting in less drag during take-off and more drag during landing. This study enhances the understanding of the aerodynamic performance of bird with coupled motions in different flight phases and provides theoretical guidance for the design of bionic flapping-wing aircraft with multi-degree-of-freedom wings.

Design of Dielectric Elastomer Actuator and Its Application in Flexible Gripper.

Dielectric elastomer actuators (DEAs) are difficult to apply to flexible grippers due to their small deformation range and low output force. Hence, a DEA with a large bending deformation range and output force was designed, and a corresponding flexible gripper was developed to realize the function of grasping objects of different shapes. The relationship between the pre-stretch ratio and DEA deformation degree was tested by experiments. Based on the performance test results of the dielectric elastomer (DE), the bending deformation process of DEAs with different shapes was simulated by Finite Element Method (FEM) simulation. DEAs with different shapes were prepared through laser cutting and the relationship between the voltage and the bending angle, and the output force of the DEAs was measured. The result shows that under uniaxial stretching, the deformation of the DEA in the stretching direction gradually increases and decreases in the unstretched direction with the increase in the pre-stretch ratio. Under biaxial stretching, DEA deformation increases with the increase in the pre-stretch ratio. The shape of the DEA has a certain influence on the bending deformation range under the same conditions, and the elliptical DEA has a larger bending deformation range and higher output force compared with the rectangular DEA and the trapezium DEA. The elliptical DEA can produce a bending deformation of 40° and an output force of 37.2 mN at a voltage of 24 kV. The three-finger flexible gripper composed of an elliptical DEA can realize the grasping of a paper cup.

Numerical Simulation Study on the Effect of Bend Angle on the Flow Characteristics of Natural Gas Hydrate Particles

ABSTRACTBend pipe is a commonly used part of long‐distance pipelines. It is very important to study the flow law of hydrate particles in the bend pipe to optimize pipeline design. In addition, the efficiency and safety of pipeline gas transmission will be improved. The flow of hydrate particles in the bend pipe is the research object of this paper, and the short twist tape is used as the spiral device, and numerical simulation methods are used to study the effects of the bend angle and the twist rate on the velocity distribution, turbulence intensity distribution, wall shear, particle movement and pressure drop distribution of the spiral flow carrying hydrate particles. The results show that as the twist rate of the twist tape is smaller, and the spiral flow is stronger, the fluid can generate a larger tangential velocity when flowing through the bend. The maximum speed at the section closest to the entrance is 28% higher than at the section furthest. Maximum tangential speed increased by 2 times. When the angle of the bend is larger, and velocity is more conducive to maintaining the spiral flow pattern of the particles, it is also more conducive to maintain. However, the twist rate is smaller, and the resistance is greater, then the pressure drop is greater, and the resistance coefficient of the bend pipe section is greater. With the increase of torsion, the pressure drop decreased by 52%. When the angle of the bend pipe section becomes smaller, it increases the collision frequency between the pipe wall and the natural gas. Unit pressure drop loss increased by 13%. When the angle is smaller, the change in the direction of the velocity of the particles will be more violent, and the pressure drop is larger, and the drag coefficient is larger. In the same section, the maximum turbulence intensity is about twice the minimum.

Low compression smart clothing for respiratory rate monitoring using a bending angle sensor based on double-layer capacitance

Low compression smart clothing for respiratory rate monitoring using a bending angle sensor based on double-layer capacitance

Effect of variable angular piping bends geometry on turbulent flow of supercritical water in an SCWR Plant piping network: a 3-D CFD investigation

Abstract One of the most critical components of Super Critical Water Reactor (SCWR) plant is pipe bend, carrying massive volume of supercritical water. Because of its intense fluctuation of velocity and pressure, it can exhibit unusual flow pattern in pipe bends. This unusual flow pattern may finally destroy the integrity of the piping network. Alternatively, because of unique chemical and physical properties, transportation of SCW can adversely effect on the integrity of the pipe bends, indicating probable failure of piping network. Therefore, intensive studies of SCW flow in bends is a must while designing an efficient plant piping network. This article presents CFD analysis, carried out to examine the effect of variable pipe bend angle (90, 120 & 135;) on turbulent flow of SCW. The analysis indicates, the portion of the straight inlet pipe with fully developed flow shows no variation of results in all bend configurations. The study also reveals that secondary currents strengthen at lower bend angles and culminate the formation of vertices at the outlet of the right-angled elbow. The study shows that a greater part of the cross-sectional area is covered by the vortices at the bend mid-planes compared to the bend outlets, where mixing of stream wise flow occurs as well. It is found that the radial positions of each vortex center are closer to the circumference of the pipe, and appear to be insensitive to bend angle. The study is ended with the comparison between supercritical and normal water at standard conditions.

Nanowrinkle waveguide in graphene for enabling secure Dirac fermion transport

Abstract Localized states in graphene have garnered significant attention in quantum information science due to their potential applications. Despite graphene’s superior transport and electronic properties compared to other semiconductors, achieving nanoscale confinement remains challenging due to its gapless nature. In this study, we explore the unique transport properties along nanowrinkles in monolayer graphene. We demonstrate the creation of a one-dimensional conduction channel by alternating pseudomagnetic fields along the nanowrinkle, enabling ballistic Dirac fermion transport without leakage. This suggests a feasible method for secure quantum information transfer over long distances. Furthermore, we extend our analysis to bent nanowrinkles, showcasing well-guided Dirac fermion propagation unless the bent angle is sufficiently large. Our demonstration of the nanowrinkle waveguide in graphene introduces a novel approach to controlling Dirac fermion transport through strain engineering, for quantum information technology applications.

Numerical Simulation of Gas–Liquid–Solid Erosive Wear in Gas Storage Columns

Gas reservoirs play an increasingly important role in oil and gas consumption and safety in China. To study the problem of erosion and wear caused by gas-carrying particles in the process of gas extraction from gas storage reservoirs, a mathematical model of gas–liquid–solid three-phase erosion of gas storage reservoir columns was established through theories of multiphase flow and particle motion. Based on this model, the effects of the water volume fraction, gas extraction rate, particle mass flow rate, particle size, and bending angle on the erosion location and rate of the pipe columns were investigated. The findings indicate that when the water content volume fraction is low, the water production volume minimally affects the maximum erosion rate of pipe columns. Conversely, the gas extraction rate exerted the most significant influence on the column erosion, showing a power function relationship between the two. When gas extraction volume exceeds 60 × 104 m3/d, the maximum erosion rate surpasses the critical erosion rate of 0.076 mm/a. This coincided with the increased sand mass flow rate, although the maximum erosion rate of the pipe columns remained relatively steady. The salt mass flow rate demonstrated a linear relationship with the erosion rate, with the maximum erosion rate exceeding the critical erosion rate of 0.076 mm/a. The maximum erosion rate of the pipe columns increased, stabilized with larger sand and salt particle sizes, and exhibited an increasing trend with the bending angle. For gas extraction volumes exceeding 46.4 × 104 m3/d and salt mass flow rates exceeding 22 kg/d, the maximum erosion rate of pipe columns exceeds the critical erosion rate of 0.076 mm/a. The conclusions of this study are of some importance for the clarification of the influencing law of pipe column erosion under high temperature and high pressure in gas storage reservoirs and for the formulation of measures for the prevention and control of pipe column erosion in gas storage reservoirs.

A mouse coccygeal intervertebral disc degeneration model with tail-looping constructed using a suturing method.

Intervertebral disc degeneration (IDD) is one of the common degenerative diseases. Due to ethical constraints, it is difficult to obtain sufficient research on humans, so the use of an animal model of IDD is very important to clarify the pathogenesis and treatment mechanism of the disease. In this study, thirty 2-month-old mice were selected for operation to establish a coccygeal IDD model. The distal tail portion of the tail (beyond the 17th coccygeal vertebra) and a small piece of skin above the 8th coccygeal vertebra were excised, and the two incisions were brought together after flexion, and secured with sutures. The heights and signal intensities of the intervertebral discs (IVDs) were assessed using microcomputed tomography (μCT) and magnetic resonance imaging (MRI) at 0, 6, 12 weeks postoperatively. The overall tissue morphology, cell distribution and density, and extracellular matrix of the IVDs were also assessed using Hematoxylin and Eosin (HE), Safranin O-Fast Green and immunohistochemical staining. All mice in the experimental group survived after the operation, and there were no complications such as wound infection, tail necrosis and suture shedding. The experimental results demonstrated that the suturing method can successfully initiate IDD. Different severity levels of IDD can be induced by controlling the bending angle of the IVDs within the tail loop; however, for consistency, histologic and imaging results should be obtained at the same bending angle and looping period. This IDD model is an effective method for studying the etiology and treatment of degenerative IVD disease.

Manipulation of field-effect transistors by flexoelectric effect

Flexoelectric field-effect transistors (FE-FETs) hold significant potential for applications in biomedical and healthcare sensing fields. While existing piezoelectric FETs sense physiological signals based on pressure or compressive strain, movements such as bending of the elbow or knee joints are more common in physiological activities than external pressure. To address this, this study innovatively introduces FE-FETs that are regulated through the flexoelectric effect induced by bending. In this study, MoS2 with flexoelectric properties is utilized as the channel region. By bending the FE-FETs, the flexoelectric effect is induced, generating a flexoelectric response voltage that alters the Schottky barrier. The results confirm that varying the bending angle of the FE-FETs effectively modulates their transconductance and carrier mobility. Remarkably, the combination of traditional gate voltage and the flexoelectric effect results in a maximum carrier mobility of 49.63 cm2/V · s within a drain voltage range of 0–1 V, which is approximately 10.6 times higher than the carrier mobility of 4.68 cm2/V·s under traditional gate voltage alone. This study provides an effective approach to regulating FE-FETs and expands the possibilities for their application in wearable technology.

Spindle-Shaped Ni-Fe-Layered Double Hydroxide: Effect of Etching Time on Flexible Energy Storage.

The rising demand for efficient energy storage in flexible electronics is driving the search for materials that are well-suited for the fabrication of these devices. Layered Double Hydroxides (LDHs) stand out as a remarkable material with a layered structure that embodies exceptional electrochemical properties. In this study, both double-shelled and single-shelled NiFe-Layered Double Hydroxide (LDH) particles are prepared using spindle-shaped MIL-101(Fe) as the template. These NiFe-LDH particles are then utilized to develop a flexible energy storage device. Transmission electron microscopy(TEM) analysis revealed that the as-synthesized NiFe-LDH particles transformed into hollow single-shells from a double-shelled structure as the aging time increased, which significantly influenced the electrochemical performances. Despite the decreasing specific capacitance and energy density with longer etching times, the sample etched for 2h (NiFe-LDH 2h) demonstrated the highest capacitance of 9.24 mF·cm⁻2 and an energy density of 0.46 µW·h·cm⁻2, highlighting its promising performance for energy storage applications. X-ray photoelectron spectroscopy (XPS) analysis revealed the highest Ni2+: Ni3+ ratio, and Fe: Ni ratio for NiFe- LDH 2h samples, which further influences the energy storage properties. The ability to maintain the high performance of these materials across different bending angles further emphasizes its versatility and relevance in emerging flexible electronics markets.

Triboelectric Bending Sensors for AI-Enabled Sign Language Recognition.

Human-machine interfacesand wearable electronics, as fundamentals to achieve human-machine interactions, are becoming increasingly essential in the era of the Internet of Things. However, contemporary wearable sensors based on resistive and capacitive mechanisms demand an external power, impeding them from extensive and diverse deployment. Herein, a smart wearable system is developed encompassing five arch-structured self-powered triboelectric sensors, a five-channel data acquisition unit to collect finger bending signals, and an artificial intelligence (AI) methodology, specifically a long short-term memory (LSTM) network, to recognize signal patterns. A slider-crank mechanism that precisely controls the bending angle is designed to quantitively assess the sensor's performance. Thirty signal patterns of sign language of each letter are collected and analyzed after the environment noise and cross-talks among different channels are reduced and removed, respectively, by leveraging low pass filters. Two LSTM models are trained using different training sets, and four indexes are introduced to evaluate their performance, achieving a recognition accuracy of 96.15%. This work demonstrates a novel integration of triboelectric sensors with AI for sign language recognition, paving a new application avenue of triboelectric sensors in wearable electronics.

Lightweight flexible self-powered photo-supercapacitors with good stability through photoelectrochemical deposition of tellurium on PPy–V2O5 films as a new visible light active dual photoelectrode

Lightweight flexible solid-state photosupercapacitors (FSSPC) with two identical Te@PPy–V2O5 photoelectrodes showed good performance and maintained functionality under different bending angles. They also demonstrated stability from −10 °C to 50 °C.