Effect Of Bending Deformation Research Articles

Effect of bending deformation on the electronic and optical properties of O atoms adsorbed by Be3N2.

In this paper, the optimum coverage of 4.44% and the optimum adsorption sites were determined for the Be3N2 adsorption system of O atoms at different coverages based on density functional theory. The electronic and optical properties of the model were investigated by applying bending deformation to the model at these coverage and adsorption sites. Adsorption of O atoms disrupts the geometrical symmetry of Be3N2, resulting in orbital rehybridization and lowering its band gap. Bending deformation causes the band gap of the adsorbed O atom structure of Be3N2 to first increase and then decrease, resulting in the modulation of its band gap. With increasing bending deformation, the adsorbed system is redshifts, and the degree of redshift increases with increasing bending deformation. All calculations in this paper were performed using the first-principles-based CASTEP module of Materials Studio (MS). The generalized gradient approximation (GGA) plane-wave pseudopotential method and the Perdew-Burke-Ernzerhof (PBE) Perdew et al. Phys Rev Lett 77:3865, 1996 generalized functional were used in the geometry optimization and calculation process to calculate the exchange-correlation potential between electrons. The effect of coverage on the electronic and optical properties of the Be3N2-adsorbed O atom system was investigated by adsorbing different numbers of O atoms on a monolayer of Be3N2. The Be3N2 protocell contains two N atoms and three Be atoms with a space community of P6/MMM (No.191). The original cell was expanded 3 times along the direction of the base vectors a and b in the Be3N2 plane to create a 3 × 3 × 1 monolayer Be3N2 supercell system. A vacuum layer of 15Å is set in the direction of the crystal plane of the vertical monolayer Be3N2 supercell to eliminate interactions between adjacent layers. In the overall energy convergence test of the Be3N2 supercell, the plane wave truncation energy was set to 500eV, and the energy difference between the calculations given in the literature Reyes-Serrato et al. J Phys Chem Solids 59:743-6, 1998 using 550eV was less than 0.01eV, verifying the reliability of the data at a truncation energy of 500eV. The Monkhorst-Pack special k-point sampling method Monkhorst et al. Phys Rev B 13:5188, 1976 was used in the structural calculations, and the grid was set to 3 × 3 × 1. The geometric optimization parameters are set as follows: the self-consistent field iteration convergence criterion is 2.0 × 10-6eV, and the iterative accuracy convergence value is not less than 1.0 × 10-5eV/atom for the total force of each atom and less than 0.03eV/Å for all atomic forces. In addition the high-symmetry k-point path is taken as Γ(0,0,0) → M(0,0.5,0) → K(- 1/3,2/3,0) → Γ(0,0,0) Chen et al, AIP Adv 8:105105, 2018.

Effect of bending deformation on suspended topological insulator nanowires: Towards a topological insulator based NEM switch

Nanodevices consisting of the suspended and supported parts of topological insulator Bi2Se3 nanowires were fabricated and measured at low and room temperatures. Probing of topological surface states, accompanied by the electrostatic field effect used to dynamically manipulate bending deformation, was carried out to monitor the external strain introduced into the suspended and supported parts within the same Bi2Se3 nanowire. Depending on the device geometry, pure elastic and elastoplastic types of concave deformation, as well as convex buckling deformation, were realized in the suspended parts of the nanowires. For various types of observed deformations, different magnitudes of increase in the Source-Drain resistance of the deformed part compared to the relaxed part of the same devices were determined. All suspended devices exhibit external strain-sensitive Shubnikov-de Haas oscillation frequencies representing the carriers of top and bottom surface states and bulk, whereas, in the case of supported devices, the bottom surface states are masked by a trivial 2DEG. The obtained results may be useful for strain engineering of TI materials, as well as for applications in NEMS and other areas related to suspended nanostructures.

Effect of bending deformation on the corrosion behavior of non-brazed and brazed Al composite

This study provides an insight into the effect of bending deformation on the corrosion behavior of non-brazed and brazed AA4343/AA4047/AA3003/AA4047/AA4343 composite sheet from the rolling direction (RD) and the transverse direction (TD) cross sections, by combining electrochemical measurements, scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD) techniques. Grain size had a greater effect on the corrosion resistance, as compared with the textures. Localized corrosion initiated from intermetallic particles (IMPs) for both non-brazed and brazed samples whether bending or not. After bending deformation, stress concentrations at the outer layer were found in non-brazed and brazed samples. For non-brazed samples, bending deformation had little effect on the corrosion behavior due to the absence of intergranular corrosion (IGC). For brazed samples, Si “needles” provided effective corrosion propagation path, leading to a reduction of corrosion resistance.

Effect of Bending Deformation on the Lateral Force of Spinning Projectiles with Large Aspect Ratio

The bending deformation can affect the lateral force of spinning projectiles with large aspect ratios, thus interfering with their flight stability. Based on the established spin–deformation coupling motion model, the unsteady Reynolds averaged Navier–Stokes (URANS) equations are solved to simulate the flow over a large−aspect−ratio projectile undergoing spin and spin−deformation coupling motion by using the dual−time stepping method and dynamic mesh technique, obtaining the lateral force. Furtherly, the flow mechanism is analyzed for the changed lateral force induced by the bending deformation. The results indicate that the variation of transient lateral force for the head of a projectile is consistent with that of the deformation−induced additional sideslip angle; affected by the deformation−induced compression wave and expansion wave, the time−averaged lateral force for the middle of a projectile will be increased at small angles of attack, but changed little at large angles of attack; at small angles of attack, the change trend of transient lateral force for the tail of a projectile is similar to that of additional angle of attack caused by the deformation; at large angles of attack, the characteristic of phase lag is presented between the transient lateral force for the tail of a projectile and the additional sideslip angle.

Bending-deformation-induced inhomogeneous aging behavior and accelerated precipitation kinetics of extruded AZ80 alloy

In this study, the effects of bending deformation on the precipitation behavior of an extruded AZ80 alloy are investigated by subjecting a plate of the alloy to three-point bending and subsequent aging at 200 °C. In the upper region of the bent specimen (denoted as CZ), numerous {10−12} extension twins are formed. In the lower region of the bent specimen (denoted as TZ), small quantities of {10−12} extension twins, {10−11} contraction twins, and {10−11}–{10−12} double twins are formed, and most of the bending deformation is accommodated by dislocation slip. In the central region of the bent specimen (denoted as NZ), few twins are formed, and the microstructural characteristics of this region are almost identical to those of the initial material. When the bent specimen is aged, the peak-aging time of the CZ and TZ (8 h) is 60% shorter than that of the NZ (20 h), which is attributed to the accelerated precipitation caused by the abundant twins in and high internal strain energy of the CZ and TZ. In the CZ, nucleation and growth of continuous Mg 17 Al 12 precipitates (CPs) occur rapidly, especially inside the {10−12} twins, and this accelerated CP formation inhibits the formation of discontinuous Mg 17 Al 12 precipitates (DPs). Because of the high internal strain energy of the TZ, promoted formation of CPs occurs in the early stage of aging, which, in turn, suppresses the formation of DPs. In contrast, the NZ, because of its low internal strain energy and insufficient twins, exhibits slower CP formation behavior and has a considerably larger amount of DPs than the CZ and TZ. Although the bending deformation before aging induces inhomogeneous precipitation behaviors, the prebending deformation shortens the overall peak-aging time of the material and increases its peak hardness. • An extruded AZ80 alloy plate is subjected to bending and subsequent aging. • The bent plate has an inhomogeneous microstructure and internal strain energy. • Its upper and lower regions show a faster aging rate than its central region. • Continuous and discontinuous precipitation behaviors are different in each region. • Bending deformation shortens the peak-aging time and improves the peak hardness.

Effect of strain on degradation behaviors of WE43, Fe and Zn wires

The biodegradable metallic devices undergo stress/strain-induced corrosion when they are used for load-bearing applications. The stress/strain induced-corrosion behavior causes differences in corrosion rate, corrosion morphology, strain distribution and mechanical performance of the devices. One representative example is the biodegradable stent. Biodegradable stents undergo complex inhomogeneous deformation that can cause dramatic non-uniform stent degradation, resulting in stress concentration and stents failure. The degradation of biodegradable devices requires special attention to the mutual effect between the applied strain and degradation.The quantitative relationship between strain and corrosion of the sample alloys (WE43, Fe and Zn), selected from three typical biodegradable metals, is firstly investigated and compared in this study. The in vitro degradation and the strength retention of WE43, Fe and Zn wires were investigated under different elastic and plastic strain levels ranging from 0.1% to 30%. The results indicated that the applied strain could bring down the corrosion potential, increase corrosion current and accelerate the degradation of three biodegradable metals. Specifically, remarkable enhanced localized corrosion was observed for plastic strained WE43 compared with those with elastic strains. This localized corrosion morphology significantly accelerated the strength decline at first, while the differences diminished with longer immersion period. Fe and Zn exhibited increased degradation with plastic strain applications than those under elastic strains. However, the degradation was not further increased with the increasing magnitude of plastic strains. Moreover, the bended wires were subcutaneously implanted in the dorsal aspect of the rats and the effect of bending deformation on in vitro and in vivo degradation of three metallic wires were also compared. The U-bended WE43 wires suffered more severe in vitro degradation at the stress concentrated region. Surprisingly, the early fracture of the undeformed regions was observed in the in vivo test. In conclusion, the corrosion rate, corrosion morphology and mechanical properties of WE43, Fe and Zn was sensitive to magnitude of the applied strains. The quantification results provided new insights into understanding the strain-dependent corrosion of three biodegradable metals both in vitro and in vivo. Statement of SignificanceBiodegradable implants are subjected to various mechanical environment during the deployment and subsequent physiological activity. It is necessary to have a clear understanding of the effects of the applied stress on degradation. This study addresses the quantitative effects of applied strain/stress on the in vitro and in vivo degradation of three typical biodegradable metals (Mg, Fe and Zn). These quantification results provide new insights into understanding the strain-induced corrosion of three metals.

Use of localized necking and fracture as a failure criterion in ship collision analysis

This study explores the use of localized necking for failure modeling in maritime crash analysis, using large shell elements. The assumption that the failure of a large shell element occurs simultaneously with the onset of localized necking is revisited. This study particularly investigates the numerical implementation of the localized necking condition and its implications on the results of ship collision analysis involving not only plate rupture but also various failure mechanisms such as the crushing and tearing of web girders, stringers, and their intersections. Through a series of large-scale collision simulations, the effects of bending deformation on the initiation of necking, non-proportional loading paths, and ductile fractures not preceded by localized necking, are investigated. It is demonstrated that a localized necking-based fracture model provides a reasonable, relatively mesh-insensitive estimate of the onset of fracture in the outer hull panels; however, fracture propagation is very sensitive to the numerical implementation of the necking and fracture model, especially for the cases involving the crushing of web frames and stringers.

Highly Bendable Planar Hall Resistance Sensor

A set of planar Hall resistance (PHR) sensors was fabricated on rigid and flexible substrates. High signal-to-noise ratio, low offset voltage, nearly zero hysteresis of signal, and excellent linearity were demonstrated for sensors, based on Ta (5 nm)/NiFe (10 nm)/IrMn (10 nm)/Ta (5 nm) thin films, grown on polydimethylsiloxane (PDMS) and parylene C polymeric substrates. The effect of bending on the performance of the PHR sensors was studied. The effect of bending deformation on the performance characteristics of the fabricated PHR sensors is reversible until the bending angle reaches a critical one. The critical bending angle is shown to depend on the substrate composition. An irreversible deformation of a sensor's film, accompanied by the formation of wrinkles and cracks, occurs when the bending angle exceeds the critical one. This deformation originates from the difference between the values of Young's modulus of the substrate and the film. The bending stability of a PHR sensor, grown on PDMS substrate, was improved by deposition of 1 µm of parylene C as a buffer and as a capping layer. The performance characteristics of the designed bendable PHR sensors are compatible with requirements for applications in wearable electronics and medical diagnostic devices.

Flexible Temperature Sensor Integrated with Soft Pneumatic Microactuators for Functional Microfingers

The integration of a flexible temperature sensor with a soft microactuator (a pneumatic balloon actuator) for a functional microfinger is presented herein. A sensor integrated with a microactuator can actively approach a target for contact detection when a distance exists from the target or when the target moves. This paper presents a microfinger with temperature sensing functionality. Moreover, thermocouples, which detect temperature based on the Seebeck effect, are designed for use as flexible temperature sensors. Thermocouples are formed by a pair of dissimilar metals or alloys, such as copper and constantan. Thin-film metals or alloys are patterned and integrated in the microfinger. Two typical thermocouples (K-type and T-type) are designed in this study. A 2.0 mm × 2.0 mm sensing area is designed on the microfinger (3.0 mm × 12 mm × 400 μm). Characterization indicates that the output voltage of the sensor is proportional to temperature, as designed. It is important to guarantee the performance of the sensor against actuation effects. Therefore, in addition to the fundamental characterization of the temperature sensors, the effect of bending deformation on the characteristics of the temperature sensors is examined with a repeated bending test consisting of 1000 cycles.

The Effect of Bending Deformation on Charge Transport and Electron Effective Mass of p‐doped GaAs Nanowires

The Effect of Bending Deformation on Charge Transport and Electron Effective Mass of p‐doped GaAs Nanowires

The Effect of Bending Deformation on Charge Transport and Electron Effective Mass of p‐doped GaAs Nanowires

The crystal and electronic structure of semiconductor nanowire systems have shown sensitive response to mechanical strain, enabling novel and improved electrical, and optoelectrical properties in nanowires by strain engineering. Here, the response of current–voltage (I–V) characteristics and band structure of individual p‐doped GaAs nanowires to bending deformation is studied by in situ electron microscopy combined with theoretical simulations. The I–V characteristics of the nanowire change from linear to nonlinear as bending deformation is applied. The nonlinearity increases with strain. As opposed to the case of uniaxial strain in GaAs, the bending deformation does not give rise to a change in the band gap of GaAs nanowire according to in situ electron energy loss spectroscopy (EELS) measurements. Instead, the response to bending deformation can be explained by strain induced valence band shift, which results in an energy barrier for charge carrier transport along the nanowire. Moreover, the electron effective mass decreases as the strain changes from compressive to tensile across the GaAs nanowire in the bent region. Results from this study shed light on the complex interplay between lattice strain, band structure, and charge transport in semiconductor nanomaterials.

弯曲水生植物周围的水流变化特征研究

弯曲水生植物周围的水流变化特征研究

A new jig-shape optimization method for the high aspect ratio wing

Purpose Computational efficiency is always the major concern in aircraft design. The purpose of this research is to investigate an efficient jig-shape optimization design method. A new jig-shape optimization method is presented in the current study and its application on the high aspect ratio wing is discussed. Design/methodology/approach First, the effects of bending and torsion on aerodynamic distribution were discussed. The effect of bending deformation was equivalent to the change of attack angle through a new equivalent method. The equivalent attack angle showed a linear dependence on the quadratic function of bending. Then, a new jig-shape optimization method taking integrated structural deformation into account was proposed. The method was realized by four substeps: object decomposition, optimization design, inversion and evaluation. Findings After the new jig-shape optimization design, both aerodynamic distribution and structural configuration have satisfactory results. Meanwhile, the method takes both bending and torsion deformation into account. Practical implications The new jig-shape optimization method can be well used for the high aspect ratio wing. Originality/value The new method is an innovation based on the traditional single parameter design method. It is suitable for engineering application.

Special Features of Structure Formation in an Explosion-Welded Magnesium-Aluminum Composite Under Deformation and Subsequent Heat Treatment

The effect of bending deformation and subsequent heat treatment on the variation of microhardness and structure of explosion-welded magnesium-aluminum layered composite material MA2-1 – AD1 is studied.

STRUCTURAL CHANGES IN EXPLOSION-WELDING PRODUCED MAGNESIUM-ALUMINUM COMPOSITE AFTER BENDING AND HEAT TREATMENT

The effect of bending deformation and subsequent heat treatment on the behavior of micromechanical properties and fine structure of explosion welded АD1-MA2-0 magnesium-aluminum composite material has been investigated. It is established that after heat treatment (t = 300 and 400 °C, τ = 1 h) explosion welded and bent composite material shows formation of an intermetallic layer, which significantly affects the fine structure characteristics.

Effect of bending deformation on photovoltaic performance of flexible graphene/Ag electrode-based polymer solar cells

Photovoltaic characteristics of flexible graphene/Ag electrode – based polymer solar cells as a function of electrode thickness under bending deformation.

Structural changes in magnesium-aluminum composite obtained by explosion welding after bending and thermal treatment

The effect of bending deformation and subsequent thermal treatment on the behavior of the micromechanical properties and characteristics of a fine structure of the AD1-MA2-0 magnesium-aluminum composite material (CM) after explosion welding (EW) is investigated. It is found that an intermetallic interlayer is formed after the thermal treatment (t = 300 and 400°C, τ = 1 h) of the composite welded by explosion and subjected to bending, which substantially affects the behavior of the characteristics of a fine structure.

A numerical model for simulating mechanical behavior of flexible fibers

A numerical method is developed for simulating the mechanical behavior of flexible fibers. A circular crossed fiber is represented by a number of cylindrical segments linked by spring dash-pot systems. Segments are lined up and bonded to each neighbor. Each bond can be stretched or compressed by changing the bond distance. Bending deflection and twist movement occur, respectively, in the bending and torsion planes. While the bending angle is determined by the positions of two neighboring bonds, a reference twist vector is introduced to record the torsion motion along the segment chain. Fluid drag forces are calculated based on the Stokes’ Law, where a free draining assumption is made. The motion of the fiber is determined by solving the translational and rotational equations of individual segments. Computer simulation has been conducted to verify the single fiber model with elastic theory and excellent agreements have been found between the simulation results and the theory in various situations such as beam deflection under static loads, vibrating cantilevers, and dynamics of helical shaped fibers. Examining orientations of rigid fibers in a viscous shear flow, simulation results suggest that the rotational time is sensitive to the fluid drag torque which is related to the shape of the segments. For highly flexible fibers, the effect of bending deformation on the period of rotation and the rotation orbits is also investigated. This numerical model for single flexible fibers linked by discrete segments provides a framework in the future studies on fibrous assemblies.

Influence of deformations before instability on the parametric instability of conical shells under periodic pressure

On the basis of the dynamic version of linear Donnell type equations and with deformations before instability taken into account, the dynamic instability of clamped, truncated conical shells under periodic pressure is analyzed. The principal instability regions are determined by combining Bolotin's method and a finite difference procedure. Calculations are carried out for two kinds of conical shell. The effect of bending deformations before instability is found to change the width of the principal instability regions in the vicinities of twice the natural frequencies of asymmetric vibration. Other principal instability regions are detected in the neighborhoods of the resonances of symmetrically forced vibrations.

Influence of Deformations Prior to Instability on the Dynamic Instability of Conical Shells Under Periodic Axial Load

The dynamic instability of clamped, truncated conical shells under periodic axial load is studied using the Donnell-type basic equation and considering the effect of bending deformations before instability. Two principal instability regions are determined by combining Bolotin’s method and a finite-difference method. One of these belongs to double the natural frequencies of asymmetrical vibration; the other corresponds to the resonance of symmetrically forced vibrations. The effects of static axial load and end-plate mass on the principal instability regions are also investigated.