Bent Form Research Articles

A Rare Case of Anti-N-Methyl-D-Aspartate Receptor Encephalitis in an Infant Presenting with Regression and Movement Disorder.

A Rare Case of Anti-N-Methyl-D-Aspartate Receptor Encephalitis in an Infant Presenting with Regression and Movement Disorder.

Study of the conditional flexibility effect of compressed chord on the overall stability of corrugated beams

In this paper, the calculation of cut corrugated beams loaded with uniformly distributed load in the plane of the wall, with a wall height of 333 and 500 mm (54 sizes), chord width from 160 to 400 mm and chord thickness from 6 to 30 mm for general stability in accordance with Building Codes (BC) 294.1325800.2017 is made. A geometric criterion has been defined which defines the boundaries of the load-carrying capacity of Russian corrugated beams between the flat bending form stability and the strength of the normal section under the action of the bending moment in the plane of the wall.

Research on Suppression Strategy of Plane Distortion in Laser Bending Forming of Specialty‑Shaped Corrugated Sheet

Research on Suppression Strategy of Plane Distortion in Laser Bending Forming of Specialty‑Shaped Corrugated Sheet

Significant analysis of the influence of process parameters on the wrinkling of aluminum alloy double-wall gap tube in rotary draw bending

Aluminum alloy double-wall gap tube is prone to wrinke in the rotary draw bending because the rigidity of the inner and outer tubes of the thin-walled structure is low, the mechanical properties between the tubes and the polymer filling medium are different greatly, and the bending forming is a complex nonlinear process of multi-mold coordination and multifactor coupling. While the process parameters are the main factors that affect the wrinkling of inner and outer tube, there are many process parameters and there are interactions among them. Therefore, based on the platform of ABAQUS/Explicit, elastic-plastic 3D-FE model of double-wall gap tube’s bending is established to study the influence mechanism of process parameters on the wrinkling aluminum alloy double-wall gap tube in rotary draw bending. The results show that the clearance between mandrel and inner tube, clearance between pressure die and outer tube, the anti-wrinkle die and the outer tube have significant effects on the wrinkling of the inner tube. The clearance between inner tube and core die, filling medium and inner tube and clearance between anti-wrinkle die and outer tube have significant effects on the wrinkling of inner tube. The wrinkling of the outer tube is more obvious than that of the inner tube. The results can provide a theoretical basis for optimizing the process parameters to suppress the wrinkling of aluminum alloy double-wall gap tube in the rotary-draw bending.

Experimental study on laser peen forming of aluminium alloy 2024-T351 plate

Laser peen forming technology LPF is proposed on the basis of laser peen strengthening technology and mechanical peen forming technology. It is an advanced high-efficiency and long-life manufacturing technology for panels. This forming technology has a wide application prospect in the field of aerospace manufacturing. In the forming process, there are many factors affecting the forming process, such as laser pulse energy, shot peening times, shot peening path, material, structure and so on. At present, there are few studies on the influence of laser peen forming process parameters on the shape of parts, which can not meet the technical requirements of forming process. In this paper, based on the single curvature bending forming of al2024-T351 aluminum alloy, the elastic-plastic deformation of metal surface formed by laser shot peening is investigated. The spot morphology formed by laser shot peening is analyzed. The influence law of different forming process parameters on the forming shape of parts is established. The results show that the thickness is the main influencing factor for the curvature radius of the impact area. The radius of curvature increases with the increase of thickness, and decreases with the increase of pulse energy and coverage. Using the regression analysis method, the mathematical model of laser peen forming curvature radius is established. The predicted results are consistent with the experimental results, and the maximum relative deviation is 2.6%.

Residual stress analysis and its effect on springback for multi-step pressbrake bending

Pressbrake bending is a multi-step metal forming process and widely applied in the fields of aerospace, shipbuilding, and offshore industry. However, the bending residual stress that arise from the previous-pass bending step will affect the stress distribution of the next-pass bending step, and finally affect the springback after unloading, which results in the difficulty to guarantee the dimensional accuracy of the forming part. In this study, the residual stresses for multi-pass pressbrake forming and its influence on springback are systematically investigated. First, the analytical model for the residual stress of the bent specimen with initial curvature is deduced based on geometric relationship and elastic–plastic bending theory. Second, the calculation method of rigid body position redefine to simulate the multi-pass bending forming process is developed, and the numerical method is confirmed by comparison with experimental method. The analytical model to predict the residual stress is shown to be in close agreement with results from numerical method, demonstrating the validity of the analytical model. Finally, the impact of residual stress in single-pass and multi-pass bending forming on springback are discussed thoroughly. It is found that, as the number of forming passes increases, the equivalent plastic strain will increase to 9% of three-pass loading from 7.8% of one-pass loading, which explains the reason of increasing the number of bending passes can not only reduce springback, but also reduce the residual effect of bending forming.

Theoretical Investigation of Forming Process of Aluminum Alloy Rail Vehicle Side Window

With the vigorous development of rail transit trains around the world and the emergence of global environmental pollution and energy shortages, the world has an urgent need for manufacturing technology for lightweight aluminum alloy rail transit train components. This paper mainly studied the superplastic forming law of 5083Al for rail transit. Through the high-temperature tensile test and blowing forming experiments, the superplastic properties of 5083Al were determined. Based on this, the die design, finite element simulation, and forming experiment of the rail vehicle side window were carried out. In order to study the superplastic deformation behavior of industrial 5083Al under complex stress conditions, the influence of the depth, area ratio, and friction coefficient of the pre-forming die on the part thickness distribution is simulated. The side window is made of a high-strength 5083Al sheet in the form of bending at both ends to ensure the strength of the connection between the overall side window and the side wall skeleton. The variation law of the side wall forming height of 5083Al box-shaped parts was studied. The efficient manufacture of parts that meet quality standards was made possible by the optimization of the pressure profile. The microstructure changes of the material after superplastic forming were studied by Energy Dispersive Spectrometer (EDS) and Electron Backscattered Diffraction (EBSD).

Influence of mandrel-cores filling on size effect of cross-section distortion of bimetallic thin-walled composite bending tube

Two new size factors of cross-section hollow coefficient and bending degree are introduced to reveal the size effect of bending forming of bimetallic composite tube. Hollow coefficient and bending degree can limit the commonly used bent tube to the size description range of (0, 2.00). The evolution laws of the cross-section distortion forms in the hollow coefficient-bending degree interval are revealed as well as the action of the mandrel-cores on the size effect. Results show the mandrel-cores filling can expand the forming limit of the bent tube, but also bring two other forming defects of wrinkle and rupture. The identification factor (hollow coefficient multiply bending degree) provides a method for querying the cross-section distortion forms of all composite bending tubes. In the identification factor interval (0, 1.00), the distribution area of bending forming defects of the composite tube is continuous. The thin-walled composite bending tube collapses when identification factor in (0, 0.39), wrinkles when identification factor in [0.39, 0.50), and ruptures when identification factor in [0.50, 1.00). The mathematical model of size effect is derived, by which the average cross-section distortion rate is found to distribute like a radial leaf in the hollow coefficient-bending degree qualified forming space. The best forming zone is hollow coefficient 0.46–0.68, and bending degree 0.25–0.47.

Electronic properties of rutile and anatase TiO2 and their effect on CO2 adsorption: A comparison of first principle approaches

• The choice of suitable functional is dependent on the desired property. • A high U value or hybrid functional is required for credible electronic properties. • Grimme D3 is needed for adsorptions, but not for electronic and optical properties. • Activated CO 2 displays strong adsorption, bending and charge transfer. Photocatalysis is a promising technique for utilizing solar light in chemical synthesis. Among several effective photocatalysts, TiO 2 remains the archetypal representative. Using density functional theory calculations, we characterized the geometric, mechanical, electronic and optical properties of rutile and anatase TiO 2 . We show that a proper choice of the functional and corrections is of paramount importance. While the geometric and mechanical properties are well reproduced with conventional GGA functionals, electronic properties require at least a Hubbard approach. Despite being revered as superior, hybrid functionals do not necessarily perform better and a prudent choice is required. On the contrary, a lower Hubbard correction is desirable for a proper description of interactions, defects and structures. Lastly, CO 2 adsorption was studied on several surfaces. Pristine anatase and rutile surfaces poorly activate CO 2 , with the exception of rutile (0 0 1), which binds CO 2 strongly in a bent form, showing considerable charge transfer and activation.

Research on the Height of the Water-Conducting Fracture Zone in Fully Mechanized Top Coal Caving Face under Combined-Strata Structure

In order to study the development height of the water-conducting fracture zone in a fully mechanized top coal caving face. The E2311 working face of Gaohe Coal Mine was chosen as the research object, and the combined-strata structure and the rock layer synergistic movement mechanism were determined by combining engineering geological investigation and theoretical analysis. The height of the water-conducting fracture zone at the working face was calculated based on the combined-strata structure, and then the theoretical results were verified by numerical simulation and field measurement. The results show that after the coal seam is extracted from the working face, the movement of the overlying rock layers is in the form of bending and sinking movement of the rock layer group as a unit. Each rock layer group is controlled by a supportive lower layer with greater thickness and strength, driving the upper layers of weaker rock layers to synchronize and coordinate the movement; the sinking curvature is the same, after the lowermost support layer is bent and broken, its overlying weaker rock layers will move and break at the same time. The height of the water-conducting fracture zone of the working face were obtained by theoretical calculation, numerical simulation, and field measurements, which are 83.82 m, 84.3 m, and 86.6 m, respectively. The results are nearly consistent, thus the prediction of the height of the water-conducting fracture zone under the combined-strata structure is more accurate.

Uji Mekanisme Antagonis Rizobakteri Terhadap Sclerotium rolfsii Penyebab Rebah Semai pada Tanaman Kacang Tanah

Sclerotium rolfsii is an important disease in peanut plants. S. rolfsii causes yield losses 25-50%. This research aims was to determine the mechanism of antagonists rhizobacteria in inhibiting the growth of S. rolfsii and suppressing the occurrence of damping off disease in peanut plants. The research stage include selecting rhizobacteria isolates trhough antagonistic test against S. rolfsii, observing hyphae abnormalities, analysis hydrolytic enzyme production, molecular identification 16S rRNA rhizobacteria, and test for suppression of damping off disease in peanut plants. The results showed that of the 16 rhizobacteria isolates, there were 4 isolates that were effective in inhibited the growth of S. rolfsii. Rhizobacteria that are effective in inhibited S. rolfsii cause abnormalities on hyphae in the form of hyphae colling, bending, shrinking, and lysis. Four isolates of antagonistic rhizobacteria were produce hydrolytic enzymes such as cellulase, chitinase, and protease. A total of 2 selected rhizobacteria isolates were able to increase the height plants and as many as 3 selected rhizobacteria isolates were able to increase the number of leaves of peanut plants compared to controls. Based on the disease suppression test, 4 selected rhizobacteria isolates were able to suppress the incidence of damping off disease in peanut plants equivalent to fungicides. Based on the moleculer identification 16S rRNA isolates G19, K009, R27, and R54 consecutively were identified as Klebsiella pneumoniae, Pseudomonas aeruginosa, Pseudomonas aeruginosa, and Enterobacter asburiae.

Front Cover: Bond Strength of a Diatomic Acceptor Ligand: A Reliable Measure of Its Antibond Occupation and Its Charge? (Eur. J. Inorg. Chem. 32/2022)

The Front Cover shows, pictorially as the collapse of a house of cards, the repeal of the customary correlation of a nitrosyl ligand's charge and the strength of its N−O bond. Isomeric couples comprising both a linear and a bent MNO moiety show, in fact, a weaker bond of the bent form in terms of a markedly red-shifted NO stretch. However, the charge of the NO group is not a function of the bond strength. Hence, the assignment of an 1NO− to a bent-bonded nitrosyl and NO+ to a linear-bonded one is unjustified as unraveled by local-mode and QTAIM analysis. More information can be found in the Research Article by J. Popp and P. Klüfers.

Analysis of influence of bending radius on strength of titanium alloy tube

Titanium alloy has excellent performance, and the application of titanium alloy in aviation hydraulic pipeline could meet the requirements of high performance and light weight of the hydraulic system. However, the titanium alloy is difficult to be processed and formed, and the titanium alloy tube is easy to be thinned and distorted during the bending process, which affects the performance of the tube. In this paper, the forming process of TA18 titanium alloy tube with three bending radii was simulated, and the influence of bending radius on the thickness thinning rate and ovality of the bent tube was studied. Based on the forming simulation results, the bearing capacity of each bent tube after forming was studied, and the influence of bending radius on the service strength of the hydraulic tube was analyzed then. The results showed that increasing the bending radius could reduce the wall thickness thinning rate and ovality of the bending part, and enhance the service strength, which would provide data support for the bending forming and performance evaluation of titanium alloy tube.

Systematic Generation of Arbitrary Antenna Geometries

Applications for conformal, wearable antennas are growing for consumer electronics. Hence, it is important to assess to what degree antenna performance can be tolerant to <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> deformations that can take the form of bending, crumpling, and twisting and combinations of these effects. However, generating geometries of arbitrary antenna deformations such as bending, crumpling, and twisting, which can be processed by standard electromagnetic (EM) software, is a major challenge that significantly complicates full assessment of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> antenna performance. Constructive solid geometry methods of generating geometries is difficult to robustly apply to nonconformal antennas and more flexible techniques required to progress the antenna studies further. To address this challenge, this article investigates the utility of the green coordinate (GC) method for spatial manipulation of 3-D objects. First, calibration of a straightforward application of the GC method against a reference case of a patch antenna bent over a cylindrical surface, which can also be generated exactly, is undertaken. This article shows that systemic scaling distortions are introduced by the GC method and introduces a compensation method that can overcome these distortions. Subsequently, the compensated method is used to obtain new predictions of the EM performance of patch antennas with deformations.

Reversible, voluminous and tunable patterning of multiwalled carbon nanotubes in ferrofluid: Partial or complete?

A new kind of hybrid fluids showing multiwalled carbon nanotubes (MWCNTs) coupled with magnetic nanoparticles have been synthesized and investigated for their structural, magnetic, and magneto-viscoelastic properties. The experimental results confirmed the cooperative coupling between MWCNTs and Fe3O4 nanoparticles forming the basis of magnetorheological mechanism which narrates the rheological properties. The molecular dynamics (MD) simulation and interaction calculations for particle-particle, particle-tube and tube-tube have been described and explained comprehensively in view of the interface properties of nanoparticles and nanotubes. The whole of the experimental and theoretical investigations confirms the bulk alignment of bent MWCNTs in ferrofluidic system which can be tuned with an applied magnetic field. The MD simulation predicts a weak and short-range molecular ordering mediated via free oleic acid molecules between MWCNTs and coated nanoparticles of ferrofluid. The interparticle interaction calculations (van der Waals, steric and magnetic energies) showed that the surface coated magnetic nanoparticles are kinetically stable in the fluid while the MWCNTs form chain-like aggregates. Moreover, by application of classical beam theory, a thermodynamic energy barrier comparison was made for the unbending of particle impregnated MWCNTs. Thus, considering the dimensional compatibility of nanotubes and nanoparticles, a field-induced partial alignment of MWNCTs by virtue of their bent form in ferrofluidic system is proposed. A partial or complete accomplishment of the reversibility and tunability of the patterning of MWCNTs on a large scale in ferrofluid has been investigated in detail.

Toward axial accuracy prediction and optimization of metal tube bending forming: A novel GRU-integrated Pb-NSGA-III optimization framework

Springback is particularly common in metal tube bending, which extremely affects the metal tube axial accuracy. At present, the springback mechanism still remains unclear due to the complex plastic deformation characteristics of metal materials. It is difficult to obtain the accurate axial springback information before bending forming, not to mention formulating a reasonable processing plan to compensate springback. To alleviate this difficulty, a novel optimization framework is constructed which takes the radius changes series (RCS) as the new axial accuracy evaluation index for the first time. The optimization framework contains a GRU-based deep learning network as the prediction module to predict the springback more reliably. Subsequently, NSGA-III has been improved by the proposed guiding factor (GF) and dynamic reference points (DRF) algorithm, i.e, priority-based NSGA-III (Pb-NSGA-III), which can more efficiently deal with the objectives with different priorities when generating the processing plan. With the help of the finite element (FE) and bending experiment, the springback dataset construction and the accuracy verification can be achieved. The results show that the framework can achieve high-precision and robust prediction of the tube axial accuracy. Compared with the existing commonly used multi-objective algorithms, the proposed Pb-NSGA-III shows its superiority in engineering application.

DNA Bending Force Facilitates Z-DNA Formation under Physiological Salt Conditions.

Z-DNA, a noncanonical helical structure of double-stranded DNA (dsDNA), plays pivotal roles in various biological processes, including transcription regulation. Mechanical stresses on dsDNA, such as twisting and stretching, help to form Z-DNA. However, the effect of DNA bending, one of the most common dsDNA deformations, on Z-DNA formation is utterly unknown. Here, we show that DNA bending induces the formation of Z-DNA, that is, more Z-DNA is formed as the bending force becomes stronger. We regulated the bending force on dsDNA by using D-shaped DNA nanostructures. The B–Z transition was observed by single-molecule fluorescence resonance energy transfer. We found that as the bending force became stronger, Z-DNA was formed at lower Mg2+ concentrations. When dsDNA contained cytosine methylations, the B–Z transition occurred at 78 mM Mg2+ (midpoint) in the absence of the bending force. However, the B–Z transition occurred at a 28-fold lower Mg2+ concentration (2.8 mM) in the presence of the bending force. Monte Carlo simulation suggested that the B–Z transition stabilizes the bent form via the formation of the B–Z junction with base extrusion, which effectively releases the bending stress on DNA. Our results clearly show that the bending force facilitates the B–Z transition under physiological salt conditions.

Structure of twin boundaries of cholesteric blue phase I

We investigate numerically the structure of twin boundaries of cholesteric blue phases. Our study is based on the Landau-de Gennes continuum theory describing the orientational order of the liquid crystal by a second-rank tensor. We pay particular attention to blue phase I (BP I) with body-centered-cubic symmetry and consider twin boundaries between BP I lattices in which their (110) planes are shared and the (1[over ¯]12) plane of one lattice is parallel to the (11[over ¯]2) plane of the other as observed in previous experiments [Jin etal., Sci. Adv. 6, eaay5986 (2020)10.1126/sciadv.aay5986; Zhang etal., ACS Appl. Mater. Interf. 13, 36130 (2021)1944-824410.1021/acsami.1c06873]. We discuss two plausible cases in which the twin boundaries are parallel to the {112} planes or the {111} planes. In the former, disclination lines of obtusely bent form penetrate the twin boundaries, and in the latter straight disclination lines as well as bent ones are found at the twin boundaries. The former twin boundaries are energetically less costly, consistent with previous experimental identifications. From our numerical results the free energy of a twin boundary per unit area is estimated to be ≃4×10^{-6}Jm^{-2}, which indeed indicates that the formation of twin boundaries is not prohibitively costly.

Effects of Process Parameters on Springback of High Strength 21-6-9 Tube Bending Considering Variation of Elastic Modulus

In order to improve forming quality of high strength 21-6-9 tube bending and achieve its precise bending forming, the springback behaviors of high strength 21-6-9 tube in rotary draw bending are investigated. Based on explicit/implicit finite element (FE) software of ABAQUS, the whole rotary draw bending FE model of high strength 21-6-9 tube considering variation of elastic modulus was established, and its reliability was verified. Then, the springback behaviors considering varied elastic modulus of high strength 21-6-9 tube in rotary draw bending under different process parameters were explored and compared that with constant elastic modulus. The results show that the variation tendencies of springback angle are similar with or without considering varied elastic modulus, but augments the value of springback angle with considering varied elastic modulus. Springback angle augments with the increase of the friction coefficient of tube versus mandrel, the friction coefficient of tube versus wiper die or with the decrease of the friction coefficient of tube versus pressure die, while the springback angle firstly declines and then augments with increasing the clearance of tube versus pressure die and the clearance of tube versus wiper die.

Research on the axial elongation and springback law of thick-walled tubes in cold bending forming

Research on the axial elongation and springback law of thick-walled tubes in cold bending forming