Increase In Bending Angle Research Articles

Single chamber multiple degree-of-freedom soft pneumatic actuator enabled by adjustable stiffness layers

Soft pneumatic actuators promise simple, adaptable, and safe manipulation, but the nature of pneumatic circuits limits the scalability of this approach. This paper introduces a method to augment the degrees-of-freedom of soft pneumatic actuators without increasing the number of independent pressure sources or complex valving networks. Our method achieves multiple degree-of-freedom actuation from a single soft pneumatic chamber by utilizing adjustable stiffness layers based on a thermoplastic polyurethane shape memory polymer (SMP), which changes stiffness when thermally activated. We incorporate SMP layers into a soft pneumatic actuator, allowing multiple degrees of soft deformation to be achieved from a single pressure source by selective activation of SMP layers. A custom printed circuit board acts as a control unit to modularize and enable closed-loop control of the proposed pneumatic actuator. We validated our proposed system and method by varying the temperature of the SMP layer on one side of the actuator while keeping the other side stable near room temperature and observed an increase in bending angle of the pneumatic actuator as a function of temperature. Furthermore, we connected two actuators in series and demonstrated independent actuation, allowing the actuators to form different shapes with a single pressure source. Our results show that the proposed method can augment the degrees of freedom of soft pneumatic actuators as an alternative to multi-chamber or multi-valve systems.

Increasing bending angle in thick-walled pipes with wide heating

The spot heating of a metal part leads to many small deformations. The applications of this method are straightening the bridge parts, turbo-machinery shafts, and so forth. The movement of the heat source on a given path (line heating) leads to an increase in the deformation and the possibility of creating complex bends. However, it is complicated to predict and control the path and velocity of the heat source as well as determining the heat intensity. In the pipes, this method requires simultaneous control over the two torches on both sides of the pipe. The present study aims at investigating the mechanism of deformation and increasing the bending angle in thick pipes by means of a simple heating method. At first, the maximum bending in heating a large circular zone (entitled “wide heating”) is obtained by simulating the process using finite element method and optimizing it applying the genetic aggregation algorithm. Then, a new method for simultaneous heating within two zones is introduced. The interaction between two zones leads to the development of the shortening mechanism in the pipe wall and a significant increase in the bending angle. In this method, there is no need to move the torch where the temperature is controlled more accurately. To evaluate the finite element model, several pipe heating tests are performed with their results being agreed well with the simulation results.

Construction of nanoporous gold/g-C3N4 heterostructure for electrochemical supercapacitor

Hybrids with two-dimensional and three-dimensional nanostructures have attracted great interest in the construction of supercapacitor electrodes due to their unique structural features. Graphitic carbon nitride (g-C3N4) nanosheets are deposited on the surface of a nanoporous gold (NPG) film via an electrochemical method to form a hybrid electrode of NPG/g-C3N4 with an ultra-thin, ultra-light and good flexible characteristics. The electrochemical tests show that the hybrid electrode exhibits a good supercapacitive performance, such as an admirable specific capacitance (440 F g−1 at 2 A g−1) in 0.5 M Na2SO4 solution and a favorable cycling durability (maintaining 98% capacity after 10000 cycles). More interesting, the NPG/g-C3N4 electrode displays a striking enhancement of supercapacitive performance with the increase of bending angle. This superior property can be attributed to the unique nanosheets on nanoporous structure by a strong interfacial effect between the defected Au atoms of NPG and g-C3N4.

Carbocisteine stimulated an increase in ciliary bend angle via a decrease in [Cl-]i in mouse airway cilia.

Carbocisteine (CCis), a mucoactive agent, is widely used to improve respiratory diseases. This study demonstrated that CCis increases ciliary bend angle (CBA) by 30% and ciliary beat frequency (CBF) by 10% in mouse airway ciliary cells. These increases were induced by an elevation in intracellular pH (pHi; the pHi pathway) and a decrease in the intracellular Cl- concentration ([Cl-]i; the Cl- pathway) stimulated by CCis. The Cl- pathway, which is independent of CO2/HCO3-, increased CBA by 20%. This pathway activated Cl- release via activation of Cl- channels, leading to a decrease in [Cl-]i, and was inhibited by Cl- channel blockers (5-nitro-2-(3-phenylpropylamino) benzoic acid and CFTR(inh)-172). Under the CO2/HCO3--free condition, the CBA increase stimulated by CCis was mimicked by the Cl--free NO3- solution. The pHi pathway, which depends on CO2/HCO3-, increased CBF and CBA by 10%. This pathway activated HCO3- entry via Na+/HCO3- cotransport (NBC), leading to a pHi elevation, and was inhibited by 4,4'-diisothiocyano-2,2'-stilbenedisulfonic acid. The effects of CCis were not affected by a protein kinase A inhibitor (1μM PKI-A) or Ca2+-free solution. Thus, CCis decreased [Cl-]i via activation of Cl- channels including CFTR, increasing CBA by 20%, and elevated pHi via NBC activation, increasing CBF and CBA by 10%.

Morphological evolution and migration behavior of silver thin films on flexible substrates during thermal cycle testing

To understand morphological evolution and migration behavior caused by stress migration and thermal fatigue of silver thin films on flexible substrates, bending tests were conducted with different bending angles for two types of thermal tests. Furthermore, the effect of stress migration and thermal fatigue on the electrical conductivity of the silver thin films was discussed. The experimental samples were silver thin films printed on flexible paper for these tests. In an ultra-low cycle thermal test, the electrical conductivity of a silver film decreased with increasing bending angle because of the occurrence of voids caused by stress migration. Meanwhile, a high-cycle thermal test caused cracks to form and caused further deterioration of the electrical conductivity owing to a combination of stress migration and thermal fatigue.

The Impact of Strain Heterogeneity and Transformation of Metastable Austenite on Springback Behavior in Quenching and Partitioning Steel

Multiple strengthening methods, such as high dislocation density, high twin density, small grain size, and metastable austenite phase can give high strength to ultra-high strength steels (UHSSs). However, the high strength of UHSSs often results in a greater tendency for springback when applied in manufacturing vehicle components. In the present study, two types of UHSSs, dual-phase (DP) steel and quenching and partitioning (QP) steel are investigated to study the springback behavior during the bending process. Results indicated that both the strain heterogeneity and the transformation of retained austenite impacted the springback behavior. The springback angle of the DP steel increased with the increase in bending angle, which was caused by the increasing degree of strain heterogeneity. However, the springback angle of the QP steel decreased to a 14.75° when QP specimens were strained at a 104° bending angle due to the inhibiting effect of the phase transformation. This indicated that there was preferential phase transformation in the thickness direction in the retained austenite of the outer and inner zones. The phase transformation caused low strain heterogeneity, which resulted in a lower tendency for springback. The results suggested that QP steel could possess lower springback at a proper bending angle.

Interfacial thermal conductance of buckling carbon nanotubes

Bond transition of sp2 to sp3 in carbon nanotube can be realized through bending operation at buckling location, which affects the electronic, mechanical and thermal properties of buckled carbon nanotube. In this work, thermal properties of buckled tri-walled carbon nanotube with sp3 bonds are explored using molecular dynamics. Our results reveal that interfacial thermal conductance at buckling location is sensitive to the bending angle, which decreases exponentially with increasing bending angle until 90 degree because of increasing the number of interlayer sp3 bonds. When the bending angle is beyond 90 degree, there are sp3 bonds formed on the outer-tube walls which provide new paths for heat transfer. The insight of mechanism of thermal properties is analyzed by determining atomic micro-heat flux scattering. Our findings provide a flexible and applicable method to design thermal management device. This unusual phenomenon is explained by the micro-heat flux migration and stress distributions.

Density functional theory study on the electronic structure and optical properties of S absorbed graphene

The effect of bend angle on the stability, electronic structure and optical properties of S absorbed graphene system is studied by using density functional theory based on the first - principles. Within the scope of the current study, it is found that the C atoms which are closest to the S atom are pulled up, the graphene plane is distorted, and the band gap of the graphene is opened, which changes graphene from quasi-metal to semiconductors. Bending deformation decreases the structural stability of S atom adsorbed on graphene system. The adsorption energy decreases with the increase of bending angle. After the intrinsic graphene is bent, the band gap is opened, and the bandgap increases with the bending angle. When the bending angle is between 0°–20°, it still corresponds to the quasi-metal property. When the bending angle increases to 25°, it gradually changes from small bandgap semiconductor to medium bandgap semiconductor. The band gap of graphene adsorbed S atom system decreases with the increase of the bending angle, and it always corresponds to medium bandgap semiconductors. When the angle is increased to 30°, the system loses its stability. The rate of increase of absorption coefficient increases with the increase of bending angle. The deformation causes the maximum absorption peak and the maximum reflection peak of the system to red shift, and the degree of red shift increases with the increase of the bending angle.

Identification of two aluminum alloys and springback behaviors in cold bending

Aluminum alloys have drawn more and more attention in automobile and electronics industry. However, springback is a big challenge in cold forming of aluminum alloy sheets. In order to identify two aluminum alloys and their heat treatment condition, chemical composition detections, microstructure observation by OM (Optical Microscope), SEM (Scanning Electron Microscopy) and TEM (Transmission Electron Microscope) were carried out. With additional hardness tests, the results indicate that the two aluminum alloys should be 6xxx aluminum alloy. They went through solution heat treatment after hot rolling and then underwent different time of natural aging. For the purpose of investigating springback behaviors of the two aluminum alloys sheets in cold forming, strain hardening exponents (n), strength coefficient (K) and plastic strain ratios (r) in three directions were calculated by tensile tests. Then cold bending experiments and finite element (FE) simulations with the implementation of the calculated n and r were carried out. The tensile results show that the formability of the two aluminum alloy sheets in cold forming is poor for the small values of n and anisotropy was found based on the r values. The cold bending results indicate that the springback decreased with the increasing bending angle and thicker sheets had smaller springback. Besides, the simulation and experiments agreed well with each other, indicating that the springback prediction using the calculated values of n and r were suitable. It will provide significant guide in in springback prediction of aluminum alloys in cold forming and help to design the tools.

Research on reflection of L(0,1) guided wave from pipe elbow based on modal assurance criteria calculation

The reflection characteristic of L(0,1) mode guided wave from pipe elbow is investigated and a new analysis method based on modal assurance criteria (MAC) is proposed in this paper to investigate reflection of L(0,1) mode guided wave from pipe elbow. The mode conversion and effect of frequency, bending radius and bending angle have been analyzed through numerical simulation method. The guided wave reflection extent caused by elbow is expressed by guided wave modal assurance criteria. The trend of reflection extent changing with frequency and bending radius has been compared with numerical results and experimental results. The results indicate that partial L(0,1) mode converts to F(1,1) mode with the orientation being identical to the extrados-intrados direction. With the increase of frequency and bending radius, the amplitude of reflected guided wave decreases monotonously. With the increase of bending angle, the amplitude of reflected guided wave changes non-monotonically. The trend of guided wave reflection extent expressed by MAC changing with frequency and bending radius is identical with the numerical results. The experimental results verify the trend further. The research results will provide theoretical guide and a new analysis method for the inspection of pipes with elbows using L(0,1) mode guided wave.

Effect of various bending angles on a passive light pipe for eco-daylighting systems

Daylighting systems is one of alternative to reduce a high energy consumption that caused by artificial lighting. However the use of passive light pipes in daylighting systems with various bending angles may affect the efficiency of light transfer from the sunlight to the room. Thus this paper is proposed to study the effect of various bending angles on a light pipe. Three bending angles of light pipe, which are 0°, 30° and 45°, were analyzed through the experimental works. A test bed room was constructed in order to simulate daylighting in a room. The results were then visualized in graphs based on the efficiency by considering the maximum average internal illuminance achieved by each light pipe. From the results, it shows that when the bending angle increases, the average internal illuminance decreases. And the highest average internal illuminance was achieved by 0° light pipe.

Boron-assisted growth of silica nanowire arrays and silica microflowers for bendable capacitor application

Aligned silica nanowire arrays and silica microflowers were fabricated using boron as the catalyst and under the flow N2 gas. The obtained product had no catalyst contamination. And silica nanowires had long lengths of a few hundreds. The growth of nanowire arrays and microflowers was explained using mechanism. Parallel-plate capacitors using silica nanowire mat as the dielectric were fabricated. The silica nanowire capacitor shows a specific capacitance of 0.24nF/cm2 at the frequency of 100Hz. The capacitor is not monotone changing with the frequency. The measurement of mechanical properties shows that the tunneling current increases along with an increase in bending angle of the capacitor.

Effects of Task Type, Task Duration, and Age on Body Kinematics and Subjective Fatigue

Investigating the effects of workload on body kinematics is the first step to identify, monitor, and ultimately reduce the incidence of fatigue, a prevalent phenomenon in the workplace that leads to chronic disorders, loss of productivity, and absenteeism (Lu, Megahed, Sesek, & Cavuoto, 2017, In Press; Ricci, Chee, Lorandeau, & Berger, 2007). In fa- tigue monitoring, kinematic measures including acceleration, jerk, and body posture have been found to be informative (Lu et al., 2017, In Press; Maman, Yazdi, Cavuoto, & Megahed, 2017; Ricci et al., 2007); however, none of the previous studies have considered a comprehensive set of these kinematic metrics during simulated manufacturing tasks. This study assessed the effects of duration, ease of task, and age as three factors on different body kinematic metrics and subjective ratings as a substitute “ground truth” for fatigue development. This will serve to inform feature selection for modeling fatigue development over a broad range of industrial tasks. Nineteen participants (divided into two age groups of younger (<25, 6 males and 4 females) and older (>40, 8 males and 1 female)) completed three, three-hour sessions of parts assembly (light), supply pickup and insertion (moderate), and manual material handling (difficult). Inertial measurement units (IMUs) were attached on right wrist, middle of the trunk, the right side of the hip, and right ankle. The mean and peak values of acceleration, jerk, and posture for each body location along with the minimum value (with respect to the horizontal plane) of trunk bending posture were considered as the kinematic variables of interest. The Borg rating of perceived exertion (RPE) and subjective fatigue level (SFL) were recorded at the start of each session, and then every ten minutes for RPE, and every thirty minutes for SFL. Perceived workload, rated using the NASA Task Load Index (TLX), was obtained every one hour. The TLX, RPE, and SFL at the end of hour 1 (the first time point where all three ratings are obtained) were considered as the pre-fatigue values and at hour 3 of the tasks as the post-fatigue. Similarly, the pre-fatigue kinematic data of the IMUs was the period from minutes 10 to 20 and the post-fatigue data was the period from minutes 160 to 170. The results of repeated measures ANOVA showed a significant time ( p < 0.001) effect on all three subjective ratings. In addition, time and age interacted to affect RPE ( p = 0.018) with a 36% increase in younger and 28% in the older group. Time had significant effects only on a few of kinematic variables including mean trunk acceleration (8% decreased), mean trunk posture (3% less bent), and peak hip acceleration (10% increased) after fatigue. Moreover, there was a significant age and task interaction for peak hip acceleration (~1 m/s2 decreased), mean and peak leg posture (~4o increased and ~12o decreased, respectively), and minimum trunk posture (~5o increased) from the younger group to the older group. In addition, there was significant interaction ( p = 0.011) between time and task in bending posture denoted by hip and trunk, which provides insight into the different effects of fatigue on different tasks, i.e., 2% more bending after fatigue in manual material handling and supply pickup and insertion in comparison to parts assembly. This increased bending angle following fatigue was in agreement with the findings of Strohrmann, Harms, Kappeler-Setz, and Troster (2012). There were significant differences between the younger group to the older group in terms of kinematics, i.e., peak hip acceleration, mean and peak leg posture, and minimum trunk posture that may be attributable to different quadriceps strength and postural stability between the age groups. Overall, the results present a set of kinematic parameters influenced by fatigue; however, further analysis is required to explore more temporal and spatial movement variables from IMUs for a better understanding of fatigue effects and indicators.

Branch bending affected floral bud development and nutrient accumulation in shoot terminals of ‘Fuji’ and ‘Gala’ apples

Branch bending has been practiced for decades in China to induce flower buds in ‘Fuji’ apple. However, the optimum bending angle is yet to be elucidated. The main objectives of this study were to compare the effect of branch bending angles (70°, 90° and 110°) on the flowering and nutrient accumulation of 1-year-old shoots of ‘Fuji’ and ‘Gala’ apples and to determine the optimum branch bending angle for each cultivar. In both cultivars, the production of spurs and terminal flower buds, and the total sugar concentration and the carbon-to-nitrogen (C/N) ratio in the shoot terminals increased, whereas the N concentration decreased with increasing bending angles. The nutrient concentration was significantly higher in spurs than in medium and long shoots. The distinction between the changing patterns of C and N concentrations in the bent shoots during the growing season in our study suggested the competition of these two nutrients caused by vegetative and reproductive growth at different growing times. In ‘Fuji’ apple, the proportion of flowering buds appeared to increase more rapidly with the increase of bending angle from 70° to 110° than that in ‘Gala’ apple, and particularly a higher proportion of spurs was observed on ‘Fuji’ branches bent at a larger angle. The increase in the total sugar concentration and the C/N ratio in the shoot terminals of the bent branches might be involved in inducing floral buds after bending. The optimum bending angle was about 90° for ‘Gala’ apple and 110° for ‘Fuji’ apple, respectively. Bending could help farmers to reduce the severity of biennial fruiting in ‘Fuji’ apple.

Comparison of photon organ and effective dose coefficients for PIMAL stylized phantom in bent positions in standard irradiation geometries

Computational phantoms with articulated arms and legs have been constructed to enable the estimation of radiation dose in different postures. Through a graphical user interface, the Phantom wIth Moving Arms and Legs (PIMAL) version 4.1.0 software can be employed to articulate the posture of a phantom and generate a corresponding input deck for the Monte Carlo N-Particle (MCNP) radiation transport code. In this work, photon fluence-to-dose coefficients were computed using PIMAL to compare organ and effective doses for a stylized phantom in the standard upright position with those for phantoms in realistic work postures. The articulated phantoms represent working positions including fully and half bent torsos with extended arms for both the male and female reference adults. Dose coefficients are compared for both the upright and bent positions across monoenergetic photon energies: 0.05, 0.1, 0.5, 1.0, and 5.0MeV. Additionally, the organ doses are compared across the International Commission on Radiological Protection's standard external radiation exposure geometries: antero-posterior, postero-anterior, left and right lateral, and isotropic (AP, PA, LLAT, RLAT, and ISO). For the AP and PA irradiation geometries, differences in organ doses compared to the upright phantom become more profound with increasing bending angles and have doses largely overestimated for all organs except the brain in AP and bladder in PA. In LLAT and RLAT irradiation geometries, energy deposition for organs is more likely to be underestimated compared to the upright phantom, with no overall change despite increased bending angle. The ISO source geometry did not cause a significant difference in absorbed organ dose between the different phantoms, regardless of position. Organ and effective fluence-to-dose coefficients are tabulated. In the AP geometry, the effective dose at the 45° bent position is overestimated compared to the upright phantom below 1MeV by as much as 27% and 82% in the 90° position. The effective dose in the 45° bent position was comparable to that in the 90° bent position for the LLAT and RLAT irradiation geometries. However, the upright phantom underestimates the effective dose to PIMAL in the LLAT and RLAT geometries by as much as 30% at 50keV.

Study on the ridge grooves deformation of double-ridged waveguide tube in rotary draw bending based on analytical and simulative methods

Cross sectional deformation of double-ridged waveguide tube easily occurs in rotary draw bending due to its structural features of hollowness, thin-wall and shape complexity. Particularly, the ridge grooves deformation would largely affect the transmission characteristics of double-ridged waveguide tube. Thus, using plasticity deformation theory, an analytical method to investigate the ridge grooves deformation is proposed, in which the ridge grooves deformation is considered to be resulted from three parts of deformation, including flange sagging, web deflection and variation of flange width. Then, the analytical method is verified by a FE model from various viewpoints. Finally, the contribution of every part to the ridge grooves deformation under different conditions is analyzed combining analytical and simulative methods. The results show that: (1) The contribution of flange sagging to the width deformation of outer and inner ridge grooves is usually far small and can be omitted. The web deflection results in the decrease of width deformation of outer ridge groove, but the variation of flange width increases that. The web deflection and variation of flange width all lead to the increase of width deformation of inner ridge groove. (2) With the increase of bending angle, the width deformation of outer ridge groove changes little while the absolute value of width deformation of inner ridge groove increases. When the bending radius decreases, the absolute value of width deformation of outer and inner ridge grooves all increase. With the increase of core number, the width deformation of outer ridge groove changes from shrinking to widening while there is no change for the width deformation of inner ridge groove.

A Refractive Index Sensor Based on the Tapering Theory

A refractive index (RI) sensor has been realized to measure RI, hardly affected by temperature. A fused biconical taper machine is used to receive two same diameter tapers, which are cascaded by a fusion splicer. This paper studies the spectral characteristics of the RI sensor with a different bending angle in tapers, and finds that with the increase of bending angle (from 0° to 100°), the extinction ratio will be improved while the spectrum moved down. When two tapers are bent to 90°, the RI sensor can serve as a sensing probe (the RI sensitivity was ~126.15 nm/RIU). The RI sensor has significant applications, and the measurement error is <;1%.

Stochastic elastic wave analysis of angled beams

The stochastic finite element method is employed to obtain a stochastic dynamic model of angled beams subjected to impact loads when uncertain material properties are described by random fields. Using the perturbation technique in conjunction with a precise time integration method, a random analysis approach is developed for efficient analysis of random elastic waves. Formulas for the mean, variance and covariance of displacement, strain and stress are introduced. Statistics of displacement and stress waves is analyzed and effects of bend angle and material stochasticity on wave propagation are studied. It is found that the elastic wave correlation in the angled section is the most significant. The mean, variance and covariance of the stress wave amplitude decrease with an increase in bend angle. The standard deviation of the beam material density plays an important role in longitudinal displacement wave covariance.

Biogenic corrosion on ribbed reinforcing steel bars with different bending angles in sewage systems

Reinforcement steel rebar corrosion leads to a deterioration of the bond between the concrete and the steel bars. The serviceability and ultimate strength of concrete elements within reinforced structures are accordingly affected. Many studies have been done on the different types of steel bar corrosion. However, very few studies have investigated the effects of restrictions on the degradation of steel when exposed to sulfuric acid corrosion on bent steel rebars. In the present paper, investigations were carried out to study the corrosion behavior of unprotected low-carbon ribbed reinforcing steel exposed to different concentrations of H2SO4 solutions. The ribbed steel bars were of size Ø12, Ø14, Ø16 and bent at angles of angles of 0°, 45°, 90° and 135°. The weight loss method was used for the estimation of the corrosion. The results show that the corrosion rate and cross-section loss of steel bars increases with increasing acid concentration from 0.5M to 1.5M. On the other hand, corrosion deterioration was decreased with an increased bending angle.

Effect of bending on the dynamic changes of endogenous hormones in shoot terminals of ‘Fuji’ and ‘Gala’ apple trees

Branch bending has been practiced for decades as an effective means of inducing floral buds in ‘Fuji’ apple in China. Endogenous hormones play an important role in apple flowering. The main purpose of this study is to investigate the hormone concentrations (ABA, ZR, IAA and GA) in spurs, medium and long shoot terminals of ‘Fuji’ and ‘Gala’ apple trees subjected to bending of different angles (70°, 90° or 110°). In both cultivars, the proportion of floral buds and spurs increased, but that of medium and long shoots decreased with increasing bending angles. The ABA and ZR concentrations in shoot terminals increased, but the IAA and GA concentrations decreased as the bending angles increased from 70° to 110°. The ZR concentration increased monotonically in spurs apexes, but in medium and long shoot terminals it increased from a minimum on May 10 to a maximum on June 20 for ‘Fuji’ apple trees or on July 20 for ‘Gala’ apple trees, and then decreased thereafter. It was also observed that the ‘Gala’ apple trees had a higher ABA concentration but a lower IAA concentration in shoot terminals than the ‘Fuji’ apple trees. The ZR concentration in spurs apexes of ‘Gala’ apple trees was higher before July 1, and the GA concentration was higher before June 20, but lower after July 20 than the ‘Fuji’. The (IAA + GA + ZR)/ABA ratio of spurs apexes in ‘Fuji’ apple trees decreased with increasing bending angles during the whole growth season, with a significant difference between those bent at 110° and those bent at 70°. There was no significant difference for the ‘Gala’ apple trees. The (IAA + GA + ZR)/ABA ratio peaked on June 20, and it was higher in ‘Fuji’ than in ‘Gala’ apple trees throughout the study period.