Increase In Bending Angle Research Articles

Behavior of a defect in a flexible carbon nanotube

Abstract Carbon nanotubes (CNTs) play an indispensable role in the design and application of flexible devices due to their unique physical and chemical properties. ‌This study theoretically investigates the behavior of defects in bent CNTs. The results indicate that when the defect is under compressive strain, the conductance of the device decreases as the bending angle increases. Conversely, when the defect is under tensile strain, the conductance of the device increases with a larger bending angle.This phenomenon is primarily attributed to the enhancement of scattering states corresponding to the defect under tensile strain and the weakening of these states under compressive strain. Under bias voltage, similar patterns are observed for transmission peaks corresponding to the defect. These findings contribute to the device design process, enabling the exploitation of advantages and avoidance of disadvantages, ultimately leading to the development of flexible CNTs- devices.‌

Research on the Internal Flow Properties of the Bending Pipeline Based on the CFD

Abstract Pipeline connection is the main connection of hydraulic parts. For the study of pipe diameter, turning Angle and the turning radius of pipe, the influence law of the internal flow characteristics. this paper adopts CFD 3D simulation technology to explore the influence law of 5 kinds of bending radius, 6 kinds of bending Angle and 4 kinds of pipe diameter on the pressure loss of the pipeline. The results show that there are pressure difference and velocity difference in the inner wall and the outer wall of the bend, due to the impact of the fluid inertia force on the bend, when the fluid flows in the bend. As bending radius and pipe diameter increases, the pressure difference and speed difference of the inner and outer walls at the turning point of the pipeline are reduced, the local pressure loss at the bending is reduced, the internal pressure loss of the pipeline is reduced, and the flow is more uniform. With the increase of bending angle, the pressure difference and velocity difference of the inner and outer walls of the pipeline bending increase, the local pressure loss increases, and the overall pipeline pressure loss increases. The research results of this paper can provide some reference for pipeline hydraulic design and optimization.

The effect of bending angle on a flexible electrode DBD plasma under sinusoidal excitation

There is a critical demand for sophisticated surface disinfection and sterilization devices accessible to the public by using cold atmospheric pressure air plasmas. A flexible printed circuit design of a dielectric barrier discharge reactor under non-bending and two bending configurations with an angle of 120° and 180° was studied. The characteristics of power consumption, the optical emission spectrum, dynamic process, electrode temperature and ozone concentration are evaluated. The non-bending configuration produces more O3, as compared to the bending configuration at the same applied voltage. The 180° configuration has a maximum concentration of excited species at the expense of higher electrode temperature. Both bending configurations demonstrated the propagation of filaments to bending axis where the continues luminescence is observed due to the high electrical field. The energy efficiency for plasma-generated reactive species reaches to 40% for non-bending configuration and decreases with the increase of bending angle. This research provides a new strategy for perspective into the plasma generated reactive species in biomedical and environmental applications.

Design and Driving Performance Study of Soft Actuators for Hand Rehabilitation Training.

To address the application requirements of soft actuators in rehabilitation training gloves, and in combination with ergonomic requirements, we designed a segmented soft actuator with bending and elongation modules. This actuator can achieve independent or coupled movements of the finger joints. A finite element model of the joint actuator was established to compare the driving performance of actuators with different structural forms. Numerical calculations were used to analyze the effects of structural size parameters on the bending characteristics and end output force of the actuator. The design was then refined based on these analyses. The joint actuator designed in this study demonstrated a 71% increase in bending angle compared to the standard fast pneumatic network structure. Key factors affecting the driving performance include the thickness of the constraint layer, the inner wall thickness of the chamber, chamber height, chamber width, chamber spacing, chamber length, and the number of chambers. After improvements, the bending angle of the joint actuator increased by 60.6%, and the output force increased by 145.9%, indicating significant improvement. This study designed and improved a soft actuator for hand rehabilitation training, achieving independent and coupled joint movements. The bending angle, bending shape, and joint driving force of the soft actuator meet the requirements for finger rehabilitation training.

Mechanical properties and regulatory strategy of twinned tetrahedral lattice structures

Given the outstanding mechanical performance of lattice metamaterials, novel structural forms and performance modulation strategies have garnered considerable attention. Herein, we develop a twined tetrahedral lattice structure (TTL) with a bending defect inside the unit cell. Mechanical properties before and after the introduction of defects in TTLs were studied using experiments and numerical simulations. The developed structure exhibits strictly stretching-dominated properties in the absence of bending defects. Whereas, the bending-dominant component of TTLs is elevated with increasing bending angle that can increase energy absorption efficiency. Moreover, the relative elastic modulus and initial peak stress can be reduced by even more than 70 % and 50 %, respectively, as the bending angle increases. Besides, a theoretical model for the relative elastic modulus of TTL at θ = 0° was established based on the displacement method on the Representative Volume Element (RVE), including both Euler-Bernoulli beam theory and Timoshenko beam theory. However, the two solutions show consistent results for strictly stretching-dominated structures. The accuracy of solutions is verified by experiments and simulations. The plateau stress theoretical model for TTLs was derived from the deformation process of the RVE based on plastic hinge theory. The theoretical solutions under different θ align well with numerical and experimental results. Overall, TTLs have superior relative elastic modulus, relative yield strength, and specific energy absorption compared to common lattice structures. The developed TTLs provide a new perspective on the property regulation of mechanical metamaterials.

Effects of Laser Scanning Strategy on Bending Behavior and Microstructure of DP980 Steel

Laser bending is a kind of cumulative forming technology and bending efficiency is one of its most important indexes. This study investigates the bending behavior and the microstructure of DP980 steel plates under different laser scanning strategies, using an IPG laser system. Two sets of experiments varied the accumulated line energy density (AED) by altering the laser scanning velocity and number of scans. The results show that, for the single laser scanning process, the bending angle of the plate increases with AED, due to a larger temperature gradient through the thickness direction; however, this relationship is nonlinear. A higher AED led to a sharper initial increase in bending angle, which then plateaued. Under the same AED conditions, the bending angle of the plate undergoing multiple laser scans increases by at least 26% compared to the single one, due to the microstructure changes. It is revealed that the bending efficiency is affected by both the AED and the resultant microstructure evolution in the DP980 steel. Higher AED values and appropriate peak temperatures facilitate better bending behavior due to the formation of uniform martensite and grain refinement. Conversely, excessive peak temperatures can hinder bending due to grain growth.

Numerical simulation analysis of high-temperature bent sodium heat pipes

Abstract High-temperature bent heat pipes are safety-level heat transfer components used in heat pipe cooled reactor, and their applications are becoming increasingly widespread. In this study, a comprehensive three-dimensional numerical model was established to evaluate the effects of different bending angles and radii on the performance of high-temperature heat pipes. The model solved for the temperature, pressure, and velocity fields in the wall, wick, and evaporator, considers the compressibility effect of the vapor. The study investigated parameters such as vapor pressure, vapor velocity, radial secondary flow field, wall temperature, wick temperature, and equivalent thermal resistance of powder sintered core sodium heat pipes with bending angles of 45°, 90°, 135°, 180°, and a bending radius under 90°. The results showed that when sodium vapor enters the bent pipe, the vapor flow deviates towards the outer side, resulting in higher vapor pressure at the outer side than the vapor pressure at the inner side, and the generation of radial secondary vortex. This leads to higher temperature in the evaporator and adiabatic sections of the bent heat pipe, while lower temperature in the condenser. Fractal patterns are observed in the outer and inner wall temperature curve in the adiabatic section, with lower temperatures on the inner side and higher temperatures on the outer side. The bent heat pipe exhibits higher equivalent thermal resistance than that of a straight heat pipe, and the equivalent thermal resistance increases with increasing bending angle, and the equivalent thermal resistance decreases with increasing bending radius.

Forming Characteristics of Tailor Rolled Blank of Aluminum Alloy during Three-Point Bending.

This paper presents an investigation on the forming characteristics of the tailor rolled blank of an aluminum alloy (Al-TRB) during three-point bending at room temperature through experiments and finite element simulations. The strain distribution, spring-back characteristics, and metal flow law of 6000 series Al-TRB during three-point bending are explored. The prepared Al-TRB has good bending properties, and no surface cracks appear in the bending region of the Al-TRB when bent to 180°. Surface roughening occurs on the outside of the bending region. Since the strain in the thick zone is greater than that in the thin zone, the surface roughening in the thick zone is more obvious than that in the thin zone. The spring-back angle in the thin zone is higher than that in the thick zone after three-point bending, and the overall spring-back angle of Al-TRB becomes larger with an increasing bending angle. When the transition zone of Al-TRB is centered and the length of the transition zone is certain, as the length of the equal-thickness zone increases, the spring-back angle of the thin zone is larger, while the spring-back angle of the thick zone is smaller. Under the premise of a certain total length of Al-TRB and the length of the transition zone, the larger the length proportion of the thin zone, the larger the overall spring-back angle of Al-TRB, and the larger the length proportion of the thick zone, the smaller the overall spring-back angle of Al-TRB. In addition, a slight metal flow phenomenon exists during three-point bending, which shows that the metal in the bending region will flow to the thick zone, and the metal at the edge will flow to the thin zone. At the same time, there are localized thickening and thinning phenomena in Al-TRB. This study is helpful because it provides theoretical guidance for designing molds for the actual production of Al-TRB parts for automotives.

Experimental study on heat transfer and storage of a heating system coupled with solar flat heat pipe and phase change material unit

Using renewable energy, especially solar energy, is essential to achieve a low-carbon society. PCMs suffer from low thermal conductivity, which hinders the efficiency of phase change thermal storage systems. Heat pipes exhibit vastly superior thermal conductivity, making them a promising candidate for enhancing PCM-based systems. To solve the contradiction between building insulation and importing solar energy into buildings in winter, this study proposes a new building heating ceiling system consisting of a flat-plate heat pipe (FHP) coordinated with a phase change material (PCM), and establishes a platform for a heat stockpiling device integrating the FHP and PCM. This research investigates the impact of heating power and bending angle on the heat transfer efficiency of the heat pipe and phase change heat storage system. The experimental findings demonstrate a direct relationship between increasing heating power and the enhancement of the FHP's heat transfer efficiency. When the FHP is bent at a 5° angle and heating power is increased from 20 W to 80 W, to store heat energy into the PCM cavities, the effective thermal conductivity rises significantly, escalating from 7.26 × 104 W/(m·°C) to 15.1 × 104 W/(m·°C), marking a remarkable 108 % rise. Moreover, although increasing the bending angle leads to heightened effective thermal conductivity of the FHP under constant heat input, and the heat transfer in PCM cavities will be weakened within a bending angle of 15°, experimental results demonstrate that the melting time of PCM still decreases with the increase of bending angle; the heat transfer inertia of phase change materials is dominant.

Optimization of cooling condition and energy parameters during laser bending of Duplex-2205

ABSTRACT In this study, the impact of process parameters on bend angle was explored under varying cooling conditions. Optimization of process parameters and cooling conditions was performed to maximize bend angle with minimum energy input. A regression fit function was generated and experimentally validated, and the mechanical and metallurgical properties at the optimum condition were analyzed. The study revealed that forced cooling at the lower surface significantly improved the bend angle, achieving a 35.2% increase compared to natural cooling. Process parameters were found to have varying effects at different cooling conditions. Optimization using Pareto front optimality and genetic algorithm resulted in a 7.5% increase in bend angle and a 22.14% improvement in bend angle per line energy rate. The tensile strength and hardness of the bend specimen at the optimum condition were increased at the expense of ductility, attributed to phase distribution rearrangement in the laser irradiation region.

Investigation on the wall thickness variation of an eccentric tube in the rotary draw bending process

PurposeWhen bending a large diameter thin-walled tube, the thickn ess of outer side wall will reduce greatly, which leads to a decrease of structural strength of the tube. To solve this problem, this paper investigated the deformation principles of an eccentric tube in the rotary draw bending process, trying to find a way to reduce the wall thickness difference between inner and outer diameters.Design/methodology/approachAn finite element model is established for analyzing the deformation of an eccentric tube in rotary draw bending process. The wall thickness distribution of the formed pipe was analyzed along the axis and diameter, respectively.FindingsIt is found that there exists an optimal eccentricity between the inner and outer circle center of the tube cross-section. If the eccentricity of the tube is chosen properly, it is possible to get a bent tube with equal thickness of inner and outer side walls. In addition, it is also found the optimal eccentricity on the cross-section can be influenced by bending radius, wall thickness, diameter and bending angle. The optimal eccentricity increases greatly with the decreasing of bending radius, the increase of outer diameter and the increase of wall thickness. The influence of bending angle on the optimal eccentricity can be divided into two situations. When the bending angle is small, the optimal eccentricity increases with the increase of bending angle. When the bending angle exceeds a certain value, the pipe enters a stable forming state. The optimal eccentricity of the stable forming region does not change with the bending angle.Originality/valueSuch a research is beneficial for reducing the thickness difference between inner and outer side walls in the rotary draw bending process.

A scientific view on composite inlays in running shoes: The influence of epoxy crosslink density on bending and fatigue properties

This study highlights the need for a deeper understanding of the structure-property relationships of carbon fiber reinforced thermosets applications, whenever considered as a functional part for running footwear. This is done, investigating the static and dynamic flexural properties of three different epoxy resins in prepreg-based carbon fiber composite laminates, varying the glass transition temperature (Tg). In this way, the inherent morphology of the resin was correlated with the fatigue properties of the laminate, which is crucial for the design of composite stiffening inlays for running shoes. First, it was shown that the crosslink density and aromatic content of the resin, which correlates with Tg, drastically affect the compressive strength of the matrix and are therefore crucial for the static and dynamic flexural properties of CFRP. Increasing the Tg from 147 °C to 269 °C leads to stiffening of the resin and thus increased resistance to fiber buckling, resulting in improved bending stiffness, flexural strength, bending angle, overall fatigue strength and thus durability of CFRP plates for running shoes. Moreover, the percentage of fibers in the loading direction can be considered as the main factor affecting the flexural properties of the laminate. Here, a quasi-isotropic stacking order leads to an increased bending angle but to a decrease in bending stiffness, flexural strength and fatigue strength compared to a unidirectionally reinforced composite due to a high load bearing capacity of the 0° fibers. This knowledge creates a basis to bridging the gap between composite material and biomechanical sports science for future work.

Diagnostic posture control system for seated-style echocardiography robot

PurposeConventional robotic ultrasound systems were utilized with patients in supine positions. Meanwhile, the limitation of the systems is that it is difficult to evacuate the patients in case of emergency (e.g., patient discomfort and system failure) because the patients are restricted between the robot system and bed. Therefore, we validated a feasibility study of seated-style echocardiography using a robot.MethodPreliminary experiments were conducted to verify the following two points: (1) diagnostic image quality due to the sitting posture angle and (2) physical load due to the sitting posture angle. For reducing the physical burden, two unique mechanisms were incorporated into the system: (1) a leg pendulum base mechanism to reduce the load on the legs when the lateral bending angle increases, and (2) a roll angle division by a lumbar lateral bending and thoracic rotation mechanisms.ResultsPreliminary results demonstrated that adjusting the diagnostic posture angle allowed to obtain the views, including cardiac disease features, as in the conventional examination. The results also demonstrated that the body load reduction mechanism incorporated in the results could reduce the physical load in the seated echocardiography. Furthermore, this system was shown to provide greater safety and shorter evacuation times than conventional systems.ConclusionThese results indicate that diagnostic echocardiographic images can be obtained by seated-style echocardiography. It was also suggested that the proposed system can reduce the physical load and guarantee a sense of safety and emergency evacuation. These results demonstrated the possibility of the usage of the seated-style echocardiography robot.

Development of Pneumatic Artificial Rubber Muscle Using Segmented Shape-Memory Polymer Sheets

We have developed a pneumatic artificial rubber muscle using two shape-memory polymer (SMP) sheets. We attached the SMP sheets to a linear pneumatic artificial rubber muscle. Utilizing the large difference in the elastic modulus below and above the glass transition temperature, the shape fixity and shape recovery of SMPs, the bending direction and the initial shape can be changed. In this study, in order to increase the bending motion range, we developed a segmented SMP sheet with embedded electrical heating wires, and evaluated its mechanical properties using bending and tensile tests. Moreover, we attached such sheets to an artificial muscle and evaluated the bending motion. Bending tests showed that segmenting the SMP sheets greatly reduced their bending stiffness. In tensile tests at temperatures below the glass transition temperature, it was found that the artificial muscle with the attached sheet withstood high elongating loads without failure. Attachment of such segmented SMP sheets to an artificial muscle resulted in an increased bending angle. Through isotonic and isometric tests, we showed that the prototype actuator could bend in two directions.

Effect of Segment Types on Characterization of Soft Sensing Textile Actuators for Soft Wearable Robots.

The use of textiles in soft robotics is gaining popularity because of the advantages textiles offer over other materials in terms of weight, conformability, and ease of manufacture. The purpose of this research is to examine the stitching process used to construct fabric-based pneumatic bending actuators as well as the effect of segment types on the actuators' properties when used in soft robotic glove applications. To impart bending motion to actuators, two techniques have been used: asymmetry between weave and weft knit fabric layers and mechanical anisotropy between these two textiles. The impacts of various segment types on the actuators' grip force and bending angle were investigated further. According to experiments, segmenting the actuator with a sewing technique increases the bending angle. It was discovered that actuators with high anisotropy differences in their fabric combinations have high gripping forces. Textile-based capacitive strain sensors are also added to selected segmented actuator types, which possess desirable properties such as increased grip force, increased bending angle, and reduced radial expansion. The sensors were used to demonstrate the controllability of a soft robotic glove using a closed-loop system. Finally, we demonstrated that actuators integrated into a soft wearable glove are capable of grasping a variety of items and performing various grasp types.

Investigation on mechanical properties of lightweight sandwich exterior wall with thermal blocking shear connector

In order to solve the problems of obvious thermal bridge effect for metal shear connectors and the lower shear bearing capacity for non-metal shear connectors, two new types of thermal blocking shear connectors (TBSC) were investigated. One is made by bond stress between glass fiber reinforced polymer (GFRP) sleeve and reinforcement, and the other is made by mechanical connection between the steel sleeve and GFRP bar. The goal is to study the mechanical properties of the lightweight sandwich exterior wall with TBSC. There are 18 specimens were conducted based on the mechanical properties, and the parameters of different types, different embedded depths and different bending angles were considered. The pull-out and direct shear tests were carried out, and each parameter's influence on the result was compared and analyzed. The test results show that with the increase of bending angle, the bearing capacity of GFRP sleeve TBSC increases. When the embedded depth of the TBSC increases from 25 mm to 40 mm, the pull-out test and direct shear test values increase by 95 % and 59 %, respectively. The main failure mode of specimens is the concrete anchorage failure. According to the phenomenon of concrete anchorage failure, the calculation formulas of flexural and direct shear capacity were proposed. Moreover, the finite element simulation is used to extend and validate, providing a theoretical reference for designing and applying a lightweight sandwich external wall with TBSC.

Experimental analysis of fluid‐assisted injection molding of pipe fittings with different angles by short‐shot method

AbstractBased on the self‐assisted injection experimental platform, experimental studies on gas‐assisted injection molding (GAIM), and water‐assisted injection molding (WAIM) of 2 curved pipe fittings by adopting short‐shot method were carried out. UDF model was constructed for numerical simulation analysis. The influence rules of auxiliary medium and bending angle on the terminal morphology, inner wall surface quality at bending angle, medial and lateral residual wall thickness, variation range, and residual wall thickness deviation rate of short‐shot fluid assisted injection molding (SSFAIM) bending samples were compared. Meanwhile, the influence mechanism was investigated. The following experimental findings were obtained. SSFAIM had secondary penetration, while water produced multiple penetrations. There are multiple vacuum shrinkage pores in the unpenetrated area at the end of the SSWAIM sample, as well as serious shrinkage depressions on the surface. The shape of the penetration front of water is arc‐shaped with many penetration holes. The shape of the penetration front of the gas at the end of the SSGAIM sample is “pointy.” Compared with the SSWAIM sample, the residual wall thickness of SSGAIM has a narrow distribution range when the bending angle is 0°. With the increase of the bending angle, the “foaming” phenomenon of the inner wall surface quality at the bending angle of the SSGAIM sample becomes less and less obvious. Moreover, the deviation of the inner and outer residual wall thickness of SSGAIM is more obvious than that of SSWAIM due to the increase of bending angle.

Numerical Investigation and Optimization of the Flow Characteristics of Bend Pipe with Different Bending Angles

The bend pipe with a circular section, which is widely used in hydropower, chemical industry and other fields, is a common form in pipeline systems. However, secondary flow occurs when the fluid flows through the bend pipe, thereby affecting the stability of the pipeline system. Different bending angles have various effects. Therefore, this paper establishes 3D models of a circular bend pipe with different bending angles. The influence of bending angle on flow field distribution and downstream flow is analyzed numerically. The larger the bending angle is, the more obvious the flow distribution and even the unevenness at the elbow will be, hence resulting in poor stability. The distance required to restore flow uniformity also increases. The pressure energy loss of the bend pipe with different bending angles is investigated. Results show that with the increase in bending angle, the global pressure loss presents a trend of “increase-decrease-increase.” The closer the bending angle is to 90°, the greater the influence of centrifugal force is on the flow, and the more obvious the secondary flow phenomenon will be. Aiming at the nonuniformity phenomenon, the structure optimization of a 90° bend pipe with the greatest influence is conducted. The improvement of the flow characteristics of bend pipe with different thick-diameter ratio and length-diameter ratio is compared. The deflector with a certain thickness can enhance the uniformity, safety and useful life of the bend pipe. The sharp-end length can improve the velocity uniformity to a certain extent but has minimal influence on flow characteristics compared with the thick-diameter ratio. This paper aims to study and improve the flow performance of a multi-structure bend pipe to make it suitable for more complex conditions.

Laser bending angle and deformation mechanism under different auxiliary loads

Auxiliary load laser forming is a new direction developed based on laser forming. This direction has the advantages of a large forming angle and high surface quality of the workpiece and achieves the effect of traditional mechanical forming. Currently, the auxiliary load is applied in a single way, which will not be conducive to the enrichment and development of this direction. Accordingly, four auxiliary methods are proposed, and these different approaches are modelled. The bending angles of these different methods are compared, and the deformation mechanism is discussed. Results showed that the four methods can effectively increase the bending angle. Amongst them, method 3 can effectively increase the bending angle by 4.51 times because the positive bending moment effect formed by the line load and the negative bending moment effect formed by the surface load are conducive to the increase in bending angle. The bending angles under the four methods linearly increase with the increase in load value. The larger the high-temperature distribution area is at the same temperature value, the larger the bending angle will be.

Determination of bend angle and shape imperfection effect on collapse load of pipe bends under in-plane opening moment

This study uses a three-dimensional nonlinear finite-element method to investigate the effects of bend angle ([Formula: see text]) and shape imperfection on the collapse load of pipe bends subjected to in-plane opening bending moment using large displacement analysis. ABAQUS was used to create a pipe bend model, whereas by virtue of symmetry about the longitudinal axis, half of the pipe bend model was built. The bend angle was varied from 30° to 180° with an interval of 30°, and shape imperfections, namely ovality ( Co) and thinning ( Ct), were varied from 0% to 20% each at 5% intervals. Elastic-perfectly plastic is thought to be the material of choice for the pipe bend. The results show that the bend angle has a significant impact on the collapse load of pipe bends between 30° and 120°, after which a significant decline was observed. The ovality impact increases with an increase in bend angle for pipe bends with a large thickness, whereas the opposite effect was found for smaller thicknesses with a small bend radius. The effect of bend radius and thickness was significant for large bend angles. Thinning ( Ct) and thickening ( Cth) have no effect on collapse load. A new mathematical equation has been proposed to predict the integrated effect of bend angle and shape imperfection.