Semiconductor laser beam bending
YILDIRIM, REMZİ; ÇELEBİ, FATİH VEHBİ
2015-01-01
This study is about a single-component cylindrical structured lens with a gradient curve that was used for bending laser beams. It operates under atmospheric conditions and bends the laser beam independently of temperature, pressure, polarity, polarization, magnetic field, electric field, radioactivity, and gravity. A single-piece cylindrical lens that can bend laser beams was developed. Lenses are made of transparent, tinted, or colored glass and are used to undermine or absorb the energy of...
2002-01-01
A Japanese team has found a way to bend and shape silicon substrates by growing a thin layer of diamond on top. The technique has been proposed as an alternative to mechanical bending, which is currently used to make reflective lenses for X-ray systems and particle physics systems (2 paragraphs).
Sheet Bending using Soft Tools
Sinke, J.
2011-05-01
Sheet bending is usually performed by air bending and V-die bending processes. Both processes apply rigid tools. These solid tools facilitate the generation of software for the numerical control of those processes. When the lower rigid die is replaced with a soft or rubber tool, the numerical control becomes much more difficult, since the soft tool deforms too. Compared to other bending processes the rubber backed bending process has some distinct advantages, like large radius-to-thickness ratios, applicability to materials with topcoats, well defined radii, and the feasibility of forming details (ridges, beads). These advantages may give the process exclusive benefits over conventional bending processes, not only for industries related to mechanical engineering and sheet metal forming, but also for other disciplines like Architecture and Industrial Design The largest disadvantage is that also the soft (rubber) tool deforms. Although the tool deformation is elastic and recovers after each process cycle, the applied force during bending is related to the deformation of the metal sheet and the deformation of the rubber. The deformation of the rubber interacts with the process but also with sheet parameters. This makes the numerical control of the process much more complicated. This paper presents a model for the bending of sheet materials using a rubber lower die. This model can be implemented in software in order to control the bending process numerically. The model itself is based on numerical and experimental research. In this research a number of variables related to the tooling and the material have been evaluated. The numerical part of the research was used to investigate the influence of the features of the soft lower tool, like the hardness and dimensions, and the influence of the sheet thickness, which also interacts with the soft tool deformation. The experimental research was focused on the relation between the machine control parameters and the most
Institute of Scientific and Technical Information of China (English)
无
2000-01-01
A new kind of bend sensor is introduced.It can be used to detect the bend angle of an object or inclination between two objects.It has characteristics of small size, lightweight, high reliability, fine flexibility and plasticity.When this bend sensor is used with a proper converting circuit, it can implement dynamic measuring the bend angle of an object conveniently.The application of the bend sensor in dataglove is also described.
Bending characteristics of resin concretes
Directory of Open Access Journals (Sweden)
Ribeiro Maria Cristina Santos
2003-01-01
Full Text Available In this research work the influence of composition and curing conditions in bending strength of polyester and epoxy concrete is analyzed. Various mixtures of resin and aggregates were considered in view of an optimal combination. The Taguchi methodology was applied in order to reduce the number of tests, and in order to evaluate the influence of various parameters in concrete properties. This methodology is very useful for the planning of experiments. Test results, analyzed by this methodology, shown that the most significant factors affecting bending strength properties of resin concretes are the type of resin, resin content and charge content. An optimal formulation leading to a maximum bending strength was achieved in terms of material parameters.
Bending behavior of lapped plastic ehv cables
Energy Technology Data Exchange (ETDEWEB)
Morgan, G H; Muller, A C
1980-01-01
One of the factors delaying the development of lapped polymeric cables has been their reputed poor bending characteristics. Complementary programs were begun at BNL several years ago to mathematically model the bending of synthetic tape cables and to develop novel plastic tapes designed to have moduli more favorable to bending. A series of bend tests was recently completed to evaluate the bending performance of several tapes developed for use in experimental superconducting cables. The program is discussed and the results of the bend tests are summarized.
Hormonal regulation of gravitropic bending
Hu, X.; Cui, D.; Xu, X.; Hu, L.; Cai, W.
Gravitropic bending is an important subject in the research of plant Recent data support the basics of the Cholodny-Went hypothesis indicating that differential growth in gravitropism is due to redistribution of auxin to the lower sides of gravistimulated roots but little is known regarding the molecular details of such effects So we carried a series of work surround the signals induced by auxin end center We found the endogenous signaling molecules nitric oxide NO and cGMP mediate responses to gravistimulation in primary roots of soybean Glycine max Horizontal orientation of soybean roots caused the accumulation of both NO and cGMP in the primary root tip Fluorescence confocal microcopy revealed that the accumulation of NO was asymmetric with NO concentrating in the lower side of the root Auxin induced NO accumulation in root protoplasts and asymmetric NO accumulation in root tips Gravistimulation NO and auxin also induced the accumulation of cGMP a response inhibited by removal of NO or by inhibitors of guanylyl cyclase compounds that also reduced gravitropic bending Asymmetric NO accumulation and gravitropic bending were both inhibited by an auxin transport inhibitor and the inhibition of bending was overcome by treatment with NO or 8-bromo-cGMP a cell-permeable analog of cGMP These data indicate that auxin-induced NO and cGMP mediate gravitropic curvature in soybean roots From Hu et al Plant Physiol 2005 137 663-670 The asymmetric distribution of auxin plays a fundamental role in plant gravitropic bending
Bending and stretching of plates
Mansfield, E H; Hemp, W S
1964-01-01
The Bending and Stretching of Plates deals with elastic plate theory, particularly on small- and large-deflexion theory. Small-deflexion theory concerns derivation of basic equations, rectangular plates, plates of various shapes, plates whose boundaries are amenable to conformal transformation, plates with variable rigidity, and approximate methods. Large-deflexion theory includes general equations and some exact solutions, approximate methods in large-deflexion theory, asymptotic large-deflexion theories for very thin plates. Asymptotic theories covers membrane theory, tension field theory, a
Garment-Integrated Bend Sensor
Directory of Open Access Journals (Sweden)
Guido Gioberto
2014-09-01
Full Text Available Garment-integrated sensors equip clothes with a smart sensing capability, while preserving the comfort of the user. However, this benefit can be to the detriment of sensing accuracy due to the unpredictability of garment movement (which affects sensor positioning and textile folds (which can affect sensor orientation. However, sensors integrated directly into garments or fabric structures can also be used to detect the movement of the garment during wearing. Specifically, a textile bend sensor could be used to sense folds in the garment. We tested a garment-integrated stitched sensor for five types of folds, stitched on five different weights of un-stretchable denim fabric and analyzed the effects of fold complexity and fabric stiffness, under un-insulated and insulated conditions. Results show that insulation improves the linearity and repeatability of the sensor response, particularly for higher fold complexity. Stiffer fabrics show greater sensitivity, but less linearity. Sensor response amplitude is larger for more complex fold geometries. The utility of a linear bending response (insulated and a binary shorting response (un-insulated is discussed. Overall, the sensor exhibits excellent repeatability and accuracy, particularly for a fiber-based, textile-integrated sensor.
FACTORS INFLUENCING BENDING RIGIDITY OF SUBMERGED VEGETATION
Institute of Scientific and Technical Information of China (English)
WU Long-hua; YANG Xiao-li
2011-01-01
The bending rigidity of submerged vegetation is closely related with vegetative drag force.This work aims at determining the effects of flow conditions and characteristics of vegetation on the bending rigidity of submerged vegetation.Based on the dimensional analysis method,the factors influencing the bending rigidity of individual submerged vegetation were analyzed.The relationship between the relative bending rigidity and its influencing factors was investigated by experimental observation,and a relative bending rigidity expression for submerged vegetation was obtained by means of multiple linear regression method.The results show that the submerged vegetation has three states under different inflow conditions,and the each critical relative bending rigidity of individual submerged vegetation was determined for the different states of submerged vegetation.
Minimum Membrane Bending Energies of Fusion Pores
Jackson, Meyer B.
2009-01-01
Membranes fuse by forming highly curved intermediates, culminating in structures described as fusion pores. These hourglass-like figures that join two fusing membranes have high bending energies, which can be estimated using continuum elasticity models. Fusion pore bending energies depend strongly on shape, and the present study developed a method for determining the shape that minimizes bending energy. This was first applied to a fusion pore modeled as a single surface and then extended to a...
Multilevel light bending in nanoplasmonics
El Sherif, Mohamed H.; Ahmed, Osman S.; Bakr, Mohamed H.; Swillam, Mohamed A.
2014-03-01
Nanoplasmonic optical interconnects is proposed to mitigate challenges facing electronics integration. It provides fast and miniaturized data channel that overcome the diffraction limit. We present a three dimensional plasmonic coupler that vertically bends the light to multilevel circuit configurations. It exploits light guiding in nanoscale plasmonic slot waveguides (PSWs). A triangularly-shaped plasmonic slot waveguide rotator is introduced to attain such coupling with good efficiency over a wide bandwidth. Using this approach, light propagating in a horizontal direction is easily converted and coupled to propagate in the vertical direction and vice versa. The proposed configuration is further extended to the design of a multilayer power divider/combiner with ultra-compact footprint that guides the light to multiple channels. A detailed study of the triangular rotator is demonstrated with the analysis of multiple configurations. This structure is suitable for efficient coupling and splitting in multilevel nano circuit environment.
2010-10-01
....1 of ASME B31.1 (incorporated by reference; see 46 CFR 56.01-2). This shall not prohibit the use of..., DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING PIPING SYSTEMS AND APPURTENANCES Bending and Forming § 56.80-5 Bending. Pipe may be bent by any hot or cold method and to any radius which will...
Discontinious Galerkin formulations for thin bending problems
Nguyen, T.D.
2008-01-01
A structural thin bending problem is essentially associated with a fourth-order partial differential equation. Within the finite element framework, the numerical solution of thin bending problems demands the use of C^1 continuous shape functions. Elements using these functions are challenging and di
Bends and splitters in graphene nanoribbon waveguides
DEFF Research Database (Denmark)
Zhu, Xiaolong; Yan, Wei; Mortensen, N. Asger;
2013-01-01
We investigate the performance of bends and splitters in graphene nanoribbon waveguides. Although the graphene waveguides are lossy themselves, we show that bends and splitters do not induce any additional loss provided that the nanoribbon width is sub-wavelength. We use transmission line theory...
Bandwidth engineering of photonic crystal waveguide bends
DEFF Research Database (Denmark)
Borel, Peter Ingo; Frandsen, Lars Hagedorn; Harpøth, Anders;
2004-01-01
An effective design principle has been applied to photonic crystal waveguide bends fabricated in silicon-on-insulator material using deep UV lithography resulting in a large increase in the low-loss bandwidth of the bends. Furthermore, it is experimentally demonstrated that the absolute bandwidth...
Bending of light in conformal Weyl gravity
Sultana, Joseph; Kazanas, Demosthenes
2010-06-01
We reexamine the bending of light issue associated with the metric of the static, spherically symmetric solution of Weyl gravity discovered by Mannheim and Kazanas (1989). To this end we employ the procedure used recently by Rindler and Ishak to obtain the bending angle of light by a centrally concentrated spherically symmetric matter distribution in a Schwarzschild-de Sitter background. In earlier studies the term γr in the metric led to the paradoxical result of a bending angle proportional to the photon impact parameter, when using the usual formalism appropriate to asymptotically flat space-times. However, employing the approach of light bending of Rindler and Ishak we show that the effects of this term are in fact insignificant, with the discrepancy between the two procedures attributed to the definition of the bending angle between the asymptotically flat and nonflat spaces.
Wire and Cable Cold Bending Test
Colozza, Anthony
2010-01-01
One of the factors in assessing the applicability of wire or cable on the lunar surface is its flexibility under extreme cold conditions. Existing wire specifications did not address their mechanical behavior under cold, cryogenic temperature conditions. Therefore tests were performed to provide this information. To assess this characteristic 35 different insulated wire and cable pieces were cold soaked in liquid nitrogen. The segments were then subjected to bending and the force was recorded. Any failure of the insulation or jacketing was also documented for each sample tested. The bending force tests were performed at room temperature to provide a comparison to the change in force needed to bend the samples due to the low temperature conditions. The results from the bending tests were plotted and showed how various types of insulated wire and cable responded to bending under cold conditions. These results were then used to estimate the torque needed to unroll the wire under these low temperature conditions.
49 CFR 195.212 - Bending of pipe.
2010-10-01
... 49 Transportation 3 2010-10-01 2010-10-01 false Bending of pipe. 195.212 Section 195.212... PIPELINE Construction § 195.212 Bending of pipe. (a) Pipe must not have a wrinkle bend. (b) Each field bend must comply with the following: (1) A bend must not impair the serviceability of the pipe. (2)...
Bend Properties of Sapphire Fibers at Elevated Temperatures. 1; Bend Survivability
Morscher, Gregory N.; Sayir, Haluk
1995-01-01
The effect of temperature on the bend radius that a c-axis-oriented sapphire fiber can withstand was determined for fibers of various diameter. Bend stress rupture tests were performed for times of 1-100 h and temperatures of 300-1700 C. Fibers would survive the bend test undeformed, would fracture or would deform. The bend survival radius was determined to be the radius above which no fibers fractured or deformed for a given time-temperature treatment. It was found that the ability of fibers to withstand curvature decreases substantially with time and increasing temperature and that fibers of smaller diameter (46-83 micron) withstood smaller bend radii than would be expected from just a difference in fiber diameter when compared with the bend results of the fibers of large diameter (144 micron). This was probably due to different flaw populations, causing high temperature bend failure for the tested sapphire fibers of different diameters.
Low Loss S-Bend Structure With Tapered Curved Waveguides
Institute of Scientific and Technical Information of China (English)
无
2003-01-01
A novel S-bend with tapered curved waveguides is proposed. The normalized transmitted power is greater than the conventional bend with weakly guided waveguides. Small size and low loss can be reached by the proposed S-bend.
Bending stresses in Facetted Glass Shells
DEFF Research Database (Denmark)
Bagger, Anne; Jönsson, Jeppe; Almegaard, Henrik
2008-01-01
A shell structure of glass combines a highly effective structural principle with a material of optimal permeability to light. A facetted shell structure has a piecewise plane geometry, and together the facets form an approximation to a curved surface. A distributed load on a plane-based facetted...... structure will locally cause bending moments in the loaded facets. The bending stresses are dependent on the stiffness of the joints. Approximate solutions are developed to estimate the magnitude of the bending stresses. A FE-model of a facetted glass shell structure is used to validate the expressions...
Numerical Evaluation of Bending Load Effect on the Failure Pressure of Wall-Thinned Pipe Bends
International Nuclear Information System (INIS)
During the normal operating conditions, piping systems in nuclear power plants (NPPs) are subject not only to internal pressure but also to bending loads induced by deadweight, thermal expansion, and internal pressure. Bending is thus considered to be an important factor in evaluating the integrity of piping components in NPPs. Local wall-thinning due to flow accelerated corrosion is a main degradation mechanism of carbon steel piping components in NPPs, and the integrity evaluation of wall-thinned piping components has become an important issue. This study investigated the effects of bending load on the failure of wall-thinned pipe bends under internal pressure. Our previous study experimentally evaluated the bending load effects on the failure pressure of wall-thinned elbows under displacement controlled in-plane bending load, but the numbers of experimental data were insufficient to determine the effects of bending load on the failure pressure of wall-thinned pipe bends. Therefore, the present study systematically evaluates the effects of bending load on the failure pressure of wall-thinned pipe bends using parametric finite element analyses
A derivation of the generalized model of strains during bending of metal tubes at bending machines
Directory of Open Access Journals (Sweden)
Śloderbach Z.
2014-02-01
Full Text Available According to the postulate concerning a local change of the “actual active radius” with a bending angle in the bend zone, a generalized model of strain during metal tube bending was derived. The tubes should be subjected to bending at tube bending machines by the method of wrapping at the rotating template and with the use of a lubricated steel mandrel. The model is represented by three components of strain in the analytic form, including displacement of the neutral axis. Generalization of the model during bending metal tubes at the tube bending machines as compared with the existing papers (Śloderbach, 1999; Śloderbach and Rechul, 2000 consists in including the neutral axis displacement and possibility of determination of strains at each point along the thickness of the wall of the bent tube in the bending and bend zone. The derived scheme of strain satisfies initial and boundary kinematic conditions of the bending process, conditions of continuity and inseparability of strains. The obtained analytic expressions can be classified as acceptable from the kinematic point of view
Estimation of tensile properties of pipe bends manufactured by cold bending
International Nuclear Information System (INIS)
In this study, tensile tests were performed on specimens that simulated the cold bending and heat treatment of pipe bends to understand the mechanical properties of pipe bends manufactured by cold bending followed by heat treatment for relieving residual stress. The strength and ductility of cold worked materials were respectively found to be higher and lower than those of the parent material although heat treatment was carried out to relieve residual stress. In addition, the increase in strength and decrease in ductility were proportional to the applied strain levels for cold working. It was thus inferred that the intrados and extrados regions of pipe bends that were cold bended and heat treated show higher strength and lower ductility compared to the parent straight pipe and that the mechanical properties at the crown region are nearly the same as those of the parent straight pipe
This is a slice of a LEP dipole bending magnet, made as a concrete and iron sandwich The bending field needed in LEP is small (about 1000 Gauss), equivalent to two of the magnets people stick on fridge doors. Because it is very difficult to keep a low field steady, a high field was used in iron plates embedded in concrete. A CERN breakthrough in magnet design, LEP dipoles can be tuned easily and are cheaper than conventional magnets.
This is a slice of a LEP dipole bending magnet, made as a concrete and iron sandwich. The bending field needed in LEP is small (about 1000 Gauss), equivalent to two of the magnets people stick on fridge doors. Because it is very difficult to keep a low field steady, a high field was used in iron plates embedded in concrete. A CERN breakthrough in magnet design, LEP dipoles can be tuned easily and are cheaper than conventional magnets.
Pipes under internal pressure and bending
Catinaccio, A
2009-01-01
This article covers the general behaviour of a straight uniform pipe, with built-in open ends, subject to internal pressure and in plane bending or curvature. It is intended as a summary of the basic equations driving the unintuitive phenomena of bending and instability of pipes under internal pressure. The analysis covers in addition the investigation of opposite pressure stabilisation effects that can be observed in some orthotropic material pipes like composite pressure hoses.
A transparent bending-insensitive pressure sensor
Lee, Sungwon; Reuveny, Amir; Reeder, Jonathan; Lee, Sunghoon; Jin, Hanbit; Liu, Qihan; Yokota, Tomoyuki; Sekitani, Tsuyoshi; Isoyama, Takashi; Abe, Yusuke; Suo, Zhigang; Someya, Takao
2016-05-01
Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 μm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 μm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions.
A transparent bending-insensitive pressure sensor.
Lee, Sungwon; Reuveny, Amir; Reeder, Jonathan; Lee, Sunghoon; Jin, Hanbit; Liu, Qihan; Yokota, Tomoyuki; Sekitani, Tsuyoshi; Isoyama, Takashi; Abe, Yusuke; Suo, Zhigang; Someya, Takao
2016-05-01
Measuring small normal pressures is essential to accurately evaluate external stimuli in curvilinear and dynamic surfaces such as natural tissues. Usually, sensitive and spatially accurate pressure sensors are achieved through conformal contact with the surface; however, this also makes them sensitive to mechanical deformation (bending). Indeed, when a soft object is pressed by another soft object, the normal pressure cannot be measured independently from the mechanical stress. Here, we show a pressure sensor that measures only the normal pressure, even under extreme bending conditions. To reduce the bending sensitivity, we use composite nanofibres of carbon nanotubes and graphene. Our simulations show that these fibres change their relative alignment to accommodate bending deformation, thus reducing the strain in individual fibres. Pressure sensitivity is maintained down to a bending radius of 80 μm. To test the suitability of our sensor for soft robotics and medical applications, we fabricated an integrated sensor matrix that is only 2 μm thick. We show real-time (response time of ∼20 ms), large-area, normal pressure monitoring under different, complex bending conditions.
Bending rigidity of composite resin coating clasps.
Ikebe, K; Kibi, M; Ono, T; Nokubi, T
1993-12-01
The purpose of this study is to examine the bending profiles of composite resin coating cast clasps. The cobalt-chromium alloy cast clasps were made using tapered wax pattern. Silane coupling method (Silicoater MD, Kulzer Co.) was used to attach composite resin to metal surface. The breakage and the bending rigidity of composite resin coating clasps were evaluated. Results were as follows: 1) After the repeated bending test to the tips of clasp arm at 10,000 times in 0.25 mm deflection, neither crack on composite resin surface nor separation at resin/metal interface was observed in any specimen. 2) There was no significant difference in the bending rigidity of clasp arms between before and after composite resin coating. From these results, it was demonstrated that the composite resin coating cast clasp was available in clinical cases and coating with composite resin had little influence on the bending rigidity of clasp arms. Therefore, it was suggested that our clasp designing and fabricating system to control the bending rigidity of clasp arms could be applied to composite resin coating clasps. PMID:8935086
New Equation for Bending Development of Arbitrary Rods and Application to Palm Fronds Bending
Abdullah, Mikrajuddin
2016-01-01
A new general equation to explain bending of arbitrary rods (from arbitrary materials, cross sections, densities, strengthnesses, bending angles, etc) was proposed. This equation can solve several problems found in classical equations, which have many limitations such as only applies for small bending angles or must be solved using very complex schemes. Experiments were also conducted to confirm the theoretical predictions. The equation might be used to explain bending of palm fronds in a very simple way. The proposed equation may be used to obtain solution of several problems which are usually obtain with iteration procedures.
Forming characteristics of thin-walled tube bending process with small bending radius
Institute of Scientific and Technical Information of China (English)
LI Heng; YANG He; ZHAN Mei; GU Rui-Jie
2006-01-01
Currently requirements of thin-walled tube with small bending radius cause the defects such as wrinkling,overthinning and cross-section distortion more prone to occur in bending process. Based on the analysis of the forming characteristics by analytical and experimental methods,a complete 3D elastic-plastic FEM model of the process was developed using ABAQUS/Explicit code,including bending process,balls retracting and unloading process,and thus the plastic deformation characteristics with small bending radius were investigated. The main results show that: 1) The utmost deformation feature of the NC bending process is its continuous progressive deformation. 2) The occurring conditions of the defects such as wrinkling and tension instability in the process are obtained. The wrinkling is traditional on the double compressive stresses state and the tension instability is on the double tension stresses state. 3) The enhanced non-uniform deformation in thin-walled tube with small bending radius is demonstrated by comparing the stress/ strains distributions under the 1.5D and 1D bending conditions. 4) For 1D small bending process,a new method-"stepped mandrel retraction" is proposed to improve the bending quality in experiment according to the FE simulation. The simulation results are verified by experiment.
Sharp bends of phononic crystal surface modes
International Nuclear Information System (INIS)
Sharp bending of surface waves at the interface of a two-dimensional phononic crystal (PnC) of steel cylinders in air and the method of using a diagonally offset cylindrical scatterer are numerically demonstrated by finite-element method simulations. The radii of the diagonally offset scatterer and the cylinder at the PnC corner, along with the distance between them, are treated as optimization parameters in the genetic algorithm optimization of sharp bends. Surface wave transmittance of at most 5% for the unmodified sharp bend is significantly enhanced to approximately 75% as a result of optimization. A series of transmittance peaks whose maxima increase exponentially, as their widths reduce, with increasing frequency is observed for the optimized sharp bend. The transmittance peaks appear at frequencies corresponding to integer plus half-beat periods, depending on the finite surface length. The optimal parameters are such that the cylinder radius at the PnC corner is not significantly modified, whereas a diagonally offset scatterer having a diameter of almost two periods and a shortest distance of about 0.7 periods between them is required for the strongest transmittance peak. Utilization of PnC surface sharp bends as acoustic ring resonators is demonstrated. (paper)
Sharp bends of phononic crystal surface modes
Cicek, Ahmet; Salman, Aysevil; Adem Kaya, Olgun; Ulug, Bulent
2015-12-01
Sharp bending of surface waves at the interface of a two-dimensional phononic crystal (PnC) of steel cylinders in air and the method of using a diagonally offset cylindrical scatterer are numerically demonstrated by finite-element method simulations. The radii of the diagonally offset scatterer and the cylinder at the PnC corner, along with the distance between them, are treated as optimization parameters in the genetic algorithm optimization of sharp bends. Surface wave transmittance of at most 5% for the unmodified sharp bend is significantly enhanced to approximately 75% as a result of optimization. A series of transmittance peaks whose maxima increase exponentially, as their widths reduce, with increasing frequency is observed for the optimized sharp bend. The transmittance peaks appear at frequencies corresponding to integer plus half-beat periods, depending on the finite surface length. The optimal parameters are such that the cylinder radius at the PnC corner is not significantly modified, whereas a diagonally offset scatterer having a diameter of almost two periods and a shortest distance of about 0.7 periods between them is required for the strongest transmittance peak. Utilization of PnC surface sharp bends as acoustic ring resonators is demonstrated.
Tunable thermoelectric properties in bended graphene nanoribbons
Institute of Scientific and Technical Information of China (English)
潘长宁; 何军; 方卯发
2016-01-01
The ballistic thermoelectric properties in bended graphene nanoribbons (GNRs) are systematically investigated by using atomistic simulation of electron and phonon transport. We find that the electron resonant tunneling effect occurs in the metallic–semiconducting linked ZZ-GNRs (the bended GNRs with zigzag edge leads). The electron-wave quan-tum interference effect occurs in the metallic–metallic linked AA-GNRs (the bended GNRs with armchair edge leads). These different physical mechanisms lead to the large Seebeck coefficient S and high electron conductance in bended ZZ-GNRs/AA-GNRs. Combined with the reduced lattice thermal conduction, the significant enhancement of the figure of merit ZT is predicted. Moreover, we find that the ZTmax (the maximum peak of ZT) is sensitive to the structural parameters. It can be conveniently tuned by changing the interbend length of bended GNRs. The magnitude of ZT ranges from the 0.15 to 0.72. Geometry-controlled ballistic thermoelectric effect offers an effective way to design thermoelectric devices such as thermocouples based on graphene.
Tunable thermoelectric properties in bended graphene nanoribbons
Chang-Ning, Pan; Jun, He; Mao-Fa, Fang
2016-07-01
The ballistic thermoelectric properties in bended graphene nanoribbons (GNRs) are systematically investigated by using atomistic simulation of electron and phonon transport. We find that the electron resonant tunneling effect occurs in the metallic-semiconducting linked ZZ-GNRs (the bended GNRs with zigzag edge leads). The electron-wave quantum interference effect occurs in the metallic-metallic linked AA-GNRs (the bended GNRs with armchair edge leads). These different physical mechanisms lead to the large Seebeck coefficient S and high electron conductance in bended ZZ-GNRs/AA-GNRs. Combined with the reduced lattice thermal conduction, the significant enhancement of the figure of merit ZT is predicted. Moreover, we find that the ZTmax (the maximum peak of ZT) is sensitive to the structural parameters. It can be conveniently tuned by changing the interbend length of bended GNRs. The magnitude of ZT ranges from the 0.15 to 0.72. Geometry-controlled ballistic thermoelectric effect offers an effective way to design thermoelectric devices such as thermocouples based on graphene. Project supported by the National Natural Science Foundation of China (Grant No. 61401153) and the Natural Science Foundation of Hunan Province, China (Grant Nos. 2015JJ2050 and 14JJ3126).
Pure plate bending in couple stress theories
Hadjesfandiari, Ali R; Dargush, Gary F
2016-01-01
In this paper, we examine the pure bending of plates within the framework of modified couple stress theory (M-CST) and consistent couple stress theory (C-CST). In this development, it is demonstrated that M-CST does not describe pure bending of a plate properly. Particularly, M-CST predicts no couple-stresses and no size effect for the pure bending of the plate into a spherical shell. This contradicts our expectation that couple stress theory should predict some size effect for such a deformation pattern. Therefore, this result clearly demonstrates another inconsistency of indeterminate symmetric modified couple stress theory (M-CST), which is based on considering the symmetric torsion tensor as the curvature tensor. On the other hand, the fully determinate skew-symmetric consistent couple stress theory (C-CST) predicts results for pure plate bending that tend to agree with mechanics intuition and experimental evidence. Particularly, C-CST predicts couple-stresses and size effects for the pure bending of the ...
Finger-jointed beams in bending
DEFF Research Database (Denmark)
Andreasen, Lotte; Hoffmeyer, Preben
1997-01-01
An investigation of the dynamic and static fatique of finger-jointed beams in bending was carried out. Results were obtained for five different frequencies from static loading to a load cycle period of two minutes. A total of seven series were long-term tested and five series were short-term tested...
Inelastic Deformation Analysis of Aluminum Bending Members
Institute of Scientific and Technical Information of China (English)
CHENG Ming; SHI Yongjiu; WANG Yuanqing
2006-01-01
Aluminum alloys are typical nonlinear materials, and consequently bending members made of this material exhibit a nonlinear behavior. Most design codes do not pay much attention to such deformations and adopt a simple linear analysis for the calculation of deflections. This paper presents an investigation of the nonlinear deformation of aluminum bending members using the finite-element analysis (FEA). The plastic adaptation coefficient, which can be used to limit the residual deflection, is introduced, and the influence of residual deflection is investigated. A method for evaluating the plastic adoption coefficient is proposed. This paper also shows the load-deflection curve of aluminum bending members and the influence of several parameters. A semi-empirical formula is derived, and some numerical examples are given by FEA. The coefficients of the semi-empirical formula are modified by the FEA results using the nonlinear fitting method. Based on these results, two improved design methods for strength and deformation of aluminum bending members are proposed. Through the comparison with test data, these methods are proved to be suitable for structural design.
Demonstration model of LEP bending magnet
CERN PhotoLab
1981-01-01
To save iron and raise the flux density, the LEP bending magnet laminations were separated by spacers and the space between the laminations was filled with concrete. This is a demonstration model, part of it with the spaced laminations only, the other part filled with concrete.
Axisymmetric bending oscillations of stellar disks
Sellwood, J A
1996-01-01
Self-gravitating stellar disks with random motion support both exponentially growing and, in some cases, purely oscillatory axisymmetric bending modes, unlike their cold disk counterparts. A razor-thin disk with even a very small degree of random motion in the plane is both unstable and possesses a discrete spectrum of neutral modes, irrespective of the sharpness of the edge. Random motion normal to the disk plane has a stabilizing effect but at the same time allows bending waves to couple to the internal vibrations of the particles, which causes the formerly neutral modes to decay through Landau damping. Focusing first on instabilities, I here determine the degree of random motion normal to the plane needed to suppress global, axisymmetric, bending instabilities in a family of self-gravitating disks. As found previously, bending instabilities are suppressed only when the thickness exceeds that expected from a na\\"\\i ve local criterion when the degree of pressure support within the disk plane is comparable to...
Aerosol deposition in bends with turbulent flow
Energy Technology Data Exchange (ETDEWEB)
McFarland, A.R.; Gong, H.; Wente, W.B. [Texas A& M Univ., College Station, TX (United States)] [and others
1997-08-01
The losses of aerosol particles in bends were determined numerically for a broad range of design and operational conditions. Experimental data were used to check the validity of the numerical model, where the latter employs a commercially available computational fluid dynamics code for characterizing the fluid flow field and Lagrangian particle tracking technique for characterizing aerosol losses. Physical experiments have been conducted to examine the effect of curvature ratio and distortion of the cross section of bends. If it curvature ratio ({delta} = R/a) is greater than about 4, it has little effect on deposition, which is in contrast with the recommendation given in ANSI N13.1-1969 for a minimum curvature ratio of 10. Also, experimental results show that if the tube cross section is flattened by 25% or less, the flattening also has little effect on deposition. Results of numerical tests have been used to develop a correlation of aerosol penetration through a bend as a function of Stokes number (Stk), curvature ratio ({delta}) and the bend angle ({theta}). 17 refs., 10 figs., 2 tabs.
Fuzzy model for Laser Assisted Bending Process
Directory of Open Access Journals (Sweden)
Giannini Oliviero
2016-01-01
Full Text Available In the present study, a fuzzy model was developed to predict the residual bending in a conventional metal bending process assisted by a high power diode laser. The study was focused on AA6082T6 aluminium thin sheets. In most dynamic sheet metal forming operations, the highly nonlinear deformation processes cause large amounts of elastic strain energy stored in the formed material. The novel hybrid forming process was thus aimed at inducing the local heating of the mechanically bent workpiece in order to decrease or eliminate the related springback phenomena. In particular, the influence on the extent of springback phenomena of laser process parameters such as source power, scan speed and starting elastic deformation of mechanically bent sheets, was experimentally assessed. Consistent trends in experimental response according to operational parameters were found. Accordingly, 3D process maps of the extent of the springback phenomena according to operational parameters were constructed. The effect of the inherent uncertainties on the predicted residual bending caused by the approximation in the model parameters was evaluated. In particular, a fuzzy-logic based approach was used to describe the model uncertainties and the transformation method was applied to propagate their effect on the residual bending.
Tubular lining material for pipelines having bends
Energy Technology Data Exchange (ETDEWEB)
Moringa, A.; Sakaguchi, Y.; Hyodo, M.; Yagi, I.
1987-03-24
A tubular lining material for pipelines having bends or curved portions comprises a tubular textile jacket made of warps and wefts woven in a tubular form overlaid with a coating of a flexible synthetic resin. It is applicable onto the inner surface of a pipeline having bends or curved portions in such manner that the tubular lining material with a binder onto the inner surface thereof is inserted into the pipeline and allowed to advance within the pipeline, with or without the aid of a leading rope-like elongated element, while turning the tubular lining material inside out under fluid pressure. In this manner the tubular lining material is applied onto the inner surface of the pipeline with the binder being interposed between the pipeline and the tubular lining material. The lining material is characterized in that a part of all of the warps are comprised of an elastic yarn around which, over the full length thereof, a synthetic fiber yarn or yarns have been left-and/or right-handedly coiled. This tubular lining material is particularly suitable for lining a pipeline having an inner diameter of 25-200 mm and a plurality of bends, such as gas service pipelines or house pipelines, without occurrence of wrinkles in the lining material in a bend.
Bending of a thin flexible plate
Energy Technology Data Exchange (ETDEWEB)
Pobedria, B.E.
1990-12-01
A system of equations is derived which describes the one-dimensional deformation of thin shells. The analysis does not impose any constraints on the relative elongation and deflections. As an example, a solution is presented for the problem of the bending of a thin plate under uniform pressure.
Symmetric bends how to join two lengths of cord
Miles, Roger E
1995-01-01
A bend is a knot securely joining together two lengths of cord (or string or rope), thereby yielding a single longer length. There are many possible different bends, and a natural question that has probably occurred to many is: "Is there a 'best' bend and, if so, what is it?"Most of the well-known bends happen to be symmetric - that is, the two constituent cords within the bend have the same geometric shape and size, and interrelationship with the other. Such 'symmetric bends' have great beauty, especially when the two cords bear different colours. Moreover, they have the practical advantage o
Finite Element Analysis for Bending Process of U-Bending Specimens
Energy Technology Data Exchange (ETDEWEB)
Park, Won Dong; Bahn, Chi Bum [Pusan National University, Busan (Korea, Republic of)
2015-10-15
ASTM G30 suggests that the applied strain can be calculated by dividing thickness by a bend radius. It should be noted, however, that the formula is reliable under an assumption that the ratio of thickness to bend radius is less than 0.2. Typically, to increase the applied stress/strain, the ratio of thickness to bend radius becomes larger than 0.2. This suggests that the estimated strain values by ASTM G30 are not reliable to predict the actual residual strain state of the highly deformed U-bend specimen. For this reason, finite element analysis (FEA) for the bending process of Ubend specimens was conducted by using a commercial finite element analysis software ABAQUS. ver.6.14- 2;2014. From the results of FEA, PWSCC initiation time and U-bend specimen size can be determined exactly. Since local stress and strain have a significant effect on the initiation of PWSCC, it was inappropriate to apply results of ASTM G30 to the PWSCC test directly. According to results of finite element analysis (FEA), elastic relaxation can cause inaccuracy in intended final residual stress. To modify this inaccuracy, additional process reducing the spring back is required. However this additional process also may cause uncertainty of stress/strain state. Therefore, the U-bending specimen size which is not creating uncertainty should be optimized and selected. With the bending radius of 8.3 mm, the thickness of 3 mm and the roller distance of 32.6 mm, calculated maximum stress and strain were 670 MPa and 0.21, respectively.
Plastic collapse loads in shape-imperfect pipe bends under in-plane opening bending moment
International Nuclear Information System (INIS)
The combined effect of ovality and thinning/thickening on collapse load of pipe bends under in-plane opening bending moment was investigated using finite element limit analysis considering large geometric change effect. The material is assumed to be elastic-perfectly plastic. Twice-elastic-slope method is used to obtain collapse moment from moment–rotation curves drawn for each bend. Variation of thickness due to thinning in the cross section of pipe bend produces negligible effect on collapse load. The effect of ovality is significant except for pipe ratio 20 with λ = 0.5. A new closed-form solution is proposed to determine collapse moment of pipe bends with ovality and it is validated with existing experimental data. -- Highlights: • Collapse loads for shape-imperfect pipe bends is determined. • Ovality and thinning are the shape imperfections considered. • Finite element limit analysis uses large geometry change effects. • Twice-elastic-slope method was used to obtain plastic loads. • Ovality needs to be considered to determine collapse load while thinning produces negligible effect
When Blood Cells Bend: Understanding Sickle Cell Disease
... please review our exit disclaimer . Subscribe When Blood Cells Bend Understanding Sickle Cell Disease For people who don’t suspect they ... Cells Bend Wise Choices Links Living with Sickle Cell Disease See a sickle cell disease expert regularly. ...
A preliminary bending fatigue spectrum for steel monostrand cables
DEFF Research Database (Denmark)
Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.;
2011-01-01
service life expectancy. The presented preliminary bending fatigue spectrum of high-strength monostrands is currently unavailable in the published literature. The presented results provide relevant information on the bending mechanism and fatigue characteristics of monostrand steel cables in tension...
The design of an agent to bend DNA.
Akiyama, T; Hogan, M E
1996-01-01
An artificial DNA bending agent has been designed to assess helix flexibility over regions as small as a protein binding site. Bending was obtained by linking a pair of 15-base-long triple helix forming oligonucleotides (TFOs) by an adjustable polymeric linker. By design, DNA bending was introduced into the double helix within a 10-bp spacer region positioned between the two sites of 15-base triple helix formation. The existence of this bend has been confirmed by circular permutation and phas...
Bending strength analysis of steel-composite submerged floating tunnels
Han, T H; Won, D.; Han, S. H.; Park, W. S.; Yum, K.D.
2013-01-01
A submerged floating tunnel (SFT) must have enough strength to resist to various external loadings such as bending, torsion, tension, and compression. The expected main deformation of SFT is caused by bending moment. And this bending moment makes tensile stress and compression stress on the wall of SFT. Thus, bending moment is a main affecting factor on the safety of SFT. Until now, a reinforced concrete tunnel was suggested for SFT by other researchers. In this study, an internal...
Nuclear fuels accounting interface: River Bend experience
Energy Technology Data Exchange (ETDEWEB)
Barry, J.E.
1986-01-01
This presentation describes nuclear fuel accounting activities from the perspective of nuclear fuels management and its interfaces. Generally, Nuclear Fuels-River Bend Nuclear Group (RBNG) is involved on a day-by-day basis with nuclear fuel materials accounting in carrying out is procurement, contract administration, processing, and inventory management duties, including those associated with its special nuclear materials (SNM)-isotopics accountability oversight responsibilities as the Central Accountability Office for the River Bend Station. As much as possible, these duties are carried out in an integrated, interdependent manner. From these primary functions devolve Nuclear Fuels interfacing activities with fuel cost and tax accounting. Noting that nuclear fuel tax accounting support is of both an esoteric and intermittent nature, Nuclear Fuels-RBNG support of developments and applications associated with nuclear fuel cost accounting is stressed in this presentation.
Nuclear fuels accounting interface: River Bend experience
International Nuclear Information System (INIS)
This presentation describes nuclear fuel accounting activities from the perspective of nuclear fuels management and its interfaces. Generally, Nuclear Fuels-River Bend Nuclear Group (RBNG) is involved on a day-by-day basis with nuclear fuel materials accounting in carrying out is procurement, contract administration, processing, and inventory management duties, including those associated with its special nuclear materials (SNM)-isotopics accountability oversight responsibilities as the Central Accountability Office for the River Bend Station. As much as possible, these duties are carried out in an integrated, interdependent manner. From these primary functions devolve Nuclear Fuels interfacing activities with fuel cost and tax accounting. Noting that nuclear fuel tax accounting support is of both an esoteric and intermittent nature, Nuclear Fuels-RBNG support of developments and applications associated with nuclear fuel cost accounting is stressed in this presentation
Thermal Analysis of Bending Under Tension Test
DEFF Research Database (Denmark)
Ceron, Ermanno; Martins, Paulo A.F.; Bay, Niels
2014-01-01
during testing is similar to the one in the production tool. A universal sheet tribo-tester has been developed, which can run multiple tests automatically from coil. This allows emulating the temperature increase as in production. The present work performs finite element analysis of the evolution...... and distribution of temperature in the bending under tension test by making use of boundary conditions and calibration values directly measured from experiments. The overall methodology combines 2D and 3D models of the bending under tension test with steady state and transient thermal and thermo......-mechanical procedures. Results show that the proposed methodology applied to a single stroke can effectively and accurately predict the interface temperature in the test tool, thus avoiding the otherwise required thousands of thermo-mechanical FEM analyses of temperature development during testing before thermal steady...
Rock bending creep and disturbance effects
Institute of Scientific and Technical Information of China (English)
付志亮; 郑颖人; 刘元雪
2008-01-01
The bending creep and its disturbance effects of red sandstone rock beam and oil shale rock beam were studied by adopting the self-developed gravitation level style rock creep test machine and bending creep test system,and the constitutive equations were established.It is found that fracture morphology of rock beams under no disturbance load is regular,cracking position of fractures is on part of loading concentration,the crack starts from a neutral plane.However,fracture morphology of rock beams under disturbance load is irregular,cracking position of fractures deviates from a neutral plane.Delayed instability of rock beam occurs for some time under constant disturbance load.When disturbance load is beyond a certain range,suddenly instability of occurs rock beam in a certain time.The results show that there is a guiding significance for creep stability in the geotechnical engineering fields.
Monitoring thermoplastic composites under cyclic bending tests
Boccardi, Simone; Meola, Carosena; Carlomagno, Giovanni Maria; Simeoli, Giorgio; Acierno, Domenico; Russo, Pietro
2016-05-01
This work is concerned with the use of infrared thermography to visualize temperature variations linked to thermo-elastic effects developing over the surface of a specimen undergoing deflection under bending tests. Several specimens are herein considered, which involve change of matrix and/or reinforcement. More specifically, the matrix is either a pure polypropylene, or a polypropylene added with a certain percentage of compatibilizing agent; the reinforcement is made of glass, or jute. Cyclic bending tests are carried out by the aid of an electromechanical actuator. Each specimen is viewed, during deflection, from one surface by an infrared imaging device. As main finding the different specimens display surface temperature variations which depend on the type of material in terms of both matrix and reinforcement.
Ultrasonic fatigue testing device under biaxial bending
Directory of Open Access Journals (Sweden)
C. Brugger
2016-07-01
Full Text Available A new fatigue testing device has been developed to test specimens under biaxial loading at 20 kHz. A flat smooth specimen with a disc geometry is placed on a torus frame and cyclically loaded at the center of its upper face. Disc bending generates a biaxial proportional stress state at the center of the lower face. Any positive loading ratio can be applied. A cast aluminum alloy (used to produce cylinder heads has been tested under biaxial bending using this device in order to determine its fatigue strength at 109 cycles under high hydrostatic pressure. Self-heating is moderate but macroscopic fatigue cracks after testing are very long. First results in VHCF regime are consistent with literature results obtained under similar stress state but in HCF regime and at 20 Hz.
Parallel monostrand stay cable bending fatigue
DEFF Research Database (Denmark)
Winkler, Jan Pawel
This dissertation investigates the bending fatigue response of high-strength steel monostrands and multistrand stay cables to cyclic transverse deformations. Increasing bridge stock numbers and a push for longer cable-supported span lengths have led to an increased number of reported incidents...... of damage and replacement of bridge stay cables due to wind and traffic-induced fatigue. The understanding of fatigue mechanisms in most steel structures is well established. However, in the case of cables composed of steel strands, many important aspects related with bending fatigue remain to be clarified....... The thesis starts with a literature review of the state-of-the-art in the fields of stay cable fatigue testing and cable fatigue resistance. The study helped to systemize the understanding of the fatigue characteristics of bridge cables subjected to cyclic transverse displacements, failure mechanisms...
Oide Effect and Radiation in Bending Magnets
Blanco, Oscar; Bambade, Philip
2014-01-01
Including radiation effects during lattice design optimization is crucial in high energy accelerators. Oide effect and radiation in bending magnets are reviewed aiming to include them in the optical design process to minimize the IP beam size. The Oide double integral is expressed in simpler terms in order to speed up calculations, concluding in how longer quadrupoles with lower gradients may help reducing the Oide effect. Radiation in bending magnets is reviewed for linear lattices, generalizing to the case when the final dispersion is different from zero and making comparisons with theoretical results and particle tracking. An agreement between the theory, the implemented approximation included in MAPCLASS2 and the six-dimensional tracking in PLACET has been found.
Hydrodynamic processes in sharp meander bends and their morphological implications
Blanckaert, K.
2011-01-01
The migration rate of sharp meander bends exhibits large variance and indicates that some sharply curved bends tend to stabilize. These observations remain unexplained. This paper examines three hydrodynamic processes in sharp bends with fixed banks and discusses their morphological implications: se
Superconducting beam bending magnets at CERN
1977-01-01
The photo shows Gerhard Kesseler with the cyogenic vessels for one of the 10.8 Tesla-metre beam bending magnets. The magnet itself (not visible) is sitting inside the superinsukated helium vessel (white). The next larger shell and the biggest tubular structure (with the largest part behind the person) is the insulation vacuum tank. See CERN Courier 1970 pp. 228-229 CERN Courier 1973 pp. 144-145 Yellow Report CERN 78-03, 1978
Electron cooling device without bending magnets
Sharapa, A. N.; Shemyakin, A. V.
1993-11-01
The scheme of an axisymmetric electron cooling device without bending magnets is proposed. Solutions for the most important elements, i.e., a gun and a recuperator, are considered. The main characteristics of the recuperator of the Faraday cup type having a reflector and a gun with a ring emitter are explored. In the gun, the beam is formed, the diameter of which is 40 mm and the dimension of a disturbance region is several millimeters.
AA, assembly of wide bending magnet
1980-01-01
The very particular lattice of the AA required 2 types of dipoles (bending magnets; BST, short and wide; BLG, long and narrow). The wide ones had a steel length of 2.71 m, a "good field" width of 0.564 m, and a weight of about 75 t. Here we see the copper coils being hoisted onto the lower half of a BST. See also 7811105, 8006050. For a BLG, see 8001044.
Drag Reduction, from Bending to Pruning
Lopez, Diego; Michelin, Sébastien; de Langre, Emmanuel
2013-01-01
Most plants and benthic organisms have evolved efficient reconfiguration mechanisms to resist flow-induced loads. These mechanisms can be divided into bending, in which plants reduce their sail area through elastic deformation, and pruning, in which the loads are decreased through partial breakage of the structure. In this work, we show by using idealized models that these two mechanisms or, in fact, any combination of the two, are equally efficient to reduce the drag experienced by terrestrial and aquatic vegetation.
Large deformation dynamic bending of composite beams
Derian, Edward J.
1985-01-01
The large deformation response of composite beams subjected to a dynamic axial load was studied. The beams were loaded with a moderate amount of eccentricity to promote bending. The study was primarily experimental but some finite element results were obtained. Both the deformation and the failure of the beams were of interest. The static response of the beams was also studied in order to determine the difference between the static and dynamic failure. Twelve different la...
More on the bending of light !
Lake, Kayll
2007-01-01
Recently, Rindler and Ishak have argued that the bending of light is, in principle, changed by the presence of a cosmological constant since one must consider not only the null geodesic equation, but also the process of measurement. I agree with the fact that both must be considered. Here, on the basis of the mathematically exact solution to the classical bending problem, and independent of the cosmological constant, I show that the approximate argument found in the vast majority of texts (new and old) for the measured value of the bending of light for a single source is, despite getting a good answer, bogus. In fact, the measured value for a single source is in part the result of the almost perfect cancelation of two terms, one of which is seldom considered. When one considers two sources, this cancelation is of no consequence, and if the sources are opposite with the same associated apsidal distance, the approximate argument gives the rigorously correct answer (up to numerical evaluation), an answer which i...
2011-12-29
... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION PPL Bell Bend, LLC; Combined License Application for Bell Bend Nuclear Power Plant; Exemption 1.0..., Certifications, and Approvals for Nuclear Power Plants.'' This reactor is to be identified as Bell Bend...
Tunable waveguide bends with graphene-based anisotropic metamaterials
Chen, Zhao-xian
2016-01-15
We design tunable waveguide bends filled with graphene-based anisotropic metamaterials to achieve a nearly perfect bending effect. The anisotropic properties of the metamaterials can be described by the effective medium theory. The nearly perfect bending effect is demonstrated by finite element simulations of various structures with different bending curvatures and shapes. This effect is attributed to zero effective permittivity along the direction of propagation and matched effective impedance at the interfaces between the bending part and the dielectric waveguides. We envisage that the design will be applicable in the far-infrared and terahertz frequency ranges owing to the tunable dielectric responses of graphene.
Evolving efficiency of restraining bends within wet kaolin analog experiments
Hatem, Alexandra E.; Cooke, Michele L.; Madden, Elizabeth H.
2015-03-01
Restraining bends along strike-slip fault systems evolve by both propagation of new faults and abandonment of fault segments. Scaled analog modeling using wet kaolin allows for qualitative and quantitative observations of this evolution. To explore how bend geometry affects evolution, we model bends with a variety of initial angles, θ, from θ = 0° for a straight fault to θ = 30°. High-angle restraining bends (θ ≥ 20°) overcome initial inefficiencies by abandoning unfavorably oriented restraining segments and propagating multiple new, inwardly dipping, oblique-slip faults that are well oriented to accommodate convergence within the bend. Restraining bends with 0° < θ ≤ 15° maintain activity along the restraining bend segment and grow a single new oblique slip fault on one side of the bend. In all restraining bends, the first new fault propagates at ~5 mm of accumulated convergence. Particle Image Velocimetry analysis provides a complete velocity field throughout the experiments. From these data, we quantify the strike-slip efficiency of the system as the percentage of applied plate-parallel velocity accommodated as slip in the direction of plate motion along faults within the restraining bend. Bends with small θ initially have higher strike-slip efficiency compared to bends with large θ. Although they have different fault geometries, all systems with a 5 cm bend width reach a steady strike-slip efficiency of 80% after 50 mm of applied plate displacement. These experimental restraining bends resemble crustal faults in their asymmetric fault growth, asymmetric topographic gradient, and strike-slip efficiency.
Secondary turbulent flow in an infinte bend
DEFF Research Database (Denmark)
Christensen, H. Bo; Gislason, Kjartan; Fredsøe, Jørgen
1999-01-01
The flow in an infinite circular bend is inverstigated in both the laminar and fully turbulent flow case, by use of laminar flow solver, a k-e turbulence model, and a fully Reynolds stress turbulence model. The topic of the analysis is to investigate whether a counter-rotating secondary flow cell...... model, the influence of the curvature ratio and cross section geometry on the vortex pattern is investigated. Furthermore, it is demonstrated that an-isotropy of turbulence plays an important role for the structure of flow pattern and existence of an extra flow cell....
Storm, C; Storm, Cornelis; Nelson, Philip
2002-01-01
We formulate and solve a two-state model for the elasticity of nicked, double-stranded DNA that borrows features from both the Worm Like Chain and the Bragg--Zimm model. Our model is computationally simple, and gives an excellent fit to recent experimental data through the entire overstretching transition. The fit gives the first value for the bending stiffness of the overstretched state as about 10 nm*kbt, a value quite different from either B-form or single-stranded DNA.
Wooden Model of Wide AA Bending Magnet
1978-01-01
The very particular lattice of the AA required 2 types of dipoles (bending magnets: BLG, long and narrow; BST, short and wide). A wide one had a steel length of 2.71 m, a "good field" width of 0.564 m, and a weight of about 75 t. A wooden model was build in 1978, to gain dimensional experience. Here, Peter Zettwoch, one of the largest men at CERN at that time, is putting a hand in the mouth of the wooden BST monster.
Great Bend tornadoes of August 30, 1974
Umenhofer, T. A.; Fujita, T. T.; Dundas, R.
1977-01-01
Photogrammetric analyses of movies and still pictures taken of the Great Bend, Kansas Tornado series have been used to develop design specifications for nuclear power plants and facilities. A maximum tangential velocity of 57 m/sec and a maximum vertical velocity of 27 m/sec are determined for one suction vortex having a translational velocity of 32 m/sec. Three suction vortices with radii in the 20 to 30 m range are noted in the flow field of one tornado; these suction vortices apparently form a local convergence of inflow air inside the outer portion of the tornado core.
Bending of X65 Offshore Steel Pipes
Lofthaug, Kristoffer; Digerud, Erik
2014-01-01
This thesis is part of an ongoing research program between SIMLab and Statoil about impact loads on X65 offshore pipelines and it is a continuation of previous work.Offshore pipelines are frequently impacted by accidental loads, e.g. trawl gear or anchors. Such loads may cause severe damage to the pipe and a complex stress-strain history locally in the impacted area.Fracture have previously been found in pipes dynamically impacted. Quasi-static bending of similar pipes with the same boundary ...
Extension versus Bending for Continuum Robots
Directory of Open Access Journals (Sweden)
George Grimes
2008-11-01
Full Text Available In this paper, we analyze the capabilities of a novel class of continuous-backbone ("continuum" robots. These robots are inspired by biological "trunks, and tentacles". However, the capabilities of established continuum robot designs, which feature controlled bending but not extension, fall short of those of their biological counterparts. In this paper, we argue that the addition of controlled extension provides dual and complementary functionality, and correspondingly enhanced performance, in continuum robots. We present an interval-based analysis to show how the inclusion of controllable extension significantly enhances the workspace and capabilities of continuum robots.
COMPARATIVE STUDY ON BENDING LOSS BETWEEN DIFFERENT S-SHAPED WAVEGUIDE BENDS USING MATRIX METHOD
Directory of Open Access Journals (Sweden)
Koushik Bhattacharya
2013-02-01
Full Text Available Bending loss in the waveguide as well as the leakage losses and absorption losses along with a comparative study among different types of S-shaped bend structures has been computed with the help of a simple matrix method.This method needs simple 2×2 matrix multiplication. The effective-index profile of the bended waveguide is then transformed to an equivalent straight waveguide with the help of a suitable mapping technique and is partitioned into large number of thin sections of different refractive indices. The transfer matrix of the two adjacent layers will be a 2×2 matrix relating the field components in adjacent layers. The total transfer matrix is obtained through multiplication of all these transfer matrices. The excitation efficiency of the wave in the guiding layer shows a Lorentzian profile. The power attenuation coefficient of the bent waveguide is the full-width-half-maximum (FWHM of this peak .Now the transition losses and pure bending losses can be computed from these FWHM datas.The computation technique is quite fast and it is applicable for any waveguide having different parameters and wavelength of light for both polarizations(TE and TM.
Flexible bending of aluminum profiles with polyurethane pad
Institute of Scientific and Technical Information of China (English)
HE Zhu-bin; LIU Gang; WANG Zhong-ren
2006-01-01
The high flexibility of profile bending with hyperelastic pad enables it to be a promising method for small lot or single part production, especially for space frame and roof-rail parts in automotive and aerospace industries. Bending of two aluminum profiles with different sections was carried out to investigate the effect of main process parameters on the bending process. Results show that the shape of the cross-section and its relative thickness and section modulus in bending are the main factors that determine the bending properties of the profiles. Roller stroke, properties of polyurethane pad and constraints on profiles are key factors that determine the bending radius and section deformation of bent profiles. Failures and quality problems met in experiments were also analyzed.
Reduction Bending of Thin Crystalline Silicon Solar Cells
Institute of Scientific and Technical Information of China (English)
SHEN Lan-xian; LIU Zu-ming; LIAO Hua; TU Jie-lei; DENG Shu-kang
2009-01-01
Reported are the results of reduction the bending of thin crystalline silicon solar ceils after printing and sintering of back electrode by changing the back electrode paste and adjusting the screen printing parameters without effecting the electrical properties of the cell. Theory and experiments showed that the bending of the cell is changed with its thickness of suhstrate, the thinner cell, the more serious bending. The bending of the cell is decreased with the thickness decrease of the back contact paste. The substrate with the thickness of 190μm printing with sheet aluminum paste shows a relatively lower bend compared with that of the substrate printing with ordinary aluminum paste, and the minimum bend is 0.55 mm which is reduced by52%.
Bending strain tolerance of MgB2 superconducting wires
Kováč, P.; Hušek, I.; Melišek, T.; Kulich, M.; Kopera, L.
2016-04-01
This work describes the strain tolerance of MgB2 superconductors subjected to variable bending stresses. Bending of MgB2 wire was done at room temperature in different modes: (i) direct bending of straight annealed samples to variable diameters and by (ii) indirect bending by straightening of bent and annealed samples. I c-bending strain characteristics of samples made by in situ PIT and by the internal magnesium diffusion (IMD) process were measured at 4.2 K. The results show a good agreement between the direct and indirect bending mode, which allows easier estimation of limits important for the winding process of MgB2 superconductors with brittle filaments. A comparison of MgB2 wires made by in situ PIT and IMD processes showed improved strain tolerance for IMD due to better grain connectivity the low annealing temperature, which does not appear to reduce the mechanical strength of sheath material.
49 CFR 192.315 - Wrinkle bends in steel pipe.
2010-10-01
... 49 Transportation 3 2010-10-01 2010-10-01 false Wrinkle bends in steel pipe. 192.315 Section 192... Transmission Lines and Mains § 192.315 Wrinkle bends in steel pipe. (a) A wrinkle bend may not be made on steel pipe to be operated at a pressure that produces a hoop stress of 30 percent, or more, of SMYS. (b)...
BEND3 mediates transcriptional repression and heterochromatin organization.
Khan, Abid; Prasanth, Supriya G
2015-01-01
Transcription repression plays a central role in gene regulation. Transcription repressors utilize diverse strategies to mediate transcriptional repression. We have recently demonstrated that BEND3 (BANP, E5R and Nac1 domain) protein represses rDNA transcription by stabilizing a NoRC component. We discuss the role of BEND3 as a global regulator of gene expression and propose a model whereby BEND3 associates with chromatin remodeling complexes to modulate gene expression and heterochromatin organization.
Bamboo Taper Effect on Third Point Loading Bending Test
Naresworo Nugroho; Effendi Tri Bahtiar
2013-01-01
Geometrical shape of bamboo usually assumed as tapered hollow pipe. This study proved that the dimensional changes along the bamboo stem significantly affected to its Modulus of Rupture (SR) value which measured from third point loading bending test. Therefore if the bending test applied using third point loading configuration, the SR value should be adjusted by strength ratio of taper (Ct). Ct is theratio between (SR) calculated in the center span and the maximum bending stress along the bam...
Bending instability characteristics of double-walled carbon nanotubes
Wang, Q.; Hu, T.; Chen, G.; Jiang, Q.
2005-01-01
The bending instability characteristics of double-walled carbon nanotubes (DWNTs) of various configurations are studied using a hybrid approach in which the deformation-induced increase of the intratube interaction energy is modeled with the bending deformation energy using the elastic theory of beams. The intertube interaction energy is calculated using the van der Waals interatomic potential. This study shows that the bending instability may take place through the formation of a single kink...
PERMEABILITY OF SALTSTONE MEASUREMENT BY BEAM BENDING
Energy Technology Data Exchange (ETDEWEB)
Harbour, J; Tommy Edwards, T; Vickie Williams, V
2008-01-30
One of the goals of the Saltstone variability study is to identify (and, quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. A performance property for Saltstone mixes that is important but not routinely measured is the liquid permeability or saturated hydraulic conductivity of the cured Saltstone mix. The value for the saturated hydraulic conductivity is an input into the Performance Assessment for the SRS Z-Area vaults. Therefore, it is important to have a method available that allows for an accurate and reproducible measurement of permeability quickly and inexpensively. One such method that could potentially meet these requirements for the measurement of saturated hydraulic conductivity is the technique of beam bending, developed by Professor George Scherer at Princeton University. In order to determine the feasibility of this technique for Saltstone mixes, a summer student, David Feliciano, was hired to work at Princeton under the direction of George Scherer. This report details the results of this study which demonstrated the feasibility and applicability of the beam bending method to measurement of permeability of Saltstone samples. This research effort used samples made at Princeton from a Modular Caustic side solvent extraction Unit based simulant (MCU) and premix at a water to premix ratio of 0.60. The saturated hydraulic conductivities for these mixes were measured by the beam bending technique and the values determined were of the order of 1.4 to 3.4 x 10{sup -9} cm/sec. These values of hydraulic conductivity are consistent with independently measured values of this property on similar MCU based mixes by Dixon and Phifer. These values are also consistent with the hydraulic conductivity of a generic Saltstone mix measured by Langton in 1985. The high water to premix ratio used for Saltstone along with the relatively low degree of hydration for
PERMEABILITY OF SALTSTONE MEASUREMENT BY BEAM BENDING
International Nuclear Information System (INIS)
One of the goals of the Saltstone variability study is to identify (and, quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. A performance property for Saltstone mixes that is important but not routinely measured is the liquid permeability or saturated hydraulic conductivity of the cured Saltstone mix. The value for the saturated hydraulic conductivity is an input into the Performance Assessment for the SRS Z-Area vaults. Therefore, it is important to have a method available that allows for an accurate and reproducible measurement of permeability quickly and inexpensively. One such method that could potentially meet these requirements for the measurement of saturated hydraulic conductivity is the technique of beam bending, developed by Professor George Scherer at Princeton University. In order to determine the feasibility of this technique for Saltstone mixes, a summer student, David Feliciano, was hired to work at Princeton under the direction of George Scherer. This report details the results of this study which demonstrated the feasibility and applicability of the beam bending method to measurement of permeability of Saltstone samples. This research effort used samples made at Princeton from a Modular Caustic side solvent extraction Unit based simulant (MCU) and premix at a water to premix ratio of 0.60. The saturated hydraulic conductivities for these mixes were measured by the beam bending technique and the values determined were of the order of 1.4 to 3.4 x 10-9 cm/sec. These values of hydraulic conductivity are consistent with independently measured values of this property on similar MCU based mixes by Dixon and Phifer. These values are also consistent with the hydraulic conductivity of a generic Saltstone mix measured by Langton in 1985. The high water to premix ratio used for Saltstone along with the relatively low degree of hydration for MCU
Static Fatigue of Optical Fibers in Bending
Roberts, D.; Cuellar, E.; Middleman, L.; Zucker, J.
1987-02-01
While delayed fracture, or static fatigue, of optical fibers is well known, it is not well understood, and the prediction of the time to failure under a given set of conditions can be problematic. Unlike short term fracture, which is quite well understood and quantified in terms of the theory of linear elastic fracture mechanics, the long term strength remains empirical. The goal of this study is to determine the design criteria for optical fibers subjected to long term applied mechanical loads. One difficulty in making lifetime predictions, as pointed out by Matthewson (Reference 1) and others, is that predictions made from data taken in tension and in bending do not agree. Another difficulty is the statistical nature of the fracture of glass. In making lifetime predictions it becomes important therefore that one (a) have ample data for statistical analysis and (b) have data for the loading configuration of interest. This is the purpose of our work. Since there is less data available in bending, and since several applications (such as wiring in aircraft and missiles) require bending, the data are taken in that configuration. The most significant finding in our work so far is the very large difference in static fatigue behavior between buffer coatings. Chandan and Kalish (Reference 2) and others have reported static fatigue curves, log (time to failure) versus log (applied stress), which are not linear, but rather bimodal. Our study confirms this result, but so far only for acrylate coated fibers. Silicone coated fibers show unimodal behavior. That is, the log (time to failure) versus log (applied stress) curve is linear, at least on the time scale studied so far. Data for acrylate coated fibers at 80°C in water are linear only for time scales of about one day, where a pronounced "knee" is observed. Data for silicone coated fibers under the same conditions are linear up to at least 6 months. Longer time scale tests and tests on fibers with other buffer materials
Bend loss in surface plasmon polariton band-gap structures
DEFF Research Database (Denmark)
Bozhevolnyi, S.I.; Volkov, V.S.; Leosson, Kristjan;
2001-01-01
Using near-field optical microscopy, we investigate propagation of surface plasmon polaritons (SPPs) excited in the wavelength range of 720-830 nm at a corrugated gold-film surface with areas of 200-nm-wide and 45-nm-high scatterers arranged in a 410-nm-period triangular lattice containing line...... defects with double bends. We find that, for similar to2-mum-wide line defects and the wavelength of similar to 740 nm, the double bend losses for bend angles of 15 degrees and 30 degrees are below 2 and 10 dB, respectively. Our data indicate that the bend loss increases approximately quadratically...
Bend sensors based on periodically-tapered soft glass fibers
Wang, Y.; Richardson, D. J.; Brambilla, G; Feng, X.; Petrovich, M.N.; Ding, M.; Song, Z.(Central China Normal University, Wuhan, China)
2011-01-01
We demonstrate a technique for tapering periodically an all-solid soft glass fiber consisting of two types of lead silicate glasses by the use of a CO2 laser and investigate the bend sensing applications of the periodically-tapered soft glass fiber. Such a soft glass fiber with periodic microtapers could be used to develop a promising bend sensor with a sensitivity of ?27.75 ?W/m-1 by means of measuring the bend-induced change of light intensity. The proposed bend sensor exhibits a very low m...
SRI CAT Section 1 bending magnet beamline description
International Nuclear Information System (INIS)
This report discusses: APS bending magnet source; beamline layout; beamline optical components; beamline operation; time-resolved studies station; polarization studies station; and commissioning and operational schedule
Bending of pipes with inconel cladding
Energy Technology Data Exchange (ETDEWEB)
Nachpitz, Leonardo; Menezes, Carlos Eduardo B.; Vieira, Carlos R. Tavares [Primus Processamento de Tubos S.A. (PROTUBO), Macae, RJ (Brazil)
2009-07-01
The high-frequency induction bending process, using API pipes coated with Inconel 625 reconciled to a mechanical transformation for a higher degree of resistance, was developed through a careful specification and control of the manufacturing parameters and inherent heat treatments. The effects of this technology were investigated by a qualification process consisting of a sequence of tests and acceptance criteria typically required by the offshore industry, and through the obtained results was proved the effectiveness of this entire manufacturing process, without causing interference in the properties and the quality of the inconel cladding, adding a gain of resistance to the base material, guaranteed by the requirements of the API 5L Standard. (author)
Bending the Cost Curve in Childhood Cancer.
Russell, Heidi; Bernhardt, M Brooke
2016-08-01
Healthcare for children with cancer costs significantly more than other children. Cost reduction efforts aimed toward relatively small populations of patients that use a disproportionate amount of care, like childhood cancer, could have a dramatic impact on healthcare spending. The aims of this review are to provide stakeholders with an overview of the drivers of financial costs of childhood cancer and to identify possible directions to curb or decrease these costs. Costs are incurred throughout the spectrum of care. Recent trends in pharmaceutical costs, evidence identifying the contribution of administration costs, and overuse of surveillance studies are described. Awareness of cost and value, i.e., the outcome achieved per dollar or burden spent, in delivery of care and research is necessary to bend the cost curve. Incorporation of these dimensions of care requires methodology development, prioritization, and ethical balance. PMID:27193602
Design Study: ELENA Bending Magnet Prototype
Schoerling, D
2013-01-01
The ELENA bending magnet prototype shall prove that the proposed design meets the requirements set by the ELENA beam dynamics. The following points will be discussed in detail: (i) production process of a magnetic yoke diluted with stainless steel plates, (ii) the stability and repeatability of the field homogeneity of such a yoke over the full working range, (iii) choice of soft magnetic steel, (iv) hysteresis effects, (v) mechanical deformations, (vi) thermal insulation to intercept heat load from baking for activation of NEG coating in the vacuum chamber, (vii) end shim design. In order to verify these points the following measurements will be performed: (i) Hall probe scanning, (ii) integrated field homogeneity measurement (DC), (iii) integrated field homogeneity measurement (AC).
Separation of blood in microchannel bends
Blattert, Christoph; Jurischka, Reinhold; Schoth, Andreas; Kerth, Paul; Menz, Wolfgang
2004-01-01
Biological applications of micro assay devices require integrated on-chip microfluidics for separation of plasma or serum from blood. This is achieved by a new blood separation technique based on a microchannel bend structure developed within the collaborative Micro-Tele-BioChip (μTBC) project co-funded by the German Ministry For Education and Research (BMBF). Different prototype polymer chips have been manufactured with an UV-LIGA process and hot embossing technology. The separation efficiency of these chips has been determined by experimental measurements using human whole blood. Results show different separation efficiencies for cells and plasma depending on microchannel geometry and blood sample characteristics and suggest an alternative blood separation method as compared to existing micro separation technologies.
The effect of cracks on the limit load of pipe bends under in-plane bending
International Nuclear Information System (INIS)
The limit analysis of the in-plane bending of curved tubes had received attention previously, but the effect of defects in the tube has not been considered. A lower bound has been established which, with no defects present, is in agreement with previous theoretical work. The method of linear programming allows cracks to be introduced into analysis, and results have been obtained for various geometries of defect. The results show that the presence of cracks in the pipe bend can have a marked effect on the theoretical limit load: a part-through crack penetrating only half the wall thickness will reduce the limit moment by up to 10%. The worst possible case of a through-crack may reduce the limit load by 60%. (author)
Turbulence characteristics in sharp open-channel bends
Blanckaert, K.; De Vriend, H.J.
2005-01-01
In spite of its importance, little is known about the turbulence characteristics in open-channel bends. This paper reports on an experimental investigation of turbulence in one cross section of an open-channel bend. Typical flow features are a bicellular pattern of cross-stream circulation (secondar
On the Bending Problem for Large Scale Mapping
Esteban, I.; Booij, O.; Dijk, J.; Groen, F.
2010-01-01
During Simultaneous Localization And Mapping, geometrical constraints are established between map features. These constraints, introduced through measurements and motion prediction, produce a bending effect in the event of closing a large loop. In this paper we present a discussion of the bending pr
On the bending problem for large scale mapping
I. Esteban; O. Booij; J. Dijk; F. Groen
2009-01-01
During Simultaneous Localization And Mapping, geometrical constraints are established between map features. These constraints, introduced through measurements and motion prediction, produce a bending effect in the event of closing a large loop. In this paper we present a discussion of the bending pr
APPLICABILITY OF THE BEND DEVELOPMENT THEORY IN NATURAL ALLUVIAL RIVERS
Institute of Scientific and Technical Information of China (English)
M.M.RAHMAN; M.A.HAQUE; M.M.HOQUE
2002-01-01
The theoretical conditions for the bend development or attenuation have been reviewed and tested for a study reach of the Meghna river.The field observations in the natural alluvial meander do not support the theories developed for bend development.The limitations of the theory to apply in the natural meandering river are discussed.
36 CFR 7.41 - Big Bend National Park.
2010-07-01
... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Big Bend National Park. 7.41 Section 7.41 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.41 Big Bend National Park. (a) Fishing; closed...
Regulation of transcription by synthetic DNA-bending agents.
Bednarski, David; Firestine, Steven M
2006-11-01
Gene expression is regulated by a complex interplay between binding and the three-dimensional arrangement of transcription factors with RNA polymerase and DNA. Previous studies have supported a direct role for DNA bending and conformation in gene expression, which suggests that agents that induce bends in DNA might be able to control gene expression. To test this hypothesis, we examined the effect of triple-helix-forming oligonucleotide (TFO) bending agents on the transcription of luciferase in an in vitro transcriptional/translational system. We find that transcription is regulated only by a TFO that induces a bend in the DNA. Related TFOs that do not induce bends in DNA have no effect on transcription. Reporter expression can be increased by as much as 80 % or decreased by as much as 50 % depending on the phasing of the upstream bend relative to the promoter. We interpret the results as follows: when the bend is positioned such that the upstream DNA is curved toward the RNA polymerase on the same DNA face, transcription is enhanced. When the upstream DNA is curved away, transcription is attenuated. These results support the hypothesis that DNA-bending agents might have the capability to regulate gene expression, thereby opening up a previously undervalued avenue in research on the artificial control of gene expression. PMID:17004274
System effects influencing the bending strength of timber beams
DEFF Research Database (Denmark)
Ditlevsen, Ove Dalager; Källsner, B.
1998-01-01
A stochastic model of hierarchical series system type for the bending strength of spruce beams isdefined from the anticipation that the bending failure takes place at a cross-section with a defect cluster formed by knots or grain irregularities. The parameters of the model are estimated from meas...
A numerical investigation of the continuous bending under tension test
Hadoush, A.; Boogaard, van den A.H.; Emmens, W.C.
2011-01-01
In this paper the continuous bending under tension test is analyzed by numerical simulation. The ability of achieving high strains by combined stretching and bending is considered. This deformation mode has similarities with the deformation that takes place in incremental sheet forming (ISF) and may
Ultrasensitive vector bending sensor based on multicore optical fiber.
Villatoro, Joel; Van Newkirk, Amy; Antonio-Lopez, Enrique; Zubia, Joseba; Schülzgen, Axel; Amezcua-Correa, Rodrigo
2016-02-15
In this Letter, we demonstrate a compellingly simple directional bending sensor based on multicore optical fibers (MCF). The device operates in reflection mode and consists of a short segment of a three-core MCF that is fusion spliced at the distal end of a standard single mode optical fiber. The asymmetry of our MCF along with the high sensitivity of the supermodes of the MCF make the small bending on the MCF induce drastic changes in the supermodes, their excitation, and, consequently, on the reflected spectrum. Our MCF bending sensor was found to be highly sensitive (4094 pm/deg) to small bending angles. Moreover, it is capable of distinguishing multiple bending orientations. PMID:26872200
Sorting of bending magnets for the SSRF booster
Institute of Scientific and Technical Information of China (English)
HOU Jie; LIU Gui-Min; LI Hao-Hu; ZHANG Man-Zhou
2008-01-01
The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.
Sorting of bending magnets for the SSRF booster
Hou, Jie; Liu, Gui-Min; Li, Hao-Hu; Zhang, Man-Zhou
2008-04-01
The Shanghai Synchrotron Radiation Facility (SSRF)booster ring, a full energy injector for the storage ring, is deigned to accelerate the electron beam energy from 150 MeV to 3.5 GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping. Closed orbit distortion (COD) caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting. Considering the affections of random errors in measurement, both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5 is given as the final installation sequence of the booster bending magnets in this paper. Supported by SSRF Project
Analysis and Simulation of Adiabatic Bend Transitions in Optical Fibers
Institute of Scientific and Technical Information of China (English)
YAO Lei; LOU Shu-Qin; JIAN Shui-Sheng
2009-01-01
A low-loss criterion for bend transitions in optical fibers is proposed. An optical fiber can be tightly bent with low loss to be adiabatic for the fundamental mode, provided that an approximate upper bound on the rate of change of bend curvature for a given bend curvature is satisfied. Two typical adiabatic bend transition paths, the optimum profile and linear profile, are analyzed and studied numerically. A realizable adiabatic transition with an Archimedean spiral profile is introduced for low bend loss in tightly bent optical fibers. Design of the transitions is based on modeling of the propagation and coupling characteristics of the core and cladding modes,which clearly illustrate the physical processes involved.
Ultimate Bending Capacity of Strain Hardening Steel Pipes
Institute of Scientific and Technical Information of China (English)
陈严飞; 张娟; 张宏; 李昕; 周晶; 曹静
2016-01-01
Based on Hencky’s total strain theory of plasticity, ultimate bending capacity of steel pipes can be determined analytically assuming an elastic-linear strain hardening material, the simplified analytical solution is proposed as well. Good agreement is observed when ultimate bending capacities obtained from analytical solutions are compared with experimental results from full-size tests of steel pipes. Parametric study conducted as part of this paper indicates that the strain hardening effect has significant influence on the ultimate bending capacity of steel pipes. It is shown that pipe considering strain hardening yields higher bending capacity than that of pipe assumed as elastic-perfectly plastic material. Thus, the ignorance of strain hardening effect, as commonly assumed in current codes, may underestimate the ultimate bending capacity of steel pipes. The solutions proposed in this paper are applicable in the design of offshore/onshore steel pipes, supports of offshore platforms and other tubular structural steel members.
Atmospheric Refractive Electromagnetic Wave Bending and Propagation Delay
Mangum, Jeffrey G
2014-01-01
In this tutorial we summarize the physics and mathematics behind refractive electromagnetic wave bending and delay. Refractive bending and delay through the Earth's atmosphere at both radio/millimetric and optical/IR wavelengths are discussed, but with most emphasis on the former, and with Atacama Large Millimeter Array (ALMA) applications in mind. As modern astronomical measurements often require sub-arcsecond position accuracy, care is required when selecting refractive bending and delay algorithms. For the spherically-uniform model atmospheres generally used for all refractive bending and delay algorithms, positional accuracies $\\lesssim 1^{\\prime\\prime}$ are achievable when observing at zenith angles $\\lesssim 75^\\circ$. A number of computationally economical approximate methods for atmospheric refractive bending and delay calculation are presented, appropriate for astronomical observations under these conditions. For observations under more realistic atmospheric conditions, for zenith angles $\\gtrsim 75^...
Bending Modulus Measurement of Single High Performance Fiber
Institute of Scientific and Technical Information of China (English)
无
2007-01-01
The bending modulus property of high performance fiber is an important property for both polymer science and engineering. The measurement of the bending performance is, however, difficult because of the thin size of the fiber. We have measured this property by the axial compression bending method where single fiber with suitable slenderness is compressed in the fiber axial direction to obtain the peak point of the force-displacement curve. Then the bending modulus and the flexural rigidity can be calculated by measuring the protruding length and diameter of fiber needles and the critical force, Pcr. The measured data show that the bending characteristics of all kinds of high performance fiber are dissimilar evidently.
2010-11-24
... decision-making process so interested and affected public may ] participate and contribute to the final... improve forest health and fuel conditions within the 25,700-acre West Bend planning area. The planning..., and on the west by the Bend Watershed Roadless Area. The planning area is entirely within public...
Field measurement for large bending magnets
Energy Technology Data Exchange (ETDEWEB)
Lazzaro, A. [INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania (Italy); Cappuzzello, F. [INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95123 Catania (Italy)], E-mail: cappuzzello@lns.infn.it; Cunsolo, A.; Cavallaro, M. [INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania (Italy); Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Foti, A. [Dipartimento di Fisica e Astronomia, Universita di Catania, Via S. Sofia 64, I-95123 Catania (Italy); INFN-Sezione di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Orrigo, S.E.A.; Rodrigues, M.R.D.; Winfield, J.S. [INFN-Laboratori Nazionali del Sud, Via S. Sofia 62, I-95123 Catania (Italy)
2008-02-01
The results of magnetic field measurements of the large bending magnet of the MAGNEX spectrometer are presented. The experimental values are used to build an Enge function by the least-squares method. The resulting field is compared to the measured one, showing too large deviation for application to ray reconstruction techniques. Similarly, the experimental values are compared with results from a three-dimensional finite elements calculation. Again the deviations between measured and calculated field are too large for a direct application of the latter to ray reconstruction, while its reliability is sufficient for analysis purposes. In particular, it has been applied to study the effect of the inaccuracies in the probe location and orientation on the precision of field reconstruction, and to establish the requirements for the field interpolation. These inaccuracies are found to be rather important, especially for the transversal components of the field, with the consequence that their effect on the reconstructed field should be minimized by special interpolation algorithms.
Bending strength of delaminated aerospace composites.
Kinawy, Moustafa; Butler, Richard; Hunt, Giles W
2012-04-28
Buckling-driven delamination is considered among the most critical failure modes in composite laminates. This paper examines the propagation of delaminations in a beam under pure bending. A pre-developed analytical model to predict the critical buckling moment of a thin sub-laminate is extended to account for propagation prediction, using mixed-mode fracture analysis. Fractography analysis is performed to distinguish between mode I and mode II contributions to the final failure of specimens. Comparison between experimental results and analysis shows agreement to within 5 per cent in static propagation moment for two different materials. It is concluded that static fracture is almost entirely driven by mode II effects. This result was unexpected because it arises from a buckling mode that opens the delamination. For this reason, and because of the excellent repeatability of the experiments, the method of testing may be a promising means of establishing the critical value of mode II fracture toughness, G(IIC), of the material. Fatigue testing on similar samples showed that buckled delamination resulted in a fatigue threshold that was over 80 per cent lower than the static propagation moment. Such an outcome highlights the significance of predicting snap-buckling moment and subsequent propagation for design purposes.
Bending analysis of laminated composite box beams
Energy Technology Data Exchange (ETDEWEB)
Tripathy, A.K.; Patel, H.J.; Pang, S.S. (Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Mechanical Engineering)
1994-01-01
Box beams are widely used in weight reduction structures such as aircraft wings. The use of composite box beams further reduces the weight factor for such structures with the same deflection and stress as that of isotropic box beams. The difference in the behavior of composite box beam with different fiber orientation, number of plies, and number of stringers also provides a wide range of designing parameters to achieve the required performance for a given problem. A bending analysis has been carried out for the study of deflections and stresses for box beams of different material (isotropic and laminated composites), size, and number of stringers subjected to different kinds of loading conditions. A finite element model has been developed based on the strain energy principle, and the results are compared with an available commercial code COSMOS/M.'' Experiments using aluminum and scotchply composite laminates were conducted to verify the results. An optimal design for size and number of stiffeners for a given loading condition has been achieved. Investigations have also been carried out to find the effect of transverse shear on the span-wise normal stress.
Occipital bending (Yakovlevian torque) in bipolar depression.
Maller, Jerome J; Anderson, Rodney; Thomson, Richard H; Rosenfeld, Jeffrey V; Daskalakis, Zafiris J; Fitzgerald, Paul B
2015-01-30
Differing levels of occipital lobe asymmetry and enlarged lateral ventricles have been reported within patients with bipolar disorder (BD) compared with healthy controls, suggesting different rates of occipital bending (OB). This may exert pressure on subcortical structures, such as the hippocampus, reduced among psychiatric patients. We investigated OB prevalence in 35 patients with BD and 36 healthy controls, and ventricular and occipital volumes. Prevalence was four times higher among BD patients (12/35 [34.3%]) than in control subjects (3/36 [8.3%]), as well as larger lateral ventricular volumes (LVVs). Furthermore, we found OB to relate to left-to-right ventricular and occipital lobe volume (OLV) ratios. Those with OB also had reduced left-to-right hippocampal volume ratios. The results suggest that OB is more common among BD patients than healthy subjects, and prevalent in both BD Type I and Type II patients. We posit that anomalies in neural pruning or ventricular enlargement may precipitate OB, consequently resulting in one occipital lobe twisting around the other. Although the clinical implications of these results are unclear, the study suggests that asymmetrical ventricular volume matched with a pattern of oppositely asymmetrical occipital volume is related to OB and may be a marker of psychiatric illness. PMID:25480522
PROGRESS IN STUDIES ON ICE ACCUMULATION IN RIVER BENDS
Institute of Scientific and Technical Information of China (English)
WANG Jun; CHEN Pang-pang; SUI Jue-yi
2011-01-01
River ice is an important hydraulic element in temperate and polar environments and would affect hydrodynamic conditions of rivers through changes both in the boundary conditions and the thermal regime.The river bend has been reported as the common location for the initiation of ice jams because the water flow along a river bend is markedly affected by the channel curvature.In this article,the experimental studies about the ice accumulation in a river bend are reviewed.Based on experiments conducted so far,the criteria for the formation of ice jams in the river bend,the mechanisms of the ice accumulation in the river bend and the thickness profile of the ice accumulation in the river bend are discussed.The k- ε two-equation turbulence model is used to simulate the ice accumulation under an ice cover along a river bend.A formula is proposed for describing the deformation of the ice jam bottom.Our results indicate that all simulated thickness of the ice accumulation agrees reasonably well with the measured thickness of the ice accumulation in the laboratory.
Response of Flexible Risers in Bend Stiffener Area
Løseth, Kim
2011-01-01
Flexible risers is a vital part of a floating production system (FPS). In order to predict the riser life time, many procedure may be applied. In this thesis it is assumed that the pipe could be represented with help of performing two sets of global anlayis. Where in the first set it is assumed that the bending stiffness of the pipe is similar to the stick region of the flexible pipe and in the second part the bending stiffness it is assumed a bending stiffness similar to the slip regime of t...
Response of Flexible Risers in Bend Stiffener Area
Løseth, Kim
2011-01-01
Flexible risers is a vital part of a floating production system (FPS). In order to predict the riser life time, many procedure may be applied.In this thesis it is assumed that the pipe could be represented with help of performing two sets of global anlayis. Where in the first set it is assumed that the bending stiffness of the pipe is similar to the stick region of the flexible pipe and in the second part the bending stiffness it is assumed a bending stiffness similar to the slip regime of th...
Buffers Affect the Bending Rigidity of Model Lipid Membranes
DEFF Research Database (Denmark)
Bouvrais, H.; Duelund, L.; Ipsen, J. H.
2014-01-01
In biophysical and biochemical studies of lipid bilayers the influence of the used buffer is often ignored or assumed to be negligible on membrane structure, elasticity, or physical properties. However, we here present experimental evidence, through bending rigidity measurements performed on giant...... vesicles, of a more complex behavior, where the buffering molecules may considerably affect the bending rigidity of phosphatidylcholine bilayers. Furthermore, a synergistic effect on the bending modulus is observed in the presence of both salt and buffer molecules, which serves as a warning...... to experimentalists in the data interpretation of their studies, since typical lipid bilayer studies contain buffer and ion molecules....
Investigation of ion induced bending mechanism for nanostructures
International Nuclear Information System (INIS)
Ion induced bending is a promising controlled technique for manipulating nanoscale structures. However, the underlying mechanism of the process is not well understood. In this letter, we report a detailed study of the bending mechanism of Si nanowires (NWs) under Ga+ irradiation. The microstructural changes in the NW due to ion beam irradiation are studied and molecular dynamics simulations are used to explore the ion–NW interaction processes. The simulation results are compared with the microstructural studies of the NW. The investigations inform a generic understanding of the bending process in crystalline materials, which we suggest to be feasible as a versatile manipulation and integration technique in nanotechnology. (paper)
Bends in nanotubes allow electric spin control and coupling
DEFF Research Database (Denmark)
Flensberg, Karsten; Marcus, Charles Masamed
2010-01-01
We investigate combined effects of spin-orbit coupling and magnetic field in carbon nanotubes containing one or more bends along their length. We show how bends can be used to provide electrical control of confined spins, while spins confined in straight segments remain insensitive to electric...... fields. Device geometries that allow general rotation of single spins are presented and analyzed. In addition, capacitive coupling along bends provides coherent spin-spin interaction, including between otherwise disconnected nanotubes, completing a universal set of one- and two-qubit gates....
Hamiltonian system for orthotropic plate bending based on analogy theory
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Based on analogy between plane elasticity and plate bending as well as variational principles of mixed energy, Hamiltonian system is further led to orthotropic plate bending problems in this paper. Thus many effective methods of mathematical physics such as separation of variables and eigenfunction expansion can be employed in orthotropic plate bending problems as they are used in plane elasticity. Analytical solutions of rectangular plate are presented directly, which expands the range of analytical solutions. There is an essential distinction between this method and traditional semi-inverse method. Numerical results of orthotropic plate with two lateral sides fixed are included to demonstrate the effectiveness and accuracy of this method.
Damage Analysis of Rectangular Section Composite Beam under Pure Bending
Liu, Yiping; Xiao, Fan; Liu, Zejia; Tang, Liqun; Fang, Daining
2013-02-01
Laminated composite beams are commonly used in engineering applications involving macro to nano structures. Based on the assumption that plain sections remain plain after deformation, this paper analyzes stress distributions in cross-ply laminated composite beams with rectangular cross-sections, and formulates the basic damage equations through Kachanov's damage definition and Janson's failure criterion. The location of the neutral axis and the ultimate bending moment are obtained for pure bending cases. The effect of the elastic modulus of the two layers on the damage evolution is analyzed; a reasonable damage composite beam model is proposed to predict the ultimate bending moment.
Localized bending fatigue behavior of high-strength steel monostrands
DEFF Research Database (Denmark)
Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.
2012-01-01
strain distribution in the strand and helps in identifying potential failure mechanisms along the strand and at the wedge location. Initial analysis of the deformations shows that the bending fatigue behavior of the monostrand may be controlled either by local bending deformations or by relative......In this paper, the localized bending fatigue behavior of pretensioned high strength steel monostrands is investigated. Furthermore, a new methodology using an optical photogrammetry system, which can quantify surface deformations on the strand is presented. The system allows measurement of the...
Bending Analysis of Symmetrically Laminated Plates
Directory of Open Access Journals (Sweden)
Bouazza MOKHTAR
2010-12-01
Full Text Available In the classical plate theory, it is assumed that the plane cross sections initially normal to the plate midsurface before deformation remain plane and normal to that surface during deformation. This is the result of neglecting the transverse shear strains. However, in thick and moderately thick laminated plates, significant transverse shear strains occur, and the theory gives inaccurate results for the plates. So, it is obvious that the shear strains have to be taken into account. There are numerous theories of plates and laminated plates that include the transverse shear strains. One of them is the Reissner and Midlin theory , known as the first-order shear deformation theory, which defines the displacement field as linear variations of midplane displacements. This theory, where the relation between the resultant shear forces and the shear strains is obtained by using shear correction factors, has some advantages due to its simplicity and low computational cost. Some other plate theories, namely the higher-order shear deformation theories, include the effect of transverse shear strains . For example, the theory developed by Reddy allows not only for the transverse shear strains, but also for parabolic variations in the strains across the plate thickness, and thus there is no need to use shear correction coefficients in computing the shear stresses. The present stud is a survey of plate bending of cross-ply laminate by using the finite element method (F.E.M. Using ANSYS, the most known software in the domain for it, two types of modeling are proposed: the first is modeling using a type of shell element, Shell 99 and the second is an approach based on a of type solid element, Solid 46. The results obtained are compared with the results of the theory of Reddy.
Advantages of customer/supplier involvement in the upgrade of River Bend`s IST program
Energy Technology Data Exchange (ETDEWEB)
Womack, R.L.; Addison, J.A.
1996-12-01
At River Bend Station, IST testing had problems. Operations could not perform the test with the required repeatability; engineering could not reliably trend test data to detect degradation; licensing was heavily burdened with regulatory concerns; and maintenance could not do preventative maintenance because of poor prediction of system health status. Using Energy`s Total Quality principles, it was determined that the causes were: lack of ownership, inadequate test equipment usage, lack of adequate procedures, and lack of program maintenance. After identifying the customers and suppliers of the IST program data, Energy management put together an upgrade team to address these concerns. These customers and suppliers made up the IST upgrade team. The team`s mission was to supply River Bend with a reliable, functional, industry correct and user friendly IST program. The IST program in place went through a verification process that identified and corrected over 400 individual program discrepancies. Over 200 components were identified for improved testing methods. An IST basis document was developed. The operations department was trained on ASME Section XI testing. All IST tests have been simplified and shortened, due to heavy involvement by operations in the procedure development process. This significantly reduced testing time, resulting in lower cost, less dose and greater system availability.
NUMERICAL INVESTIGATION ON FLOW CHARACTERISTICS IN RIBBED BEND
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Previous research［1］by the author has proved that ribbed bend technology is a simple and efficient anti-erosion method. The present paper is a further study to unveil the mechanism of the technology by using numerical method. The flow characteristics in ribbed bend were studied. A k-ε turbulence model was used and the simulations were carried out in the body-fitted coordinates. This procedure was confirmed to be credible by showing the satisfactory agreement between the predications and experimental results. It is concluded that the character of the longitudinal flow in ribbed bend especially in the concave parts between ribs has a beneficial effect on increasing the anti-erosion ability of ribbed bend but the secondary flow will have little effect on determining the particle trajectory.
Monitoring Composites under Bending Tests with Infrared Thermography
Directory of Open Access Journals (Sweden)
Carosena Meola
2012-01-01
Full Text Available The attention of the present paper is focused on the use of an infrared imaging device to monitor the thermal response of composite materials under cyclic bending. Three types of composites are considered including an epoxy matrix reinforced with either carbon fibres (CFRP or glass fibres (GFRP and a hybrid composite involving glass fibres and aluminium layers (FRML. The specimen surface, under bending, displays temperature variations pursuing the load variations with cooling down under tension and warming up under compression; such temperature variations are in agreement with the bending moment. It has been observed that the amplitude of temperature variations over the specimen surface depends on the material characteristics. In particular, the presence of a defect inside the material affects the temperature distribution with deviation from the usual bending moment trend.
Computational Strategies for the Architectural Design of Bending Active Structures
DEFF Research Database (Denmark)
Tamke, Martin; Nicholas, Paul
2013-01-01
Active bending introduces a new level of integration into the design of architectural structures, and opens up new complexities for the architectural design process. In particular, the introduction of material variation reconfigures the design space. Through the precise specification...... of their stiffness, it is possible to control and pre-calibrate the bending behaviour of a composite element. This material capacity challenges architecture’s existing methods for design, specification and prediction. In this paper, we demonstrate how architects might connect the designed nature of composites...... with the design of bending-active structures, through computational strategies. We report three built structures that develop architecturally oriented design methods for bending-active systems using composite materials. These projects demonstrate the application and limits of the introduction of advanced...
Holla Bend National Wildlife Refuge: Comprehensive Conservation Plan
US Fish and Wildlife Service, Department of the Interior — This Comprehensive Conservation Plan (CCP) was written to guide management on Holla Bend NWR for the next 15 years. This plan outlines the Refuge vision and purpose...
Preliminary Project Investigation : Holla Bend National Wildlife Refuge
US Fish and Wildlife Service, Department of the Interior — This report covers the proposed expansion of Holla Bend National Wildlife Refuge to increase the quantity and quality of wintering habitat primarily for mallards...
1984 Deer Harvest Summary for Holla Bend National Wildlife Refuge
US Fish and Wildlife Service, Department of the Interior — This memo summarizes the 1984 deer harvest for Holla Bend National Wildlife Refuge. Tables summarize numerical findings, including bucks, does, and points.
Fishery Manangement Plan : Holla Bend National Wildlife Refuge
US Fish and Wildlife Service, Department of the Interior — This plan describes fishery management for Holla Bend National Wildlife Refuge in 1990. The plan outlines goals, objectives for fishery management for the benefit...
Theory of bending waves with applications to disk galaxies
International Nuclear Information System (INIS)
A theory of bending waves is surveyed which provides an explanation for the required amplification of the warp in the Milky Way. It also provides for self-generated warps in isolated external galaxies. The shape of observed warps and partly their existence in isolated galaxies are indicative of substantial spheroidal components. The theory also provides a plausible explanation for the bending of the inner disk (<2 kpc) of the Milky Way
Dynamics of fast charged particle beam rotation in bended crystals
International Nuclear Information System (INIS)
Dynamics of fast charged particle beam rotation in a bended monocrystal is considered. Face and volume mechanisms of capture in channels are taken into account simultaneously in the model presented. Functions of distribution in transverse energies (φ) of channeled and dechanneled particles are obtained. Charge-energy ''scale invariance'' in ion channeling with charge Z in a bended crystal determined by scale parameter W=pv/Z (p and v are pulse and velocity local to transverse planes) follows from the model presented
Theory of bending waves with applications to disk galaxies
Energy Technology Data Exchange (ETDEWEB)
Mark, J.W.K.
1982-01-01
A theory of bending waves is surveyed which provides an explanation for the required amplification of the warp in the Milky Way. It also provides for self-generated warps in isolated external galaxies. The shape of observed warps and partly their existence in isolated galaxies are indicative of substantial spheroidal components. The theory also provides a plausible explanation for the bending of the inner disk (<2 kpc) of the Milky Way.
Optimal Orthogonal Graph Drawing with Convex Bend Costs
Bläsius, Thomas; Wagner, Dorothea
2012-01-01
Traditionally, the quality of orthogonal planar drawings is quantified by either the total number of bends, or the maximum number of bends per edge. However, this neglects that in typical applications, edges have varying importance. Moreover, as bend minimization over all planar embeddings is NP-hard, most approaches focus on a fixed planar embedding. We consider the problem OptimalFlexDraw that is defined as follows. Given a planar graph G on n vertices with maximum degree 4 and for each edge e a cost function cost_e : N_0 --> R defining costs depending on the number of bends on e, compute an orthogonal drawing of G of minimum cost. Note that this optimizes over all planar embeddings of the input graphs, and the cost functions allow fine-grained control on the bends of edges. In this generality OptimalFlexDraw is NP-hard. We show that it can be solved efficiently if 1) the cost function of each edge is convex and 2) the first bend on each edge does not cause any cost (which is a condition similar to the posi...
Tunable characteristics of bending resonance frequency in magnetoelectric laminated composites
Chen, Lei; Li, Ping; Wen, Yu-Mei; Zhu, Yong
2013-07-01
As the magnetoelectric (ME) effect in piezoelectric/magnetostrictive laminated composites is mediated by mechanical deformation, the ME effect is significantly enhanced in the vicinity of resonance frequency. The bending resonance frequency (fr) of bilayered Terfenol-D/PZT (MP) laminated composites is studied, and our analysis predicts that (i) the bending resonance frequency of an MP laminated composite can be tuned by an applied dc magnetic bias (Hdc) due to the ΔE effect; (ii) the bending resonance frequency of the MP laminated composite can be controlled by incorporating FeCuNbSiB layers with different thicknesses. The experimental results show that with Hdc increasing from 0 Oe (1 Oe=79.5775 A/m) to 700 Oe, the bending resonance frequency can be shifted in a range of 32.68 kHz bending resonance frequency of the MP laminated composite gradually increases from 33.66 kHz to 39.18 kHz. This study offers a method of adjusting the strength of dc magnetic bias or the thicknesses of the FeCuNbSiB layer to tune the bending resonance frequency for ME composite, which plays a guiding role in the ME composite design for real applications.
Tunable characteristics of bending resonance frequency in magnetoelectric laminated composites
Institute of Scientific and Technical Information of China (English)
Chen Lei; Li Ping; Wen Yu-Mei; Zhu Yong
2013-01-01
As the magnetoelectric (ME) effect in piezoelectric/magnetostrictive laminated composites is mediated by mechanical deformation,the ME effect is significantly enhanced in the vicinity of resonance frequency.The bending resonance frequency (fr) of bilayered Terfenol-D/PZT (MP) laminated composites is studied,and our analysis predicts that (i) the bending resonance frequency of an MP laminated composite can be tuned by an applied dc magnetic bias (Hdc) due to the △E effect; (ii) the bending resonance frequency of the MP laminated composite can be controlled by incorporating FeCuNbSiB layers with different thicknesses.The experimental results show that with Hdc increasing from 0Oe (1 Oe=79.5775 A/m)to 700 Oe,the bending resonance frequency can be shifted in a range of 32.68 kHz ≤ fr ≤ 33.96 kHz.In addition,with the thickness of the FeCuNbSiB layer increasing from 0 μm to 90 μm,the bending resonance frequency of the MP laminated composite gradually increases from 33.66 kHz to 39.18 kHz.This study offers a method of adjusting the strength of dc magnetic bias or the thicknesses of the FeCuNbSiB layer to tune the bending resonance frequency for ME composite,which plays a guiding role in the ME composite design for real applications.
Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells
Nemeth, Michael P.; Smeltzer, Stanley S., III
2000-01-01
A study of the attenuation of bending boundary layers in balanced and unbalanced, symmetrically and unsymmetrically laminated cylindrical shells is presented for nine contemporary material systems. The analysis is based on the linear Sanders-Koiter shell equations and specializations to the Love-Kirchhoff shell equations and Donnell's equations are included. Two nondimensional parameters are identified that characterize the effects of laminate orthotropy and anisotropy on the bending boundary-layer decay length in a very general manner. A substantial number of structural design technology results are presented for a wide range of laminated-composite cylinders. For all laminates considered, the results show that the differences between results obtained with the Sanders-Koiter shell equations, the Love-Kirchhoff shell equations, and Donnell's equations are negligible. The results also show that the effect of anisotropy in the form of coupling between pure bending and twisting has a negligible effect on the size of the bending boundary-layer decay length of the balanced, symmetrically laminated cylinders considered. Moreover, the results show that coupling between the various types of shell anisotropies has a negligible effect on the calculation of the bending boundary-layer decay length in most cases. The results also show that, in some cases, neglecting the shell anisotropy results in underestimating the bending boundary-layer decay length and, in other cases, results in an overestimation.
Impact of Road Bends on Traffic Flow in a Single-Lane Traffic System
Directory of Open Access Journals (Sweden)
Zeng Junwei
2014-01-01
Full Text Available Taking the characteristics of road bends as a research object, this work proposes the cellular model (CA with road bends based on the NaSch model, with which the traffic flow is examined under different conditions, such as bend radius, bend arc length, and road friction coefficiency. The simulation results show that, with the increase of the bend radius, the peak flow will be continuously increased, and the fundamental diagram will become more similar to that of the classic NaSch model; the smaller the bend radius is, the easier it is for the occurrence of blockage; for different bend lengths, all the corresponding traffic flows show that the phenomenon of go-and-stop and the bends exert slight inhibitory effect on traffic flow; under the same bend radius, the inhibition effect of the bends on the traffic flow will be weakened with the increase of the friction coefficiency.
Advances and Trends on Tube Bending Forming Technologies
Institute of Scientific and Technical Information of China (English)
YANG He; LI Heng; ZHANG Zhiyong; ZHAN Mei; LIU Jing; LI Guangjun
2012-01-01
As one kind of key components with enormous quantities and diversities,the bent tube parts satisfy the increasing needs for lightweight and high-strength product from both materials and structure aspects.The bent tubes have been widely used in many high-end industries such as aviation,aerospaee,shipbuilding,automobile,energy and health care.The tube bending has become one of the key manufacturing technologies for lightweight product forming.Via the analysis of bending characteristics and multiple defects,advances on exploring the common issues in tube bending are summarized regarding wrinkling instability at the intrados,wall thinning (cracking) at the extrados,springback phenomenon,cross-section deformation,forming limit and process/tooling design/optimization.Some currently developed bending techniques are reviewed in terms of their advantages and limitations.Finally,in view of the urgent requirements of high-performance complex bent tube components with difficult-to-deform and lightweight materials in aviation and aerospace fields,the development trends and corresponding challenges are presented for realizing the precise and high-efficiency tube bending deformation.
Temperature Induced Instabilities in Macro-bend Fiber Based Wavelength Measurement Systems
Rajan, Ginu; Semenova, Yuliya; Wang, Pengfei; Farrell, Gerald
2009-01-01
An investigation of temperature-induced instabilities in a wavelength measurement system based on macro-bend fiber filter used in the ratiometric scheme are presented. Two wavelength measurement systems based on macro-bend fiber, a standard low bend loss single-mode fiber filter based system and a high bend loss fiber filter based system are considered. In the case of a low bend loss fiber filter based system, the oscillatory variation in the ratio response with temperature and the difference...
Segmental Bridges under Combined Torsion, Bending and Shear
Institute of Scientific and Technical Information of China (English)
黄真; 刘西拉
2003-01-01
Segmental bridges with unbonded prestressed tendons have some advantages, such as the weather independence and the corrosion protection of prestressing tendons. This paper analyzed the behavior of a prestressed segmental bridge with unbonded tendons under combined loading of torsion, bending and shear. According to the experiment research, a modified skew bending model was developed to calculate the bearing capacity of segmental bridges subjected to combined bending, shear and torsion. The finite element method was used to investigate the deflection behaviors of such structure, also to check the theoretical model. The theoretical and FEM research resuits were compared favorably with the test results from Technical University of Braunschweig, Germany. Finally, suggestion for the design and construction of segmental bridges with external prestressing was made.
Flow resistance of ice slurry in bends and elbow pipes
Niezgoda-Żelasko, B.; Żelasko, J.
2014-08-01
The present paper covers the flow of ice slurry made of a 10.6% ethanol solution through small-radius bends and elbow pipes. The paper presents the results of experimental research on the flow resistances of Bingham-fluid ice slurry in bends and elbows. The research, performed for three pipe diameters and a relative bend radius of 1<=D/di<=2, has made it possible to take into consideration the influence of friction resistances as well the of the flow geometry on the total local resistance coefficients. The study attempts to make the local resistance coefficient dependent on the Dean number defined for a generalized Reynolds number according to Metzner-Reade
Strain localization and damage development in 2060 alloy during bending
Institute of Scientific and Technical Information of China (English)
Xiao Jin; Bao-qin Fu; Cheng-lu Zhang; Wei Liu
2015-01-01
The microstructure evolution and damage development of the third-generation Al–Li alloy 2060 (T8) were studied using in situ bending tests. Specimens were loaded with a series of punches of different radii, and the microstructure evolution was studied by scanning electron microscopy, electron backscatter diffraction, and digital image correlation (DIC) methods. The evolution of the microscopic fracture strain distribution and microstructure in 2060 alloy during bending was characterized, where the dispersion distribution of precipitates was recorded by backscattered electron imaging and later inputted into a DIC system for strain calculations. The experimental results showed that strain localization in the free surface of bent specimens induced damage to the microstructure. The region of crack initiation lies on the free surface with maximum strain, and the shear crack propagates along the macro-shear band in the early stages of bending. Crack propagation in the later stages was interpreted on the basis of the conventional mechanism of ductile fracture.
Contact and Bending Durability Calculation for Spiral-Bevel Gears
Vijayakar, Sandeep
2016-01-01
The objective of this project is to extend the capabilities of the gear contact analysis solver Calyx, and associated packages Transmission3D, HypoidFaceMilled, HypoidFaceHobbed. A calculation process for the surface durability was implemented using the Dowson-Higginson correlation for fluid film thickness. Comparisons to failure data from NASA's Spiral Bevel Gear Fatigue rig were carried out. A bending fatigue calculation has been implemented that allows the use of the stress-life calculation at each individual fillet point. The gears in the NASA test rig did not exhibit any bending fatigue failure, so the bending fatigue calculations are presented in this report by using significantly lowered strength numbers.
Bend-twist coupling potential of wind turbine blades
DEFF Research Database (Denmark)
Fedorov, Vladimir; Berggreen, Christian
2014-01-01
and tested on small-scale coupled composite beams. In the proposed method the coupling coefficient for a generic beam is introduced based on the Euler-Bernoulli beam formulation. By applying the developed method for analysis of a commercial wind turbine blade structure it is demonstrated that a bend......In the present study an evaluation of the potential for bend-twist coupling effects in wind turbine blades is addressed. A method for evaluation of the coupling magnitude based on the results of finite element modeling and full-field displacement measurements obtained by experiments is developed......-twist coupling magnitude of up to 0.2 is feasible to achieve in the baseline blade structure made of glass-fiber reinforced plastics. Further, by substituting the glass-fibers with carbon-fibers the coupling effect can be increased to 0.4. Additionally, the effect of introduction of bend-twist coupling...
Platonic scattering cancellation for bending waves in a thin plate
Farhat, M.
2014-04-10
We propose an ultra-thin elastic cloak to control the scattering of bending waves in isotropic heterogeneous thin plates. The cloak design makes use of the scattering cancellation technique applied, for the first time, to the biharmonic operator describing the propagation of bending waves in thin plates. We first analyze scattering from hard and soft cylindrical objects in the quasistatic limit, then we prove that the scattering of bending waves from an object in the near and far-field regions can be suppressed significantly by covering it with a suitably designed coating. Beyond camouflaging, these findings may have potential applications in protection of buildings from earthquakes and isolating structures from vibrations in the motor vehicle industry.
Bending failure of laminated fibrous composite plates with a hole
Energy Technology Data Exchange (ETDEWEB)
Kwon, Y.W.; Yang, S.T. [Naval Postgraduate School, Monterey, CA (United States). Dept. of Mechanical Engineering
1995-08-01
This study investigates failure modes and failure strengths of laminated fibrous composite plates with stress concentration and subjected to bending loads. Graphite/epoxy composites are used for the present study. Lamina material properties, such as stiffness and strength, of the composite are determined from experiments. A series of four-point bending tests are conducted for laminated, graphite/epoxy composite plates with and without a hole to examine their failure modes and strengths. The paper compares different failure modes and strengths of various composite specimens. In addition, finite element analyses are performed to compute stress distributions around holes of the composite plates subjected to bending loads. Numerically predicted failure loads agree well with experimental results.
Bending of the looping heart: differential growth revisited.
Shi, Yunfei; Yao, Jiang; Xu, Gang; Taber, Larry A
2014-08-01
In the early embryo, the primitive heart tube (HT) undergoes the morphogenetic process of c-looping as it bends and twists into a c-shaped tube. Despite intensive study for nearly a century, the physical forces that drive looping remain poorly understood. This is especially true for the bending component, which is the focus of this paper. For decades, experimental measurements of mitotic rates had seemingly eliminated differential growth as the cause of HT bending, as it has commonly been thought that the heart grows almost exclusively via hyperplasia before birth and hypertrophy after birth. Recently published data, however, suggests that hypertrophic growth may play a role in looping. To test this idea, we developed finite-element models that include regionally measured changes in myocardial volume over the HT. First, models based on idealized cylindrical geometry were used to simulate the bending process in isolated hearts, which bend without the complicating effects of external loads. With the number of free parameters in the model reduced to the extent possible, stress and strain distributions were compared to those measured in embryonic chick hearts that were isolated and cultured for 24 h. The results show that differential growth alone yields results that agree reasonably well with the trends in our data, but adding active changes in myocardial cell shape provides closer quantitative agreement with stress measurements. Next, the estimated parameters were extrapolated to a model based on realistic 3D geometry reconstructed from images of an actual chick heart. This model yields similar results and captures quite well the basic morphology of the looped heart. Overall, our study suggests that differential hypertrophic growth in the myocardium (MY) is the primary cause of the bending component of c-looping, with other mechanisms possibly playing lesser roles.
Bending of light in modified gravity at large distances
Sultana, Joseph; Kazanas, Demosthenes
2012-04-01
We discuss the bending of light in a recent model for gravity at large distances containing a Rindler-type acceleration proposed by Grumiller [Phys. Rev. Lett. 105, 211303 (2010)10.1103/PhysRevLett.105.211303PRLTAO0031-9007]. We consider the static, spherically symmetric metric with cosmological constant Λ and Rindler-like term 2ar presented in this model, and we use the procedure by Rindler and Ishak [W. Rindler and M. Ishak, Phys. Rev. DPRVDAQ1550-7998 76, 043006 (2007).10.1103/PhysRevD.76.043006] to obtain the bending angle of light in this metric. Earlier work on light bending in this model by Carloni, Grumiller, and Preis [Phys. Rev. DPRVDAQ1550-7998 83, 124024 (2011)10.1103/PhysRevD.83.124024], using the method normally employed for asymptotically flat space-times, led to a conflicting result (caused by the Rindler-like term in the metric) of a bending angle that increases with the distance of closest approach r0 of the light ray from the centrally concentrated spherically symmetric matter distribution. However, when using the alternative approach for light bending in nonasymptotically flat space-times, we show that the linear Rindler-like term produces a small correction to the general relativistic result that is inversely proportional to r0. This will in turn affect the bounds on Rindler acceleration obtained earlier from light bending and casts doubts on the nature of the linear term 2ar in the metric.
Bruce NGS B U-bend support stabilization
International Nuclear Information System (INIS)
The steam generators at Bruce NGS B have experienced a degree of tube fretting at the U-bend scalloped bar support locations. Investigation attributed the tube fretting to flow induced vibration induced wear as a result of U-bend supports which were too widely spaced (compared to current criteria), and insufficiently rigid. The paper describes the problem, the development of a stabilization configuration, its qualification, its installation tooling and procedures, and the installation of the initial trial assemblies. 4 refs., 9 figs
On the global ship hull bending energy in ship collisions
DEFF Research Database (Denmark)
Pedersen, Preben Terndrup; Li, Yujie
2009-01-01
of the struck ship hull during ship–ship collisions. The striking ship is still considered as a rigid body. The local interaction between the two ships is modeled by a linear load–deflection relation. The analysis results for a simplified model of a struck coaster and of a large tanker show that the elastic...... is confined to the impact location and where local and global bending vibration modes are neglected. That is, the structural deformation problem is considered quasi-static. In this paper a simple uniform free–free beam model is presented for estimating the energy transported into the global bending vibrations...
On the Global Ship Hull Bending Energy in Ship Collisions
DEFF Research Database (Denmark)
Pedersen, Preben Terndrup; Li, Y.
2004-01-01
ship hull during ship-ship collisions. The striking ship is still considered as a rigid body. The local interaction between the two ships is modeled by a linear load-deflection relation. The analysis results for a simplified model of a struck coaster and of a large tanker show that the elastic energy...... to the impact location and where local and global bending vibration modes are neglected. That is, the structural deformation problem is considered quasi-static. In this paper a simple uniform free-free beam model is presented for estimating the energy transported into the global bending vibrations of the struck...
Nonstandard bending mechanism in Bi2Te3 single crystals
International Nuclear Information System (INIS)
Nonstandard bending mechanism for layered Bi2Te3 single crystals is studied by their three-point loading in the direction perpendicular to the cleavage planes (0001). It is shown that the Bi2Te3 sample under the influence of external load acquires complex internal substructure analogous to the known mechanism two-dimensional plane-parallel spring-actuated suspension. Change in form of the sample bend from the V-type regular one for monolithic solid bodies to the Ω-type nonstandard from. 7 refs.; 5 figs
Four point bending setup for characterization of semiconductor piezoresistance
DEFF Research Database (Denmark)
Richter, Jacob; Arnoldus, Morten Berg; Hansen, Ole;
2008-01-01
We present a four point bending setup suitable for high precision characterization of piezoresistance in semiconductors. The compact setup has a total size of 635 cm3. Thermal stability is ensured by an aluminum housing wherein the actual four point bending fixture is located. The four point...... characterization. As a proof of concept, we show measurements of the piezocoefficient pi44 in p-type silicon at three different doping concentrations in the temperature range from T=30 °C to T=80 °C. The extracted piezocoefficients are determined with an uncertainty of 1.8%. ©2008 American Institute of Physics...
Quasimolecular Dynamic Simulation for Bending Fracture of Laminar Composite Materials
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
Recently, quasimolecular dynamics has been successfully used to simulate the deformation characteristics of actual size solid materials. In quasimolecular dynamics, which is an attempt to bridge the gap between atomistic and continuum simulations, molecules are aggregated into large units, called quasimolecules, to evaluate large scale material behavior. In this paper, a 2-dimensional numerical simulation using quasimolecular dynamics was performed to investigate laminar composite material fractures and crack propagation behavior in the uniform bending of laminar composite materials. It was verified that under bending deformation laminar composite materials deform quite differently from homogeneous materials
Solution structure of an A-tract DNA bend.
MacDonald, D; Herbert, K; Zhang, X; Pologruto, T; Lu, P; Polgruto, T
2001-03-01
The solution structure of a DNA dodecamer d(GGCAAAAAACGG)/d(CCGTTTTTTGCC) containing an A-tract has been determined by NMR spectroscopy with residual dipolar couplings. The structure shows an overall helix axis bend of 19 degrees in a geometry consistent with solution and gel electrophoresis experiments. Fourteen degrees of the bending occurs in the GC regions flanking the A-tract. The remaining 5 degrees is spread evenly over its six AT base-pairs. The A-tract is characterized by decreasing minor groove width from the 5' to the 3' direction along the A strand. This is a result of propeller twist in the AT pairs and the increasing negative inclination of the adenine bases at the 3' side of the run of adenine bases. The four central thymine bases all have negative inclination throughout the A-tract with an average value of -6.1 degrees. Although this negative inclination makes the geometry of the A-tract different from all X-ray structures, the proton on N6 of adenine and the O4 of thymine one step down the helix are within distance to form bifurcated hydrogen bonds. The 5' bend of 4 degrees occurs at the junction between the GC flank and the A-tract through a combination of tilt and roll. The larger 3' bend, 10 degrees, occurs in two base steps: the first composed of tilt, -4.1 degrees, and the second a combination of tilt, -4.2 degrees, and roll, 6.0 degrees. This second step is a direct consequence of the change in inclination between an adjacent cytosine base, which has an inclination of -12 degrees, and the next base, a guanine, which has 3 degrees inclination. This bend is a combination of tilt and roll. The large change in inclination allows the formation of a hydrogen bond between the protons of N4 of the 3' cytosine and the O6 of the next 3' base, a guanine, stabilizing the roll component in the bend. These structural features differ from existing models for A-tract bends.For comparison, we also determined the structure of the control sequence, d
Proteomic Analysis of Fruit Bending in Cucumber (Cucumis sativus L.)
Institute of Scientific and Technical Information of China (English)
WANG Li-li; ZHANG Peng; QIN Zhi-wei; ZHOU Xiu-yan
2014-01-01
In cucumber, fruit shape is an important quality criterion, and fruit bending is known to limit growth, yield, and taste. To investigate the post-transcriptional changes that regulate fruit bending and to better understand the underlying molecular mechanisms, we generated a proteomic proifle of the abdomen and back of cucumber bending fruit. Two-dimensional gel electrophoresis (2-DE) allowed the detection of approximately 900 distinct protein spots in each gel, 32 of which were differentially expressed in the abdomen and back of bending cucumber fruit. Ten of the differentially expressed proteins were analyzed using matrix-assisted laser ionization time of lfight mass spectrometry (MALDI-TOF/MS). A search of primary databases showed that the identiifed proteins are involved in various metabolic processes and cellular responses, including photosynthesis metabolism, energy metabolism, defense and stress response, and regulation. The identiifed proteins included large subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase, which are involved in photosynthesis and photorespiratory metabolism, and isocitrate dehydrogenase, which is involved in the tricarboxylic acid cycle. It is possible that imbalances in catabolic and anabolic processes directly affect the bending of cucumber fruit. The predicted function of the cobalamin-independent methionine synthase isozyme is closely related to ethylene biosynthesis; fruit bending may be regulated by ethylene, or by ethylene signaling crosstalk during fruit development. The 14-3-3 protein is usually considered to be a regulation-related protein, which plays a role in regulating cell hyperplasia, cell differentiation during growth, and apoptosis during senescence. Involvement of guanosine triphosphate (GTP)-binding proteins in signal transmission is known to regulate the development of cells in cucumber fruits and to play a role in fruit shape variation. Patterns of protein expression showed high repeatability. We hypothesize
Ballistic thermoelectric properties in double-bend graphene nanoribbons
International Nuclear Information System (INIS)
Ballistic thermoelectric properties in double-bend graphene nanoribbons (GNRs) are investigated by using the nonequilibrium Green's function. We find that due to the elastic scattering caused by the interface mismatching, the thermal conductance contributed by phonons is greatly reduced, while ballistic transport behaviors for electrons are dramatically demolished, and even some gaps can be opened at antiresonance energies. Near these antiresonance gaps, the maximum value of ZT (ZTmax) can be observed, much larger than that for straight GNRs. Moreover, this ZTmax can be effectively tuned by modulating the length or width of double-bend GNRs.
Elastostatic bending of a bimaterial plate with a circular interface
Ogbonna, Nkem
2015-08-01
The elastostatic bending of an arbitrarily loaded bimaterial plate with a circular interface is analysed. It is shown that the deflections in the composite solid are directly related to the deflection in the corresponding homogeneous material by integral and differential operators. It is further shown that, by a simple transformation of elastic constants, the Airy stress function induced in the composite by a stretching singularity can be deduced from the deflection induced by a bending singularity. This result is significant for reduction of mathematical labour and for systematic construction of solutions for more complex structures with circular geometry.
Bending of solitons in weak and slowly varying inhomogeneous plasma
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, Abhik, E-mail: abhik.mukherjee@saha.ac.in; Janaki, M. S., E-mail: ms.janaki@saha.ac.in; Kundu, Anjan, E-mail: anjan.kundu@saha.ac.in [Saha Institute of Nuclear Physics, Kolkata-700064 (India)
2015-12-15
The bending of solitons in two dimensional plane is presented in the presence of weak and slowly varying inhomogeneous ion density for the propagation of ion acoustic soliton in unmagnetized cold plasma with isothermal electrons. Using reductive perturbation technique, a modified Kadomtsev-Petviashvili equation is obtained with a chosen unperturbed ion density profile. The exact solution of the equation shows that the phase of the solitary wave gets modified by a function related to the unperturbed inhomogeneous ion density causing the soliton to bend in the two dimensional plane, while the amplitude of the soliton remains constant.
Bending strength model for internal spur gear teeth
Savage, Michael; Rubadeux, K. L.; Coe, H. H.
1995-01-01
Internal spur gear teeth are normally stronger than pinion teeth of the same pitch and face width since external teeth are smaller at the base. However, ring gears which are narrower have an unequal addendum or are made of a material with a lower strength than that of the meshing pinion may be loaded more critically in bending. In this study, a model for the bending strength of an internal gear tooth as a function of the applied load pressure angle is presented which is based on the inscribed Lewis constant strength parabolic beam. The bending model includes a stress concentration factor and an axial compression term which are extensions of the model for an external gear tooth. The geometry of the Lewis factor determination is presented, the iteration to determine the factor is described, and the bending strength J factor is compared to that of an external gear tooth. This strength model will assist optimal design efforts for unequal addendum gears and gears of mixed materials.
Optimization of bandwidth in 60^o photonic crystal waveguide bends
DEFF Research Database (Denmark)
Xing, P. F.; Borel, Peter Ingo; Frandsen, Lars Hagedorn;
2005-01-01
A systematic scheme utilizing 2D and 3D finite-difference time-domain calculations to design 60^o photonic crystal waveguide bends is presented. The method results in an improved transmission bandwidth from 70 to 160 nm in 2D simulations, and from 50 to 100 nm in 3D simulations. The design...
Secondary flow in sharp open-channel bends
Blanckaert, K.; De Vriend, H.J.
2004-01-01
Secondary currents are a characteristic feature of flow in open-channel bends. Besides the classical helical motion (centre-region cell), a weaker and smaller counter-rotating circulation cell (outer-bank cell) is often observed near the outer bank, which is believed to play an important role in ban
Space charge effects in a bending magnet system
International Nuclear Information System (INIS)
In order to examine problems and phenomena associated with space charge in a beam bending system, the beam dynamics code HICURB has been written. Its principal features include momentum variations, vertical and horizontal envelope dynamics coupled to the off-axis centroid, curvature effect on fields, and images. Preliminary results for an achromatic lattice configuration are presented
Band bending and electrical transport at chemically modified silicon surfaces
Lopinski, Greg; Ward, Tim; Hul'Ko, Oleksa; Boukherroub, Rabah
2002-03-01
High resolution electron energy loss spectroscopy (HREELS) and electrical transport measurements have been used to investigate how various chemical modifications give rise to band bending and alter the conductivity of Si(111) surfaces. HREELS is a sensitive probe of band bending through observations of the low frequency free carrier plasmon mode. For hydrogen terminated surfaces, prepared by the standard etch in ammonium flouride, HREELS measurements on both n and n+ substrates are consistent with nearly flat bands. Chlorination of these surfaces results in substantial upward band bending due to the strong electron withdrawing nature of the chlorine, driving the surface into inversion. The presence of this inversion layer on high resistivity n-type samples is observed through a substantial enhancement of the surface conductivity (relative to the H-terminated surface), as well as through broadening of the quasi-elastic peak in the HREELS measurements. We have also begun to examine organically modified silicon surfaces, prepared by various wet chemical reactions with the H-terminated surface. Decyl modified Si(111) surfaces are seen to exhibit a small degree of band bending, attributed to extrinsic defect states cause by a small degree of oxidation accompanying the modification reaction. The prospects of using conductivity as an in-situ monitor of the rate of these reactions will be discussed.
A theoretical model for suspended sediment transport in river bends
Talmon, A.M.
1989-01-01
A two dimensional depth-averaged model for the concentration field of suspended sediment in river bend flow is formulated. Transport of suspended sediment in horizontal and vertical directions is modelled. Convection by the main and secondary flow and turbulent diffusion are incorporated. The model
Tidal bending of glaciers: a linear viscoelastic approach
DEFF Research Database (Denmark)
Reeh, Niels; Christensen, Erik Lintz; Mayer, Christoph;
2003-01-01
glaciers are in the range 0.9-3 GPa. It has therefore been suggested that the elastic-beam model with a single value of E approximate to 1 GPa adequately describes tidal bending of glaciers.In contrast, laboratory experiments with ice give E =93 GPa, i.e. 3-10 times higher than the glacier-derived values...
Basic Characteristics of a New Flexible Pneumatic Bending Joint
Institute of Scientific and Technical Information of China (English)
SHAO Tiefeng; ZHANG Libin; BAO Guanjun; LUO Xinyuan; YANG Qinghua
2014-01-01
Several typical flexible pneumatic actuators (FPA) and different mechanical models describing their behaviors have been proposed, however, it is difficult to balance compliance and load capacity in conventional designs, and these models still have limitations in predicting behavior of FPAs. A new flexible pneumatic bending joint (FPBJ) with special anisotropic rigidity structure is proposed. The FPBJ is developed as an improvement with regard to existing types of FPA, and its principal characteristic is derived from the special anisotropic rigidity structure. With this structure, the load capacity in the direction perpendicular to bending plane is strengthened. The structure of the new FPBJ is explained and a mathematical model is derived based on Euler-Bernoulli beam model and Hook’s law. To obtain optimum design and usage, some key structure parameters and input-output characteristics are simulated. The simulation results reveal that the relationship between the structure parameters and FPBJ’s bending angle is nonlinear. At last, according to the simulation results, the FPBJ is manufactured with optional parameters and tested. The experimental results show that the joint’s statics characteristics are reflected by the mathematical model accurately when the FPBJ is deflated. The maximum relative error between simulation and experimental results is less than 6%. However, the model still has limitations. When the joint is inflated, the maximum relative error reaches 20%. This paper proposes a new flexible pneumatic bending joint which has sufficient load capacity and compliance, and the mathematical model provides theoretical guidance for the FPBJ’s structure design.
Finite element analysis of damage in pipeline bends
Swart, A.E.; Karamanos, S.A.; Scarpas, A.; Blaauwendraad, J.
2010-01-01
The present paper describes a numerical formulation for the analysis of damage in steel pipeline bends. In particular, the numerical implementation of Gurson plasticity model is described in the framework of a special element, referred to as “tube element”. This is a three-node element, which simula
A COMBINED HYBRID FINITE ELEMENT METHOD FOR PLATE BENDING PROBLEMS
Institute of Scientific and Technical Information of China (English)
Tian-xiao Zhou; Xiao-ping Xie
2003-01-01
In this paper, a combined hybrid method is applied to finite element discretization ofplate bending problems. It is shown that the resultant schemes are stabilized, i.e., theconvergence of the schemes is independent of inf-sup conditions and any other patch test.Based on this, two new series of plate elements are proposed.
Enhanced resolution of long-period grating bend sensor
DEFF Research Database (Denmark)
Glavind, Lars; Gao, S; Cook, K;
2013-01-01
We present an optical fiber bend sensor with enhanced resolution based on the principle of a Mach-Zehnder interferometer in transmission. The sensor is based on two identical Long-Period Gratings separated by approximately 100 mm in a D-shaped single-mode optical fiber. The sensor provides a narrow...
Multiphase fluid structure interaction in bends and T-joints
Cargnelutti, M.F.; Belfroid, S.P.C.; Schiferli, W.; Osch, M.M.E. van
2010-01-01
Air-water experiments were carried out in a horizontal 1" pipe system to measure the magnitude of the forces induced by the multiphase flow. Forces and accelerations were measured on a number of bends and T-joint configurations for a wide range of operating conditions. Five different configurations
Size Effects on the Bending Behaviour of Reinforced Concrete Beams
DEFF Research Database (Denmark)
Brincker, Rune; Henriksen, M. S.; Christensen, F. A.;
1999-01-01
Load-deformation curves for reinforced concrete beams subjected to bending show size effects due to tensile failure of the concrete at early stages in the failure process and due to compression failure of the concrete when the final failure takes place. In this paper these effects are modelled...
The Clinch Bend Regional Industrial Site and economic development opportunities
Energy Technology Data Exchange (ETDEWEB)
NONE
1995-12-31
This effort focuses initially on the Clinch Bend site. Other sites and developable tracts of land are identified with the assistance of communities in proximity to Oak Ridge, the State of Tennessee, and others, and compared with the projected site requirements for large industrial facilities.
A Second Look at Brian Simon's "Bending the Rules"
Cox, Sue
2016-01-01
In this article the author revisits an important book: Brian Simon's "Bending the Rules: the Baker reform of education." Written by a key figure in the history of the journal FORUM as well as in the history of education, Simon's book documented the features of the Education Reform Bill of 1987 (the precursor to the Education Reform Act…
Photoacoustic elastic bending in thin film—Substrate system
Energy Technology Data Exchange (ETDEWEB)
Todorović, D. M., E-mail: dmtodor@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, P.O. Box 33, 11030 Belgrade (Serbia); Rabasović, M. D.; Markushev, D. D. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade-Zemun (Serbia)
2013-12-07
Theoretical model for optically excited two-layer elastic plate, which includes plasmaelastic, thermoelastic, and thermodiffusion mechanisms, is given in order to study the dependence of the photoacoustic (PA) elastic bending signal on the optical, thermal, and elastic properties of thin film—substrate system. Thin film-semiconductor sample (in our case Silicon) is modeled by simultaneous analysis of the plasma, thermal, and elastic wave equations. Multireflection effects in thin film are included in theoretical model and analyzed. Relations for the amplitude and phase of electronic and thermal elastic bending in the optically excited two-layer mechanically-supported circular plate are derived. Theoretical analysis of the thermodiffusion, plasmaelastic, and thermoelastic effects in a sample-gas-microphone photoacoustic detection configuration is given. Two normalization procedures of the photoacoustic elastic bending signal in function of the modulation frequency of the optical excitation are established. Given theoretical model can be used for various photoacoustic detection configurations, for example, in the study of optical, thermal, and elastic properties of the dielectric-semiconductor or metal-semiconductor structure, etc., Theoretical analysis shows that it is possible to develop new noncontact and nondestructive experimental method—PA elastic bending method for thin film study, with possibility to obtain the optical, thermal, and elastic parameters of the film thinner than 1 μm.
Fresh-stem bending of silver fir and Norway spruce.
Lundström, Tor; Stoffel, Markus; Stöckli, Veronika
2008-03-01
The bending and growth characteristics of large fresh stems from four silver fir (Abies alba Mill.) and three Norway spruce (Picea abies (L.) Karst.) trees were studied. Twenty logs taken from different stem heights were subjected to four-point bending tests. From the bending test records, we calculated stress-strain curves, which accounted for detailed log taper, shear deformation and self weight. From these curves we determined, among other parameters, the modulus of elasticity (MOE), the modulus of rupture (MOR) and the work absorbed in bending (W). No significant differences were found between species for the wood properties examined. Values of MOE, MOR and W generally decreased with stem height, with MOR in the range of 43 to 59 MPa and MOE ranging from 10.6 to 15.6 GPa. These MOE values are twice or more those reported for stems of young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees. Based on the radial growth properties measured in discs from the logs, we calculated predicted values of MOE and MOR for the stem cross section. The predictions of MOE were precise, whereas those of MOR were approximate because of a complex combination of different failure mechanisms. Methods to test and calculate MOE, MOR and W for the stems of living trees are discussed with the aim of improving analyses of tree biomechanics and assessments of forest stability protection.
Ultrathin 90-degree sharp bends for spoof surface plasmon polaritons
DEFF Research Database (Denmark)
Yang, Yihao; Chen, Hongsheng; Xiao, Sanshui;
2015-01-01
surface plasmons around 90-degree sharp bends on ultrathin metallic films in the microwave regime. We demonstrate that by judiciously engineering the structure, the dispersion relation can be designed to reduce the scattering. Furthermore, the reflection can be suppressed by proper structural decoration...
A Novel Rotary Piezoelectric Motor Using First Bending Hybrid Transducers
Directory of Open Access Journals (Sweden)
Yingxiang Liu
2015-08-01
Full Text Available We report a novel rotary piezoelectric motor using bending transducers in this work. Three transducers are used to drive a disk-shaped rotor together by the elliptical movements of their driving tips; these motions are produced by the hybrid of two first bending vibration modes. The proposed piezoelectric transducer has a simple structure as it only contains an aluminum alloy beam and four pieces of PZT plates. Symmetrical structure is the only necessary condition in the design process as it will ensure the resonance frequencies of the two orthogonal first bending modes are equal. Transducers with first bending resonance frequency of about 53 kHz were fabricated and assembled into a rotary motor. The proposed motor exhibits good performance on speed and torque control. Under a working frequency of 53.2 kHz, the maximum no-load speed and the maximum torque of the prototype are tested to be 53.3 rpm and of 27 mN·m.
Influence of Additional Tensile Force on Springback of Tube Under Rotary Draw Bending
E, Daxin; Guan, Zhiping; Chen, Jisheng
2012-11-01
According to the characteristics of tube under rotary draw bending, the formulae were derived to calculate the springback angles of tubes subjected to combined bending and additional tension. Especially, as the neutral layer (NL) moves to the inner concave surface of the bend, the analytical values agree very well with the experimental results. The analysis shows that the additional tensile force causes the movement of the NL toward the bending center and makes the deformation behavior under rotary draw bending or numerically controlled (NC) bending different with that under pure bending, and also it could enlarge the springback angle if taking the movement of the NL into consideration. In some range, the springback angle would increase slightly with larger wall thickness/diameter ratio and decrease with wall thinning. The investigation could provide reference for the analysis of rotary draw bending, the design of NC tube bender and the related techniques.
Jui-Chang Lin; Kingsun Lee
2015-01-01
The three-dimensional tube (or pipe) is manufactured by CNC tube bending machine. The key techniques are determined by tube diameter, wall thickness, material, and bending radius. The obtained technique through experience and the trial and error method is unreliable. Finite element method (FEM) simulation for the tube bending process before production can avoid wasting manpower and raw materials. The computer-aided engineering (CAE) software ABAQUS 6.12 is applied to simulate bending characte...
An All-fiber Temperature Sensor Based on a Macro-bend Singlemode Fiber Loop
Rajan, Ginu; Semenova, Yuliya; Farrell, Gerald
2008-01-01
An all-fibre temperature sensor is proposed based on a macro-bend singlemode fibre loop using a ratiometric power measurement scheme. The sensor has a linear characteristic with temperature at a fixed wavelength and bend radius. A direct linear relationship between the bend loss of the singlemode fibre and temperature is reported for the first time. By measuring the change in bend loss of the system a change in temperature can be measured assuming the system is calibrated. The proposed sensor...
Bending characteristic of a cantilevered magnetostrictive film-substrate system
Institute of Scientific and Technical Information of China (English)
B.; Narsu
2007-01-01
The bending problem of a film-substrate cantilever with arbitrary film-to-substrate thickness ratio is solved exactly by employing the force equilibrium equation, and then the optimization and application of the bending characteristic of the magne-tostrictive cantilever is discussed. Furthermore, the influence of geometrical and physical parameters of the two cantilever components on the maximum free-end deflection of the cantilever is addressed. The results indicate that as the substrate thickness is kept constant, the greater film-to-substrate stiffness ratio will induce a larger deflection, while for the case of fixed total cantilever thickness, the optimal cantilever deflection is independent of the physical parameters of the materials such as Young’s modulus and Poisson’s ratio.
Bending characteristic of a cantilevered magnetostrictive film-substrate system
Institute of Scientific and Technical Information of China (English)
B. Narsu; YUN GuoHong
2007-01-01
The bending problem of a film-substrate cantilever with arbitrary film-to-substrate thickness ratio is solved exactly by employing the force equilibrium equation, and then the optimization and application of the bending characteristic of the magnetostrictive cantilever is discussed. Furthermore, the influence of geometrical and physical parameters of the two cantilever components on the maximum free-end deflection of the cantilever is addressed. The results indicate that as the substrate thickness is kept constant, the greater film-to-substrate stiffness ratio will induce a larger deflection, while for the case of fixed total cantilever thickness, the optimal cantilever deflection is independent of the physical parameters of the materials such as Young's modulus and Poisson's ratio.
NUMERICAL MODELING OF SUSPENDED SEDIMENT TRANSPORT IN CHANNEL BENDS
Institute of Scientific and Technical Information of China (English)
HUANG Sui-liang; JIA Y. F.; WANG Sam S. Y.
2006-01-01
An algorithm to compute three-dimensional sediment transport effect was proposed in this paper to enhance the capability of depth-averaged numerical models. This algorithm took into account of non-uniform distributions of flow velocities and suspended sediment concentrations along water depth, it significantly enhanced the applicability of 2D models in simulating open channel flows, especially in channel bends. Preliminary numerical experiments in a U-shaped and a sine-generated experimental channel indicate that the proposed method performs quite well in predicting the change of bed-deformation in channel bends due to suspended sediment transport. This method provides an effective alternative for the simulations of channel morphodynamic changes.
Analytical dynamic modeling of fast trilayer polypyrrole bending actuators
International Nuclear Information System (INIS)
Analytical modeling of conjugated polymer actuators with complicated electro-chemo-mechanical dynamics is an interesting area for research, due to the wide range of applications including biomimetic robots and biomedical devices. Although there have been extensive reports on modeling the electrochemical dynamics of polypyrrole (PPy) bending actuators, mechanical dynamics modeling of the actuators remains unexplored. PPy actuators can operate with low voltage while producing large displacement in comparison to robotic joints, they do not have friction or backlash, but they suffer from some disadvantages such as creep and hysteresis. In this paper, a complete analytical dynamic model for fast trilayer polypyrrole bending actuators has been proposed and named the analytical multi-domain dynamic actuator (AMDDA) model. First an electrical admittance model of the actuator will be obtained based on a distributed RC line; subsequently a proper mechanical dynamic model will be derived, based on Hamilton's principle. The purposed modeling approach will be validated based on recently published experimental results
About resonance frequencies of aluminium alloy bending vibrations
International Nuclear Information System (INIS)
Using ultrasonic method resonance frequencies of bending vibrations and elastic moduli of aluminium alloy SAV-1 samples are investigated. On the base of spectra of bending vibrations in low-frequency range data on values of a number of elastic properties are obtained as well as dispersion characteristics of main moduli for number of frequencies before and after ionizing irradiation (60Co, 5x103-1.6x107 Gy) of samples. Considerable stability of sample elastic moduli during common storage conditions and nonlinear dose dependence of these parameters within wide range of absorbed doses are pointed out. Possible causes of revealed effects of radiation modification of elastic properties of SAV-1 alloy are analyzed
Plastic Optical Fiber Displacement Sensor Based on Dual Cycling Bending
Directory of Open Access Journals (Sweden)
Yung-Chuan Chen
2010-11-01
Full Text Available In this study, a high sensitivity and easy fabricated plastic optical fiber (POF displacement sensor is proposed. A POF specimen subjected to dual cyclic bending is used to improve the sensitivity of the POF displacement sensor. The effects of interval between rollers, relative displacement and number of rollers on the sensitivity of the displacement sensor are analyzed both experimentally and numerically. A good agreement between the experimental measurements and numerical calculations is obtained. The results show that the interval between rollers affects sensitivity most significantly than the other design parameters. Based on the experimental data, a linear equation is derived to estimate the relationship between the power loss and the relative displacement. The difference between the estimated results and the experimental results is found to be less than 8%. The results also show that the proposed POF displacement sensor based on dual cyclic bending can be used to detect displacement accurately.
Pure Bending Characteristic of Tilted Fiber Bragg Grating
Institute of Scientific and Technical Information of China (English)
Bo Liu; Yin-Ping Miao; Hai-Bin Zhou; Qi-Da Zhao
2008-01-01
a novel structure of the pure macro-bending sensor based on the tilted fiber Bragg grating (TFBG) is proposed. The TFBG located in the half circle with the different diameters is bent at a constant angle with respect to the tilted grating planes. With the variations of the curvature, the core-mode resonance is unchanged and the transmission power of cladding modes detected by the photodiodes varies linearly with curvature, while the ghost mode changes by the form of two-order polynomial. So we can use the transmission power of ghost mode or other cladding modes to detect bending curvature as shape sensor. From a practical point of view, the sensor proposed here is simple, low cost and easy to implement. Moreover, it is possible to make a temperature-insensitive shape sensor due to the same temperature characteristic between the core mode and the cladding modes.
Flow resistance in a compound gravel-bed bend
Indian Academy of Sciences (India)
Hossein Afzalimehr; Manouchehr Heidarpour; Alireza Salimi
2006-12-01
In this paper, the effect of a gravel-bed in a compound bend (similar to sinusoidal top view) of a natural river (Zayandehrud River ﬂowing through Isfahan, Iran) has been investigated for ﬂow resistance analysis, measuring the velocity with a micro current meter. The data were analysed and the following observations were made. In a compound bend, the law of the wall can be valid for up to 66% of the ﬂow depth from the bed. The parabolic law is the most effective method for the determination of shear velocity. Based on the existing criteria for verifying the equilibrium boundary layer, the ﬂow cannot be in equilibrium. The shear stress distribution and the sediment transport parameters have considerable inﬂuence on resistance to ﬂow. Froude number and the ﬂow depth relative to the representative gravel size have little effect on the ﬂow resistance estimation.
Elastoswellability: Will it bend or will it buckle?
Holmes, Douglas; Pandey, Anupam
2013-03-01
Soft mechanical structures such as biological tissues and gels exhibit motion, instabilities, and large morphological changes when subjected to external stimuli. Swelling is a robust approach for inducing structural change as it occurs naturally in humid environments and can be easily adapted for industrial design. Small volumes of fluid that interact favorably with a material can cause large, dramatic, and geometrically nonlinear deformations including beam bending, plate buckling, and surface wrinkling. In this talk we address an overarching question regarding swelling-induced deformations: will the structural change occur globally, or will it be confined to the material's surface? We introduce a materials and geometry defined transition point that describes a fluid-structure's characteristic ``elastoswellability'' lengthscale. By locally swelling unconstrained slender beams and plates with solvents of varying solubility, we identify a transition between local surface wrinkling and global structural bending.
Effect of Accelerated Global Expansion on Bending of Light
Aghili, Mir Emad; Bombelli, Luca
2014-01-01
In 2007 Rindler and Ishak showed that, contrary to previous claims, the value of the cosmological constant does have an effect on light deflection by a gravitating object in an expanding universe, modeled by a Schwarzschild-de~Sitter spacetime. In this paper we consider light bending in the more general situation of a gravitating object in a cosmological background with varying expansion rate $H(t)$. We calculate numerically the null geodesics representing light rays deflected by a black hole in an accelerating Friedmann-Lema\\^itre-Robertson-Walker universe, modeled by a McVittie metric. Keeping the values of the distances from the observer to the lensing object and to the source fixed, we plot the dependence of the bending angle measured by two different sets of observers in this spacetime on the rate of change of $H(t)$.
Transfer matrices of dipoles with bending radius variation
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
With the increasing demand of high brightness in light source, the uniform dipole can not meet the needs of low emittance, and thus the dipole with bending radius variation is introduced in this paper. The transfer matrix of a non-uniform dipole whose bending radius is linearly changed is chosen as an example and a very simple calculation formula of non-uniform dipole transfer matrices is given. The transfer matrices of some common profile non-uniform dipoles are also listed. The comparison of these transfer matrices and the matrices calculated with slices method verifies the numerical accuracy of this formula. This method can make the non-uniform beam dynamic problem simpler, very helpful for emittance research and lattice design with non-uniform dipoles.
Bending and rotational behaviour of semi-continuous composite beams
Institute of Scientific and Technical Information of China (English)
2008-01-01
Stresses and deflections were measured in various semi-continuous composite beams.The bending and rotational capacities of the composite connections were measured in terms of beam curvatures and deflections by using two full-scale semi-rigid composite frames with monotonic loadings.The effect of semi-rigid connections on the performance of composite beams with various loadings was compared with predictions and codes.The tests show that the semi-continuous composite beams are more economic and effective than the simple or continuous composite beams.The semi-rigid connections affect the bending capacities and beam deflections,so the connection behavior should be considered in the design of composite beams.Yielding analysis of the steel beam bottom flange has some influence on the deflection calculation of composite beams.
Elasticity solutions for functionally graded plates in cylindrical bending
Institute of Scientific and Technical Information of China (English)
YANG Bo; DING Hao-jiang; CHEN Wei-qiu
2008-01-01
The plate theory of functionally graded materials suggested by Mian and Spencer is extended to analyze the cylindrical bending problem of a functionally graded rectangular plate subject to uniform load. The expansion formula for displacements is adopted. While keeping the assumption that the material parameters can vary along the thickness direction in an arbitrary fashion, this paper considers orthotropic materials rather than isotropic materials. In addition, the traction-free condition on the top surface is replaced with the condition of uniform load applied on the top surface. The plate theory for the particular case of cylindrical bending is presented by considering an infinite extent in the y-direction. Effects of boundary conditions and material inhomogeneity on the static response of functionally graded plates are investigated through a numerical example.
Influence of bending test configuration on cracking behavior of FRC
DEFF Research Database (Denmark)
Finazzi, Silvia; Paegle, Ieva; Fischer, Gregor;
2014-01-01
This paper describes an investigation of the influence of the testing configuration for Fiber Reinforced Concrete in bending and aims at evaluating the influence of the test configuration details on the characterization of the material. Two different types of FRC, Steel Fiber Reinforced Concrete...... (SFRC) and Engineered Cementitious Composites (ECC), were tested and are described in this study. The materials were chosen so that one of them would be strain hardening (ECC) and the other tension softening (SFRC). Notched and un-notched three- and four-point bending tests were carried out to determine...... the flexural load-deformation response of FRC. This research focuses particularly on the influence of the appearance and depth of the notch on the cracking behavior of FRC. For this purpose, several specimens, both un-notched and notched with different depths of the notch (25 mm and 45 mm), were tested...
A new set of bending Td symmetry coordinates for MX4 molecules.
Schmidling, David
2013-12-15
The conventional set of Td symmetry coordinates for the bending modes of MX4 molecules can lead to ambiguous geometries when displacements from equilibrium are large. It is proposed here to use internal coordinates that are haversines of the bending angles divided by their sum. The A1 representation becomes a constant, enabling recovery of the bending angles unambiguously, analytically, and without approximation.
Requirements for Bend Insensitive Fiber in Millimeter-Wave Fronthaul Systems
DEFF Research Database (Denmark)
Rommel, Simon; Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José;
2015-01-01
The impact of fiber bending on mm-wave radioover-fiber transmission is investigated and the need for bend insensitive fiber for front-haul installation confirmed. A 70m Wband hybrid photonic-wireless link including bend insensitive fiber is demonstrated with BER
BENDING-SHEAR INTERACTION OF LONGITUDINALLY STIFFENED GIRDERS
Beg, Darko; Sinur, Franc
2011-01-01
To understand behaviour of longitudinally stiffened plated girders subjected to high bending moments and shear forces, four tests on large scale test specimens were performed. The results of these tests were used to verify the numerical model, which was employed for further parametric studies. With a verified simplified numerical model a parametric nonlinear analysis was systematically carried out to determine the resistance of longitudinally stiffened plated girders. Based on 630 numerical s...
Wooden models of an AA quadrupole between bending magnets
1978-01-01
At two points in the AA lattice, a quadrupole (QDN, defocusing, narrow) was tightly wedged between two bending magnets (BST, short, wide). This picture of wooden models lets one imagine the strong interaction between their magnetic fields. There was no way one could calculate with the necessary accuracy the magnetic effects and their consequences for the machine optics. The necessary corrections were made after measurements with a circulating beam, in a tedious iterative procedure, with corrrection coils and shims.
Problems with cryogenic operation of piezoelectric bending elements
Duffield, C. L.; Moreland, John; Fickett, F. R.
1986-05-01
Piezoelectric bimorphs constructed from lead titanate-zirconate (PZT) ceramic bonded to a brass sheet have been tested at cryogenic temperatures to determine their suitability for use in a low-temperature micropositioner. Experimental data are presented on bimorph sensitivity (displacement per volt) as a function of the number of temperature cycles. Results indicate that bimorphs of this type cannot be calibrated because of irreversible changes in the bending characteristics that occur while cycling from room temperature to 4 K.
Bending rigid molecular rods: formation of oligoproline macrocycles.
Scully, Conor C G; Rai, Vishal; Poda, Gennadiy; Zaretsky, Serge; Burns, Darcy C; Houliston, R Scott; Lou, Tiantong; Yudin, Andrei K
2012-12-01
Bent but not broken: cyclic oligoprolines are accessed in a reaction that effectively bends rigid oligoproline peptides (see scheme; TBDMS=tert-butyldimethylsilyl). The stitching is accomplished during macrocyclization enabled by aziridine aldehydes and isocyanides. Molecular modeling studies suggest that electrostatic attraction between the termini of the linear peptide is pivotal for macrocyclization. The macrocycles were studied by circular dichroism with a polyproline II structure being observed in larger macrocycles.
Influence of Whipping on Long term Vertical Bending Moment
DEFF Research Database (Denmark)
Baarholm, G. S.; Jensen, Jørgen Juncher
2004-01-01
This paper is concerned with estimating the response value corresponding to a long return period, say a twenty years. Time domain simulation is required to obtain the nonlinear response, and long time series are required to limit the statistical uncertainty in the simulations. It is crucial to in......). Results are presented for the S-175 container ship, (15th & 16th ITTC Seakeeping Committee 1983). The analysis shoes that whipping increases the vertical bending moment and that the correlation is significant...
GFRP Bar: Determining Tensile Strength with Bending Test
Almerich Chulia, Ana Isabel; Fenollosa Forner, Ernesto Jesús; Cabrera Fausto, Ivan
2015-01-01
In order to obtain GFRP reinforcement bars it is necessary to undertake tests regulated code which require important mechanical tools. This paper presents a method which allows for determining GFRP rebars tensile strength value from their flexural strength value which has been obtained with a simple, inexpensive and reliable test. This method results will be verified by applying it to values obtained in a series of bending tests and comparing these results with values obtained in tensile test...
Bending and Deformation of Sandwich Panels Due to Localized Pressure
Bambang K. Hadi; Fajar, A.
2005-01-01
Bending and deformation of sandwich panels due to localized pressure were analyzed using both Rayleigh-Ritz and finite element methods. The faces were made of laminated composite plates, while the core was a honeycomb material. Carbon fiber and glass fiber reinforced plastics were used for composite plate faces. In the case of Rayleigh-Ritz method, first the total energy of the system was calculated and then taking the variations of the total energy, the sandwich panel deflections could be co...
Predicting the static bending behavior of pallets with panel decks
Mackes, Kurt H.
1998-01-01
With increased use of pallets constructed utilizing structural panel decks, there is a need for a standardized, reliability-based design system, PDS-PANEL, to assist in the design and manufacture of panel-deck pallets. The primary objective of this research was to develop finite element models which predict the static bending behavior of pallets with at least one panel deck. stringer and block pallets were modeled using plate elements to simulate deck behavior and were...
Bending Capacity of Middle Joints of Upholstered Furniture Frames
Directory of Open Access Journals (Sweden)
Vasiliki Kamperidou, Vasileios Vasileiou
2012-12-01
Full Text Available This study evaluates the edgewise bending moment capacity of the four most frequently used middle joints in the upholstered furniture frames. The research included the following joints: Mortise and Tenon, double Dowel, Corner Blocks and double Gusset Plates, designed in the form of middle joints and made of beech and poplar solid wood. The test results indicated that regarding the edgewise bending force, the strongest middle joint was the double dowel joint made of beech wood (1896.9 N, while the respective joint made of poplar marked quite a low value of bending force (937.2 N. The strength of wooden corner blocks was proved to be quite powerful, made either of beech wood, poplar wood or the combination of the two wood species (beech: 1881.8 N, poplar: 1237.6 N, beech-poplar: 1783.6 N. The gusset plate joint made of beech resulted in weaker values (1378.2 N, compared to the dowel and corner block joints made of beech, whereas the same joint made of poplar demonstrated very satisfying values of edgewise bending force (1471.8 N. Finally, the mortise and tenon joint appeared to have the lowest strength, both in the case of beech (1306 N and poplar (634 N. The highest coeffi cient of elasticity (CE derived from double gusset plate joint, made of beech. All the joints showed good elasticity, except the mortise and tenon joint made of poplar, as well as, the dowel joint made of poplar, which recorded the lowest elasticity values of all. Generally, beech wood resulted in stronger and more elastic joints compared to poplar.
[On fatigue bending strength of PMMA-specimen (author's transl)].
Rojczyk, M; Rojczyk-Pflüger, J
1980-01-01
The fatigue response of PMMA-specimen was tested under cyclic bending of 1.5 Hz in a particularly designed testing device. Specimen were tested that a "Wöhler" curve and the corresponding fatigue strength could be evaluated. The fatigue strength was reached after a comparatively short time and ranged in the order of 33 per cent of static breaking strength. PMID:7447658
Bending and compressive behaviours of a new cement composite
P. Rossi; ARCA, A; PARANT, E; FAKHRI, P
2005-01-01
The Laboratoire Central des Ponts et Chaussées (LCPC) has recently developed and patented a new cement composite, the CEMTECmultiscale, which is stress hardening in tension and has a very high uniaxial tensile strength, more than 20 MPa. This paper is about the determination of the compressive and bending behaviors of the CEMTECmultiscale used in the frame of ribbed slabs. The principal results obtained are the following: - the characteristic modulus of rupture is equal to 42 MPa for the "sla...
Bending resistance of composite steel truss and concrete beam
Silva, Mickael; Piloto, P.A.G.; Roque, Sérgio; VILA REAL Paulo; Plizzari, Giovanni
2013-01-01
This study presents the numerical simulation of the bending resistance of CSTCB in stage 1 (element made only by the self-supported steel truss and base plate). Two different base plates were considered (Steel and Concrete) and two different types of steel trusses (Type I and II). The numerical results are also compared with analytical results, assuming the full interaction between steel truss and concrete, neglecting the tensile strength of concrete, considering the effective area of concret...
BENDING ANALYSIS OF COMPOSITE PLATES USING HIGHER ORDER THEORY
N UPENDRA; B. Sidda Reddy; K TIRUPATI REDDY; AJAY KUMAR REDDY K
2013-01-01
In this paper, an analytical formulation and solutions are developed to investigate the bending characteristics of laminated composite plates based on higher order shear deformation theory. The equation ofmotion of laminated plates is deduced using Hamilton’s principle. Closed-form solutions are obtained by using the Navier’s technique for simply supported boundary conditions. The effect of side to thickness ratio, aspect ratio, degree of orthotropic, stacking sequence ad no of layers on defl...
How two-dimensional bending can extraordinarily stiffen thin sheets
Pini, V.; Ruz, J. J.; Kosaka, P. M.; Malvar, O.; Calleja, M.; Tamayo, J.
2016-07-01
Curved thin sheets are ubiquitously found in nature and manmade structures from macro- to nanoscale. Within the framework of classical thin plate theory, the stiffness of thin sheets is independent of its bending state for small deflections. This assumption, however, goes against intuition. Simple experiments with a cantilever sheet made of paper show that the cantilever stiffness largely increases with small amounts of transversal curvature. We here demonstrate by using simple geometric arguments that thin sheets subject to two-dimensional bending necessarily develop internal stresses. The coupling between the internal stresses and the bending moments can increase the stiffness of the plate by several times. We develop a theory that describes the stiffness of curved thin sheets with simple equations in terms of the longitudinal and transversal curvatures. The theory predicts experimental results with a macroscopic cantilever sheet as well as numerical simulations by the finite element method. The results shed new light on plant and insect wing biomechanics and provide an easy route to engineer micro- and nanomechanical structures based on thin materials with extraordinary stiffness tunability.
Cylindrical Bending of Deformable Textile Rectangular Patch Antennas
Directory of Open Access Journals (Sweden)
Freek Boeykens
2012-01-01
Full Text Available Textile patch antennas are well known as basic components for wearable systems that allow communication between a human body and the external world. Due to their flexibility, textile antennas are subjected to bending when worn, causing a variation in resonance frequency and radiation pattern with respect to the flat state in which their nominal design is performed. Hence, it is important for textile antenna engineers to be able to predict these performance parameters as a function of the bending radius. Therefore, we propose a comprehensive analytical model that extends the cylindrical cavity model for conformal rigid patch antennas by incorporating the effects of patch stretching and substrate compression. It allows to predict the resonance frequency and the radiation pattern as a function of the bending radius. Its validity has been verified experimentally. Unlike previous contributions, which concerned only qualitative studies by means of measurements and numerical full-wave simulations, the proposed model offers advantages in terms of physical insight, accuracy, speed, and cost.
Modeling of a cracked beam section under bending
International Nuclear Information System (INIS)
Numerical simulations are widely used to study the dynamical behaviour of turbines cracked shaft as this event is rare and then doesn't enable to have an useful industrial feedback. A new method, which enables to calculate the constitutive law of a cracked beam subjected to bending was previously proposed. Based on three-dimensional computations taking into account the unilateral contact between both lips of the crack, it consists in defining a (non-linear) behaviour relation between the bending moment applied to the cracked section and the resulting field of displacements, compatible with the beam theory so that it can be used in rotor-dynamics software. The aim of this paper is to complete this first model by adding shear effects. For some crack geometries, a simpler model can be derived, based on the recognition that bending moments and shear forces are uncoupled and the dependence of the behaviour law with respect to the shear forces becomes linear. Developments have been achieved in this case and some results of the validation tests are shown. (authors)
A missing-bending-magnet scheme for PEP
International Nuclear Information System (INIS)
This article presents a missing-bending-magnet scheme for PEP as a modification that could be considered if PEP were available as a fully dedicated synchrotron radiation source. The scheme can be applied to one or more PEP sextants without changing the rest. By removing some bending magnets, rearranging the remaining magnets, and adding two quadrupoles, ten additional straight sections per sextant can be created, each 5 m or more in length, for insertion devices. Beam lines therefrom, plus possible beam lines from bending magnets would enter a continuous experimental hall instead of individual tunnels and halls for each beam line. This should result in construction cost savings and increased operations efficiency. The ideal beam orbit is unchanged at the two ends and the middle of the sextant. At the end of the curved part of the sextant the lattice functions match those of the long interaction region straight section in the low emittance configuration of PEP. The electron beam characteristics in the newly created straight sections are described, including the enlargement of the horizontal beam size due to the nonzero dispersion. Some disadvantages of the scheme are increased operations complexity due to the need for nine new quadrupole families, increased beam emittance (by 14.5% is one sextant is modified), and reduced dynamic aperture. However, the dynamic aperture is still about as large as the physical aperture and should be adequate for good beam lifetime and injection. (orig.)
Bamboo Taper Effect on Third Point Loading Bending Test
Directory of Open Access Journals (Sweden)
Naresworo Nugroho
2013-06-01
Full Text Available Geometrical shape of bamboo usually assumed as tapered hollow pipe. This study proved that the dimensional changes along the bamboo stem significantly affected to its Modulus of Rupture (SR value which measured from third point loading bending test. Therefore if the bending test applied using third point loading configuration, the SR value should be adjusted by strength ratio of taper (Ct. Ct is theratio between (SR calculated in the center span and the maximum bending stress along the bamboo beam. This study resulted mathematical formulae to calculate the Ct value for overall range of bamboo taper based on six species namely Tali (Gigantochloa apus (Bl.Ex Schult.f Kurz, Hitam (Gigantochloa atroviolaceae Widjaja, Andong (Gigantochloa psedorundinaceae, Ampel (Bambusa vulgaris Schrad, Gombong (Gigantochloa verticillata (Willd Munro, and Mayan (Gigantochloa robusta Kurz. The first tree species were obtained from the Bogor market, while the others were harvested from bamboo clumps in Arboretum Bamboo – Bogor Agricultural University. Then the formula was applied to sketch the graphical style in order to simplify the result.
Optimal Recursive Digital Filters for Active Bending Stabilization
Orr, Jeb S.
2013-01-01
In the design of flight control systems for large flexible boosters, it is common practice to utilize active feedback control of the first lateral structural bending mode so as to suppress transients and reduce gust loading. Typically, active stabilization or phase stabilization is achieved by carefully shaping the loop transfer function in the frequency domain via the use of compensating filters combined with the frequency response characteristics of the nozzle/actuator system. In this paper we present a new approach for parameterizing and determining optimal low-order recursive linear digital filters so as to satisfy phase shaping constraints for bending and sloshing dynamics while simultaneously maximizing attenuation in other frequency bands of interest, e.g. near higher frequency parasitic structural modes. By parameterizing the filter directly in the z-plane with certain restrictions, the search space of candidate filter designs that satisfy the constraints is restricted to stable, minimum phase recursive low-pass filters with well-conditioned coefficients. Combined with optimal output feedback blending from multiple rate gyros, the present approach enables rapid and robust parametrization of autopilot bending filters to attain flight control performance objectives. Numerical results are presented that illustrate the application of the present technique to the development of rate gyro filters for an exploration-class multi-engined space launch vehicle.
Biomorphodynamic modelling of inner bank advance in migrating meander bends
Zen, Simone; Zolezzi, Guido; Toffolon, Marco; Gurnell, Angela M.
2016-07-01
We propose a bio-morphodynamic model at bend cross-sectional scale for the lateral migration of river meander bends, where the two banks can migrate separately as a result of the mutual interaction between river flow, sediments and riparian vegetation, particularly at the interface between the permanently wet channel and the advancing floodplain. The model combines a non-linear analytical model for the morphodynamic evolution of the channel bed, a quasi-1D model to account for flow unsteadiness, and an ecological model describing riparian vegetation dynamics. Simplified closures are included to estimate the feedbacks among vegetation, hydrodynamics and sediment transport, which affect the morphology of the river-floodplain system. Model tests reveal the fundamental role of riparian plants in generating bio-morphological patterns at the advancing floodplain margin. Importantly, they provide insight into the biophysical controls of the 'bar push' mechanism and into its role in the lateral migration of meander bends and in the temporal variations of the active channel width.
Bending instability in galactic discs. Advocacy of the linear theory
Rodionov, S A
2013-01-01
We demonstrate that in N-body simulations of isolated disc galaxies there is numerical vertical heating which slowly increases the vertical velocity dispersion and the disc thickness. Even for models with over a million particles in a disc, this heating can be significant. Such an effect is just the same as in numerical experiments by Sellwood (2013). We also show that in a stellar disc, outside a boxy/peanut bulge, if it presents, the saturation level of the bending instability is rather close to the value predicted by the linear theory. We pay attention to the fact that the bending instability develops and decays very fast, so it couldn't play any role in secular vertical heating. However the bending instability defines the minimal value of the ratio between the vertical and radial velocity dispersions $\\sigma_z / \\sigma_R \\approx 0.3$ (so indirectly the minimal thickness) which could have stellar discs in real galaxies. We demonstrate that observations confirm last statement.
Stress intensity factors under combined bending and torsion moments
Institute of Scientific and Technical Information of China (English)
Al Emran ISMAIL; Ahmad Kamal ARIFFIN; Shahrum ABDULLAH; Mariyam Jameelah GHAZALI; Mohammed ABDULRAZZAQ; Ruslizam DAUD
2012-01-01
This paper discusses stress intensity factor (SIF) calculations for surface cracks in round bars subjected to combined torsion and bending loadings.Different crack aspect ratios,a/b,ranging from 0.0 to 1.2 and relative crack depths,a/D,ranging from 0.1 to 0.6 were considered.Since the loading was non-symmetrical for torsion loadings,a whole finite element model was constructed.Then,the individual and combined bending and torsion loadings were remotely applied to the model.The equivalent SIF method,F* EQ,was then used explicitly to combine the individual SIFs from the bending and torsion loadings.A comparison was then carried out with the combined SIE F* FE,obtained using the finite element analysis (FEA) under similar loadings.It was found that the equivalent SIF method successfully predicted the combined SIF for Mode (I).However,discrepancies between the results determined from the different approaches occurred when FⅢ was involved.It was also noted that the predicted F* FE using FEA was higher than the F* EQ predicted through the equivalent SIF method due to the difference in crack face interactions.
Bending-induced Symmetry Breaking of Lithiation in Germanium Nanowires
Energy Technology Data Exchange (ETDEWEB)
Gu, Meng; Yang, Hui; Perea, Daniel E.; Zhang, Jiguang; Zhang, Sulin; Wang, Chong M.
2014-08-01
From signal transduction of living cells to oxidation and corrosion of metals, mechanical stress intimately couples with chemical reactions, regulating these biological and physiochemical processes. The coupled effect is particularly evident in electrochemical lithiation/delithiation cycling of high-capacity electrodes, such as silicon (Si), where on one hand lithiation-generated stress mediates lithiation kinetics, and on the other electrochemical reaction rate regulates stress generation and mechanical failure of the electrodes. Here we report for the first time the evidence on the controlled lithiation in germanium nanowires (GeNWs) through external bending. Contrary to the symmetric core-shell lithiation in free-standing GeNWs, we show bending GeNWs breaks the lithiation symmetry, speeding up lithaition at the tensile side while slowing down at the compressive side of the GeNWs. The bending-induced symmetry breaking of lithiation in GeNWs is further corroborated by chemomechanical modeling. In the light of the coupled effect between lithiation kinetics and mechanical stress in the electrochemical cycling, our findings shed light on strain/stress engineering of durable high-rate electrodes and energy harvesting through mechanical motion.
Bending light on demand by holographic sculpturing its wavefront
Latychevskaia, Tatiana
2015-01-01
A classical light beam propagates along a straight line and does not bend unless in a medium of variable refractive index. It is well known that by modifying the wavefront in a certain manner, the light intensity can be turned into a certain shape. Examples are optical lenses or Fresnel Zone Plates for focusing an incident wave to a point at the focal plane. Another example are Airy beams created by modifying the phase distribution of the wavefront into an Airy function resulting in a bending of the light intensity while propagating. A further example is holography, where the phase of the wavefront passing through a hologram is changed to mimic the object wavefront, thus providing the illusion that the original object is present in space. However, all these known techniques allow for limited light modifications: either focusing within a limited region in space2 or shaping a certain class of parametric curves along the optical axis or creating a bend in a quadratic-dependent declination as in the case of Airy ...
Bending-induced symmetry breaking of lithiation in germanium nanowires.
Gu, Meng; Yang, Hui; Perea, Daniel E; Zhang, Ji-Guang; Zhang, Sulin; Wang, Chong-Min
2014-08-13
From signal transduction of living cells to oxidation and corrosion of metals, mechanical stress intimately couples with chemical reactions, regulating these biological and physiochemical processes. The coupled effect is particularly evident in the electrochemical lithiation/delithiation cycling of high-capacity electrodes, such as silicon (Si), where on the one hand lithiation-generated stress mediates lithiation kinetics and on the other the electrochemical reaction rate regulates stress generation and mechanical failure of the electrodes. Here we report for the first time the evidence on the controlled lithiation in germanium nanowires (GeNWs) through external bending. Contrary to the symmetric core-shell lithiation in free-standing GeNWs, we show bending the GeNWs breaks the lithiation symmetry, speeding up lithaition at the tensile side while slowing down at the compressive side of the GeNWs. The bending-induced symmetry breaking of lithiation in GeNWs is further corroborated by chemomechanical modeling. In the light of the coupled effect between lithiation kinetics and mechanical stress in the electrochemical cycling, our findings shed light on strain/stress engineering of durable high-rate electrodes and energy harvesting through mechanical motion. PMID:25025296
Electro-active material (EAM) based bend sensors
LaComb, Ronald; LaComb, Julie
2010-04-01
The capability to accurately estimate strain and orientation of cables in an undersea environment is important for a multitude of applications. One way to estimate the positional location of a submersed cable is to utilize a network of distributed bend sensors providing inputs to a curve fitting algorithm. In this work commercially available bend sensors are characterized for small deflections. In addition proto-type devices are presented which can potentially improve device sensitivity. Commercially available bend sensors are based upon electro-active materials and variable resistance materials. Electro-active materials (EAM) are known for their actuator functionality but certain EAMs are capable of sensing as well. New advances in materials such as Ionic Polymer Metal Composites (IPMC) are proving suitable for quasi-static sensor applications. These sensors are low power, conformal and produce directionally dependent output voltages which are linearly proportional to deflection, with voltage polarity representative of the deflection direction. IPMCs are capable of being morphed for increased sensitivity. Variable resistivity sensors are based on smart epoxy polymer and carbon loaded inks. These sensors are inexpensive and conformal and unlike EAMs provide static measurements.
Bending elasticity of charged surfactant layers: the effect of mixing.
Bergström, L Magnus
2006-08-01
Expressions have been derived from which the spontaneous curvature (H(0)), bending rigidity (k(c)), and saddle-splay constant (k(c)) of mixed monolayers and bilayers may be calculated from molecular and solution properties as well as experimentally available quantities such as the macroscopic hydrophobic-hydrophilic interfacial tension. Three different cases of binary surfactant mixtures have been treated in detail: (i) mixtures of an ionic and a nonionic surfactant, (ii) mixtures of two oppositely charged surfactants, and (iii) mixtures of two ionic surfactants with identical headgroups but different tail volumes. It is demonstrated that k(c)H(0), k(c), and k(c) for mixtures of surfactants with flexible tails may be subdivided into one contribution that is due to bending properties of an infinitely thin surface as calculated from the Poisson-Boltzmann mean field theory and one contribution appearing as a result of the surfactant film having a finite thickness with the surface of charge located somewhat outside the hydrophobic-hydrophilic interface. As a matter of fact, the picture becomes completely different as finite layer thickness effects are taken into account, and as a result, the spontaneous curvature is extensively lowered whereas the bending rigidity is raised. Furthermore, an additional contribution to k(c) is present for surfactant mixtures but is absent for k(c)H(0) and k(c). This contribution appears as a consequence of the minimization of the free energy with respect to the composition of a surfactant layer that is open in the thermodynamic sense and must always be negative (i.e., k(c) is generally found to be brought down by the process of mixing two or more surfactants). The magnitude of the reduction of k(c) increases with increasing asymmetry between two surfactants with respect to headgroup charge number and tail volume. As a consequence, the bending rigidity assumes the lowest values for layers formed in mixtures of two oppositely charged
Effect of Bend Curvature Ratio on Flow Pattern at a Mixing Tee after a 90 Degree Bend
Directory of Open Access Journals (Sweden)
Hidetoshi Hashizumeh
2009-11-01
Full Text Available Many nuclear power plants report high cycle thermal fatigue in their cooling system, caused by temperature fluctuation in a non-isothermal mixing area. One of these areas is the T-junction, in which fluids of various temperatures and velocities blend. The objective of this research is to classify turbulent jet mechanics in order to examine the flow-field structure under various operating conditions. Furthermore, this research discovers the optimum operating conditions of the mixing tee in this piping system. An experimental model, including the T-junction with a 90 degree bend upstream, is operated to analyze this mixing phenomenon based on the real operation design of the Phenix Reactor. The temperature and velocity data show that a 90 degree bend has a strong effect on the fluid mixing mechanism and the momentum ratio between the main velocity and the branch velocity of the T-junction, which could be an important parameter for the classification of the fluid mixing mechanism. By comparing their mean velocity distributions, velocity fluctuations and time-series data, the behavior of the branch jet is categorized into four types of turbulent jets; sorted from the highest to the lowest momentum ratios, the jets are categorized as follows: the wall jet, the re-attached jet, the turn jet, and the impinging jet. Ultimately, the momentum ration of the turn jet was selected as the optimum operating condition as it has the lowest velocity and the lowest temperature fluctuations near the wall of the mixing tee. By changing the bending ratio from 1.41 to 1.0 the results show that most of data are in the turn jet region. Therefore, with the sharpened bend, the re-attached region is compressed.
EXPERIMENTAL STUDY ON BED SCOUR IN A 90°CHANNEL BEND
Institute of Scientific and Technical Information of China (English)
Masoud GHODSIAN; S. Kamal MOUSAVI
2006-01-01
The special feature of bend flow leads to scouring of the bed and bank. Various parameters like flow depth, flow velocity or discharge, geometry of bend and characteristics of bed material may affect the scour process. Experiments were carried out to study the effect of some important parameters on bend scour under clear water condition. Experiments were conducted in a 0.6m wide and 0.7m high flume with 90 degree bend. The lateral variations of bed slope were studied. The maximum depth of scour was correlated to densimetric Froude number, relative bend radius and relative depth of flow.
Energy Technology Data Exchange (ETDEWEB)
Kohno, Hideo, E-mail: kohno.hideo@kochi-tech.ac.jp [School of Environmental Science and Engineering, Kochi University of Technology, Kami, Kochi 782-8502 (Japan); Masuda, Yusuke [Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043 (Japan)
2015-05-11
When the direction of flattening of a carbon nanotube changes during growth mediated by a metal nanoparticle, a carbon nanotetrahedron is formed in the middle of the carbon nanoribbon. We report the bending properties of the carbon nanotetrahedron/nanoribbon structure using a micro-manipulator system in a transmission electron microscope. In many cases, bending occurs at an edge of the carbon nanotetrahedron. No significant change is observed in the tetrahedron's shape during bending, and the bending is reversible and repeatable. Our results show that the carbon nanotetrahedron/nanoribbon structure has good durability against mechanical bending.
Optimal r/b ratio of bend channel in centrifugal compressor
Institute of Scientific and Technical Information of China (English)
Suping WEN; Xiaowen HU; Yong ZHANG; Jun WANG; Tingbin LI
2008-01-01
A numerical investigation on the flow in a bend channel by coupling the impeller with the vaneless diffuser in a centrifugal compressor with different r/b ratios (bend radius r to bend channel width b) is presented. The jet-wake effect of the impeller outlet is considered and flow pattern in the bend channel and the performance of the centrifugal compressor stage are investigated. The results indicate that there is an optimal r/b ratio for increasing the stage efficiency to the highest for a specific compressor stage. The change in r/b ratio significantly affects the flow angle of the bend chan-nel outlet. The prime reason for the total pressure loss in the bend channel is the wall friction in the bend channel.
Influence of Characteristics on Bending Strength of Layered Steel Fiber Reinforced Concrete
Institute of Scientific and Technical Information of China (English)
DAI Shao-bin; SONG Ming-hai; HUANG Jun
2005-01-01
The influence of two main characteristics of steel fiber, the aspect ratio (Df) and volume fraction (pf), on the bending strength of Layered Steel Fiber Reinforced Concrete (LSFRC) is investigated by using orthogonal test. Via the variance analysis on the experimental results and trend analysis on the two characteristics, Df is found significantly related to the bending strength of LSFRC. The influence ratio is 63.3%. The bending strength of LSFRC increases if Df increases, makes better when Df reaches 100. ρf has ordinary influence on the bending strength of LSFRC. The influence ratio is 29.2%. Other characteristics, such as the shape of steel fiber and the mix proportion, have less influence. The best ρf contributing to the bending strength of LSFRC is 1.5 %. If pf is greater than 1.5 %, it has negative influence on the bending strength of LSFRC. So, pf makes a limited contribution to the bending strength of LSFRC.
Geologic map of Big Bend National Park, Texas
Turner, Kenzie J.; Berry, Margaret E.; Page, William R.; Lehman, Thomas M.; Bohannon, Robert G.; Scott, Robert B.; Miggins, Daniel P.; Budahn, James R.; Cooper, Roger W.; Drenth, Benjamin J.; Anderson, Eric D.; Williams, Van S.
2011-01-01
The purpose of this map is to provide the National Park Service and the public with an updated digital geologic map of Big Bend National Park (BBNP). The geologic map report of Maxwell and others (1967) provides a fully comprehensive account of the important volcanic, structural, geomorphological, and paleontological features that define BBNP. However, the map is on a geographically distorted planimetric base and lacks topography, which has caused difficulty in conducting GIS-based data analyses and georeferencing the many geologic features investigated and depicted on the map. In addition, the map is outdated, excluding significant data from numerous studies that have been carried out since its publication more than 40 years ago. This report includes a modern digital geologic map that can be utilized with standard GIS applications to aid BBNP researchers in geologic data analysis, natural resource and ecosystem management, monitoring, assessment, inventory activities, and educational and recreational uses. The digital map incorporates new data, many revisions, and greater detail than the original map. Although some geologic issues remain unresolved for BBNP, the updated map serves as a foundation for addressing those issues. Funding for the Big Bend National Park geologic map was provided by the United States Geological Survey (USGS) National Cooperative Geologic Mapping Program and the National Park Service. The Big Bend mapping project was administered by staff in the USGS Geology and Environmental Change Science Center, Denver, Colo. Members of the USGS Mineral and Environmental Resources Science Center completed investigations in parallel with the geologic mapping project. Results of these investigations addressed some significant current issues in BBNP and the U.S.-Mexico border region, including contaminants and human health, ecosystems, and water resources. Funding for the high-resolution aeromagnetic survey in BBNP, and associated data analyses and
On the bending algorithms for soft objects in flows
Guckenberger, Achim; Schraml, Marcel P.; Chen, Paul G.; Leonetti, Marc; Gekle, Stephan
2016-10-01
One of the most challenging aspects in the accurate simulation of three-dimensional soft objects such as vesicles or biological cells is the computation of membrane bending forces. The origin of this difficulty stems from the need to numerically evaluate a fourth order derivative on the discretized surface geometry. Here we investigate six different algorithms to compute membrane bending forces, including regularly used methods as well as novel ones. All are based on the same physical model (due to Canham and Helfrich) and start from a surface discretization with flat triangles. At the same time, they differ substantially in their numerical approach. We start by comparing the numerically obtained mean curvature, the Laplace-Beltrami operator of the mean curvature and finally the surface force density to analytical results for the discocyte resting shape of a red blood cell. We find that none of the considered algorithms converges to zero error at all nodes and that for some algorithms the error even diverges. There is furthermore a pronounced influence of the mesh structure: Discretizations with more irregular triangles and node connectivity present serious difficulties for most investigated methods. To assess the behavior of the algorithms in a realistic physical application, we investigate the deformation of an initially spherical capsule in a linear shear flow at small Reynolds numbers. To exclude any influence of the flow solver, two conceptually very different solvers are employed: the Lattice-Boltzmann and the Boundary Integral Method. Despite the largely different quality of the bending algorithms when applied to the static red blood cell, we find that in the actual flow situation most algorithms give consistent results for both hydrodynamic solvers. Even so, a short review of earlier works reveals a wide scattering of reported results for, e.g., the Taylor deformation parameter. Besides the presented application to biofluidic systems, the investigated
NONLINEAR BENDING THEORY OF DIAGONAL SQUARE PYRAMID RETICULATED SHALLOW SHELLS
Institute of Scientific and Technical Information of China (English)
肖潭; 刘人怀
2001-01-01
Double-deck reticulated shells are a main form of large space structures. One of the shells is the diagonal square pyramid reticulated shallow shell, whose its upper and lower faces bear most of the load but its core is comparatively flexible. According to its geometrical and mechanical characteristics, the diagonal square pyramid reticulated shallow shell is treated as a shallow sandwich shell on the basis of three basic assumptions. Its constitutive relations are analyzed from the point of view of energy and internal force equivalence. Basic equations of the geometrically nonlinear bending theory of the diagonal square pyramid reticulated shallow shell are established by means of the virtual work principle .
TRAPEZOIDAL PLATE BENDING ELEMENT WITH DOUBLE SET PARAMETERS
Institute of Scientific and Technical Information of China (English)
Shao-chun Chen; Dong-yang Shi; I chiro Hagiwara
2003-01-01
Using double set parameter method, a 12-parameter trapezoidal plate bending element is presented. The first set of degrees of freedom, which make the element convergent, are the values at the four vertices and the middle points of the four sides together with the mean values of the outer normal derivatives along four sides. The second set of degree of freedom, which make the number of unknowns in the resulting discrete system small and computation convenient are values and the first derivatives at the four vertices of the element. The convergence of the element is proved.
Fiber-Optic Bend Sensor Based on Double Cladding Fiber
Ivanov, Oleg V.; Alexey A. Chertoriyskiy
2015-01-01
We develop and investigate fiber-optic bend sensor, which is formed by a section of double cladding SM630 fiber between standard SMF-28 fibers. The principle of operation of the sensor is based on coupling of the fiber core and cladding modes at the splices of fibers having different refractive index profiles. We use two sources with wavelengths 1328 and 1545 nm to interrogate the sensor. The dependences of transmission on curvature at these wavelengths are significantly different. We show th...
Bending modulus of bidisperse particle rafts: Local and collective contributions
Petit, Pauline; Biance, Anne-Laure; Lorenceau, Elise; Planchette, Carole
2016-04-01
The bending modulus of air-water interfaces covered by a monolayer of bidisperse particles is probed experimentally under quasistatic conditions via the compression of the monolayer, and under dynamical conditions studying capillary-wave propagation. Simple averaging of the modulus obtained solely with small or large particles fails to describe our data. Indeed, as observed in other configurations for monodisperse systems, bidisperse rafts have both a granular and an elastic character: chain forces and collective effects must be taken into account to fully understand our results.
Homogenization of long fiber reinforced composites including fiber bending effects
DEFF Research Database (Denmark)
Poulios, Konstantinos; Niordson, Christian Frithiof
2016-01-01
to maintain the kinematics of the two material phases independent from the assumed constitutive models, so that stress-deformation relationships, can be expressed in the framework of hyper-elasticity and hyper-elastoplasticity for the fiber and the matrix materials respectively. The bending stiffness......This paper presents a homogenization method, which accounts for intrinsic size effects related to the fiber diameter in long fiber reinforced composite materials with two independent constitutive models for the matrix and fiber materials. A new choice of internal kinematic variables allows...... of the matrix and the fibers....
Wake-induced bending of two-dimensional plasma crystals
Röcker, T B; Zhdanov, S K; Couëdel, L; Morfill, G E
2014-01-01
It is shown that the wake-mediated interactions between microparticles in a two-dimensional plasma crystal affect the shape of the monolayer, making it non-flat. The equilibrium shape is calculated for various distributions of the particle number density in the monolayer. For typical experimental conditions, the levitation height of particles in the center of the crystal can be noticeably smaller than at the periphery. It is suggested that the effect of wake-induced bending can be utilized in experiments, to deduce important characteristics of the interparticle interaction.
Wake-induced bending of two-dimensional plasma crystals
Energy Technology Data Exchange (ETDEWEB)
Röcker, T. B., E-mail: tbr@mpe.mpg.de; Ivlev, A. V., E-mail: ivlev@mpe.mpg.de; Zhdanov, S. K.; Morfill, G. E. [Max Planck Institute for Extraterrestrial Physics, 85741 Garching (Germany); Couëdel, L. [CNRS, Aix-Marseille-Université, Laboratoire de Physique des Interactions Ioniques et Moléculaires, UMR 7345, 13397 Marseille Cedex 20 (France)
2014-07-15
It is shown that the wake-mediated interactions between microparticles in a two-dimensional plasma crystal affect the shape of the monolayer, making it non-flat. The equilibrium shape is calculated for various distributions of the particle number density in the monolayer. For typical experimental conditions, the levitation height of particles in the center of the crystal can be noticeably smaller than at the periphery. It is suggested that the effect of wake-induced bending can be utilized in experiments, to deduce important characteristics of the interparticle interaction.
Microstructure controlled bending response in AA6016 Al alloys
International Nuclear Information System (INIS)
Highlights: → The hemmability of two AA6016-type aluminium alloys in T4P temper state is studied. → High Mg content and long solutionizing times increase the precipitation potential. → Inhomogeneous grain boundary particles form by precipitation of alloying elements. → Large amount of particles combined with high matrix strength reduce the hemmability. → Intergranular fracture is promoted by grain boundary debonding and voids formation. - Abstract: A contemporary approach in the car weight reduction is the use of low weight and high strength Al alloys sheets for hang-on body panels production. The final step in the forming route of such panels is the attachment of the outer skin to the inner part of the panel by applying a hemming operation. This joining method is cheap, easy to perform and environment-friendly, but requires severe 180 deg. bending of the edges of the outer skin which quite often results in cracking or complete tearing of the bend surface. Such kind of failure restricts the further application of the hemmed products. The microstructures after solution heat treatment and pre-aging (T4P temper state) of two grades age-hardening AA6016-type aluminium alloy sheets were studied in this work by means of optical microscopy, scanning electron microscopy and electron backscatter diffraction. The obtained results were related to the hemming response of the grades. It was found that the alloy composition is one of the main parameters controlling the bendability of these grades through the amount of the formed strengthening phases. However, the applied thermal treatment remains the key factor responsible for the favorable distribution of these phases into the microstructure. The grain size and the volume fraction of the constituent particles were found to play secondary role in forming the material bending properties and can be only used for their fine tuning. The presence of Mg2Si (β-phase) and/or Al1.9CuMg4.1Si3.3 (Q-phase) particles in the grain
Tilted bending magnet for SPS target area TCC2
1976-01-01
A slow-extracted proton beam from the SPS goes to the underground target zone TCC2. The part of the primary beam which traverses target T4 is recuperated and transported over some 800 m, for further use in the North Area High Intensity facility (NAHIF). The curved and sloped trajectory required 4 of the bending magnets to be tilted. Here we see one of them being attended by Gilbert Françon in hall 867, ready for installation in TCC2.
BENDING ANALYSIS OF COMPOSITE PLATES USING HIGHER ORDER THEORY
Directory of Open Access Journals (Sweden)
N UPENDRA
2013-10-01
Full Text Available In this paper, an analytical formulation and solutions are developed to investigate the bending characteristics of laminated composite plates based on higher order shear deformation theory. The equation ofmotion of laminated plates is deduced using Hamilton’s principle. Closed-form solutions are obtained by using the Navier’s technique for simply supported boundary conditions. The effect of side to thickness ratio, aspect ratio, degree of orthotropic, stacking sequence ad no of layers on deflection and stresses are investigated. The results predicted by the present theory are in good agreement with the solutions of other plate theories available in the literature.
A Novel Low-Cost, Large Curvature Bend Sensor Based on a Bowden-Cable.
Jeong, Useok; Cho, Kyu-Jin
2016-06-24
Bend sensors have been developed based on conductive ink, optical fiber, and electronic textiles. Each type has advantages and disadvantages in terms of performance, ease of use, and cost. This study proposes a new and low-cost bend sensor that can measure a wide range of accumulated bend angles with large curvatures. This bend sensor utilizes a Bowden-cable, which consists of a coil sheath and an inner wire. Displacement changes of the Bowden-cable's inner wire, when the shape of the sheath changes, have been considered to be a position error in previous studies. However, this study takes advantage of this position error to detect the bend angle of the sheath. The bend angle of the sensor can be calculated from the displacement measurement of the sensing wire using a Hall-effect sensor or a potentiometer. Simulations and experiments have shown that the accumulated bend angle of the sensor is linearly related to the sensor signal, with an R-square value up to 0.9969 and a root mean square error of 2% of the full sensing range. The proposed sensor is not affected by a bend curvature of up to 80.0 m(-1), unlike previous bend sensors. The proposed sensor is expected to be useful for various applications, including motion capture devices, wearable robots, surgical devices, or generally any device that requires an affordable and low-cost bend sensor.
Takahashi, Asami; Ishigure, Takaaki
2015-02-01
We fabricate low-loss graded index (GI) circular core multimode polymer optical waveguides with 90o bending and demonstrate low bending loss even if the bend radius is as small as 1 mm. In the several fabrication methods for GI-core polymer waveguides already proposed, we adopt the "Mosquito method" that utilize a microdispenser because the Mosquito method makes it possible to fabricate waveguides directly on board at desired places on a printed circuit board, and to draw various patterns of cores including curves. However, in the waveguides including such curved cores, the additional transmission loss due to the bending (bending loss) is a concern. Thus, we characterize the fabricated GI-core polymer waveguides with bending: using two kinds of cladding monomer with different refractive indexes for fabricating waveguides with bending. We found when the NA of waveguides was as high as 0.35, no additional loss due to bending was observed even if the bending radius is as small as 1 mm. The core diameter of the fabricated waveguides is 50 μm, and it is possible to further decrease the bending loss in the waveguides with smaller core diameter. Furthermore, utilizing the Mosquito method, we fabricate waveguides with not only horizontally curved cores but also vertically curved ones. Waveguides with vertically curved cores could make it possible to realize three-dimensionally optical wiring applicable to on-board optical interconnects.
Static Pull and Push Bending Properties of RTM-made TWF Composite Tee-joints
Institute of Scientific and Technical Information of China (English)
LUO Chuyang; XIONG Junjiang
2012-01-01
This paper deals with static pull and push bending tests on two-dimensional (2D) orthogonal EW220/5284 twill weave fabric (TWF) composite tee-joints processed with the resin transfer moulding (RTM) technique.Static pull and push bending properties are determined and failure initiation mechanism is deduced from experimental observations.The experiments show that the failure initiation load,on average,is greater for push bending than for pull bending,whereas the scatter is smaller for push bending than for pull bending.The failure mode of RTM-made tee-joints in pull bending tests can be reckoned to be characteristic of debonding of resin matrix at the interface between the triangular resin-rich zone and the curved web of tee-joint until complete separation of the curved web from the bottom plate.In contrast,as distinct from the products subject to pull bending loading,the RTM tee-joints in push bending tests experience matrix cracking and fibre fracture from outer layers to inner layers of the bottom plate until catastrophic collapse resulting from the bending.Three-dimensional finite element (FE) models are presented to simulate the load transfer path and failure initiation mechanism of RTM-made TWF composite tee-joint based on the maximum stress criterion.Good correlation between experimental and numerical results is achieved.
Numerical Analysis of the Bending Properties of Cathay Poplar Glulam
Directory of Open Access Journals (Sweden)
Ying Gao
2015-10-01
Full Text Available This paper presents the formulae and finite element analysis models for predicting the Modulus of Elastic (MOE and Modulus of Rupture (MOR of Cathay poplar finger-jointed glulam. The formula of the MOE predicts the MOE of Cathay poplar glulam glued with one-component polyurethane precisely. Three formulae are used to predict the MOR, and Equation (12 predicts the MOR of Cathay poplar glulam precisely. The finite element analysis simulation results of both the MOE and MOR are similar to the experimental results. The predicted results of the finite element analysis are shown to be more accurate than those of the formulae, because the finite element analysis considers the glue layers, but the formulae do not. Three types of typical failure modes due to bending were summarized. The bending properties of Cathay poplar glulam were compared to those of Douglas fir glulam. The results show that Cathay poplar glulam has a lower stiffness, but a marginally higher strength. One-component polyurethane adhesive is shown to be more effective than resorcinol formaldehyde resin adhesive for Cathay poplar glulam. This study shows that Cathay poplar has the potential to be a glulam material in China.
Pressure and bending tests on fibreglass augmented steel technology pipes
Energy Technology Data Exchange (ETDEWEB)
Chen, Qishi; Ozkan, Istemi F. [C-FER Technologies, Edmonton, Alberta, (Canada); Salama, Mamdouh M. [ConocoPhillips Company, Houston, Texas, (United States)
2010-07-01
The economic manufacture of large diameter high pressure pipelines is a challenge. The FAST-PipeTM concept is fabricated from a steel liner hoop-wound with non-impregnated fibreglass stands. This report presents the qualification results of the FAST-PipeTM concept. The qualification testing program studied the effects of external environment (frozen/thawed cycle), load duration and the wrap thickness on the burst and bending capacity of the FAST-PipeTM concept. Burst and pressure-bend tests were performed under different conditions and for different thickness of fibreglass. The values obtained were compared to those from unwrapped pipes. It also established FAST-PipeTM behaviour in several loading scenarios using the FEA model. The burst tests results showed that freezing temperatures do not have an impact on the pressure capacity of FAST-PipeTM. The results of the tests showed the effectiveness of dry fibreglass wrap in increasing the internal pressure capacity of the pipe.
Bending Under Tension Test with Direct Friction Measurement
DEFF Research Database (Denmark)
Andreasen, Jan Lasson; Olsson, David Dam; Chodnikiewicz, K.;
2006-01-01
A special Bending-Under-Tension (BUT) transducer has been developed in which friction around the tool radius can be directly measured when drawing a plane sheet strip around a cylindrical tool-pin under constant back tension. The front tension, back tension and torque on the tool-pin are all meas...... in drawing of stainless steel showing the influence of varying process conditions and the performance of different lubricants.......A special Bending-Under-Tension (BUT) transducer has been developed in which friction around the tool radius can be directly measured when drawing a plane sheet strip around a cylindrical tool-pin under constant back tension. The front tension, back tension and torque on the tool-pin are all...... measured directly, thus enabling accurate measurement of friction and direct determination of lubricant film breakdown for varying normal pressure, sliding speed, tool radius and tool preheat temperature. The transducer is applied in an experimental investigation focusing on limits of lubrication...
The first ANDES elements: 9-DOF plate bending triangles
Militello, Carmelo; Felippa, Carlos A.
1991-01-01
New elements are derived to validate and assess the assumed natural deviatoric strain (ANDES) formulation. This is a brand new variant of the assumed natural strain (ANS) formulation of finite elements, which has recently attracted attention as an effective method for constructing high-performance elements for linear and nonlinear analysis. The ANDES formulation is based on an extended parametrized variational principle developed in recent publications. The key concept is that only the deviatoric part of the strains is assumed over the element whereas the mean strain part is discarded in favor of a constant stress assumption. Unlike conventional ANS elements, ANDES elements satisfy the individual element test (a stringent form of the patch test) a priori while retaining the favorable distortion-insensitivity properties of ANS elements. The first application of this formulation is the development of several Kirchhoff plate bending triangular elements with the standard nine degrees of freedom. Linear curvature variations are sampled along the three sides with the corners as gage reading points. These sample values are interpolated over the triangle using three schemes. Two schemes merge back to conventional ANS elements, one being identical to the Discrete Kirchhoff Triangle (DKT), whereas the third one produces two new ANDES elements. Numerical experiments indicate that one of the ANDES element is relatively insensitive to distortion compared to previously derived high-performance plate-bending elements, while retaining accuracy for nondistorted elements.
Xyloglucan for Generating Tensile Stress to Bend Tree Stem
Institute of Scientific and Technical Information of China (English)
Kei'ichi Baba; Yong Woo Park; Tomomi Kaku; Rumi Kaida; Miyuki Takeuchi; Masato Yoshida; Yoshihiro Hosoo; Yasuhisa Ojio; Takashi Okuyama; Toru Taniguchi; Yasunori Ohmiya; Teiji Kondo; Ziv Shani; Oded Shoseyov; Tatsuya Awano; Satoshi Serada; Naoko Norioka; Shigemi Norioka; Takahisa Hayashi
2009-01-01
In response to environmental variation, angiosperm trees bend their stems by forming tension wood, which consists of a cellulose-rich G (gelatinous)-Iayer in the walls of fiber cells and generates abnormal tensile stress in the sec-ondary xylem. We produced transgenic poplar plants overexpressing several endoglycanases to reduce each specific poly-saccharide in the cell wall, as the secondary xylem consists of primary and secondary wall layers. When placed horizontally, the basal regions of stems of transgenic poplars overexpressing xyloglucanase alone could not bend upward due to low strain in the tension side of the xylem. In the wild-type plants, xyloglucan was found in the inner surface of G-layers during multiple layering. In situ xyloglucan endotransglucosylase (XET) activity showed that the incorporation of whole xylo-glucan, potentially for wall tightening, began at the inner surface layers S1 and S2 and was retained throughout G-layer development, while the incorporation of xyloglucan heptasaccharide (XXXG) for wall loosening occurred in the primary wall of the expanding zone. We propose that the xyloglucan network is reinforced by XET to form a further connection between wall-bound and secreted xyloglucans in order to withstand the tensile stress created within the cellulose G-layer microfibrils.
Inertia and Double Bending of Light from Equivalence
Shuler, Robert L., Jr.
2010-01-01
Careful examination of light paths in an accelerated reference frame, with use of Special Relativity, can account fully for the observed bending of light in a gravitational field, not just half of it as reported in 1911. This analysis also leads to a Machian formulation of inertia similar to the one proposed by Einstein in 1912 and later derived from gravitational field equations in Minkowsky Space by Sciama in 1953. There is a clear inference from equivalence that there is some type of inertial mass increase in a gravitational field. It is the purpose of the current paper to suggest that equivalence provides a more complete picture of gravitational effects than previously thought, correctly predicting full light bending, and that since the theory of inertia is derivable from equivalence, any theory based on equivalence must take account of it. Einstein himself clearly was not satisfied with the status of inertia in GRT, as our quotes have shown. Many have tried to account for inertia and met with less than success, for example Davidson s integration of Sciama s inertia into GRT but only for a steady state cosmology [10], and the Machian gravity theory of Brans and Dicke [11]. Yet Mach s idea hasn t gone away, and now it seems that it cannot go away without also disposing of equivalence.
Composite failure prediction of π-joint structures under bending
Institute of Scientific and Technical Information of China (English)
HUANG Hong-me; YUAN Shen-fang
2012-01-01
In this article,the composite π-joint is investigated under bending loads.The "L" preform is the critical component regarding composite π-joint failure.The study is presented in the failure detection of a carbon fiber composite π-joint structure under bending loads using fiber Bragg grating (FBG) sensor.Firstly,based on the general finite element method (FEM)software,the 3-D finite element (FE) model of composite π-joint is established,and the failure process and every lamina failure load of composite π-joint are investigated by maximum stress criteria.Then,strain distributions along the length of FBG are extracted,and the reflection spectra of FBG are calculated according to the strain distribution.Finally,to verify the numerical results,a test scheme is performed and the experimental spectra of FBG are recorded.The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions,and the computational error of failure load is less than 6.4％.Furthermore,it also verifies the feasibility of the damage detection system.
Design of bending multi-layer electroactive polymer actuators
Balakrisnan, Bavani; Nacev, Alek; Smela, Elisabeth
2015-04-01
The effects of layer thickness and stiffness on multilayer bending actuator performance were investigated with an analytical mechanical model. Performance was evaluated in terms of curvature, blocked force, and work. Multilayer device designs corresponding to dielectric elastomer actuator, ionic polymer metal composite, and conjugated polymer structures were examined. Normalized plots of the performance metrics as functions of relative layer thickness and stiffness are presented that should allow initial, starting-point estimates for designs for particular applications. The results show that to achieve high curvature, layer thickness and stiffness may need to be set above or below particular bounds, or varied together, depending on the device configuration; often there is a broad plateau of combinations that work equally well. There is a conflict between achieving high bending and high force: the former requires the device to behave as much as possible like a simple bilayer with optimal ratios of thickness and modulus, while the latter requires thicker layers and shows little dependence on their moduli. Finally, to maximize work there are areas in the thickness-modulus plane that should be avoided, these areas varying with the configuration in sometimes surprising ways.
Radio occultation bending angle anomalies during tropical cyclones
Directory of Open Access Journals (Sweden)
R. Biondi
2011-02-01
Full Text Available The tropical deep convection affects the radiation balance of the atmosphere changing the water vapor mixing ratio and the temperature of the upper troposphere lower stratosphere. The aim of this work is to better understand these processes and to investigate if severe storms leave a significant signature in radio occultation profiles in the tropical tropopause layer. Using tropical cyclone best track database and data from different GPS radio occultation missions (COSMIC, GRACE, CHAMP, SACC and GPSMET, we selected 1194 profiles in a time window of 3 h and a space window of 300 km from the eye of the cyclone. We show that the bending angle anomaly of a GPS radio occultation signal is typically larger than the climatology in the upper troposphere and lower stratosphere and that a double tropopause during deep convection can easily be detected using this technique. Comparisons with co-located radiosondes, climatology of tropopause altitudes and GOES analyses are also shown to support the hypothesis that the bending angle anomaly can be used as an indicator of convective towers. The results are discussed in connection to the GPS radio occultation receiver which will be part of the Atomic Clock Ensemble in Space (ACES payload on the International Space Station.
Optical guiding and beam bending in free-electron lasers
Energy Technology Data Exchange (ETDEWEB)
Scharlemann, E.T.
1987-01-01
The electron beam in a free-electron laser (FEL) can act as an optical fiber, guiding or bending the optical beam. The refractive and gain effects of the bunched electron beam can compensate for diffraction, making possible wigglers that are many Rayleigh ranges (i.e., characteristic diffraction lengths) long. The origin of optical guiding can be understood by examining gain and refractive guiding in a fiber with a complex index of refraction, providing a mathematical description applicable also to the FEL, with some extensions. In the exponential gain regime of the FEL, the electron equations of motion must be included, but a self-consistent description of exponential gain with diffraction fully included becomes possible. The origin of the effective index of refraction of an FEL is illustrated with a simple example of bunched, radiating dipoles. Some of the properties of the index of refraction are described. The limited experimental evidence for optical beam bending is summarized. The evidence does not yet provide conclusive proof of the existence of optical guiding, but supports the idea. Finally, the importance of refractive guiding for the performance of a high-gain tapered-wiggler FEL amplifier is illustrated with numerical simulations.
Sensor enabled closed-loop bending control of soft beams
Case, Jennifer C.; White, Edward L.; Kramer, Rebecca K.
2016-04-01
Control of soft-bodied systems is challenging, as the absence of rigidity typically implies distributed deformations and infinite degrees-of-freedom. In this paper, we demonstrate closed-loop control of three elastomer beams that vary in bending stiffness. The most stiff beam is comprised of a single prismatic structure made from a single elastomer. In the next beam, increased flexibility is introduced via an indentation in the elastomer, forming a joint. The most flexible beam uses a softer elastomer in the joint section, along with an indentation. An antagonistic pair of actuators bend the joint while a pair of liquid-metal-embedded strain sensors provide angle feedback to a control loop. We were able to achieve control of the system with a proportional-integral-derivative control algorithm. The procedure we demonstrate in this work is not dependent on actuator and sensor choice and could be applied to to other hardware systems, as well as more complex multi-joint robotic structures in the future.
Relativity for everyone how space-time bends
Fischer, Kurt
2015-01-01
This book, now in a revised and updated second edition, explains the theory of special and general relativity in detail without approaching Einstein's life or the historical background. The text is formulated in such a way that the reader will be able to understand the essence intuitively, and new sections have been added on time machines, the twin paradoxes, and tensors. The first part of the book focuses on the essentials of special relativity. It explains the famous equivalence between mass and energy and tells why Einstein was able to use the theory of electrodynamics as a template for his "electrodynamics of moving bodies". General relativity is then addressed, mainly with the help of thought experiments. Reference is made to the previously introduced special relativity and the equivalence principle and, using many figures, it is explained how space-time is bending under gravity. The climax of the book is the Einstein equation of gravity, which describes the way in which matter bends space-time. The read...
Electrical Bending and Mechanical Buckling Instabilities in Electrospinning Jets
Han, Tao; Reneker, Darrell H.
2007-03-01
The electrospinning jet was a continuous fluid flow ejected from the surface of a fluid when the applied electrical force overcomes the surface tension. The jet moved straight away from the tip and then became unstable and bent into coils. This phenomenon is the electrical bending instability [1]. When the distance between the tip and collector was reduced to less than the maximal straight segment length, the electrical bending instability did not occur. The periodic buckling of a fluid jet incident onto a surface is a striking fluid mechanical instability [2]. When axial compressive stress along the jet reached a sufficient value, it produced the fluid mechanics analogue to the buckling of a slender solid column. In the electrospinning, the buckling instability occurred just above the collector where the jet was compressed as it encountered the collector. The buckling frequencies of these jets are in the range of 10^4 to 10^5 Hz. The buckling lengths of these jets are in the range of 10 to 100μm. *Reneker,D.H.; Yarin, A. L.; Fong, H.; Koombhongse, S., Journal of Applied Physics, 87, 4531, 2000 *Tchavdarov B.; Yarin, A. L.; Radev S., Journal of Fluid Mechanics; 253, 593,1993
How Does The Bone Shaft Geometry Affect its Bending Properties?
Directory of Open Access Journals (Sweden)
Kaveh P. Saffar
2009-01-01
Full Text Available In this research, ten fresh specimens of sheep tibiae were provided from slaughtered animals. Whole bone specimens were loaded in three-point bending according to standard wet bone test protocols. Mechanical properties were determined and compared with the results which were obtained from two dry bone tests. The results showed that fracture bending moment and bone extrinsic stiffness had significant relations with fracture cross-section dependent parameters (i.e., cross-section area and area moment of inertia. Where, fracture energy and ultimate strength did not have such a relation with these parameters. Finite element modeling of bone shaft was made with simplified geometry (neglecting cross-section variations along bone shaft in two steps: First, by elliptical cross-section and second, by circular cross-section, assuming linear elastic and isotropic properties for the specimens. Elastic (Youngs modulus and fracture load, evaluated from curves obtained from tests, were applied to the finite element model and close results of maximum stress in both test specimen and first (elliptical cross-section model showed up. There was an average difference of about 2% between ultimate strength of wet bone specimens and maximum (tensile stress occurred in the elliptical models. However, this value for circular models was about 16%.
Bending continuous structures with SMAs: a novel robotic fish design.
Rossi, C; Colorado, J; Coral, W; Barrientos, A
2011-12-01
In this paper, we describe our research on bio-inspired locomotion systems using deformable structures and smart materials, concretely shape memory alloys (SMAs). These types of materials allow us to explore the possibility of building motor-less and gear-less robots. A swimming underwater fish-like robot has been developed whose movements are generated using SMAs. These actuators are suitable for bending the continuous backbone of the fish, which in turn causes a change in the curvature of the body. This type of structural arrangement is inspired by fish red muscles, which are mainly recruited during steady swimming for the bending of a flexible but nearly incompressible structure such as the fishbone. This paper reviews the design process of these bio-inspired structures, from the motivations and physiological inspiration to the mechatronics design, control and simulations, leading to actual experimental trials and results. The focus of this work is to present the mechanisms by which standard swimming patterns can be reproduced with the proposed design. Moreover, the performance of the SMA-based actuators' control in terms of actuation speed and position accuracy is also addressed.
Composite failure prediction of π-joint structures under bending
Huang, Hong-mei; Yuan, Shen-fang
2012-03-01
In this article, the composite -joint is investigated under bending loads. The "L" preform is the critical component regarding composite -joint failure. The study is presented in the failure detection of a carbon fiber composite -joint structure under bending loads using fiber Bragg grating (FBG) sensor. Firstly, based on the general finite element method (FEM) software, the 3-D finite element (FE) model of composite -joint is established, and the failure process and every lamina failure load of composite -joint are investigated by maximum stress criteria. Then, strain distributions along the length of FBG are extracted, and the reflection spectra of FBG are calculated according to the strain distribution. Finally, to verify the numerical results, a test scheme is performed and the experimental spectra of FBG are recorded. The experimental results indicate that the failure sequence and the corresponding critical loads of failure are consistent with the numerical predictions, and the computational error of failure load is less than 6.4%. Furthermore, it also verifies the feasibility of the damage detection system.
Bending mechanics of the red-eared slider turtle carapace.
Achrai, Ben; Bar-On, Benny; Wagner, H Daniel
2014-02-01
The turtle shell is a natural shield that possesses complex hierarchical structure, giving rise to superior mechanical properties. The keratin-covered boney top (dorsal) part of the shell, termed carapace, is composed of rigid sandwich-like ribs made of a central foam-like interior flanked by two external cortices. The ribs are attached to one another in a 3-D interdigitated manner at soft unmineralized collagenous sutures. This unique structural combination promotes sophisticated mechanical response upon predator attacks. In the present study mechanical bending tests were performed to examine the static behavior of the red-eared slider turtle carapace, in different orientations and from various locations, as well as from whole-rib and sub-layer regions. In addition, the suture properties were evaluated as well and compared with those of the rib. A simplified classical analysis was used here to rationalize the experimental results of the whole rib viewed as a laminated composite. The measured strength (~300MPa) and bending modulus (~7-8.5GPa) of the rib were found to be of the same order of magnitude as the strength and modulus of the cortices. The theoretical prediction of the ribs' moduli, predicted in terms of the individual sub-layers moduli, agreed well with the experimental results. The suture regions were found to be more compliant and weaker than the ribs, but comparatively tough, likely due to the interlocking design of the boney zigzag elements. PMID:24333673
Overall Thermal Performance of Flexible Piping Under Simulated Bending Conditions
Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)
2001-01-01
Flexible, vacuum-insulated transfer lines for low-temperature applications have higher thermal losses than comparable rigid lines. Typical flexible piping construction uses corrugated tubes, inner and outer, with a multilayer insulation (MLI) system in the annular space. Experiments on vacuum insulation systems in a flexible geometry were conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. The effects of bending were simulated by causing the inner tube to be eccentric with the outer tube. The effects of spacers were simulated in a controlled way by inserting spacer tubes for the length of the cylindrical test articles. Two material systems, standard MLI and a layered composite insulation (LCI), were tested under the full range of vacuum levels using a liquid nitrogen boiloff calorimeter to determine the apparent thermal conductivity (k-value). The results indicate that the flexible piping under simulated bending conditions significantly degrades the thermal performance of the insulation system. These data are compared to standard MLI for both straight and flexible piping configurations. The definition of an overall k-value for actual field installations (k(sub oafi)) is described for use in design and analysis of cryogenic piping systems.
EXPERIMENTAL STUDY OF 3-D TURBULENT BEND FLOWS IN OPEN CHANNEL
Institute of Scientific and Technical Information of China (English)
LIU Yue-qin; ZHENG Shao-wen; WU Qiang
2005-01-01
A generalized bend flow model, treating a 90° single bend and 60° continuous bends, was designed to quantitatively describe 3-D turbulence mechanism of circulating not-fully-developed flow in open channels with bends.The 3-D fluctuating velocities of turbulent flow were measured and analyzed with a 3-D acoustic-Doppler velocimeter.Formula for 3-D turbulent intensity was derived using the dimension analysis approach.Expressions of vertical turbulent-intensity distributions were obtained with the multivariant-regression theory, which agree with experiment data.Distributions of turbulent intensity and turbulent stress were characterized, and their relationships were concluded.In the bend-turbulent-flow core region, longitudinal and lateral turbulent-intensity distributions are coincident with linear distribution, but in near-wall region are coincident with the Gamma distribution.Vertical turbulent intensity distributions are coincident with the Rayleigh distribution.Herein, it is concluded that the bend turbulence is anisotropic.
Directory of Open Access Journals (Sweden)
Jui-Chang Lin
2015-01-01
Full Text Available The three-dimensional tube (or pipe is manufactured by CNC tube bending machine. The key techniques are determined by tube diameter, wall thickness, material, and bending radius. The obtained technique through experience and the trial and error method is unreliable. Finite element method (FEM simulation for the tube bending process before production can avoid wasting manpower and raw materials. The computer-aided engineering (CAE software ABAQUS 6.12 is applied to simulate bending characteristics and to explore the maximum stress and strain conditions. The Taguchi method is used to find the optimal parameters of bending. The confirmation experiment is performed according to optimal parameters. Results indicate that the strain error between CAE simulation and bending experiments is within 6.39%.
Theoretical analysis on shear-bending deflection of a ring-shape piezoelectric plate
Directory of Open Access Journals (Sweden)
Zejun Yu
2016-02-01
Full Text Available In this paper, the electromechanical coupling field in shear-bending mode for a ring-shape piezoelectric plate was theoretically established. According to the classical small bending elastic plate theory and piezoelectric constitutive equations, the analytical solution to the bending deformation of the piezo-actuator under electric field and a concentrated or uniformly distributed mechanical load was achieved. The mechanism for generating bending deformation is attributed to axisymmetric shear strain, which further induces the bending deformation of the single ring-shape piezoelectric plate. This mechanism is significant different from that of piezoelectric bimorph or unimorph actuators reported before. Our analysis offers guidance for the optimum design of a ring-shape shear-bending piezo-actuator.
Experimental verification of a weak zone model for timber in bending
DEFF Research Database (Denmark)
Källsner, B.; Ditlevsen, Ove Dalager; Salmela, K.
1997-01-01
In order to verify a stochastic model for the variation of bending strength within and between structural timber members, tests with long members subjected to constant bending moment have been performed. The span with constant moment contained between five and nine weak zones, i.e. zones with a c......In order to verify a stochastic model for the variation of bending strength within and between structural timber members, tests with long members subjected to constant bending moment have been performed. The span with constant moment contained between five and nine weak zones, i.e. zones...... with a cluster of knots. In a previous investigation test specimens, each containing one weak zone, have been tested in bending separately. Based on these tests a hierarchical model with two levels was formulated. The test results show that the bending strength of the long timber members on the average is 5...
Numerical method for the prediction of bending properties of glass-epoxy composites
Directory of Open Access Journals (Sweden)
Stamenović Marina R.
2007-01-01
Full Text Available Mechanical properties of composite materials are conditioned by their structure and depend on the characteristics of structural components. In this paper is presented a numerical model by which the bending properties can be predicted on the basis of known mechanical properties of tension and pressure. Determining the relationship between these properties is justified having in mind the mechanics of fracture during bending, where the fracture takes place on the outer layer which is subjected to bending while the break ends on the layer subjected to pressure. The paper gives the values of tension, pressure and bending properties obtained by the corresponding mechanical test. A comparison of the numerical results of bending properties obtained on the basis of the model with the experimental ones, shows their satisfactory agreement. Therefore, this model can be used for some future research to predict bending properties without experiments.
Pipeline Bending Strain Measurement and Compensation Technology Based on Wavelet Neural Network
Li, Rui; Cai, Maolin; Shi, Yan; Feng, Qingshan; Liu, Shucong; ZHAO, XIAOMING
2016-01-01
The bending strain of long distance oil and gas pipelines may lead to instability of the pipeline and failure of materials, which seriously deteriorates the transportation security of oil and gas. To locate the position of the bending strain for maintenance, an Inertial Measurement Unit (IMU) is usually adopted in a Pipeline Inspection Gauge (PIG). The attitude data of the IMU is usually acquired to calculate the bending strain in the pipe. However, because of the vibrations in the pipeline a...
A shrub bending model to calculate the albedo of shrub-tundra
Ménard, Cécile B.; Essery, Richard; Pomeroy, John; Marsh, Philip; Clark, Douglas B.
2014-01-01
At high latitudes, the albedo and energy budget of shrub-tundra landscapes is determined by the relationship between the fractional snow cover and the fraction of vegetation protruding above the snowpack. The exposed vegetation fraction is affected by the bending and/or burial of shrubs in winter and their spring-up during melt. Little is known about the meteorological conditions and snowpack and shrub properties required to cause bending, and few quantitative measurements of bending processe...
FEM Simulation of Bending Formability for Laminate Steel/Resin/Steel Lightweight Composite Sheet
Institute of Scientific and Technical Information of China (English)
Guancheng Ll; Yonglin KANG
2003-01-01
The ANSYS simulation software was used to analyze the bending formability of laminate steel/resin/steel lightweight composite sheet. The skin steel at external side produces relative slipping-off change during the bending due to its composite structure. The internal stress strain states, materials effect tools parameters and intermediate layer resin of lightweight sheet on slipping-off change were analyzed. The spring back and shear stress state after bending have also been discussed.
Bending Moment Decrease of Reinforced Concrete Beam Supported by Additional CFRP
Directory of Open Access Journals (Sweden)
Mykolas Daugevičius
2011-04-01
Full Text Available The calculation method of reinforced concrete beam with additional CFRP composite is proposed in this article. This method estimates tangential angular concrete deformations in tensioned beam layers between steel and bonded carbon fiber reinforced polymer. The horizontal slip of CFRP composite reduce beam bending moment capacity. An additional coefficient to reduce CFRP resultant force is necessary for better precision of bending moment capacity. Also, various calculation methods of bending moment capacity are considered. Article in Lithuanian
Energy Technology Data Exchange (ETDEWEB)
Batista, Gilmar Zacca; Sanandres, Simon Ricardo [PETROBRAS, Rio de Janeiro, RJ (Brazil). Pipeline Engineering Division; Pinto, Percy Saavedra; Mello, Marcelo [Tubos Soldados Atlantico, Sao Paulo, SP (Brazil)
2009-07-01
The present work is a part of a comprehensive program that aims to evaluate the helical seam pipe application in pipeline construction and compare with the traditional longitudinal seam pipe that have been used in Brazil. One of the biggest concerns is the cold bending process once the Brazilian land profile is very sinuous, different than other countries where helical seam pipes have been used successfully. At this work, two pipes were used, one helical seam and one longitudinal seam, both API 5L X70 with 28 inch of diameter and 0.469 inch wall thickness. The results of cold bending tests comparing both types of pipe and the mechanical properties from the straight pipe with the bend section are shown. The research methodology includes dimensional analysis, microstructural evaluation and mechanical tests that were performed on the straight pipe and bend areas. The cold bending parameters used to obtain a bend according the design and construction standards requirements are also presented. The results showed that the cold bending process produces a helical seam pipe bend with the most critical radius allowed by the standards, without presenting any evidence of wrinkles, out-of-roundness above the limits or any type of mechanical damage. Both pipes tested met the standards requirements in terms of bending and mechanical properties. The results of this study provide technical information for future helical seam pipe application in Brazil. (author)
Stoimenov, Boyko L.; Rossiter, Jonathan M.; Mukai, Toshiharu
2007-01-01
Demands from the fields of bio-medical engineering and biologically-inspired robotics motivate a growing interest in actuators with properties similar to biological muscle, including ionic polymer-metal composites (IPMC), the focus of this study. IPMC actuators consist of an ion-conductive polymer membrane, coated with thin metal electrodes on both sides and bend when voltage is applied. Some of the advantages of IPMC actuators are their softness, lack of moving parts, easy miniaturization, light weight and low actuation voltage. When used in bio-mimetic robotic applications, such as a snake-like swimming robot, locomotion speed can be improved by increasing the bending amplitude. However, it cannot be improved much by increasing the driving voltage, because of water electrolysis. To enhance the bending response of IPMCs we created a "preferred" bending direction by anisotropic surface modification. Introduction of anisotropic roughness with grooves across the length of the actuator improved the bending response by a factor of 2.1. Artificially introduced cracks on the electrodes in direction, in which natural cracks form by bending, improved bending response by a factor of 1.6. Anisotropic surface modification is an effective method to enhance the bending response of IPMC actuators and does not compromise their rigidity under loads perpendicular to the bending plane.
Improving bending stress in spur gears using asymmetric gears and shape optimization
DEFF Research Database (Denmark)
Pedersen, Niels Leergaard
2010-01-01
Bending stress plays a significant role in gear design wherein its magnitude is controlled by the nominal bending stress and the stress concentration due to the geometrical shape. The bending stress is indirectly related to shape changes made to the cutting tool. This work shows that the bending...... stress can be reduced significantly by using asymmetric gear teeth and by shape optimizing the gear through changes made to the tool geometry. However, to obtain the largest possible stress reduction a custom tool must be designed depending on the number of teeth, but the stress reductions found...
Bending of metal-filled carbon nanotube under electron beam irradiation
Directory of Open Access Journals (Sweden)
Abha Misra
2012-03-01
Full Text Available Electron beam irradiation induced, bending of Iron filled, multiwalled carbon nanotubes is reported. Bending of both the carbon nanotube and the Iron contained within the core was achieved using two approaches with the aid of a high resolution electron microscope (HRTEM. In the first approach, bending of the nanotube structure results in response to the irradiation of a pristine kink defect site, while in the second approach, disordered sites induce bending by focusing the electron beam on the graphite walls. The HRTEM based in situ observations demonstrate the potential for using electron beam irradiation to investigate and manipulate the physical properties of confined nanoscale structures.
Intensity-measurement bend sensors based on periodically tapered soft glass fibers
Wang, Y.; Richardson, D. J.; Brambilla, G; Feng, X.; Petrovich, M.N.; Ding, M.; Song, Z.(Central China Normal University, Wuhan, China)
2011-01-01
We demonstrate a novel technique for tapering periodically an all-solid soft glass fiber, consisting of two types of lead silicate glasses, by the use of a focused CO2 laser beam and investigate the bend sensing applications of the periodically-tapered soft glass fiber. Such a soft glass fiber with periodic microtapers could be used to develop promising bend sensors with a sensitivity of -27.75 ?W/m^-1 by means of measuring the bend-induced change of light intensity. The proposed bend sensor ...
Mechanical behaviour of bending bucky-gel actuators and its representation
International Nuclear Information System (INIS)
Bucky-gel actuators are ionic electromechanically active materials that bend in response to a low-voltage excitation. While bending actuators may offer new approaches in engineering solutions, the characterization of bending poses many challenges in comparison to conventional rotary motion. It is often desired to reduce the bending behaviour to a single parameter, which may lead to the loss of accuracy in modelling. A high-speed laser profilometer is utilized to characterize the bending response of different bucky-gel actuators at their full length and to critically compare the applicability of existing representation tools for bending. The best analytical representation of the bending of a bucky-gel actuator is found to be in the form of a power function. It is also observed that, along the length of the actuator, sections closer to the electrical input clamp exhibit back-relaxation (a common drawback for bending ionic actuators) already when the far end of the bending strip is still in forward motion. (paper)
Kim, Hoonbae; Ye, Donghyun; Won, Beomhee; Yu, SeGi; Jung, Donggeun
2016-05-01
Flexible organic solar cells (OSCs) were fabricated on an indium-tin-oxide (ITO)/poly(ethylene terephthalate) (PET) substrate and were subjected to bending tests with various bending radii. We observed that the photovoltaic properties of the OSCs precipitously deteriorated at a bending radius ≤ 0.75 cm. In order to investigate the effects of the bending test, the changes in the surface morphology and the sheet resistance of the ITO-coated PET samples were investigated, and the photovoltaic properties of bent and unbent OSCs were evaluated. Thereafter, equivalent circuits for the OSCs were assumed and the change in their parameters, such as resistance and capacitance, was observed. PMID:27483935
Investigation of structural behaviour due to bend-twist couplings in wind turbine blades
DEFF Research Database (Denmark)
Fedorov, Vladimir; Dimitrov, Nikolay Krasimiroy; Berggreen, Christian;
2009-01-01
The structural behaviour of a composite wind turbine blade with implemented bend-twist coupling is examined in this paper. Several shell finite element models of the blade have been developed and validated against full-scale tests. All shell models performed well for flap-wise bending, but perfor......The structural behaviour of a composite wind turbine blade with implemented bend-twist coupling is examined in this paper. Several shell finite element models of the blade have been developed and validated against full-scale tests. All shell models performed well for flap-wise bending...
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
The torsional oscillation characteristics on the bending and torsion coupled vibration of rotary shaft system were investigated using the elasto-dynamic theory and other mathematic methods, such as difference approach, Fourier transform, and wavelet transform. It is concluded that mass eccentricity and other exciting modalities affect the bending and torsion coupled vibration of rotary shafts. Torsional vibration caused by bending vibration features linearity along with the change of amplitude of bending vibration. Meanwhile, energy spectrum concentrates on high frequency area with the wavelet analysis.
Optical diffraction for measurements of nano-mechanical bending
Hermans, Rodolfo I; Ndieyira, Joseph Wafula; McKendry, Rachel A; Aeppli, Gabriel
2015-01-01
Micromechanical transducers such as cantilevers for AFM often rely on optical readout methods that require illumination of a specific region of the microstructure. Here we explore and exploit the diffraction effects that have been previously neglected when modeling cantilever bending measurement techniques. The illumination of a cantilever end causes an asymmetric diffraction pattern at the photodetector that significantly affects the calibration of the signal in the popular optical beam deflection technique (OBDT). Conditions for optimized linear signals that avoid detection artifacts conflict with small numerical aperture illumination and narrow cantilevers which are softer and therefore more sensitive. Embracing diffraction patterns as a physical measurable allows a richer detection technique that decouples measurements of tilt and curvature and simultaneously relaxes the requirements on the alignment of illumination and detector. We show analytical results, numerical simulations and physiologically releva...
Rheology of a Twist-bend Nematic Liquid Crystal
Salili, Seyyed Muhammad; Kim, Chanjoong; Sprunt, Samuel; Gleeson, James; Parri, Owain; Jakli, Antal; Kim Lab Team; Merck Lab Team
2015-03-01
First detailed flow shear alignment studies and rheological measurements in the twist-bend nematic (Ntb) liquid crystalline phase of odd numbered flexible dimer molecules is presented. It is found that the Ntb phase is strongly shear-thinning. At shear stresses below 1 Pa the apparent viscosity of the Ntb phase is 1000 times larger than in the nematic phase. At stresses above 10 Pa the Ntb viscosity drops by two orders of magnitude and the material exhibits Newtonian fluid behavior. The results are consistent with the behavior of a system with pseudo-layer structure with layer spacing determined by the heliconical pitch. From the measurements of dynamic modulus we estimate the compression modulus of the pseudo-layers to be B ~ 2 kPa this value is discussed within the context of a simple theoretical model based upon a coarse-grained elastic free energy. www.jakligroup.com.
An analytical study of double bend achromat lattice
Fakhri, Ali Akbar; Kant, Pradeep; Singh, Gurnam; Ghodke, A. D.
2015-03-01
In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented.
Local Deplanation Of Double Reinforced Beam Cross Section Under Bending
Baltov, Anguel; Yanakieva, Ana
2015-12-01
Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model's plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB).
Acoustic emission monitoring of recycled aggregate concrete under bending
Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.
2015-03-01
The amount of construction and demolition waste has increased considerably over the last few years, making desirable the reuse of this waste in the concrete industry. In the present study concrete specimens are subjected at the age of 28 days to four-point bending with concurrent monitoring of their acoustic emission (AE) activity. Several concrete mixtures prepared using recycled aggregates at various percentages of the total coarse aggregate and also a reference mix using natural aggregates, were included to investigate their influence of the recycled aggregates on the load bearing capacity, as well as on the fracture mechanisms. The results reveal that for low levels of substitution the influence of using recycled aggregates on the flexural strength is negligible while higher levels of substitution lead into its deterioration. The total AE activity, as well as the AE signals emitted during failure, was related to flexural strength. The results obtained during test processing were found to be in agreement with visual observation.
An analytical study of double bend achromat lattice
Energy Technology Data Exchange (ETDEWEB)
Fakhri, Ali Akbar, E-mail: fakhri@rrcat.gov.in; Kant, Pradeep; Singh, Gurnam; Ghodke, A. D. [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)
2015-03-15
In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented.
An analytical study of double bend achromat lattice
International Nuclear Information System (INIS)
In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented
Homogenization of long fiber reinforced composites including fiber bending effects
Poulios, Konstantinos; Niordson, Christian F.
2016-09-01
This paper presents a homogenization method, which accounts for intrinsic size effects related to the fiber diameter in long fiber reinforced composite materials with two independent constitutive models for the matrix and fiber materials. A new choice of internal kinematic variables allows to maintain the kinematics of the two material phases independent from the assumed constitutive models, so that stress-deformation relationships, can be expressed in the framework of hyper-elasticity and hyper-elastoplasticity for the fiber and the matrix materials respectively. The bending stiffness of the reinforcing fibers is captured by higher order strain terms, resulting in an accurate representation of the micro-mechanical behavior of the composite. Numerical examples show that the accuracy of the proposed model is very close to a non-homogenized finite-element model with an explicit discretization of the matrix and the fibers.
A mechanical model for FRP-strengthened beams in bending
Directory of Open Access Journals (Sweden)
P. S. Valvo
2012-10-01
Full Text Available We analyse the problem of a simply supported beam, strengthened with a fibre-reinforced polymer (FRP strip bonded to its intrados and subjected to bending couples applied to its end sections. A mechanical model is proposed, whereby the beam and FRP strip are modelled according to classical beam theory, while the adhesive and its neighbouring layers are modelled as an interface having a piecewise linear constitutive law defined over three intervals (elastic response – softening response – debonding. The model is described by a set of differential equations with appropriate boundary conditions. An analytical solution to the problem is determined, including explicit expressions for the internal forces, displacements and interfacial stresses. The model predicts an overall non-linear mechanical response for the strengthened beam, ranging over several stages: from linearly elastic behaviour to damage, until the complete detachment of the FRP reinforcement.
Design of a Variable Thickness Plate to Focus Bending Waves
Schiller, Noah H.; Lin, Sz-Chin Steven; Cabell, Randolph H.; Huang, Tony Jun
2012-01-01
This paper describes the design of a thin plate whose thickness is tailored in order to focus bending waves to a desired location on the plate. Focusing is achieved by smoothly varying the thickness of the plate to create a type of lens, which focuses structural-borne energy. Damping treatment can then be positioned at the focal point to efficiently dissipate energy with a minimum amount of treatment. Numerical simulations of both bounded and unbounded plates show that the design is effective over a broad frequency range, focusing traveling waves to the same region of the plate regardless of frequency. This paper also quantifies the additional energy dissipated by local damping treatment installed on a variable thickness plate relative to a uniform plate.
Local Deplanation Of Double Reinforced Beam Cross Section Under Bending*
Directory of Open Access Journals (Sweden)
Baltov Anguel
2015-12-01
Full Text Available Bending of beams, double reinforced by means of thin composite layers, is considered in the study. Approximate numerical solution is proposed, considering transitional boundary areas, where smooth quadratic transition of the elasticity modulus and deformations take place. Deplanation of the cross section is also accounted for in the areas. Their thickness is found equalizing the total stiffness of the cross section and the layer stiffness. Deplanation of the cross section of the transitional area is determined via the longitudinal deformation in the reinforcing layer, accounting for the equilibrium between the internal and the external moment, generated by the longitudinal stresses in the cross section. A numerical example is given as an illustration demonstrating model’s plausibility. The model allows the design and the calculation of recycled concrete beams double reinforced by means of thin layers. The approach is in agreement with modern design of nearly zero energy buildings (NZEB.
Study on Thickness Effect of Three-Point-Bend Specimen
Kikuchi, Masanori; Ishihara, Takehito
The thickness effect of a three-point-bend (3PB) specimen on dimple fracture behavior is studied experimentally and numerically. At first, fracture toughness tests were conducted using 3PB specimens of different thicknesses. Fracture toughness values and R-curves are obtained, and the thickness effect is discussed. Using scanning electron microscopy (SEM), dimple fracture surfaces are observed precisely. It is found that the thickness effect appears clearly in the void growth process. Finite element (FEM) analyses are conducted based on these experimental data. Using Gurson’s constitutive equation, the nucleation and growth of voids during the dimple fracture process are simulated. The distribution patterns of stress triaxiality and the crack growth process are obtained. The results show a good agreement with experimental ones qualitatively. The effects of specimen thickness on R-curves are explained well on the basis of these numerical simulations.
Bending analysis of shallow sperical shells by BEM
International Nuclear Information System (INIS)
The problem of investigation of the stress-strain state of shells and plates is a problem of importance for structures. This problem has been established by finite element method, asymptotical analysis, etc. In the present paper the boundary element technique is used as a tool for numerical analysis of elastic shell bending problem. Using well known linear shallow shell theory for determination of normal displacement w and the membrane stress function f (or their complex combination-the function ψ, the inverse formulation for single fundamental equation and the fundamental solution for a weighing function) the new coupled set of integral equations is applied to the determination of the functions w and f by BEM
Spring-back of flexible roll forming bending process
Zhang, Y.; Kim, D. H.; Jung, D. W.
2015-12-01
Simulations are now widely used in the field of roll forming because of their convenience. Simulations provide a low cost, secure and fast analysis tool. Flexible roll forming provides the desired shapes with a one time forming process. For roll forming, the velocity of the sheet and friction are important factors to attain an ideal shape. Because it is a complicated process, simulations provide a better understanding of the roll forming process. Simulations were peformed using ABAQUS software linked to elastic-plastic modules which we developed taking into account of interactions between these fields [1]. The application of this method makes it possible to highlight the strain-stress and mechanical behaviour laws and the spring-back. Thus, the flexible roll forming and bending process can bewell described by the simulation software and guide the actual machine.
Three-point bending fracture characteristics of bulk metallic glasses
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
This paper presents the SEM micrographs for the three-point bending fracture surfaces of Zr-based, Ce-based and Mg-based bulk metallic glasses (BMGs), which show the dimple structures in the three kinds of BMGs. The shapes of the giant plastic deformation domain on the fracture surface are similar but the sizes are different. The fracture toughness KC and the dimple structure size of the Zr-based BMG are both the largest, and those of the Mg-based BMG are the smallest. The fracture toughness KC and the dimple structure size of the Ce-based BMG are between those of the Zr-based and the Mg-based BMG. Through analyzing the data of different fracture toughnesses of the BMGs, we find that the plastic zone width follows w = (KC/σY)2/(6π).
Geometrically nonlinear bending analysis of laminated composite plate
Dash, Padmanav; Singh, B. N.
2010-10-01
In this work, a transverse bending of shear deformable laminated composite plates in Green-Lagrange sense accounting for the transverse shear and large rotations are presented. Governing equations are developed in the framework of higher order shear deformation theory. All higher order terms arising from nonlinear strain-displacement relations are included in the formulation. The present plate theory satisfies zero transverse shear strains conditions at the top and bottom surfaces of the plate in von-Karman sense. A C0 isoparametric finite element is developed for the present nonlinear model. Numerical results for the laminated composite plates of orthotropic materials with different system parameters and boundary conditions are found out. The results are also compared with those available in the literature. Some new results with different parameters are also presented.
Prediction of nanoparticle transport and deposition in bends
Institute of Scientific and Technical Information of China (English)
Pei-feng LIN; Jian-zhong LIN
2009-01-01
Nanoparticle transport and deposition in bends with circular cross-section are solved for different Reynolds numbers and Schmidt numbers. The perturbation method is used in solving the equations. The results show that the particle transport patterns are similar and independent of the particle size and other parameters when suspended nanoparticles flow in a straight tube. At the outside edge, particle deposition is the most intensive, while deposition at the inside edge is the weakest. In the upper and lower parts of the tube, depositions are approximately the same for different Schmidt numbers.Curvatures of tube, Reynolds number, and Schmidt number have second-order, forthorder, and first-order effects on the relative deposition efficiency, respectively.
Stabilization of helical macromolecular phases by confined bending
Williams, Matthew J
2015-01-01
By means of extensive replica-exchange simulations of generic coarse-grained models for helical polymers, we systematically investigate the structural transitions into all possible helical phases for flexible and semiflexible elastic polymers with self-interaction under the influence of torsion barriers. The competing interactions lead to a variety of conformational phases including disordered helical arrangements, single helices, and ordered, tertiary helix bundles. Most remarkably, we find that a bending restraint entails a clear separation and stabilization of the helical phases. This aids in understanding why semiflexible polymers such as double-stranded DNA tend to form pronounced helical structures and proteins often exhibit an abundance of helical structures, such as helix bundles, within their tertiary structure.
Deformation analysis of springback in L-bending of sheet metal
Directory of Open Access Journals (Sweden)
Fuh-Kuo Chen
2006-08-01
Full Text Available Purpose: In the present study, the deformation mechanics of the springback phenomenon in the L-bending ofsheet-metal was examined and a new method that could efficiently reduce springback in the L-bending of sheetmetalwas proposed.Design/methodology/approach: Both the finite element analysis and experiments were performed to analyzethe deformation mechanics and the effects of process parameters on the formation of springback.Findings: The axial stress distribution in the bent sheet obtained by the finite element simulations was classifiedinto three zones: the bending zone under the punch corner (zone I, unbending zone next to the bending zone(zone II, and the stress-free zone (zone III. It is found that the stress distribution in zone I is quite uniformand hence has little influence on the springback. While the stress distribution in zone II results in a positivespringback, whereas the stress distribution in zone III produces a negative springback. The total springbacktherefore depends on the combined effect of those produced by zone II and zone III. A reverse bend approachthat can efficiently reduce springback was also proposed to reduce the springback in the L-bending process. Thefinite element analysis performed in the present study was validated by experiments as well.Research limitations/implications: Although the reverse bend approach can reduce springback efficiently, itmay cause uneven surface at the die corner area. Hence, the use of reverse bend approach must be cautious ifhigh surface quality is required.Practical implications: The proposed reverse bend approach provides the die design engineer with a novel ideato reduce the springback occurred in the L-bending of sheet metals.Originality/value: In addition to the reverse bend approach, the analysis of defomation mechanics ofspringback performed in the present study also provides researchers with a better understanding of the formationof springback.
International Nuclear Information System (INIS)
The comparison of limit load based on small displacement limit analysis and collapse load based on large displacement analysis for shape-imperfect pipe bends, under combined in-plane closing bending and an internal pressure, were carried out using finite element method. The limit and collapse moments were obtained from moment–rotation curves drawn for each model. Twice-elastic-slope method was used to obtain collapse load. The effect of thinning on limit and collapse moments are minimal and hence thinning need not be considered for the analysis of pipe bends. The influence of ovality on both limit and collapse loads for most of the cases considered are significant. Comparison of effect of ovality on limit and collapse loads reveals that the determination of collapse load is preferable when ovality is included in the analysis of pipe bend. A closed-form solution is presented to include ovality in the determination of the collapse load of pipe bends. Highlights: ► Comparison of limit and collapse loads for shape-imperfect pipe bends is performed. ► Shape imperfections considered are ovality and thinning. ► Finite element limit analyses use small and large geometry change effects. ► Twice-elastic-slope method was used to obtain plastic loads. ► Determination of collapse load is preferable when ovality is included in the analysis.
16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig
2010-01-01
... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...
Directory of Open Access Journals (Sweden)
ALPYILDIZ Tuba
2016-05-01
Full Text Available Sandwich composites are generally used in marine applications, wind turbines, space and aircraft vehicles due to their high bending rigidities in addition to their lighter weights. The objective of this study is to investigate the effect of divided foam core and interlayer sheet of glass fabric on the bending performances of sandwich composites which are manufactured with glass fabrics as the facesheets/interlayer sheets and PVC foam as the core material. Sandwich composites with single and divided core are manufactured and compared in terms of flexural behavious via three point bending tests. It is found that the bending performance is enhanced with the use of divided core and using divided core does not affect the behaviour of the sandwich composite against bending deformations. In the case of the plain core sandwich composite, dividing the core is advised for certain applications rather than perforating the core to increase the bending stiffness and strength of the textile reinforced sandwich composites because it is possible to purchase core with any thickness and there is no need for additional process such as perforation. The proposed application could enhance the bending performances without altering the weight and cost of the sandwich composites, which are preferred due to their higher bending rigidities in relation to their lighter weights.
Flow and bathymetry in sharp open-channel bends: Experiments and predictions
Zeng, J.; Constantinescu, G.; Blanckaert, K.; Weber, L.
2008-01-01
This paper focuses on experiments and simulations conducted in very sharp open-channel bends with flat and equilibrium bathymetry, corresponding to the initial and final phases of the erosion and deposition processes, respectively. The study of flow in curved open bends is relevant for flow in natur
Reversible Bending Behaviors of Photomechanical Soft Actuators Based on Graphene Nanocomposites
Niu, Dong; Jiang, Weitao; Liu, Hongzhong; Zhao, Tingting; Lei, Biao; Li, Yonghao; Yin, Lei; Shi, Yongsheng; Chen, Bangdao; Lu, Bingheng
2016-06-01
Photomechanical nanocomposites embedded with light-absorbing nanoparticles show promising applications in photoresponsive actuations. Near infrared (nIR)-responsive nanocomposites based photomechanical soft actuators can offer lightweight functional and underexploited entry into soft robotics, active optics, drug delivery, etc. A novel graphene-based photomechanical soft actuators, constituted by Polydimethylsiloxane (PDMS)/graphene-nanoplatelets (GNPs) layer (PDMS/GNPs) and pristine PDMS layer, have been constructed. Due to the mismatch of coefficient of thermal expansion of two layers induced by dispersion of GNPs, controllable and reversible bendings response to nIR light irradiation are observed. Interestingly, two different bending behaviors are observed when the nIR light comes from different sides, i.e., a gradual single-step photomechanical bending towards PDMS/GNPs layer when irradiation from PDMS side, while a dual-step bending (finally bending to the PDMS/GNPs side but with an strong and fast backlash at the time of light is on/off) when irradiation from PDMS/GNPs side. The two distinctive photomechanical bending behaviors are investigated in terms of heat transfer and thermal expansion, which reveals that the distinctive bending behaviors can be attributed to the differences in temperature gradients along the thickness when irradiation from different sides. In addition, the versatile photomechanical bending properties will provide alternative way for drug-delivery, soft robotics and microswitches, etc.
MEMS device for bending test: measurements of fatigue and creep of electroplated nickel
DEFF Research Database (Denmark)
Larsen, Kristian Pontoppidan; Rasmussen, Anette Alsted; Ravnkilde, Jan Tue;
2003-01-01
In situ bending test devices with integrated electrostatic actuator were fabricated in electroplated nanocrystalline nickel. The device features approximately pure in-plane bending of the test beam. The excitation of the test beam has fixed displacement amplitude as the actuation electrodes are o...
Extraordinary Bending Effects in MoS2 , Phosphorene, and Graphene Nanoribbons
Yu, Liping; Ruzsinszky, Adrienn; Perdew, John
The two-dimensional (2D) materials show great potential for flexible electronics and energy applications. They have remarkable mechanical, electronic, thermal and optical properties, which are often coupled to each other. In this talk, we shall present our first principles study on the bending effects in the electronic structure of MoS2, phosphorene, and graphene nanoribbons. We predict that mechanical bending, as a unique attribute of thin 2D materials, can be used to control conductivity and Fermi-level shift. We find that bending can control the charge localization of top valence bands in both MoS2 and phosphorene nanoribbons. The donor-like in-gap edge-states of armchair MoS2 ribbon and their associated Fermi-level pinning can be removed by bending. A bending-controllable new in-gap state and accompanying direct-indirect gap transition are predicted in armchair phosphorene nanoribbon. We demonstrate that such emergent bending effects are realizable in experiment and can be attributed to the highly non-uniform and enormously large local in-plane strains induced by bending. The bending stiffness as wells as the effective thickness of 2D materials are also derived from first principles. The work was supported as part of the Center for the Computational Design of Functional Layered Materials, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science.
Friction effect in supports on resistance to brittle fracture under three-point bending
International Nuclear Information System (INIS)
Quasistatic bending of the beam of elastic material with fixed supports with an account of possible slip in the points of support and then with an account of friciton in the supports is investigated analytically. The method presented permits to improve precision of the determination of mechanical properties of the materials in brittle state (ceramics, cast iron, cast aluminium alloys) at the bending test
The Contribution of the Cosmological Constant to the Relativistic Bending of Light Revisited
Rindler, Wolfgang
2007-01-01
We study the effect of the cosmological constant $\\Lambda$ on the bending of light by a concentrated spherically symmetric mass. Contrarily to previous claims, we show that when the Schwarzschild-de Sitter geometry is taken into account, $\\Lambda$ does indeed contribute to the bending.
Numerical Analysis of Damage Iinitiation and Development in Bends of Steel Pipelines
Swart, A.E.
2010-01-01
Gasses and fluids are transported via an extensive infrastructure of steel pipelines. In the design of pipeline systems the use of elbows (pipe bends) is important because their flexibility makes them able to sustain significant deformations. These bends can be subjected to permanent deformations du
Bending rigidities of surfactant bilayers using self-consistent field theory
Leermakers, F.A.M.
2013-01-01
Self-consistent field (SCF) theory is used to find bending moduli of surfactant and lipid bilayers. Recently, we successfully applied low-memory search methods to solve the SCF equations. Using these we are now able to directly evaluate the Gaussian bending modulus for molecularly detailed models of
Galvanic vestibular stimulation may improve anterior bending posture in Parkinson's disease.
Okada, Yohei; Kita, Yorihiro; Nakamura, Junji; Kataoka, Hiroshi; Kiriyama, Takao; Ueno, Satoshi; Hiyamizu, Makoto; Morioka, Shu; Shomoto, Koji
2015-05-01
This study investigated the effects of binaural monopolar galvanic vestibular stimulation (GVS), which likely stimulates the bilateral vestibular system, on the anterior bending angle in patients with Parkinson's disease (PD) with anterior bending posture in a single-blind, randomized sham-controlled crossover trial. The seven PD patients completed two types of stimulation (binaural monopolar GVS and sham stimulation) applied in a random order 1 week apart. We measured each patient's anterior bending angles while he or she stood with eyes open and eyes closed before/after the stimulations. The anterior bending angles in both the eyes-open and the eyes-closed conditions were significantly reduced after the GVS. The amount of change in the eyes-closed condition post-GVS was significantly larger than that by sham stimulation. The amount of change in anterior bending angles in the GVS condition was not significantly correlated with Unified Parkinson's Disease Rating Scale motor score, disease duration, the duration of the postural deformities, and the anterior bending angles before the GVS. Binaural monopolar GVS might improve anterior bending posture in PD patients, irrespective of the duration and the severity of disease and postural deformities. Binaural monopolar GVS might be a novel treatment strategy to improve anterior bending posture in PD. PMID:25793635
Experimental Investigation of Macro-Bending Loss in Large Mode Area Photonic Crystal Fibers
Institute of Scientific and Technical Information of China (English)
Yinian Zhu; Joo Hin Chong; Ping Shum; Chao Lu
2003-01-01
We measured macro-bending losses for two large mode area photonic crystal fibers. Experimental results show that macro-bending loss and loss window are dependent on the parameter d/Λ and number of air-holes ring in the cladding.
Experimental Investigation of Macro-Bending Loss in Large Mode Area Photonic Crystal Fibers
Institute of Scientific and Technical Information of China (English)
Joo; Hin; Chong; Ping; Shum
2003-01-01
We measured macro-bending losses for two large mode area photonic crystal fibers. Experimental results show that macro-bending loss and loss window are dependent on the parameter d/∧ and number of air-holes ring in the cladding.
Effects of repeated bending load at room temperature for composite Nb{sub 3}Sn wires
Energy Technology Data Exchange (ETDEWEB)
Awaji, Satoshi [High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Watanabe, Kazuo [High Field Laboratory for Superconducting Materials, Institute for Materials Research, Tohoku University, Katahira 2-1-1, Aoba-ku, Sendai 980-8577 (Japan); Katagiri, Kazumune [Faculty of Engineering, Iwate University, Ueda 4-3-5, Morioka 020-8511 (Japan)
2003-09-01
In order to realize a react and wind (R and W) method for Nb{sub 3}Sn wires, the influences of a bending load at room temperature are investigated. Usually, the superconducting wires undergo bending loads at room temperature repeatedly during winding and insulation processes. We define these bending loads as 'pre-bending' treatments. We applied the pre-bending strain of 0 and 0.5% to the highly strengthened CuNb/(Nb, Ti){sub 3}Sn wires, and measured the stress/strain properties and critical currents. The improvements of stress dependence of normalized critical current and the increase of the maximum critical current by the pre-bending treatments were found. The model based on the distribution of the local tensile strain as a bending strain describes the experimental results well without the increase of the maximum critical current. When the pre-bending strain was applied, the calculated results indicate that the mechanical properties are improved due to the local work hardening, and hence the stress dependence of I{sub c} increases.
Effect of frictions on cross section quality of thin-walled tube NC bending
Institute of Scientific and Technical Information of China (English)
YANG He; GU Rui-jie; ZHAN Mei; LI Heng
2006-01-01
The effect of frictions between dies and tube on the cross section quality of thin-walled tube numerical controlled(NC) bending was studied by numerical simulation method, combined with theoretical analysis and experiment. The results show that the frictions between mandrel, wiper, pressure die, bending die and tube have a significant and complicate effect on the section quality of thin-walled tube NC bending. To improve the section quality, frictions between mandrel, wiper and tube should be decreased, but the frictions between the pressure die, bending die and tube increase. The effect on the section distortion is more significant from mandrel, wiper, pressure die to bending die and the effect on the wall thinning more significant from mandrel, pressure die, wiper, to bending die. The effects of frictions between all dies and tube on wall thinning are smaller than their effects on section distortion.Mandrel and wiper should be lubricated well and drawing oil is used to lubricate them in actual production. The frictions between pressure die, bending die and tube should be increased and the dry friction is used between pressure die, bending die and tube in actual production.
Main causes of failures in critical radius bends of fuel power plant superheater
International Nuclear Information System (INIS)
In this paper the authors made a resume of study carried out by materials laboratory of Centro de Estudios Aplicados al Desarrollo Nuclear. Establishment of the causes of the simultaneous failures and after cracking occurred in the neutral zone Of critical radius bends locating in high pressure superheater of fuel power plant long two years. Authors arrived to the conclusions that the main cause of simultaneously failures in the critical radius bends was the high sulfur content in the Steel of these bends and observed internal cracking in the plastic deformed zone (strike), made during construction of bends in the factory. These works was too Helpful in taking decision for changes all critical radiuses bends and avoid the decrease of generate electrical energy
Bending efficiency analysis of horizontal single- and multiple-slot waveguide microrings
Institute of Scientific and Technical Information of China (English)
Alireza Kargar
2011-01-01
@@ The bending efficiencies of three-dimensional (3D) horizontal single- and multiple-slot waveguide microrings are analyzed using the effective index and modified transfer matrix methods.The effects of waveguide parameters, low-index material,high-index material, asymmetric structure, and asymmetric slots on the bending loss are studied.The results show that the bending efficiency can be enhanced by applying asymmetric structures and asymmetric slots.In addition, it is demonstrated that the bending loss increases with the increase of the number of slots.However, by using proper thicknesses for different high-index layers of the horizontal multiple-slot waveguide, it is possile that the horizontal multiple-slot waveguide can provide a lower bending loss than the single-slot one.
International Nuclear Information System (INIS)
A composite of liquid crystal elastomer (LCE) incorporated with carbon nanotubes (CNTs) can convert absorbed photon energy into thermal energy to trigger the phase transition of the LCE, resulting in photo-thermo-mechanically actuated devices. We model the transient temperature distribution and the bending kinetics of a straight cantilever beam actuator under the radiation of a laser diode (LD) light. Three possible bending modes of the beam for various LD light powers are identified. The temperature distribution and the bending modes are found to be in good agreement with the reported experimental observations. The underlying deformation mechanisms and bending modes are manifested by probing the stress evolution and propagation of nonzero stress regions during the bending process. For a beam that is initially slightly curved, we also predict the possibility of snap-through instability, and three typical phases of snapping are captured. This procedure paves the way for the design of LCE-based soft actuators. (paper)
Isotope effect in normal-to-local transition of acetylene bending modes
International Nuclear Information System (INIS)
The normal-to-local transition for the bending modes of acetylene is considered a prelude to its isomerization to vinylidene. Here, such a transition in fully deuterated acetylene is investigated using a full-dimensional quantum model. It is found that the local benders emerge at much lower energies and bending quantum numbers than in the hydrogen isotopomer HCCH. This is accompanied by a transition to a second kind of bending mode called counter-rotator, again at lower energies and quantum numbers than in HCCH. These transitions are also investigated using bifurcation analysis of two empirical spectroscopic fitting Hamiltonians for pure bending modes, which helps to understand the origin of the transitions semiclassically as branchings or bifurcations out of the trans and normal bend modes when the latter become dynamically unstable. The results of the quantum model and the empirical bifurcation analysis are in very good agreement
Reduction of bend-plane emittance growth in a chicane pulse compressor
Dowell, D H
1999-01-01
Emittance preservation in beam bending systems is vitally important in the production of bright, high-current electron microbunches. Generally, the emittance increase occurs in the bend plane and results from changes in the microbunch energy distribution as the beam transits the bend. This redistribution of electron energies increases the beam's divergence, and hence the emittance, by spoiling the achromatic transport of the bending system. In this paper we investigate the correlated emittance growth in a three dipole chicane compressor due to coherent synchrotron radiation (CSR). Breaking the symmetry of the chicane partially cancels the CSR-induced correlation thereby reducing the bend plane emittance growth. The consequences of this emittance compensation scheme are discussed.
Scour and flow field around a spur dike in a 90° bend
Institute of Scientific and Technical Information of China (English)
Majid FAZLI; Masoud GHODSIAN; Seyed Ali Akbar Salehi NEYSHABOURI
2008-01-01
Spur dike is an important element in river training that creates rapid variations in flow field,sediment transport and bed topography.The mechanism of flow and sediment transport in a channel bend is very complex,especially when a spur dike is constructed in a bend.Most of previous investigations on flow behavior and scour around spur dike were carried out in straight channels.In this paper results of experiments on flow field and scour around a spur dike in a 90 degree channel bend are presented.Sand with uniform grain size was used as the bed material.Experiments were conducted for different locations and different lengths of spur dikes at the bend with different values of discharge.The three dimensional flow fields around a spur dike were investigated.The maximum depth of scour was correlated to the Froude numbers,lengths and the locations of spur dike in the bend.
Improvement of springback prediction of wide sheet metal air bending process
Institute of Scientific and Technical Information of China (English)
李建; 赵军; 孙红磊; 马瑞
2008-01-01
Accurate springback prediction of wide sheet metal air bending process is important to improve product quality and ensure the precision in dimension. The definition of elastic limit bend angle was proposed. Based on cantilever beam elastic deforming theory, the geometrical parameters of forming tools, sheet thickness and the material yielding strain were derived and validated by the finite element method (FEM). Employing the degree of elastic limit bend angle, the equation for springback prediction was constructed, the results calculated fit well with experimental data. Especially for the small bend angle, the predicted results by equation were applied to conduct the springback prediction and compensation in industries and give closer correlation to the experimental data than those calculated by engineering theory of plastic bending.
FEM equivalent model for press bend forming of aircraft integral panel
Institute of Scientific and Technical Information of China (English)
YAN Yu; WAN Min; WANG Hai-bo
2009-01-01
An original plastic equivalent model was proposed to solve the problem of excessive FEM simulation time when designing the press bend forming path and optimizing the process parameters of press bend forming of the integrally stiffened aircraft panels. Based on the in-depth analysis of the mechanics of the bending and springback of the detailed model and the equivalent model of the integral panels, the plastic equivalent model of the virtual material with special initial yield stress and hardening coefficients was constructed. FEM results indicate that the objective of getting the similar contour with the same press bend forming path is achieved with the error less than 6%, and the efficiency of FEM simulation is improved by more than 80%. The plastic equivalent model is valuable and essential for the further research on the press bend forming process of large scale complicated integral panels.
Directory of Open Access Journals (Sweden)
Hikmah Annur
2015-03-01
Full Text Available Dalam dunia kedokteran jika terapi fisik dan obat-obatan tidak dapat mengatasi kelainan atau kerusakan pada sendi rahang pasien maka jalan satu-satunya adalah dengan dilakukan perawatan bedah dengan mengganti sendi yang mengalami gangguan dengan prosthesis sebagai pengganti anggota gerak yang hilang. Dalam penelitian ini digunakan material hidroksiapatit dalam pengujian bending karena memiliki komposisi kimia yang sama dengan jaringan keras pada manusia seperti gigi dan tulang. Penelitian ini bertujuan mencari nilai tegangan bending maksimum yang bisa diterima oleh komposit hidroksiapatit. Penelitian ini dilakukan dengan mengambil variasi fraksi volume hidroksiapatit 40% HA, 50% HA, 60% HA, dan 70% HA. Setelah itu material di uji bending dengan menggunakan standar ASTM D790 dengan menggunakan metode pengujian three point bending. Dari penelitian ini didapatkan bahwa tegangan bending maksimum sebesar 31.2 Mpa pada spesimen dengan persentase hidroksiapatit 50% fraksi volume. Fraksi ini adalah fraksi yang paling optimal di antara variabel-variabel uji lain.
Directory of Open Access Journals (Sweden)
Hüseyin PEKER
1999-01-01
Full Text Available This study has designed for determination of static bending strenght of mainly boron impregnated scots pine and east beech wood. Other chemicals used as control are polyethylene glycole (PEG-400 and some commercial preservatives such as Vacsol (V, Ammonıum sulphate (AS and Diammonium phospate (DAP were used by secondary process on the boron or PEG treated wood by the aim of improving static bending strenght and avoiding the leachability of both chemicals. Result indicated that static bending strenght of scots pine wood were reduced by acidic solutions of salts. In beech wood static bending strenght were also affected by neutral pH of the solution. Water repellent , surprisingly don't show their aspected protective properties of static bending strength, in general .
Energy Technology Data Exchange (ETDEWEB)
Maeda, Takenori [Univ. of Tsukuba, Ibaraki (Japan). Institute of Engineering Mechanics
1995-11-01
This paper presents an experimental method for the determination of the bending and torsional rigidities of advanced fiber composite laminates with the aid of laser holographic interferometry. The proposed method consists of a four-point bending test and a resonance test. The bending rigidity ratio (D{sub 12}/D{sub 22}) can be determined from the fringe patterns of the four-point bending test. The bending rigidities (D{sub 11} and D{sub 22}) and the torsional rigidity (D{sub 66}) are calculated from the natural frequencies of cantilever plates of the resonance test. The test specimens are carbon/epoxy cross-ply laminates. The adequacy of the experimental method is confirmed by comparing the measured rigidities with the theoretical values obtained from classical lamination theory (CLT) by using the measured tensile properties. The results show that the present method can be used to evaluate the rigidities of orthotropic laminates with reasonably good accuracy.
Bending Moment Calculations for Piles Based on the Finite Element Method
Directory of Open Access Journals (Sweden)
Yu-xin Jie
2013-01-01
Full Text Available Using the finite element analysis program ABAQUS, a series of calculations on a cantilever beam, pile, and sheet pile wall were made to investigate the bending moment computational methods. The analyses demonstrated that the shear locking is not significant for the passive pile embedded in soil. Therefore, higher-order elements are not always necessary in the computation. The number of grids across the pile section is important for bending moment calculated with stress and less significant for that calculated with displacement. Although computing bending moment with displacement requires fewer grid numbers across the pile section, it sometimes results in variation of the results. For displacement calculation, a pile row can be suitably represented by an equivalent sheet pile wall, whereas the resulting bending moments may be different. Calculated results of bending moment may differ greatly with different grid partitions and computational methods. Therefore, a comparison of results is necessary when performing the analysis.
Simultaneously bending and tensile strain effect on critical current in YBCO coated conductors
International Nuclear Information System (INIS)
YBCO coated conductors have been expected for the application to a coil for superconducting magnetic energy storage (SMES). In the application to a superconducting coil, the coated conductors experience bending, uniaxial tensile strain and their combined strain. Therefore, the influence of simultaneous bending and tensile strain on critical current should be revealed. In this work, we developed the test method of critical current under such combined strain state. As a result, it was confirmed that compressive pre-bending can improve the stress tolerance of the YBCO coated conductors. On the other hand, compressive bending strain suppresses the initial critical current by the intrinsic strain effect. These results indicate that optimal bending radius should be selected in order to realize superior stress tolerance and high current capacity simultaneously
Evaluation of ultimate tensile strength using Miniature Disk Bend Test
Energy Technology Data Exchange (ETDEWEB)
Kumar, Kundan, E-mail: kundan@barc.gov.in [Reactor Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Pooleery, Arun; Madhusoodanan, K. [Reactor Engineering Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Singh, R.N.; Chakravartty, J.K. [Mechanical Metallurgy Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Shriwastaw, R.S. [Post Irradiation Examination Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Dutta, B.K. [Reactor Safety Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Sinha, R.K. [Atomic Energy Commission, DAE, Anushakti Bhavan, Mumbai 400001 (India)
2015-06-15
Graphical abstract: Since inception of Miniature Disk Bend Test (MDBT) technique, UTS correlations have been an open issue. Correlations based on P{sub max} of load–displacement curve are also in disagreement as the point corresponding to P{sub max} does not represent a necking situation as in case of UTS, in a uniaxial tensile test. In present work, an attempt has been made for locating necking zone, which appears prior to P{sub max}, through experiments and FEM analyses. Experimental results on disk specimens from 20MnMoNi55, CrMoV ferritic steel and SS304LN materials along with FEM analyses found that load corresponding to 0.48 mm displacement is to be very close to the necking zone, and gives best fit for a UTS correlation. (a) Plots of thickness of disk at various radial locations for different punch travel distances for 20MnMoNi55 and (b) derivative of minimum thickness on the disk with punch travel. - Highlights: • Correlations for UTS in a SPT have been an open issue since the development of this technique. • The point P{sub max} in SPT curve does not correspond to a necking as in P-δ curve in tensile test. • In this work attempt has been made to locate necking in SPT curve using experiments and FEM. • The data corresponding to 0.48 mm displacement is found to be very close to the necking zone. • It is found that correlation for UTS is best suited for data corresponding to the necking zone. - Abstract: Correlations for evaluation of Ultimate Tensile Strength (UTS) using Miniature Disk Bend Test (MDBT) or Small Punch Test (SPT) has been an open issue since the development of the techniques. The larger plastic strains, in tri-axial state of stress during SPT, make the translation to the equivalent uniaxial parameter less certain. Correlations based on P{sub max} of load–displacement curve are also in disagreement as the point corresponding to P{sub max} does not represent a necking situation as in case of UTS, in a uniaxial tensile test. In
Evaluation of ultimate tensile strength using Miniature Disk Bend Test
Kumar, Kundan; Pooleery, Arun; Madhusoodanan, K.; Singh, R. N.; Chakravartty, J. K.; Shriwastaw, R. S.; Dutta, B. K.; Sinha, R. K.
2015-06-01
Correlations for evaluation of Ultimate Tensile Strength (UTS) using Miniature Disk Bend Test (MDBT) or Small Punch Test (SPT) has been an open issue since the development of the techniques. The larger plastic strains, in tri-axial state of stress during SPT, make the translation to the equivalent uniaxial parameter less certain. Correlations based on Pmax of load-displacement curve are also in disagreement as the point corresponding to Pmax does not represent a necking situation as in case of UTS, in a uniaxial tensile test. In present work, an attempt has been made for locating necking zone, which appears prior to Pmax, through experiments and FEM analyses. Experimental results on disk specimens from 20MnMoNi55, CrMoV ferritic steel and SS304LN materials along with FEM analyses found that load corresponding to 0.48 mm displacement is to be very close to the necking zone, and gives best fit for a UTS correlation.
Bending of a nonlinear beam reposing on an unilateral foundation
Directory of Open Access Journals (Sweden)
Machalová J.
2011-06-01
Full Text Available This article is going to deal with bending of a nonlinear beam whose mathematical model was proposed by D. Y. Gao in (Gao, D. Y., Nonlinear elastic beam theory with application in contact problems and variational approaches,Mech. Research Communication, 23 (1 1996. The model is based on the Euler-Bernoulli hypothesis and under assumption of nonzero lateral stress component enables moderately large deflections but with small strains. This is here extended by the unilateralWinkler foundation. The attribution unilateral means that the foundation is not connected with the beam. For this problem we demonstrate a mathematical formulation resulting from its natural decomposition which leads to a saddle-point problem with a proper Lagrangian. Next we are concerned with methods of solution for our problem by means of the finite element method as the paper (Gao, D. Y., Nonlinear elastic beam theory with application in contact problems and variational approaches, Mech. Research Communication, 23 (1 1996 has no mention of it. The main alternatives are here the solution of a system of nonlinear nondifferentiable equations or finding of a saddle point through the use of the augmented Lagrangian method. This is illustrated by an example in the final part of the article.
Effect of Solder Joint Length on Fracture Under Bending
Akbari, Saeed; Nourani, Amir; Spelt, Jan K.
2016-01-01
Fracture tests were conducted on copper-solder-copper joints of various lengths using double-cantilever-beam (DCB) specimens under mode I loading conditions. The thickness and length of the solder joints were large enough to neglect any anisotropy associated with the solder microstructure. It was found that the critical strain energy release rate at crack initiation, G ci, was insensitive to the length of the solder joint; however, for joints shorter than a characteristic length which was a function of the thickness and the mechanical properties of the solder layer and the substrates, the fracture load increased with increasing solder joint length. A sandwich model was developed for the analysis of the stress and strain in solder joints, taking into account the influence of both the bending deformation and the shear deformation of the substrates on the solder joint stresses. Consistent with the experimental results, it was found that solder joints longer than the characteristic length have a maximum peel stress that remains unchanged with joint length, causing the joint strength to become independent of the joint length. A closed-form analytical solution was developed for the characteristic length of DCB specimens under mode I loading. The experimental results were in good agreement with the analytical model and with finite element results. The generality of the G ci failure criterion was demonstrated by comparing the experimental results and the fracture load predictions of mode I DCB solder joints with different lengths.
Disk heating and bending instability in galaxies with counterrotation
Khoperskov, Sergey
2016-01-01
With the help of high-resolution long-slit and integral-field spectroscopy observations, the number of confirmed cases of galaxies with counterrotation is increasing rapidly. The evolution of such counterrotating galaxies remains far from being well understood. In this paper we study the dynamics of counterrotating collisionless stellar disks by means of $N$-body simulations. We show that, in the presence of counterrotation, an otherwise gravitationally stable disk can naturally generate bending waves accompanied by strong disk heating across the disk plane, that is in the vertical direction. Such conclusion is found to hold even for dynamically warm systems with typical values of the initial vertical-to-radial velocity dispersion ratio $\\sigma_{\\rm R}/\\sigma_{\\rm z} \\approx 0.5$, for which the role of pressure anisotropy should be unimportant. We note that, during evolution, the $\\sigma_{\\rm R}/\\sigma_{\\rm z}$ ratio tends to rise up to values close to unity in the case of locally Jeans-stable disks, whereas ...
Bending magnets for the CBA beam-transport line
Energy Technology Data Exchange (ETDEWEB)
Thern, R.E.
1983-01-01
The beam-transport line from the AGS to CBA requires 68 large bending magnets, consisting of pure dipoles and two types of combined function gradient magnets. All three types were designed with magnetic-field calculation program POISSON, using the same exterior dimensions and coil package. The design goal of +-1% momentum acceptance for the transport line required a wide horizontal aperture, with a much-smaller vertical aperture for economy. Two prototypes of one gradient magnet were built, and a facility constructed to measure them and the later production magnets. Measurements were done using both a long coil and a point coil (Rawson-Lush gaussmeter). Preliminary results show ..delta..B/B < 0.2 x 10/sup -3/, ..delta..G/G < 0.3 x 10/sup -2/, and ..delta..B/sub 2//B < 0.3 x 10/sup -4/ cm/sup -2/ over the beam aperture. Due to end effects, the actual gradient differs from the design gradient by 1%, which has been compensated for in the beam-line design.
Working Group 2 summary: Space charge effects in bending systems
International Nuclear Information System (INIS)
At the start of the Workshop, the authors asked the Working Group 2 participants to concentrate on three basic goals: (1) survey the status of how comprehensively the physics concerning space-charge effects in bends is understood and how complete is the available ensemble of analytic and computational tools; (2) guided by data from experiments and operational experience, identify sources of, and cures for, beam degradation; and (3) review space-charge physics in rings and the limitations it introduces. As the Workshop unfolded, the third goal naturally folded into the other two goals, and these goals, they believe, were fulfilled in that the Working Group was able to compile an end product consisting of a set of recommendations for potentially fruitful future work. This summary constitutes an overview of the deliberations of the Working Group, and it is their hope that the summary clarifies the motivation for the recommended work listed at the end. The summary is organized according to the two aforementioned goals, and the prime topics of discussion appear as subsections under these goals
Investigation of cutting-induced damage in CMC bend bars
Directory of Open Access Journals (Sweden)
Neubrand A.
2015-01-01
Full Text Available Ceramic matrix composites (“CMC” with a strong fibre-matrix interface can be made damage-tolerant by introducing a highly porous matrix. Such composites typically have only a low interlaminar shear strength, which can potentially promote damage when preparing specimens or components by cutting. In order to investigate the damage induced by different cutting methods, waterjet cutting with and without abrasives, laser-cutting, wire eroding and cutoff grinding were used to cut plates of two different CMCs with a matrix porosity up to 35 vol.-%. For each combination of cutting method and composite, the flexural and interlaminar shear strength of the resulting specimens was determined. Additionally, the integrity of the regions near the cut surfaces was investigated by high-resolution x-ray computer tomography. It could be shown that the geometrical quality of the cut is strongly affected by the cutting method employed. Laser cut and waterjet cut specimens showed damage and delaminations near the cut surface leading to a reduced interlaminar shear strength of short bend bars in extreme cases.
Bending and Breathing Modes of the Galactic Disk
Widrow, Lawrence M; Chequers, Matthew H; Cheng, Edward
2014-01-01
We explore the hypothesis that a passing satellite or dark matter subhalo has excited coherent oscillations of the Milky Way's stellar disk in the direction perpendicular to the Galactic midplane. This work is motivated by recent observations of spatially dependent bulk vertical motions within ~ kpc of the Sun. A satellite can transfer a fraction of its orbital energy to the disk stars as it plunges through the Galactic midplane thereby heating and thickening the disk. Bulk motions arise during the early stages of such an event when the disk is still in an unrelaxed state. We present simple toy-model calculations and simulations of disk-satellite interactions, which show that the response of the disk depends on the relative velocity of the satellite. When the component of the satellite's velocity perpendicular to the disk is small compared with that of the stars, the perturbation is predominantly a bending mode. Conversely, breathing and higher order modes are excited when the vertical velocity of the satelli...
Soft Pneumatic Bending Actuator with Integrated Carbon Nanotube Displacement Sensor
Directory of Open Access Journals (Sweden)
Tim Giffney
2016-02-01
Full Text Available The excellent compliance and large range of motion of soft actuators controlled by fluid pressure has lead to strong interest in applying devices of this type for biomimetic and human-robot interaction applications. However, in contrast to soft actuators fabricated from stretchable silicone materials, conventional technologies for position sensing are typically rigid or bulky and are not ideal for integration into soft robotic devices. Therefore, in order to facilitate the use of soft pneumatic actuators in applications where position sensing or closed loop control is required, a soft pneumatic bending actuator with an integrated carbon nanotube position sensor has been developed. The integrated carbon nanotube position sensor presented in this work is flexible and well suited to measuring the large displacements frequently encountered in soft robotics. The sensor is produced by a simple soft lithography process during the fabrication of the soft pneumatic actuator, with a greater than 30% resistance change between the relaxed state and the maximum displacement position. It is anticipated that integrated resistive position sensors using a similar design will be useful in a wide range of soft robotic systems.
EPICS based control system of pulse bend correction coil
International Nuclear Information System (INIS)
The pulse-bend magnet in J-PARC 3-50BT has the residual magnetic field, slightly after it has sent protons to MR. Due to this effect, we can not supply protons to the MLF, during three 25Hz-cycles. A correction coil and its custom made power-supply were introduced in order to cancel out the residual magnetic field. We have constructed an EPICS-based control systems for this correction coil power supply. The control system have four components: (1) a PLC controller with a Linux CPU and I/O modules, (2) a commercial function generator, (3) a custom made power-supply to drive coil current, and (4) a timing module to provide proper trigger signals. A pattern waveform, delivered from a function generator, is used to drives the customized power supply. We have examined basic functionalities of the control system during beam studies in May and in June 2014, and confirmed its availabilities, namely status monitoring and operation controls. However, we found some problems in interlock signals of the power-supply. We will improve the system toward the next operation from this autumn. (author)
Bending and Deformation of Sandwich Panels Due to Localized Pressure
Directory of Open Access Journals (Sweden)
Bambang K. Hadi
2005-05-01
Full Text Available Bending and deformation of sandwich panels due to localized pressure were analyzed using both Rayleigh-Ritz and finite element methods. The faces were made of laminated composite plates, while the core was a honeycomb material. Carbon fiber and glass fiber reinforced plastics were used for composite plate faces. In the case of Rayleigh-Ritz method, first the total energy of the system was calculated and then taking the variations of the total energy, the sandwich panel deflections could be computed. The deflections were assumed by means of Fourier series. A finite element code NASTRAN was exploited extensively in the finite element method. 3-dimensional 8-node brick elements were used to model sandwich panels, for both the faces sheets and the core. The results were then compared to each other and in general they are in good agreements. Dimple phenomena were found in these cases. It shows that localized pressure on sandwich structures will produce dimple on the pressurize region with little effects on the rest of the structures.
Bending of Pinus jeffreyi in response to wind
Directory of Open Access Journals (Sweden)
Stephen H. Bullock
2015-12-01
Full Text Available Aim of study: To evaluate the degree of trunk sway in relation to wind velocity, with varying temporal integration and to compare this relation among seasons.Area of study: Sierra de Juárez, Baja California, MéxicoMaterials and Methods: Displacements of a 19 m tall Jeffrey pine tree were recorded at 6 m from a three dimensional digital compass during one year, at c. 4 Hz. Adjacent wind speed at 6 m was recorded at 1 Hz.Main results: Sway was essentially unaffected by wind in the same second but increasing dependence of cumulative displacement on average sustained wind speed was found for intervals of 1 to 60 minutes (r2 up to 0.89. The relation is generally log-linear but apparently differs in parameters between seasons.Research highlights: Wind-sway relations are clear from integration of several-to-many minutes. However, to estimate cumulative stress, sub-second data on sway are essential. Sub-second, precision measurements of sway can be registered from small, inexpensive sensors.Keywords: biomechanics; Pinus jeffreyi; seasonality; stress accumulation; time series; tree bending.
Flexural bending of southern Tibet in a retro foreland setting.
Wang, Erchie; Kamp, Peter J J; Xu, Ganqing; Hodges, Kip V; Meng, Kai; Chen, Lin; Wang, Gang; Luo, Hui
2015-01-01
The highest elevation of the Tibetan Plateau, lying 5,700 m above sea level, occurs within the part of the Lhasa block immediately north of the India-Tibet suture zone (Yarlung Zangbo suture zone, YZSZ), being 700 m higher than the maximum elevation of more northern parts of the plateau. Various mechanisms have been proposed to explain this differentially higher topography and the rock uplift that led to it, invoking crustal compression or extension. Here we present the results of structural investigations along the length of the high elevation belt and suture zone, which rather indicate flexural bending of the southern margin of the Lhasa block (Gangdese magmatic belt) and occurrence of an adjacent foreland basin (Kailas Basin), both elements resulting from supra-crustal loading of the Lhasa block by the Zangbo Complex (Indian plate rocks) via the Great Counter Thrust. Hence we interpret the differential elevation of the southern margin of the plateau as due originally to uplift of a forebulge in a retro foreland setting modified by subsequent processes. Identification of this flexural deformation has implications for early evolution of the India-Tibet continental collision zone, implying an initial (Late Oligocene) symmetrical architecture that subsequently transitioned into the present asymmetrical wedge architecture. PMID:26174578
Optical diffraction for measurements of nano-mechanical bending
Hermans, Rodolfo I.; Dueck, Benjamin; Ndieyira, Joseph Wafula; McKendry, Rachel A.; Aeppli, Gabriel
2016-06-01
We explore and exploit diffraction effects that have been previously neglected when modelling optical measurement techniques for the bending of micro-mechanical transducers such as cantilevers for atomic force microscopy. The illumination of a cantilever edge causes an asymmetric diffraction pattern at the photo-detector affecting the calibration of the measured signal in the popular optical beam deflection technique (OBDT). The conditions that avoid such detection artefacts conflict with the use of smaller cantilevers. Embracing diffraction patterns as data yields a potent detection technique that decouples tilt and curvature and simultaneously relaxes the requirements on the illumination alignment and detector position through a measurable which is invariant to translation and rotation. We show analytical results, numerical simulations and physiologically relevant experimental data demonstrating the utility of the diffraction patterns. We offer experimental design guidelines and quantify possible sources of systematic error in OBDT. We demonstrate a new nanometre resolution detection method that can replace OBDT, where diffraction effects from finite sized or patterned cantilevers are exploited. Such effects are readily generalized to cantilever arrays, and allow transmission detection of mechanical curvature, enabling instrumentation with simpler geometry. We highlight the comparative advantages over OBDT by detecting molecular activity of antibiotic Vancomycin.
International Nuclear Information System (INIS)
No experimental data exist within open literature, to the best knowledge of the author, for determining shakedown boundaries of 90° back-to-back pipe bends. Ninety degree back-to-back pipe bends are extensively utilized within piping networks of nuclear submarines and modern turbofan aero-engines where space limitation is considered a paramount concern. In the current research, the 90° back-to-back pipe bend setup analyzed is subjected to a spectrum of steady internal pressures and cyclic in-plane bending moments. A previously developed direct non-cyclic simplified technique for determining elastic shakedown limit loads is utilized to generate the elastic shakedown boundary of the analyzed structure. The simplified technique outcomes showed excellent correlation with the results of full elastic–plastic cyclic loading finite element simulations. - Highlights: • No shakedown experimental data exist for 90° back-to-back pipe bends. • A non-cyclic technique is utilized to generate the elastic shakedown boundary. • The non-cyclic technique succeeded in generating the structure's Bree diagram. • The non-cyclic technique correlated well with full cyclic loading FE simulations
Flexible thick-film glucose biosensor: influence of mechanical bending on the performance.
Chuang, Min-Chieh; Yang, Yang-Li; Tseng, Ta-Feng; Chou, Tzuyang; Lou, Shyh-Liang; Wang, Joseph
2010-04-15
The influence of the bending-induced mechanical stress of flexible Nafion/GOx/carbon screen-printed electrodes (SPEs) upon the performance of such glucose biosensors has been examined. Surprisingly, such flexible enzyme/polymer-SPEs operate well following a severe bending-induced mechanical stress (including a 180 degrees pinch), and actually display a substantial sensitivity enhancement following their mechanical bending. The bending-induced sensitivity enhancement is observed only for the amperometric detection of the glucose substrate but not for measurements of hydrogen peroxide, catechol or ferrocyanide at coated or bare SPEs. These (and additional) data indicate that the bending effect is associated primarily with changes in the biocatalytic activity. Such sensitivity enhancement is more pronounced at elevated glucose levels, reflecting the bending-induced changes in the biocatalytic reaction. Factors affecting the bending-induced changes in the performance are examined. While our data clearly indicate that flexible enzyme/polymer-SPEs can tolerate a severe mechanical stress and hold promise as wearable glucose biosensors, delivering the sample to the active sensor surface remains the major challenge for such continuous health monitoring. PMID:20188880
Elbow- and hinge-bending motions of IgG: Dielectric response and dynamic feature.
Hayashi, Yoshihito; Yagihara, Shin
2016-09-01
Immunoglobulin G (IgG) is a Y-shaped globular protein consisting of two Fab segments connecting to an Fc segment with a flexible hinge region, in which the Fab segments show secondary flexibility at an "elbow" region. In the present work, the hinge-bending and elbow-bending motions of aqueous solutions of IgG by microwave dielectric measurements below the freezing point of bulk water was observed. The presence of unfreezable water around the macromolecules reduced the effects of steric hindrance normally generated by ice and enabled the intramolecular motions of IgG. At the same time, the overall IgG molecule rotation was restricted by ice. Papain digestion and reduction of the disulfide linkage at the hinge region was used to generate Fab and Fc fragments. In solutions of these fragments, the dielectric relaxation process of the hinge-bending motion was absent, although the elbow-bending motion remained. Three relaxation processes were observed for papain-digested IgG. The high, middle, and low frequency processes were attributed to unfrozen water, local peptide motions cooperating with bound water, and the elbow-bending motion, respectively. In the case of the intact IgG, an additional relaxation process due to the hinge-bending motion was observed at frequencies lower than that of the elbow-bending motion. © 2016 Wiley Periodicals, Inc. Biopolymers 105: 626-632, 2016. PMID:27018805
Feature guided waves (FGW) in fiber reinforced composite plates with 90° transverse bends
Yu, Xudong; Ratassepp, Madis; Fan, Zheng; Manogharan, Prabhakaran; Rajagopal, Prabhu
2016-02-01
Fiber reinforced composite materials have been increasingly used in high performance structures such as aircraft and large wind turbine blades. 90◦ composite bends are common in reinforcing structural elements, which are prone to defects such as delamination, crack, fatigue, etc. Current techniques are based on local inspection which makes the whole bend area scanning time consuming and tedious. This paper explores the feasibility of using feature guided waves (FGW) for rapid screening of 90◦ composite laminated bends. In this study, the behavior of the bend-guided wave in the anisotropic composite material is investigated through modal studies by applying the Semi-Analytical Finite Element (SAFE) method, also 3D Finite Element (FE) simulations are performed to visualize the results and to obtain cross validation. To understand the influence of the anisotropy, three-dimensional dispersion surfaces of the guided modes in flat laminated plates are obtained, showing the dependence of the phase velocity with the frequency and the fiber orientation. S H0-like and S 0-like bend-guided modes are identified with energy concentrated in the bend region, limiting energy radiation into adjacent plates and thus achieving increased inspection length. Finally, parametric studies are carried out to further investigate the properties of these two bend-guided modes, demonstrating the variation of the group velocity, the energy concentration, and the attenuation with the frequency.
Bio-inspired bending actuator for controlling conical nose shape using piezoelectric patches.
Na, Tae-Won; Jung, Jin-Young; Oh, Ii-Kwon
2014-10-01
In this paper, a bio-inspired bending actuator was designed and fabricated using piezoelectric patches and cantilever-shaped beam for controlling nose shape. The aim of this study is to investigate the use of the bending actuator. PZT and single crystal PMN-PT actuators were used to generate translational strain and shear stress. The piezoelectric patches were attached on the clamped cantilever beam to convert their translational strains to bending motion of the beam. First, finite element analysis was performed to identify and to make an accurate estimate of the feasibility on the bending actuation by applying various voltages and frequencies. Based on the results of the FEM analysis, the experiments were also performed. Static voltages and dynamic voltages with various frequencies were applied to the bending actuators with PZTs and PMN-PTs, and the rotation angles of the nose connected to the top of bending actuators were measured, respectively. As the results, the bending actuator using PMN-PT patches showed better performances in all cases. With the increases of signal frequency and input voltage, the rotation angle also found to be increased. Especially at the frequency of 5 Hz and input voltage of 600 V, the nose generated the maximum rotation angle of 3.15 degree. PMID:25942810
Bending Characteristics of Foldable Touch Display Panel with a Protection Structure Design
Directory of Open Access Journals (Sweden)
Hsien-Chie Cheng
2015-01-01
Full Text Available The study proposes and demonstrates an enhancement of a touch display panel (TDP through a polymer-based protection structure to achieve higher bendability and reliability. The bending performance of the TDP without or with the protection structure designs is addressed using three-dimensional geometry-nonlinear finite element analysis and mechanical testing. The elastic properties of the components in the TDP structure are derived from nanoindentation and uniaxial tensile/compressive testing. The calculated results are compared with each other and also against the experimental bending fatigue test data. At last, a design guideline and optimal factor setting for enhanced bending performance are sought through parametric FE analysis and Taguchi experimental design, respectively. The optimal design is compared with the original in terms of bending stress. The simulation results show that bending would create significant tensile and compressive bending stresses on the indium tin oxide/dielectric layers, which are the main cause of several commonly observed failures, such as thin film cracking and delamination, in a thin rigid film coating on a thick compliant substrate. It also turns out that a substrate with a lower stiffness has a better mechanical stability against bending stress.
Laser Micro Bending Process of Ti6Al4V Square Bar
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Gang Chen
2014-06-01
Full Text Available Laser micro bending process of Ti6Al4V square bar are carried out using a 3D thermo-mechanical finite element analytical model (FEM. The transient temperature fields, displacement fields, stress fields and strain fields are obtained and analyzed. The results show that the bending angel during laser micro bending process is in good agreement with experimental measurements. The effects of process parameters on temperature and deformation are also investigated here. During the bending process the temperature increases with the increase of the laser power and the irradiation time. Radiation of the laser beam yields to a rapid temperature increase at the irradiated surface, which leads to the high temperature gradients between the irradiated surface and the unirradiated surface, which suggest that the mechanism of laser micro bending is the temperature gradient mechanism. The z displacement of forward direction and reverse direction increase when the laser power and irradiation time increase. Laser micro bending process can obtain the larger bending angles reverse to laser beam using higher laser power and shorter irradiation time.
Flooding characteristics of gas-liquid two-phase flow in a horizontal U bend pipe
Energy Technology Data Exchange (ETDEWEB)
Sakaguchi, T.; Hosokawa, S.; Fujii, Y. [Kobe Univ. (Japan)] [and others
1995-09-01
For next-generation nuclear reactors, hybrid safety systems which consist of active and passive safety systems have been planned. Steam generators with horizontal U bend pipelines will be used as one of the passive safety systems. It is required to clarify flow characteristics, especially the onset of flooding, in the horizontal U bend pipelines in order to examine their safety. Flooding in vertical pipes has been studied extensively. However, there is little study on flooding in the horizontal U bend pipelines. It is supposed that the onset of flooding in the horizontal U bend pipelines is different from that in vertical pipes. On the other hand, liquid is generated due to condensation of steam in pipes of the horizontal steam generators at the loss of coolant accident because the steam generators will be used as a condenser of a cooling system of steam from the reactor. It is necessary to simulate this situation by the supply of water at the middle of horizontal pipe. In the present paper, experiments were carried out using a horizontal U bend pipeline with a liquid supply section in the midway of pipeline. The onset of flooding in the horizontal U bend pipeline was measured. Effects of the length of horizontal pipe and the radius of U bend on the onset of flooding were discussed.
Axial forces and bending moments in the loaded rabbit tibia in vivo
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Reifenrath Janin
2012-03-01
Full Text Available Abstract Background Different animal models are used as fracture models in orthopaedic research prior to implant use in humans, although biomechanical forces can differ to a great extend between species due to variable anatomic conditions, particularly with regard to the gait. The rabbit is an often used fracture model, but biomechanical data are very rare. The objective of the present study was to measure axial forces, bending moments, and bending axis directly in the rabbit tibia in vivo. The following hypothesis was tested: Axial forces and bending moments in the mid-diaphysis of rabbit tibia differ from other experimental animals or indirectly calculated data. Methods A minifixateur system with 4 force sensors was developed and attached to rabbit tibia (n = 4, which were subsequently ostectomised. Axial forces, bending moments and bending angles were calculated telemetrically during weight bearing in motion between 6 and 42 days post operation. Results Highest single values were 201% body weight [% bw] for axial forces and 409% bw cm for bending moments. Whereas there was a continous decrease in axial forces over time after day 10 (P = 0.03 on day 15, a decrease in bending moments was inconsistent (P = 0.03 on day 27. High values for bending moments were frequently, but not consistently, associated with high values for axial forces. Conclusion Axial forces in rabbit tibia exceeded axial forces in sheep, and differed from indirectly calculated data. The rabbit is an appropriate fracture model because axial loads and bending moments in rabbit tibia were more closely to human conditions than in sheep tibia as an animal model.
Three Dimensional FE Analysis on Flange Bending for TC4 Alloy during Shear Spinning
Institute of Scientific and Technical Information of China (English)
Xinyu LU; Shihong ZHANG; Hongliang HOU; Jizhen LI; Lixin ZHOU; Zhiqiang LI
2006-01-01
In this paper, the 3D elastic-plastic simulation was carried out by using finite element (FE) code according to the phenomena of flange keeping straight, bending towards headstock and bending towards tailstock in the shear spinning experiments for TC4 alloy. The simulation results for the three kinds of deformations of the flange agree well with the experimental results. So it is possible to explain the reason of flange bending by analyzing the strain vectors in the flange for the three kinds of deformation, which shows that it is important to apply the FE simulation technology for predicting the defects and optimizing the spinning process of TC4 alloys.
A Temperature Sensor Based on a Polymer Optical Fiber Macro-Bend
Directory of Open Access Journals (Sweden)
Joseba Zubia Zaballa
2013-09-01
Full Text Available The design and development of a plastic optical fiber (POF macrobend temperature sensor is presented. The sensor has a linear response versus temperature at a fixed bend radius, with a sensitivity of . The sensor system used a dummy fiber-optic sensor for reference purposes having a resolution below 0.3 °C. A comprehensive experimental analysis was carried out to provide insight into the effect of different surrounding media on practical macro-bend POF sensor implementation. Experimental results are successfully compared with bend loss calculations.
Laser assisted die bending: a new application of high power diode lasers
Schuöcker, D.; Schumi, T.; Spitzer, O.; Bammer, F.; Schuöcker, G.; Sperrer, G.
2015-02-01
Nowadays high power lasers are mainly used for cutting of sheet metals, for welding, hardening and rapid prototyping. In the forming of sheet metals as bending or deep drawing lasers are not used. Nevertheless a few years ago a new application of high power lasers has been invented, where bending of materials that break at room temperature becomes possible by heating them along the bending edge with high power lasers thus allowing their treatment without cracks and rupture. For this purpose a large number of diode lasers are arranged in the bottom tool of a bending machine (a V-shaped die) which heat up the initially flat sheet metal during the bending process what is performed by pressing it into the die with a knife shaped upper tool where due to the laser heating the material is softened and thus cracks are avoided. For the technical realization of the new process of laser assisted die bending, modules equipped with numerous laser diodes and a total beam power of 2,5 kW are used. The light emitted by these modules enters a tool with a length of 15cm and is deflected towards the workpiece. By using ten of these modules with adjacent dies and by integrating those in a bending press a bending edge of sheet metals with a length of 1500mm can be realized. Such a bending press with laser assistance also needs energization with a power of practically 50kW, a respective water flow, a heat exchanger system and also a control for all functions of this system. Special measures have also been developed to avoid radiating of those tools that are not covered by a workpiece in the case of bending edges shorter than the full length of the bending tools whereas individual short circuiting of diode modules can be performed. Specific measures to ensure a safe operation without any harm to the operational person have been realized. Exploitation of the bending process has been carried out for titanium, where material thicknesses up to 3mm have been bent successfully.
Waveguiding and bending modes in a plasma photonic crystal bandgap device
Directory of Open Access Journals (Sweden)
B. Wang
2016-06-01
Full Text Available Waveguiding and bending modes are investigated in a fully tunable plasma photonic crystal. The plasma device actively controls the propagation of free space electromagnetic waves in the S to X band of the microwave spectrum. An array of discharge plasma tubes form a square crystal lattice exhibiting a well-defined bandgap, with individual active switching of the plasma elements to allow for waveguiding and bending modes to be generated dynamically. We show, through simulations and experiments, the existence of transverse electric (TE mode waveguiding and bending modes.
Analysis of supersonic stall bending flutter in axial-flow compressor by actuator disk theory
Adamczyk, J. J.
1978-01-01
An analytical model was developed for predicting the onset of supersonic stall bending flutter in axial-flow compressors. The analysis is based on two-dimensional, compressible, unsteady actuator disk theory. It is applied to a rotor blade row by considering a cascade of airfoils. The effects of shock waves and flow separation are included in the model. Calculations show that the model predicts the onset, in an unshrouded rotor, of a bending flutter mode that exhibits many of the characteristics of supersonic stall bending flutter. The validity of the analysis for predicting this flutter mode is demonstrated.
DYNAMIC BEHAVIOR OF BURIED BEND WITH THRUST RESTRAINT IN LIQUEFYING GROUND
Kawabata, Toshinori; Sawada, Yutaka; Mohri, Yoshiyuki; Ling, Hoe I.
In this study, a shaking table test was carried out in order to discuss the dynamic behavior for the bend of pressure pipeline with a concrete block and thrust restraints using geogrids or gravels in liquefying ground. As a result, it was revealed that the concrete block was largely moved and the relative displacement between the bend and the adjacent pipe became large. On the other hand, it was proved that geogrids and gravels were very effective for the lateral resistance in liquefying ground. In addition, the relative displacement was small because of the same difference between the bend and the adjacent pipe.
Analysis of the bending behaviour of flax based reinforcements used in shape forming
Bassoumi, Amal; Gillibert, Jean; Hivet, G
2013-01-01
The bending behaviour of woven perform was investigated in order to better understand the formation of some defects during sheet forming such as wrinkling and tow buckling. The fabric composition considering hybrid and pure flax fabrics as well as some test conditions like relative humidity were examined. On the one hand, the results show a drop of the bending stiffness with flax/PLA commingled fabric. On the other hand, the study points out that moisture enhances the bending rigidity especially in the case of pure flax fabric. However, an excess of humidity, for instance 100% relative humidity, leads to an opposite effect.
A Temperature Sensor Based on a Polymer Optical Fiber Macro-Bend
Moraleda, Alberto Tapetado; García, Carmen Vázquez; Zaballa, Joseba Zubia; Arrue, Jon
2013-01-01
The design and development of a plastic optical fiber (POF) macrobend temperature sensor is presented. The sensor has a linear response versus temperature at a fixed bend radius, with a sensitivity of 1.92·10−3 (°C)−1. The sensor system used a dummy fiber-optic sensor for reference purposes having a resolution below 0.3 °C. A comprehensive experimental analysis was carried out to provide insight into the effect of different surrounding media on practical macro-bend POF sensor implementation. Experimental results are successfully compared with bend loss calculations. PMID:24077323
Fujita, Yoshihisa; Ikuno, Soichiro; Kubo, Shin; Nakamura, Hiroaki
2016-01-01
The effect of the polarizer miter bend (PMB) reflector on polarization is numerically investigated by using the finite-difference time-domain (FDTD) method. The Drude model is implemented to take into account the fact that the waveguide wall is prepared from a dispersive medium. In electron cyclotron resonance heating (ECRH), the corrugated waveguide and miter bend are adopted for transmitting millimeter electromagnetic waves. In addition, PMB is employed to improve the plasma heating efficiency. The results of computations show that modes other than the input mode are also generated owing to the reflection at the miter bend mirror/PMB reflector. Moreover, it is found that elliptical polarization is observed after the linear polarization passes through PMB.
Bending of magnetic filaments under a magnetic field
Shcherbakov, Valera P.; Winklhofer, Michael
2004-12-01
Magnetic beads and superparamagnetic (SP) colloid particles have successfully been employed for micromechanical manipulation of soft material, in situ probing of elastic properties, and design of smart materials (ferrogels). Here we derive analytical expressions for the equilibrium shape of magnetic fibers, considering two end-member cases, (a) SP or single-domain particles concentrated at the free end of cantilevered rods or tubes, and (b) filaments consisting of SP particles, with this case being mathematically equivalent to tubes containing SP particles. Our analysis yields also metastable equilibrium states (MES’s), which only exist above a critical filament length, but become more stable with increasing magnetic field. The MES’s for case (a) are, like the ground state, circular arcs, but more strongly bent. The multiform MES’s in case (b), which comprise hairpin, sinuous, or even closed shapes, have recently been observed in experiments, too. We also study the effect of gravity on the balance between bending and magnetic energy, which leads to curves with inflection point if the influence of gravity is stronger than that of the magnetic field. Because of their simple experimental realization, case (a) magnetic filaments are deemed highly suitable for micromechanical experiments on long chains of polymer molecules. Another potential application of cantilevered magnetic filaments with magnetic material attached to the free end is in scanning probe microscopes. Because the magnetic field due to the magnetic tip is comparatively weak, the magnetization structure of the sample to be investigated would not be affected by the probe. Thus, for the examination of magnetically soft materials, probes in the form of magnetic filaments may hold advantages over tips usually employed in magnetic force microscopy.
Improving Bending Moment Measurements on Wind Turbine Blades
Energy Technology Data Exchange (ETDEWEB)
Post, Nathan L.
2016-03-15
Full-scale fatigue testing of wind turbine blades is conducted using resonance test techniques where the blade plus additional masses is excited at its first resonance frequency to achieve the target loading amplitude. Because there is not a direct relationship between the force applied by an actuator and the bending moment, the blade is instrumented with strain gauges that are calibrated under static loading conditions to determine the sensitivity or relationship between strain and applied moment. Then, during dynamic loading the applied moment is calculated using the strain response of the structure. A similar procedure is also used in the field to measure in-service loads on turbine blades. Because wind turbine blades are complex twisted structures and the deflections are large, there is often significant cross-talk coupling in the sensitivity of strain gauges placed on the structure. Recent work has shown that a sensitivity matrix with nonzero cross terms must be employed to find constant results when a blade is subjected to both flap and lead-lag loading. However, even under controlled laboratory conditions, potential for errors of 3 percent or more in the measured moment exist when using the typical cross-talk matrix approach due to neglecting the influence of large deformations and torsion. This is particularly critical when considering a biaxial load as would be applied on the turbine or during a biaxial fatigue test. This presentation describes these results demonstrating errors made when performing current loads measurement practices on wind turbine blades in the lab and evaluating potential improvements using enhanced cross-talk matrix approaches and calibration procedures.
Bending it like Beckham: how to visually fool the goalkeeper.
Directory of Open Access Journals (Sweden)
Joost C Dessing
Full Text Available BACKGROUND: As bending free-kicks becomes the norm in modern day soccer, implications for goalkeepers have largely been ignored. Although it has been reported that poor sensitivity to visual acceleration makes it harder for expert goalkeepers to perceptually judge where the curved free-kicks will cross the goal line, it is unknown how this affects the goalkeeper's actual movements. METHODOLOGY/PRINCIPAL FINDINGS: Here, an in-depth analysis of goalkeepers' hand movements in immersive, interactive virtual reality shows that they do not fully account for spin-induced lateral ball acceleration. Hand movements were found to be biased in the direction of initial ball heading, and for curved free-kicks this resulted in biases in a direction opposite to those necessary to save the free-kick. These movement errors result in less time to cover a now greater distance to stop the ball entering the goal. These and other details of the interceptive behaviour are explained using a simple mathematical model which shows how the goalkeeper controls his movements online with respect to the ball's current heading direction. Furthermore our results and model suggest how visual landmarks, such as the goalposts in this instance, may constrain the extent of the movement biases. CONCLUSIONS: While it has previously been shown that humans can internalize the effects of gravitational acceleration, these results show that it is much more difficult for goalkeepers to account for spin-induced visual acceleration, which varies from situation to situation. The limited sensitivity of the human visual system for detecting acceleration, suggests that curved free-kicks are an important goal-scoring opportunity in the game of soccer.
Ratcheting of corroded pipes under cyclic bending and internal pressure
International Nuclear Information System (INIS)
Corroded pipes for oil transportation can eventually undergo ratcheting after several years of operation. Evaluation of the defects caused by corrosion in these pipes is important when deciding either to repair the line or to continue its operation. Under normal operational conditions, these pipes are subjected to constant internal pressure and cyclic loading due to bending and/or tension. Under such loading conditions, regions in the pipes with a reduction in thickness due to corrosion could experience a phenomenon known as ratcheting. The objective of this paper is to study the effect of a loss in thickness due to the corrosion through combined numerical models and experiments. Three constitutive models capable of representing the ratcheting phenomenon were selected and assessed. Experimental tests were developed to verify the eventual occurrence of ratcheting in corroded pipes under typical operational load conditions. In parallel small-scale cyclic tests were performed to obtain the material parameters necessary to calibrate the constitutive models that were adopted to simulate the phenomenon. The results reveal the existence of loading combinations that cause ratcheting in the defect region, but for the intact pipe, would result in elastic behavior. Numerical and experimental results were compared and showed that a good prediction of the plastic strain along the cycles can only be achieved with the model that requires a more complex calibration, but the shakedown/ratcheting occurrence can be accurately predicted with a model calibrated solely with uniaxial tests. - Highlights: • We studied loss of thickness due to corrosion focusing on ratcheting in the defect. • We simulated corrosion defects as elliptical and axisymmetric defects. • We developed experimental tests and observe the occurrence of ratcheting in defects. • Chaboche model applied in ratcheting prediction showed good agreement with experiments. • In specific cases, pipe experiences
The viscoelastic effect in bending bucky-gel actuators
Kruusamäe, Karl; Mukai, Ken; Sugino, Takushi; Asaka, Kinji
2014-03-01
Electromechanically active polymers (EAP) are considered a good actuator candidate for a variety of reasons, e.g. they are soft, easy to miniaturize and operate without audible noise. The main structural component in EAPs is, as the name states, a type of deformable polymer. As polymers are known to exhibit a distinct mechanical response, the nature of polymer materials should never be neglected when characterizing and modeling the performance of EAP actuators. Bucky-gel actuators are a subtype of EAPs where ion-containing polymer membrane acts as an electronically insulating separator between two electrodes of carbon nanotubes and ionic liquid. In many occasions, the electrodes also contain polymer for the purpose of binding it together. Therefore, mechanically speaking, bucky-gel actuators are composite structures with layers of different mechanical nature. The viscoelastic response and the shape change property are perhaps the most characteristic effects in polymers. These effects are known to have high dependence on factors such as the type of polymer, the concentration of additives and the structural ratio of different layers. At the same time, most reports about optimization of EAP actuators describe the alteration of electromechanical performance dependent on the same factors. In this paper, the performance of bucky-gel actuators is measured as a function between the output force and bending deflection. It is observed that effective stiffness of these actuators depends on the input voltage. This finding is also supported by dynamic mechanical analysis which demonstrates that the viscoelastic response of bucky-gel laminate depends on both frequency and temperature. Moreover, the dynamic mechanical analysis reveals that in the range of standard operation temperatures, tested samples were in their glass transition region, which made it possible to alter their shape by using mechanical fixing. The mechanical fixity above 90% was obtained when high
Directory of Open Access Journals (Sweden)
Amri Royan Hidayat
2013-03-01
Full Text Available Proses pembentukan plat baja dalam industri kelautan diketahui bervariasi proses pengerjaannya, tidak hanya pengelasan saja, namun dapat pula konstruksi bending (bengkok. Bending, mempunyai dua variasi metode yaitu hot bending dan cold bending. Untuk mengetahui metode mana yang lebih tepat digunakan pada industri kelautan, dilakukan penelitian dengan menggunakan perbandingan kedua metode bending tersebut menggunakan variasi sudut yakni 90° dan 135°. Masing-masing sudut yang digunakan dibagi menjadi tiga spesimen yang akan mempengaruhi laju korosi pada plat tersebut. Uji laboratorium dengan menggunakan NaCl 2% dilakukan untuk mengetahui berapa laju korosi dari metode hot bending dan metode cold bending. Perhitungan kemudian dilakukan setelah hasil laju korosi didapat, untuk menentukan grafik laju korosi dari variasi bending tersebut. Hasil uji laju korosi pada metode cold bending dengan sudut bending 90° adalah 0,54 mm/year, dan untuk sudut bending 135° adalah 0,32 mm/year. Sedangkan hasil uji laju korosi pada metode hot bending dengan sudut bending 90° adalah 0,53 mm/year, dan untuk sudut bending 135° adalah 0,24 mm/year. Metode cold bending diketahui mempunyai nilai laju korosi lebih besar dibandingkan metode hot bending. Morfologi permukaan spesimen dianalisa dengan menggunakan Scanning Electron Microscopy (SEM. Permukaan spesimen dengan metode cold bending diketahui mengalami perubahan yang cukup besar dibanding spesimen dengan metode hot bending.
Social support modifies association between forward bending of the trunk and low-back pain
DEFF Research Database (Denmark)
Villumsen, Morten; Holtermann, Andreas; Samani, Afshin;
2016-01-01
OBJECTIVES: This study aimed to investigate the association between forward bending of the trunk and low-back pain intensity (LBPi) among blue-collar workers in Denmark as well as whether the level of social support modifies the association. METHODS: In total, 457 workers were included in the study....... The forward bending of ≥30° was computed from accelerometer recordings for several consecutive days during work, categorized into long (highest tertile) and short-moderate (remaining tertiles) duration. LBPi was measured on a 0-10 scale and categorized into low (≤5) and high (>5) pain. Self-reported social....... Workers with low social support and long duration of forward bending had higher likelihood of high LBPi [odds ratio (OR) 2.97, 95% confidence interval (95% CI) 1.11-7.95] compared to workers with high social support and long duration of forward bending. Among workers with low social support, workers...
Management Plan : Horseshoe Bend Division: Mark Twain National Wildlife Refuge- Wapello District
US Fish and Wildlife Service, Department of the Interior — The Horseshoe Bend Division of the Mark Twain National Wildlife Refuge Management Plan guides the long-range development of the Division, by identifying and...
Directory of Open Access Journals (Sweden)
Osman Zeki Karakus
2016-01-01
Conclusion: Preoperative bending of the support bar according to anthropometric measurements and fixation of the lateral stabilizers to the support bar in inverted position facilitates bar shaping and lateral stabilizer placement.
Energy losses in thermally cycled optical fibers constrained in small bend radii
Energy Technology Data Exchange (ETDEWEB)
Guild, Eric; Morelli, Gregg
2012-09-23
High energy laser pulses were fired into a 365μm diameter fiber optic cable constrained in small radii of curvature bends, resulting in a catastrophic failure. Q-switched laser pulses from a flashlamp pumped, Nd:YAG laser were injected into the cables, and the spatial intensity profile at the exit face of the fiber was observed using an infrared camera. The transmission of the radiation through the tight radii resulted in an asymmetric intensity profile with one half of the fiber core having a higher peak-to-average energy distribution. Prior to testing, the cables were thermally conditioned while constrained in the small radii of curvature bends. Single-bend, double-bend, and U-shaped eometries were tested to characterize various cable routing scenarios.
Energy Technology Data Exchange (ETDEWEB)
Zhang, B. [Univ. of Glasgow (United Kingdom). Dept. of Civil Engineering
1998-05-01
Progressive macro damage of concrete under fatigue loading is caused by the change of its internal micro-meso properties such as pore structure. In this study, porosity, pore size distribution, and specific surface area of ordinary concrete at different fatigue stages were investigated using mercury intrusion, helium flow, and nitrogen adsorption (BET) methods. These properties changed with increasing loading cycles and could be taken as micro-meso damage parameters to evaluate macro fatigue damage of concrete. Test results showed that both porosity in mortar (mainly macro pores) and interface between mortar and coarse aggregates (interfacial cracks) developed at a similar rate. The corresponding residual bending fatigue strength and dynamic bending Young`s modulus were also obtained and their relationships with these micro-meso properties were established. The intrinsic bending strength and intrinsic bending Young`s modulus were predicted from these relationships.
Development of U-frame bending system for studying the vibration integrity of spent nuclear fuel
Wang, Hong; Wang, Jy-An John; Tan, Ting; Jiang, Hao; Cox, Thomas S.; Howard, Rob L.; Bevard, Bruce B.; Flanagan, Michelle
2013-09-01
A bending fatigue system developed to evaluate the response of spent nuclear fuel rods to vibration loads is presented. A U-frame testing setup is used for imposing bending loads on the fuel rod specimen. The U-frame setup consists of two rigid arms, side connecting plates to the rigid arms, and linkages to a universal testing machine. The test specimen's curvature is obtained through a three-point deflection measurement method. The tests using surrogate specimens with stainless steel cladding revealed increased flexural rigidity under unidirectional cyclic bending, significant effect of cladding-pellets bonding on the response of surrogate rods, and substantial cyclic softening in reverse bending mode. These phenomena may cast light on the expected response of a spent nuclear fuel rod. The developed U-frame system is thus verified and demonstrated to be ready for further pursuit in hot-cell tests.
Asymmetry in the effect of magnetic field on photon detection and dark counts in bended nanostrips
Semenov, A; Lusche, R; Ilin, K; Siegel, M; Hubers, H -W; Bralovic, N; Dopf, K; Vodolazov, D Yu
2015-01-01
Current crowding in the bends of superconducting nano-structures not only restricts measurable critical current in such structures but also redistributes local probabilities for dark and light counts to appear. Using structures from strips in the form of a square spiral which contain bends with the very same curvature with respect to the directions of bias current and external magnetic field, we have shown that dark counts as well as light count at small photon energies originate from areas around the bends. The minimum in the rate of dark counts reproduces the asymmetry of the maximum critical current density as function of the magnetic field. Contrary, the minimum in the rate of light counts demonstrate opposite asymmetry. The rate of light counts become symmetric at large currents and fields. Comparing locally computed absorption probabilities for photons and the simulated threshold detection current we found approximate location of areas near bends which deliver asymmetric light counts. Any asymmetry is a...
Characterization of Optical Fiber Strength Under Applied Tensile Stress and Bending Stress
Energy Technology Data Exchange (ETDEWEB)
P.E. Klingsporn
2011-08-01
Various types of tensile testing and bend radius tests were conducted on silica core/silica cladding optical fiber of different diameters with different protective buffer coatings, fabricated by different fiber manufacturers. The tensile tests were conducted to determine not only the average fiber strengths at failure, but also the distribution in fracture strengths, as well as the influence of buffer coating on fracture strength. The times-to-failure of fiber subjected to constant applied bending stresses of various magnitudes were measured to provide a database from which failure times of 20 years or more, and the corresponding minimum bend radius, could be extrapolated in a statistically meaningful way. The overall study was done to provide an understanding of optical fiber strength in tensile loading and in applied bending stress as related to applications of optical fiber in various potential coizfgurations for weapons and enhanced surveillance campaigns.
Acceptor action of plastic bending in n-InSb single crystals
International Nuclear Information System (INIS)
Measured are the halvanomagnetic properties of the n-type InSb single crystals plastically bent up to different values of the dislocation density, so that the initial n-type crystals turned out to be recompensated into p-type crystals by plastic bending. It is shown that under the given conditions of deformation the plastic bending always results in an increase of acceptor effect in crystals studied both under α- and β bendings. The anisotropy of electric properties in bended crystals is absent. The effects observed may be explained by the influence of ionized point defects, appearing in the crystal in the process of the formation and movement of dislocations and dislocations diffused to nuclei. The position of the energy level of acceptor centers introduced is determined
Interferometric fiber-optic bending / nano-displacement sensor using plastic dual-core fiber
Qu, H; Skorobogatiy, M
2014-01-01
We demonstrate an interferometric fiber-optic bending/micro-displacement sensor based on a plastic dual-core fiber with one end coated with a silver mirror. The two fiber cores are first excited with the same laser beam, the light in each core is then back-reflected at the mirror-coated fiber-end, and, finally, the light from the two cores is made to interfere at the coupling end. Bending of the fiber leads to shifting interference fringes that can be interrogated with a slit and a single photodetector. We find experimentally that the resolution of our bending sensor is ~3x10-4 m-1 for sensing of bending curvature, as well as ~70 nm for sensing of displacement of the fiber tip. We demonstrate operation of our sensor using two examples. One is weighting of the individual micro-crystals of salt, while the other one is monitoring dynamics of isopropanol evaporation.
CALCULATION OF BIMETAL PLATE BENDING FORCE OF A GLOW DISCHARGE STARTER
Akimov, V.; Mukha, L.
2005-01-01
Calculation techniques of bending power of bimetal plate electrode causing its displacement in the direction of the electrode of glow discharge starter have been represented. Calculation of bimetal electrode displacement has been conducted in correspondence with the chosen scheme.
US Fish and Wildlife Service, Department of the Interior — The purpose of this investigation was to determine if the agricultural crop programs on Holla Bend, Wapanocca and White River refuges are producing a quantity of...
Temperature dependence of light power propagation in bending plastic optical fiber
Jing, Ning; Teng, Chuanxin; Zheng, Jie; Wang, Guanjun; Zhang, Minjuan; Wang, Zhibin
2016-09-01
This study investigates the effect of temperature variation on the light power propagation in bending plastic optical fiber (POF). The transmittance of bending POFs with curvature radius of 2-30 mm and turns of 1/4, 1/2, 1, and 2 are measured over temperature of 20-70 °C. The temperature dependent loss of the bending POF is obtained. It is found that the temperature dependent loss of the bending POF changes with curvature radius and turns. The temperature effect reaches the highest value of 0.011 dB/°C with 2 turns, and is less than 0.002 dB/°C with curvature radius greater than 25 mm.
Evolution of the texture and mechanical properties of 2060 alloy during bending
Institute of Scientific and Technical Information of China (English)
Xiao Jin; Bao-qin Fu; Cheng-lu Zhang; Wei Liu
2015-01-01
In this study, we examined the evolution of the texture and mechanical properties of 2060 (T8) alloy during bending. A pixel rota-tion method (PRM) was proposed and used to characterize the textural evolution during bending determined by electron backscatter diffrac-tion. The results showed that the textural components changed insignificantly, with the exception of a decrease in the cube texture. The ten-sile and yielding properties of the alloy were evaluated at three different orientations with respect to the rolling direction. The mechanical strength was found to increase in three directions with decreasing bending radius; thus, it was concluded that the 2060 (T8) alloy sheet satisfies the usage requirement after bending deformation.
Memo concerning Regional Office site visit to Holla Bend National Wildlife Refuge
US Fish and Wildlife Service, Department of the Interior — This memo contains the correspondence concerning the regional office's site visit to Holla Bend National Wildlife Refuge. Memo discusses the trip report and refuge...
Cox, E.R.; Havens, J.S.
1965-01-01
At Malaga Bend on the Pecos River in Eddy County, New Mexico, a brine aquifer about 1950 feet below the stream channel has a pressure head about 10 feet above the river bed. This aquifer normally discharges about 430 tons of dissolved minerals daily into the river of which about 370 tons was sodium chloride. The Malaga Bend Experimental Salinity Alleviation Project, authorized by the U.S. Congress in 1958, Public Law 85-333,is an attempt to determine if the salinity content of the Pecos River below Malaga Bend can be decreased by reducing the inflow of saline water into the river at Malaga Bend by pumping from the brine aquifer. Construction for the project was supervised by the Bureau of Reclamation, and the collection of data and its interpretation were the responsibility cooperatively of the U. S. Geological Survey and the Pecos River Commission.
Nickel multilayers and their effects on bend fatigue strength of leads
Institute of Scientific and Technical Information of China (English)
LIU Feihua; WANG Zhanhua; SHEN Zhuoshen
2004-01-01
Nickel is commonly coated on the outer leads for T8 metal package. The leads electrodeposited by conventional dull or bright nickel over 5 μm at direct current from Watt bath are hard to pass the bend fatigue test for three times. Nickel electrodeposited at multi waveform current including direct current, single and double pulse from sulfamate bath can improve the bend fatigue strength of leads. Such nickel plating has a multilayer structure, its morphology of sublayers can be clearly seen in its cross section with SEM. The electrochemical study shows that these sublayers have different corrosion potentials. The bend fatigue test of leads with such plating for T8 metal package shows that the number of bend increases with the decrease of average current density of multi waveform, which can be attributed to the reduction of every sublayer thickness and the increase of layer numbers under the same condition of total thickness.
Strength performance of mortise and loose-tenon furniture joints under uniaxial bending moment
Institute of Scientific and Technical Information of China (English)
Mohammad Derikvand; Ghanbar Ebrahimi
2014-01-01
We determined the effects of adhesive type and loose tenon dimensions (length and thickness) on bending strength of T-shaped mor-tise and loose-tenon joints. Polyvinyl acetate (PVAc) and two-component polyurethane (PU) adhesives were used to construct joint specimens. The bending moment capacity of joints increased significantly with increased length and thickness of the loose tenon. Bending moment capacity of joints constructed with PU adhesive was approximately 13%higher than for joints constructed with PVAc adhesive. We developed a predictive equation as a function of adhesive type and loose tenon dimensions to estimate the strength of the joints constructed of oriental beech (Fagus orientalis L.) under uniaxial bending load.
Coherent thermoelectric transport in single, double, and U-bend structures
Energy Technology Data Exchange (ETDEWEB)
Pye, A. J.; Faux, D. A.; Kearney, M. J. [Faculty of Engineering and Physical Sciences, University of Surrey, Guildford, Surrey GU2 7XH (United Kingdom)
2015-02-14
Coherent, i.e., ballistic, thermoelectric transport in electron waveguide structures containing right-angle bends in single, double, and U-bend configurations is investigated. A theory based on Green's functions is used to derive the transmission function (and from that the transport coefficients) and allows for the inclusion of realistic models of spatially distributed imperfections. The results for the single and double-bend structures are presented in more detail than elsewhere in the literature. In the U-bend structure, sharp resonances in the stop-band region of the transmission function lead to large-magnitude peaks in the thermopower and consequently a large thermoelectric figure of merit (of order ten in some instances). These properties are still readily apparent even in the presence of moderate edge roughness or Anderson disorder.
Large-Angle Bending Transport of Microparticles by Acoustic Half-Bessel Beams
Li, Yixiang; Xu, Shengjun; Ke, Manzhu; Liu, Zhengyou
2014-01-01
Conventional microparticle transports by light or sound are realized along a straight line. Recently, this limit has been overcome in optics as the growing up of the self-accelerating Airy beams, which are featured by many peculiar properties, e.g., bending propagation, diffraction-free and self-healing. However, the bending angles of Airy beams are rather small since they are only paraxial solutions of the two-dimensional (2D) Helmholtz equation. Here we propose a novel micromanipulation by using acoustic Half-Bessel beams, which are strict solutions of the 2D Helmholtz equation. Compared with that achieved by Airy beams, the bending angle of the particle trajectory attained here is much steeper (exceeding 90o). The large-angle bending transport of microparticles, which is robust to complex scattering environment, enables a wide range of applications from the colloidal to biological sciences.
Charles M. Russell & UL Bend NWR Report on Wilderness Character Monitoring
US Fish and Wildlife Service, Department of the Interior — This report discusses 43 possible wilderness character monitoring measures for Charles M. Russell and UL Bend National Wildlife Refuges. In 2011, measures were...
Investigation of bending loss in a single-mode optical fibre
Indian Academy of Sciences (India)
A Zendehnam; M Mirzaei; A Farashiani; L Horabadi Farahani
2010-04-01
Loss of optical power in a single-mode optical fibre due to bending has been investigated for a wavelength of 1550 nm. In this experiment, the effects of bending radius (4–15 mm, with steps of 1 mm), and wrapping turns (up to 40 turns) on loss have been studied. Twisting the optical fibre and its influence on power loss also have been investigated. Variations of bending loss with these two parameters have been measured, loss with number of turns and radius of curvature have been measured, and with the help of computer curve fitting method, semi-empirical relationships between bending loss and these two parameters have been found, which show good agreement with the obtained experimental results.
Reducing bending stress in external spur gears by redesign of the standard cutting tool
DEFF Research Database (Denmark)
Pedersen, Niels Leergaard
2009-01-01
For the design of gears the stress due to bending plays a significant role. The stress from bending is largest in the root of the gear teeth, and the magnitude of the maximum stress is controlled by the nominal bending stress and stress concentration due to the geometric shape of the tooth....... In this work the bending stress of involute teeth is minimized by shape optimizing the tip of the standard cutting tool. By redesign of the tip of the standard cutting tool we achieve that the functional part of the teeth stays the same while at the same time the root shape is changed so that a reduction...... of the stresses results. The tool tip shape is described by different parameterizations that use the super ellipse as the central shape. For shape optimization it is important that the shape is given analytically. The shape of the cut tooth that is the envelope of the cutting tool is found analytically...
Directory of Open Access Journals (Sweden)
Azaryan N. A.
2007-06-01
Full Text Available It is suggested a modification of tetragonal finite - element method, where the tasks of plate bending with taking into accountancy uninterrupted normal efforts or displacements are reduced to quadratic programming ones.
Optimum Design of Composite Sandwich Structures Subjected to Combined Torsion and Bending Loads
Li, Xiang; Li, Gangyan; Wang, Chun H.; You, Min
2012-06-01
This research is motivated by the increase use of composite sandwich structures in a wide range of industries such as automotive, aerospace and civil infrastructure. To maximise stiffness at minimum weight, the paper develops a minimum weight optimization method for sandwich structure under combined torsion and bending loads. We first extend the minimum-weight design of sandwich structures under bending load to the case of torsional deformation and then present optimum solutions for the combined requirements of both bending and torsional stiffness. Three design cases are identified for a sandwich structure required to meet multiple design constraints of torsion and bending stiffness. The optimum solutions for all three cases are derived. To illustrate the newly developed optimum design solutions, numerical examples are presented for sandwich structures made of either isotropic face skins or orthotropic composite face skins.
Stereotypical reaching movements of the octopus involve both bend propagation and arm elongation.
Hanassy, S; Botvinnik, A; Flash, T; Hochner, B
2015-05-13
The bend propagation involved in the stereotypical reaching movement of the octopus arm has been extensively studied. While these studies have analyzed the kinematics of bend propagation along the arm during its extension, possible length changes have been ignored. Here, the elongation profiles of the reaching movements of Octopus vulgaris were assessed using three-dimensional reconstructions. The analysis revealed that, in addition to bend propagation, arm extension movements involve elongation of the proximal part of the arm, i.e., the section from the base of the arm to the propagating bend. The elongations are quite substantial and highly variable, ranging from an average strain along the arm of -0.12 (i.e. shortening) up to 1.8 at the end of the movement (0.57 ± 0.41, n = 64 movements, four animals). Less variability was discovered in an additional set of experiments on reaching movements (0.64 ± 0.28, n = 30 movements, two animals), where target and octopus positions were kept more stationary. Visual observation and subsequent kinematic analysis suggest that the reaching movements can be broadly segregated into two groups. The first group involves bend propagation beginning at the base of the arm and propagating towards the arm tip. In the second, the bend is formed or present more distally and reaching is achieved mainly by elongation and straightening of the segment proximal to the bend. Only in the second type of movements is elongation significantly positively correlated with the distance of the bend from the target. We suggest that reaching towards a target is generated by a combination of both propagation of a bend along the arm and arm elongation. These two motor primitives may be combined to create a broad spectrum of reaching movements. The dynamical model, which recapitulates the biomechanics of the octopus muscular hydrostatic arm, suggests that achieving the observed elongation requires an extremely low ratio of longitudinal to transverse muscle
Experimental Research and Numerical Simulation of Wing Boxes under Pure Bending Load
Peiyan Wang; Shile Yao; Xinmei Wang; Zhufeng Yue
2014-01-01
Two full-scale wing boxes with different types of butt joints were investigated under pure bending load, and numerical methods, including global analysis and detailed analysis, were proposed to determine the reasons for failure of the wing boxes. Wing boxes were tested under bending loads applied by a multichannel force control system. The experimental results showed that the region of the butt joint was the weakest location of the wing boxes, and the damage loads were far less than the desig...
A model of the response of thermoplastic composites to bend-forming operations
Energy Technology Data Exchange (ETDEWEB)
Talbott, M.F.
1991-01-01
The model discussed in this dissertation describes the response of a thermoplastic composite laminate made from unidirection prepreg tape to operations which bend it into an arbitrarily complex singly-curved shape. It predicts, for any such bending, the extent of relative ply sliding and the stresses and strains which arise. The model contains several options for the process definition: for different locations along the laminate, the user may specify the curvatures, the perpendicular forces imposed, or the vertical displacements.
Improved design of a polarization converter based on semiconductor optical waveguide bends.
Obayya, S S; Rahman, B M; Grattan, K T; El-Mikati, H A
2001-10-20
By using an efficient vector finite-element-based beam-propagation method, we present an improved design of a polarization converter. This design relies on the use of a single-section deeply etched bent semiconductor waveguide with slanted sidewalls. By careful adjustment of the bend radius, the waveguide width, and the sidewall angle we obtained a nearly 100% polarization conversion ratio with no appreciable radiation loss and a bending angle of less than 180 degrees . PMID:18364819
An optical fibre sensor for physiological bending monitoring in clinical environment
Zawawi, Mohd Anwar
2015-01-01
peer-reviewed Health monitoring applications in clinical environment include various areas such as respiration assessment, heart rate monitoring, gait monitoring, spine bending as well as lower and upper limb motion detections. In human spine monitoring application, static and dynamic assessments of the spine bending are important and are generally preferrable as routine diagnostic procedures among chronic and acute low back pain patients. Many accurate and highly reliable devices are wide...
Nonlinear Optimization of CLIC DRS New Design with Variable Bends and High Field Wigglers
Ghasem, H.; Alabau-Gonzalvo, J.; Papadopoulou, S.; Papaphilippou, Y.
2016-01-01
The new design of CLIC damping rings is based on longitudinal variable bends and high field superconducting wiggler magnets. It provides an ultra-low horizontal normalised emittance of 412 nm-rad at 2.86 GeV. In this paper, nonlinear beam dynamics of the new design of the damping ring (DR) with trapezium field profile bending magnets have been investigated in detail. Effects of the misalignment errors have been studied in the closed orbit and dynamic aperture.
fMRI-compatible registration of jaw movements using a fiber-optic bend sensor
Directory of Open Access Journals (Sweden)
Peter Sörös
2010-03-01
Full Text Available A functional magnetic resonance imaging (fMRI-compatible fiber-optic bend sensor was investigated to assess whether the device could be used effectively to monitor opening and closing of the jaw during an fMRI experiment at 3 T. In contrast to surface electromyography, a bend sensor fixed to the chin of the participant is fast and easy to use and is not affected by strong electromagnetic fields. Bend sensor recordings are characterized by high validity (compared with concurrent video recordings of mouth opening and high reliability (comparing 2 independent measurements. The results of this study indicate that a bend sensor is able to record the opening and closing of the jaw associated with different overt speech conditions (producing the utterances /a/, /pa/, /pataka/ and the opening of the mouth without speech production. Data post-processing such as filtering was not necessary. There are several potential applications for bend sensor recordings of speech-related jaw movements. First, bend sensor recordings are a valuable tool to assess behavioral performance, such as response latencies, accuracies, and completion times, which is particularly important in children, seniors, or patients with various neurological or psychiatric conditions. Second, the timing information provided by bend sensor data may improve the predicted hemodynamic response that is used for fMRI analysis based on the general linear model (GLM. Third, bend sensor recordings may be included in GLM analyses not for statistical contrast purposes, but as a covariate of no interest, accounting for part of the data variance to model fMRI artifacts due to motion outside the field of view.
Bending Strength and Fracture Behavior of Ni50Mn29Ga21 Alloy with Terbium
Institute of Scientific and Technical Information of China (English)
ZHAO Zeng-qi; XIONG Wei; WU Shuang-xia; WANG Xin-lin
2004-01-01
The bending strength and fracture behaviors of Ni50Mn29Ga21 alloy with terbium were investigated. The results show that the bending strength of the alloy is increased dramatically with the increase of terbium content. The fracture appearance of the sample without terbium is dominated by grain boundary fracture, while that with terbium is dominated by cleavage fracture with the increase of terbium content.Moreover, the grains are refined obviously and the oxygen content is decreased after adding terbium.
Bending of electromagnetic waves in all-dielectric particle array waveguides
Energy Technology Data Exchange (ETDEWEB)
Savelev, Roman S.; Filonov, Dmitry S.; Kapitanova, Polina V.; Krasnok, Alexander E.; Belov, Pavel A. [ITMO University, St. Petersburg 197101 (Russian Federation); Miroshnichenko, Andrey E., E-mail: andrey.miroshnichenko@anu.edu.au [Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Acton, ACT 2601 (Australia); Kivshar, Yuri S. [ITMO University, St. Petersburg 197101 (Russian Federation); Nonlinear Physics Centre, Research School of Physics and Engineering, Australian National University, Acton, ACT 2601 (Australia)
2014-11-03
We propose and demonstrate experimentally an alternative approach for realizing subwavelength photonic structures, exploiting the waveguiding properties of chains of high-index dielectric disks with both electric and magnetic dipole resonances. We reveal that the electromagnetic energy can be efficiently guided through sharp corners by means of the mode polarization conversion at waveguide bends. We confirm experimentally the guidance through a 90° bend in the microwave frequency range.
Dotel, Utsav Raj
2014-01-01
Cold deformation (bending) of stainless steel tubes is one of the efficient and cost effective methods to gain the required shapes of the tube that can be useful for different practical applications. Different mechanical properties can change after the plastic deformation of the material. The purpose of this study is to investigate the corrosion (basically pitting) resistant property of cold deformed Duplex and Super Duplex materials namely UNS S32205 and UNS S32750 respectively. The bended t...
MO, Fuhao; Masson, Catherine; CESARI, Dominique; Arnoux, Pierre-Jean
2013-01-01
In car–pedestrian accidents, lateral bending and shearing kinematics have been identified as principal injury mechanisms causing permanent disabilities and impairments to the knee joint. Regarding the combined lateral bending and shearing contributions of knee joint kinematics, developing a coupled knee injury criterion is necessary for improving vehicle countermeasures to mitigate pedestrian knee injuries. The advantages of both experimental tests and finite element (FE) simulations we...
Contribution of the cosmological constant to the bending of light in Kerr-de Sitter spacetime
Sultana, Joseph
2013-08-01
We examine the effect of the cosmological constant Λ on the angle of deflection of null geodesics in the equatorial plane of the Kerr-de Sitter spacetime. This is done by employing a procedure used recently by Rindler and Ishak to obtain the bending angle of light in the Schwarzschild-de Sitter geometry. We show that this approach yields a contribution from the cosmological constant in the expression for the bending angle.
Advances in OCB mode LCDs: improvement of moving picture quality and control of bend alignment
Wakemoto, Hirofumi; Nakao, Kenji; Takimoto, Akio
2006-02-01
We invented a new bend transition method using the twisted electric field in OCB mode LCD. And by introducing a pseudo-impulse display method which inserted a black period between two successive fields and scanning backlight system, the motion blur in TFT-LCD was drastically improved. In addition, we clarified the stability of the dynamic bend alignment when adopting the black insert driving method.
Numerical analysis of sandwich beam with corrugated core under three-point bending
Energy Technology Data Exchange (ETDEWEB)
Wittenbeck, Leszek [Poznan University of Technology, Institute of Mathematics Piotrowo Street No. 5, 60-965 Poznan (Poland); Grygorowicz, Magdalena; Paczos, Piotr [Poznan University of Technology, Institute of Applied Mechanics Jana Pawla IIStreet No. 24, 60-965 Poznan (Poland)
2015-03-10
The strength problem of sandwich beam with corrugated core under three-point bending is presented.The beam are made of steel and formed by three mutually orthogonal corrugated layers. The finite element analysis (FEA) of the sandwich beam is performed with the use of the FEM system - ABAQUS. The relationship between the applied load and deflection in three-point bending is considered.
Membrane Bending Energy and Fusion Pore Kinetics in Ca2+-Triggered Exocytosis
Zhang, Zhen; Jackson, Meyer B.
2010-01-01
A fusion pore composed of lipid is an obligatory kinetic intermediate of membrane fusion, and its formation requires energy to bend membranes into highly curved shapes. The energetics of such deformations in viral fusion is well established, but the role of membrane bending in Ca2+-triggered exocytosis remains largely untested. Amperometry recording showed that during exocytosis in chromaffin and PC12 cells, fusion pores formed by smaller vesicles dilated more rapidly than fusion pores formed...
Charge-induced reversible bending in nanoporous alumina-aluminum composite
Cheng, Chuan; Ngan, A. H. W.
2013-05-01
Upon electrical charging, reversible bending was found in nanoporous anodic alumina-aluminum foil composites, as directly observed by an optical microscope and detected by in situ nanoindentation. The bending is thought to be the result of charge-induced surface stresses in the nanoporous alumina. The results suggest the possibility of a type of composite foil materials for applications as micro-scale actuators to transform electrical energy into mechanical energy.
Sayyad A. S.; Ghugal Y. M.; Naik N. S.
2015-01-01
A trigonometric beam theory (TBT) is developed for the bending analysis of laminated composite and sandwich beams considering the effect of transverse shear deformation. The axial displacement field uses trigonometric function in terms of thickness coordinate to include the effect of transverse shear deformation. The transverse displacement is considered as a sum of two partial displacements, the displacement due to bending and the displacement due to transverse sheari...
Stress Distribution on Sandwich Structure with Triangular Grid Cores Suffered from Bending Load
Cui Xu; Huang Yanjiao; Wang Shou; Lu Chun; Fang Luping
2015-01-01
Triangular grid reinforced by carbon fiber/epoxy (CF/EP) was designed and manufactured. The sandwich structure was prepared by gluing the core and composite skins. The mechanical properties of the sandwich structure were investigated by the finite element analysis (FEA) and three-point bending methods. The calculated bending stiffness and core shear stress were compared to the characteristics of a honeycomb sandwich structure. The results indicated that the triangular core ultimately failed u...
Behaviour of Cold-Formed Steel Built-up I Section Under Bending
Sudha K; Sukumar S
2014-01-01
This paper presents an experimental and numerical investigation on the bending strength and behaviour of cold-formed (CF) steel built-up flexural members. Eight specimens in two groups, first group of four specimens with equal flanges and second group of four specimens with unequal flanges have been fabricated and experimented. The experimental results show the modes of buckling and their influence on the bending strength and behaviour of CF built-up I sections. The experimental results are a...
On the analysis of a mixed mode bending sandwich specimen for debond fracture characterization
Quispitupa, Amilcar; Berggreen, Christian; Carlsson, Leif A.
2009-01-01
The mixed mode bending specimen originally developed for mixed mode delamination fracture characterization of unidirectional composites has been extended to the study of debond propagation in foam cored sandwich specimens. The compliance and strain energy release rate expressions for the mixed mode bending sandwich specimen are derived based on a superposition analysis of solutions for the double cantilever beam and cracked sandwich beam specimens by applying a proper kinematic relationship f...
Bending sensor combining multicore fiber with a mode-selective photonic lantern.
Newkirk, Amy Van; Antonio-Lopez, J E; Velazquez-Benitez, Amado; Albert, Jacques; Amezcua-Correa, Rodrigo; Schülzgen, Axel
2015-11-15
A bending sensor is demonstrated using the combination of a mode-selective photonic lantern (PL) and a multicore fiber. A short section of three-core fiber with strongly coupled cores is used as the bend sensitive element. The supermodes of this fiber are highly sensitive to the refractive index profiles of the cores. Small bend-induced changes result in drastic changes of the supermodes, their excitation, and interference. The multicore fiber is spliced to a few-mode fiber and excites bend dependent amounts of each of the six linearly polarized (LP) modes guided in the few-mode fiber. A mode selective PL is then used to demultiplex the modes of the few-mode fiber. Relative power measurements at the single-mode PL output ports reveal a high sensitivity to bending curvature and differential power distributions according to bending direction, without the need for spectral measurements. High direction sensitivity is demonstrated experimentally as well as in numerical simulations. Relative power shifts of up to 80% have been measured at radii of approximately 20 cm, and good sensitivity was observed with radii as large as 10 m, making this sensing system useful for applications requiring both large and small curvature measurements. PMID:26565831
Berg-Johansen, Britta; Liebenberg, Ellen C; Li, Alfred; Macias, Brandon R; Hargens, Alan R; Lotz, Jeffrey C
2016-01-01
Intervertebral disc herniation rates are quadrupled in astronauts following spaceflight. While bending motions are main contributors to herniation, the effects of microgravity on the bending properties of spinal discs are unknown. Consequently, the goal of this study was to quantify the bending properties of tail discs from mice with or without microgravity exposure. Caudal motion segments from six mice returned from a 30-day Bion M1 mission and eight vivarium controls were loaded to failure in four-point bending. After testing, specimens were processed using histology to determine the location of failure, and adjacent motion segments were scanned with micro-computed tomography (μCT) to quantify bone properties. We observed that spaceflight significantly shortened the nonlinear toe region of the force-displacement curve by 32% and reduced the bending strength by 17%. Flight mouse spinal segments tended to fail within the growth plate and epiphyseal bone, while controls tended to fail at the disc-vertebra junction. Spaceflight significantly reduced vertebral bone volume fraction, bone mineral density, and trabecular thickness, which may explain the tendency of flight specimens to fail within the epiphyseal bone. Together, these results indicate that vertebral bone loss during spaceflight may degrade spine bending properties and contribute to increased disc herniation risk in astronauts.
"Passive-bending colonoscope" significantly improves cecal intubation in difficult cases
Institute of Scientific and Technical Information of China (English)
Takeshi Mizukami; Haruhiko Ogata; Toshihumi Hibi
2012-01-01
Colonoscopy sometimes causes pain during insertion,especially in difficult cases.Over-insufflation of air causes elongation or acute angulations of the colon,making passage of the scope difficult and causing pain.We previously reported a sedative-risk-free colonoscopy insertion technique,namely,"Water Navigation Colonoscopy".Complete air suction after water infusion not only improves the vision,but also makes water flow down to the descending colon,while the sigmoid colon collapses and shortens.While non-sedative colonoscopy can be carried out without pain in most cases,some patients do complain of pain.Most of these patients have abnormal colon morphology,and the pain is caused while negotiating the "hairpin" bends of the colon.The "hairpin" bends of the colon should be negotiated by gently pushing the full-angled colonoscope.The proximal 10-20 cm from the angulated part of the conventional colonoscope is stiff,with a wide turning radius,therefore,a conventional colonoscope cannot be negotiated through the "hairpin" bends of the colon without stretching them and causing pain.The "passive-bending colonoscope" has a flexible tip with a narrow turning radius,so that the scope can be negotiated through the "hairpin" bends of the colon with a minimum turning radius and minimal discomfort.Therefore,the intubation and pain-reducing performance of the "passive-bending colonoscope" was assessed in difficult cases.
Standard Practice for Making and Using U-Bend Stress-Corrosion Test Specimens
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 This practice covers procedures for making and using U-bend specimens for the evaluation of stress-corrosion cracking in metals. The U-bend specimen is generally a rectangular strip which is bent 180° around a predetermined radius and maintained in this constant strain condition during the stress-corrosion test. Bends slightly less than or greater than 180° are sometimes used. Typical U-bend configurations showing several different methods of maintaining the applied stress are shown in Fig. 1. 1.2 U-bend specimens usually contain both elastic and plastic strain. In some cases (for example, very thin sheet or small diameter wire) it is possible to form a U-bend and produce only elastic strain. However, bent-beam (Practice G 39 or direct tension (Practice G 49)) specimens are normally used to study stress-corrosion cracking of strip or sheet under elastic strain only. 1.3 This practice is concerned only with the test specimen and not the environmental aspects of stress-corrosion testing which are discus...
Analytical investigation in bending characteristic of twisted stacked-tape cable conductor
Takayasu, Makoto; Chiesa, Luisa
2015-12-01
An analytical model to evaluate bending strains of a twisted stack-tape cable (TSTC) conductor has been developed. Through a comparison with experimental results obtained for a soldered 32-tape YBCO TSTC conductor, it has been found that a Perfect-Slip Model (PSM) taking into account the slipping between tapes in a stacked-tape cable during bending gives much better estimation of the bending performance compared to a No-Slip Model (NSM). In the PSM case the tapes can slip so that the internal longitudinal axial strain can be released. The longitudinal strains of compression and tension regions along the tape are balanced in one twist-pitch and cancel out evenly in a long cable. Therefore, in a cable the strains due to bending can be minimized. This is an important advantage of a TSTC conductor. The effect of the cable diameter size on the bending strain is also expected to be minor, and all tapes composing a TSTC conductor have the same strain response under bending, therefore the cable critical current can be characterized from a single tape behaviour.
Ductile failure of pipes with defects under combined pressure and bending
International Nuclear Information System (INIS)
The main part of the experimental programme was carried out on 3.5'' diam. pipes with a wall thickness of 0.064''. Various lengths of defect were assessed but only two depths, 0.044'' and 0.060''. Some full penetration defect tests were carried out under bending loading. The defects were 0.012'' wide and nominally flat bottomed. The tensile properties of the pipes were determined by taking specimens from each of the tubes. The pipes were exposed to pressure only test, bending only test and combined bending and pressure test. The results are given in tables. The observations led to the postulation of a design rule relating to the effect of defect in pipes under combined internal pressure and bending. It applies only to ductile situations in which the mode of failure is by a collapse mechanism: If the failure of a pipe containing an axial defect occurs by plastic collapse then provided the bending moment does not exceed half that for collapse due to bending alone, it will have a negligible effect on the failure pressure. (J.B.)
Bending Two-Dimensional Materials To Control Charge Localization and Fermi-Level Shift.
Yu, Liping; Ruzsinszky, Adrienn; Perdew, John P
2016-04-13
High-performance electronics requires the fine control of semiconductor conductivity. In atomically thin two-dimensional (2D) materials, traditional doping technique for controlling carrier concentration and carrier type may cause crystal damage and significant mobility reduction. Contact engineering for tuning carrier injection and extraction and carrier type may suffer from strong Fermi-level pinning. Here, using first-principles calculations, we predict that mechanical bending, as a unique attribute of thin 2D materials, can be used to control conductivity and Fermi-level shift. We find that bending can control the charge localization of top valence bands in both MoS2 and phosphorene nanoribbons. The donor-like in-gap edge-states of armchair MoS2 ribbon and their associated Fermi-level pinning can be removed by bending. A bending-controllable new in-gap state and accompanying direct-indirect gap transition are predicted in armchair phosphorene nanoribbon. We demonstrate that such emergent bending effects are realizable. The bending stiffness as well as the effective thickness of 2D materials are also derived from first principles. Our results are of fundamental and technological relevance and open new routes for designing functional 2D materials for applications in which flexuosity is essential. PMID:26938458
Determine Bending Moment of Plane Bending Beam by Graphical Method%用图解法确定平面弯曲梁的弯矩
Institute of Scientific and Technical Information of China (English)
闫志琴
2014-01-01
针对传统“解析法”的弊端，利用剪力图中剪力所围区域面积的代数量与弯矩图中的弯矩代数量间存在一一对应关系的特点，采用“图解法”介绍了求解、校核平面弯曲梁强度和刚度的核心内容———弯矩值，凸显了图解法快速、准确、易学、深刻记忆的优点。%Aiming at shortcomings of conventional analytical method and utilizing the characteristic of the one to one correspon‐dence between the algebra of area surrounding by shearing force and algebra of bending moment in bending moment diagram ,in this paper ,we introduced the utilization of graphical method to solve and check bending moment value which is the core contents of intensity and rigidity of plane bending beam .Our graphical method highlights the advantage of the novel method:rapidity ,ac‐curacy ,learnability ,and profound memory .
Dust deposition in ventilation and air-conditioning duct bend flows
International Nuclear Information System (INIS)
Highlights: ► We study particle deposition on the four inner surface of the duct bend. ► We analyse the effect of five ways of placements of the bend on particle deposition. ► Gravity and inertia force enhance the deposition as relaxation time rises. ► Deposition coefficient increases as air velocity or particle diameter increases. - Abstract: Particles carried by airflows in ventilation and air-conditioning systems have adverse effects on the quality of air in buildings and hence the health of building occupants. Gaining insight on particle deposition onto ventilation and air-conditioning duct bends is important for controlling pollutant dispersion. Based on the Reynolds stress transport model (RSM), this paper has taken into account the effects of drag, lift force, gravity, inertia force, turbulent diffusions, particle size and air velocity on the dimensionless deposition velocity of particles in smooth duct bends using fully developed velocity profiles. At two different air velocities of 3.0 m/s and 7.0 m/s, the aforementioned effects were predicted by Reynolds-averaged Navier–Stokes (RANS)-Lagrangian simulation on square shaped duct bends with different ways of placement. Preliminary results suggest that gravity and inertia force enhance the dimensionless deposition as dimensionless relaxation time rises. Change tendency of the dimensionless particle deposition velocity on different surfaces of bend duct agrees well with previous studies. As air velocity and particle diameter increase, a significant increase of particle deposition coefficient in the duct bends is observed. Particle deposition to intrados can be intensified by the combined action of gravity and inertia force in different direction.
‘Size effect’ related bending formability of thin-walled aluminum alloy tube
Institute of Scientific and Technical Information of China (English)
Li Heng; Yang He; Zhang Zhiyong; Wang Zekang
2013-01-01
Aluminum alloy (Al-alloy) thin-walled (D/t ＞ 20,diameter D,wall thickness t) bent tubes have attracted increasing applications in many industries with mass quantities and diverse specifications due to satisfying high strength to weigh ratio requirements of product manufacturing.However,due to nonlinear nature of bending with coupling effects of multiple factors,the similarity theory seems not applicable and there occurs a challenge for efficient and reliable evaluation of the bending formability of thin-walled tube with various bending specifications.Considering the unequal deformation and three major instabilities,the bending formability of thin-walled Al-alloy tube in changing tube sizes such as D and t are clarified via both the analytical and FE modeling/ simulations.The experiments of rotary draw bending are conducted to validate the theoretical models and further confirm ‘size effect' related bending formability.The major results show that (1) The anti-wrinkling capability of tube decreases with the larger D and smaller t,and the effect significance of t is larger than that of D even under rigid supports; (2) The wall thinning increases with the larger D and smaller t,and this tendency becomes much more obvious under rigid supports; (3) The cross-section deformation increases with the larger D and smaller t according to the analytical model obtained intrinsic relationship,while this tendency becomes opposite due to the nonlinear role of mandrel die; (4) The size factor D/t can be used as a nondimensional index to evaluate both the bending formability regarding the wall thinning and cross-section deformation.
Performance of composite I-beams under axial compression and bending load modes
Energy Technology Data Exchange (ETDEWEB)
Khalid, Y.A.; Ali, F.A.; Sahari, B.B.; Saad, E.M.A
2005-04-15
An experimental and finite-element analyses for glass/epoxy composite I-beams have been carried out. Four, six, eight and 10 layers of woven fabric glass/epoxy composite I-beams were fabricated by a hand lay-up (molding) process. Quasi-static axial crushing and bending loading modes were used for this investigation. The load-displacement response was obtained and the energy absorption values were calculated for all the composite I-beams. Three tests were done for each composite I-beams type and each loading case for the results conformation. The second part of this study includes the elastic behavior of composite I-beams of the same dimensions and materials using finite-element analysis. The woven fabric glass/epoxy composite I-beams mechanical properties have been obtained from tensile tests. Results from this investigation show that the load required and the specific energy absorption for composite I-beams under axial compression load were higher than those for three and four point bending. On the other hand, the loads required for composite I-beams under four point bending were higher than those for three point bending, while the specific energy absorption for composite I-beams under three point bending were higher than those for four point bending. The first crushing loads difference between the experimental and finite-element results fell in the 3.6-10.92% range for axial compression tests, while fell in the 1.44-12.99% and 4.94-22.0% range for three and four point bending, respectively.
International Nuclear Information System (INIS)
BEN domain-containing protein 3 (BEND3) has recently been reported to function as a heterochromatin-associated protein in transcriptional repression in the nucleus. BEND3 should have nuclear localization signals (NLSs) to localize to the nucleus in light of its molecular weight, which is higher than that allowed to pass through nuclear pore complexes. We here analyzed the subcellular localization of deletion/site-directed mutants of human BEND3 by an immunofluorescence assay in an attempt to identify the amino acids essential for its nuclear localization. We found that three basic amino acid residues located in the N-terminal region of BEND3 (BEND356–58, KRK) are essential, suggesting that these residues play a role as a functional NLS. These results provide valuable information for progressing research on BEND3. - Highlights: • BEND3 localizes to the nucleus. • The N-terminal 60 amino acids region of BEND3 contains NLS. • Amino acids located between 56 and 58 of BEND3 (KRK) are part of NLS. • KRK motif is highly conserved among BEND3 homologs
The effect of load-controlled bending load on the failure pressure of wall-thinned pipe elbows
International Nuclear Information System (INIS)
Highlights: • We evaluated bending load effect on the failure pressure of wall-thinned pipe elbows. • Burst tests were conducted on real-scale elbow specimens with local wall thinning. • The tests were performed under combined pressure and load-controlled bending. • Load-controlled bending reduced the failure pressure of wall-thinned elbows. • Bending load effect was significant for opening-mode and intrados wall-thinning case. - Abstract: In this research, burst tests were conducted on real-scale elbow specimens, each with an artificial local wall-thinning defect, under combined internal pressure and constant in-plane bending load, as well as under simple internal pressure, to evaluate the effect of load-controlled bending load on the failure pressure of locally wall-thinned pipe elbows. Ninety-degree, 65A Schedule 80 elbows, with wall-thinning defects in the intrados and extrados, were used as specimens. The bending loads were in-plane opening- and closing-mode bending, applied in load-control mode. The results clearly indicated that a load-controlled in-plane bending load reduced the failure pressure of wall-thinned pipe elbows, in contrast to observations previously made under displacement-controlled bending conditions. The effect of the bending load was more significant for opening-mode than for closing-mode bending, regardless of the wall-thinning location in the elbow. Also, the effect was greater when the wall-thinning defect was located in the intrados region of the elbow, rather than the extrados region. Existing models that have been proposed to evaluate the failure of wall-thinned elbows under simple internal pressure conservatively predicted the failure pressure of elbows subjected to a combined internal pressure and load-controlled bending load
Investigation of the dynamic bending properties of MoS2 thin films by interference colours
Wang, Peng; Xiao, Si; Li, Xiaohong; Lyu, Bosai; Huang, Yingbao; Cheng, Shubo; Huang, Han; He, Jun; Gao, Yongli
2015-12-01
A non-contact method for the observation of the elastic deformation of 2D molybdenum disulfide (MoS2) thin films using an ordinary optical microscope is reported. A pulsed laser is used to rapidly increase the bending deformation of the MoS2 thin films via heating. The bending angle of the MoS2 thin films shows high stability, changing only 5% in forty days without external forces. However, the bending angle of the MoS2 thin films substantially decreases after being wetted with the volatile polar solvent tetrahydrofuran (THF), because of its low surface tension. By removing the nano-Newton scale forces on the MoS2 thin films, the bending angle increases significantly within 4 minutes, and this feature of the thin films shows great potential for use in the fabrication of micro-force sensors. This is the first attempt to study the mechanical properties of 2D materials by optical methods. Further utilization of industrially manufactured MoS2 thin films for detecting micro-force qualitatively on the basis of their excellent bending properties would significantly reduce the production costs of micro-force sensors.
Effects of stem structure and cell wall components on bending strength in wheat
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Morphological traits, anatomical features, chemical components and bending stress in the stems of three genotypes of wheat (Triticum aestivum L.), namely Xiaoyan54, 8602 and Xiaoyan81, were examined by means of light microscopy coupled with Fourier transform infrared spectroscopy (FTIR). Noticeable changes in morphological and anatomical traits were observed, including outer radius of stem, the ratio of stem outer radius to stem wall thickness, various tissue proportions and variations among different types of vascular bundles. The results of chemical analysis revealed that Xiaoyan81 had the highest cellulose content in comparison with Xiaoyan54 and 8602, whereas lignin level in Xiaoyan81 was lower than that in 8602 but higher that that in Xiaoyan54. Bending stress analysis demonstrated that Xiaoyan81 may be the main target for identification, for it had the highest bending stress among the stems of three genotypes. Associated with bending stress, all the results presented here suggested that the ratio of stem wall thickness to its outer radius, schlerenchyma tissue proportion, the average number of big VB per unit and the cellulose content are four important factors affecting the mechanical strength of Xiaoyan81 wheat stems, which can be considered as the key parameters for selecting varieties with bending stress. Therefore, it was suggested that in the selection of lodging resistant cultivars one should consider those characterized with large ratio of outer radius of stem to stem wall thickness, greaterschlerenchyma tissue proportion, high average number of big VB per unit with high cellulose content in their stems.
Gas-liquid two phase flow through a vertical 90 elbow bend
Energy Technology Data Exchange (ETDEWEB)
Spedding, P.L.; Benard, E. [School of Aeronautical Engineering, Queen' s University Belfast, BT9 5AH (United Kingdom)
2007-07-15
Pressure drop data are reported for two phase air-water flow through a vertical to horizontal 90 elbow bend set in 0.026 m i.d. pipe. The pressure drop in the vertical inlet tangent showed some significant differences to that found for straight vertical pipe. This was caused by the elbow bend partially choking the inflow resulting in a build-up of pressure and liquid in the vertical inlet riser and differences in the structure of the flow regimes when compared to the straight vertical pipe. The horizontal outlet tangent by contrast gave data in general agreement with literature even to exhibiting a drag reduction region at low liquid rates and gas velocities between 1 and 2 m s{sup -1}. The elbow bend pressure drop was best correlated in terms of l{sub e}/d determined using the actual pressure loss in the inlet vertical riser. The data showed a general increase with fluid rates that tapered off at high fluid rates and exhibited a negative pressure region at low rates. The latter was attributed to the flow being smoothly accommodated by the bend when it passed from slug flow in the riser to smooth stratified flow in the outlet tangent. A general correlation was presented for the elbow bend pressure drop in terms of total Reynolds numbers. A modified Lockhart-Martinelli model gave prediction of the data. (author)
SIZE EFFECT ON THE BENDING AND TENSILE STRENGTH OF MICROMACHINED POLYSILICON FILMS FOR MEMS
Institute of Scientific and Technical Information of China (English)
DingJianning; YangJichang; WenShizhu
2004-01-01
The bending strength of microfabricated polysilicon beams was measured by beam bending using a nanoindenter. Also, the tensile strength of microfabricated polysilicon thin films was measured by tensile testing with a new microtensile test device. It was found that the bending strength and tensile strength of polysilicon microstructures exerts size effect on the size of the specimens. In such cases, the size effect can be traced back to the ratio of surface area to volume as the governing parameter. A statistical analysis of the bending strength for various specimen sizes shows that the average bending strength of polysilicon microcantilever beams is 2.885±0.408 GPa. The measured average value of Young's modulus, 164±1.2 GPa, falls within the theoretical bounds. The average fracture tensile strength is 1.36 GPa with a standard deviation of 0.14 GPa, and the Weibull modulus is 10.4-11.7, respectively. The tensile testing of 40 specimens on failure results in a recommendation for design that the nominal strain be maintained below 0.0057.
Microstructure-Based RVE Approach for Stretch-Bending of Dual-Phase Steels
Huang, Sheng; He, ChunFeng; Zhao, YiXi
2016-03-01
Fracture behavior and micro-failure mechanism in stretch-bending of dual-phase (DP) steels are still unclear. Representative volume elements (RVE) have been proved to be an applicable approach for describing microstructural deformation in order to reveal the micro-failure mechanism. In this paper, 2D RVE models are built. The deformation behavior of DP steels under stretch-bending is investigated by means of RVE models based on the metallographic graphs with particle geometry, distribution, and morphology. Microstructural failure modes under different loading conditions in stretch-bending tests are studied, and different failure mechanisms in stretch-bending are analyzed. The computational results and stress-strain distribution analysis indicate that in the RVE models, the strain mostly occurs in ferrite phase, while martensite phase undertakes most stress without significant strain. The failure is the results of the deformation inhomogeneity between martensite phase and ferrite phase. The various appearance and growth of initial voids are different depending on the bending radius.
Feature-guided waves (FGW) in plate structures with 90° transverse bends
Yu, Xudong; Manogharan, Prabhakaran; Fan, Zheng; Rajagopal, Prabhu
2015-03-01
Ultrasonic guided waves are attractive for rapid remote screening of large structures and today they are widely used in several practical applications including the inspection of pipe and plate installations. More recently, guided wave modal solutions confined in extended local features have attracted much research interest, offering the possibility of inspecting complex geometric or topographical features. Such feature-guided wave (FGW) modes have been reported in plate waveguides with local cross-section variation or curvature, and in annular circular cylinders with cross-sectional anomalies. This paper focuses on FGW phenomena in 90 degree structural bends in plate structures, which commonly occur in various industrial structures. Modal studies are carried out using the Semi-Analytical Finite Element (SAFE) method, while 3D finite element (FE) simulations are used to gain visualization of results and also obtain cross-validation. Our studies reveal, perhaps for the first time, the possibility of bend-guided modes of the shear-horizontal (SH) family, in addition those of the Rayleigh-Lamb family reported earlier in the literature. This mode has attractive properties including low attenuation and limited dispersion. We investigate effects of plate thickness and bend radius on the physics of FGW in bends, arguing the strong role of geometry and curvature effects in causing mode confinement. Preliminary experiments have also been carried out to validate the existence of such bend-guided mode.
Severity of the Bend and Its Effect on the Subsequent Hydroforming Process for Aluminum Alloy Tube
Gholipour, J.; Worswick, M. J.; Oliveira, D. A.; Khodayari, G.
2004-06-01
The interaction between pre-bending and subsequent hydroforming of AlMg3.5Mn aluminum tubes is examined in this paper. Pre-bending induces large strains and strain gradients in the tube, which reduce the available formability for the subsequent hydroforming process. Corner fill hydroforming operations were performed on straight tubes (R/D=∞) and pre-bent tubes with R/D=2.5, representing a transition from low severity to moderate severity bending conditions. An Eagle EPT-75 instrumented mandrel-rotary draw tube bender was used for the pre-bending stage, which records all process parameters. The experiments were modeled using an explicit dynamic finite element code, LS-DYNA. An in-house Gurson-Tvergaard-Needleman (GTN) constitutive softening model, incorporated within LS-DYNA, has been considered to predict damage and formability. Based on these results, the formability of a tube bent at an R/D=2.0 is predicted as a higher severity bend condition.
Electrostatic model of the energy-bending within organic semiconductors: experiment and simulation
Whitcher, T. J.; Wong, W. S.; Talik, A. N.; Woon, K. L.; Chanlek, N.; Nakajima, H.; Saisopa, T.; Songsiriritthigul, P.
2016-09-01
The interfacial properties between electrodes and the various organic layers that comprise an organic electronic device are of direct relevance in understanding charge injection, extraction and generation. The energy levels and energy-bending of three interfaces; indium tin oxide (ITO)/poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), ITO/poly(N-vinylcarbazole) (PVK) and PEDOT:PSS/PVK were measured using ultraviolet photoelectron spectroscopy (UPS) and x-ray photoelectron spectroscopy (XPS). By decoupling the vacuum shift and energy-bending, the energy-bending at these interfaces can be simulated using an electrostatic model that takes into account the energetic disorder of the polymers. The model is further extended to include blended mixtures of semiconductors at differing concentrations and it was found that a very good agreement exists between the experiment and theory for all interfaces. This suggests that the electrostatic model can be used to describe energy-bending at the interface between any organic semiconductors. Further investigation into the effect of the Gaussian density of states width on energy-bending is warranted.
On the influence of interfacial properties to the bending rigidity of layered structures
Peng, Shenyou; Wei, Yujie
2016-07-01
Layered structures are ubiquitous, from one-atom thick layers in two-dimensional materials, to nanoscale lipid bi-layers, and to micro and millimeter thick layers in composites. The mechanical behavior of layered structures heavily depends on the interfacial properties and is of great interest in engineering practice. In this work, we give an analytical solution of the bending rigidity of bilayered structures as a function of the interfacial shear strength. Our results show that while the critical bending stiffness when the interface starts to slide plastically is proportional to the interfacial shear strength, there is a strong nonlinearity between the rigidity and the applied bending after interfacial plastic shearing. We further give semi-analytical solutions to the bending of bilayers when both interfacial shearing and pre-existing crack are present in the interface of rectangular and circular bilayers. The analytical solutions are validated by using finite element simulations. Our analysis suggests that interfacial shearing resistance, interfacial stiffness and preexisting cracks dramatically influence the bending rigidity of bilayers. The results can be utilized to understand the significant stiffness difference in typical biostructures and novel materials, and may also be used for non-destructive detection of interfacial crack in composites when stiffness can be probed through vibration techniques.
Research on Flow Pattern of Nitrogen Tetroxide Liquid in the Different Bend Radii Pipes
Directory of Open Access Journals (Sweden)
Hao Pengfei
2016-01-01
Full Text Available N2O4 is a common rocket fuel propellants, it has the characteristics of low boiling point and a large viscosity , the friction between viscosity fluids and pipeline dramatic leads to a huge sticky heat, therefore, the vaporization phenomenon often occurs in the pipeline, particularly in bending of the viscous heat. For this reason, the research of the different bending radii vaporized fluid conditions for optimizing the piping and precise the filling flow is significant. In this paper, the MIXTURE mixed flow model is used to achieve the numerical simulation the pipelines filling of the three different bending radii, it still have not solved the mass transfer problem between the different phases. Therefore, the custom functions are needed to define the mass transfer problems from the liquid phase to the vapor phase. Though the contrast among the volume phase cloud of six different elbow models , we have the following conclusions: 1 In the entire pipeline transportation, the distribution vaporization rate from the inlet pipe to the outlet pipe follows the distribution of the first increasing and then decreasing, the gas rates of the elbow area is highest; 2Analyzing the sticky heat for different bend radii, we have the conclusion that the lowest bending vaporization the of the optimal radius is 0.45m. The above conclusions are drawn in good agreement with the actual law, can effectively guide the engineering practice, have important significance for the future design for the optimization of the fuel pipeline transportation.
Extreme sediment pulses generated by bend cutoffs along a large meandering river
Zinger, Jessica A.; Rhoads, Bruce L.; Best, James L.
2011-10-01
In meandering rivers, bend cutoffs have long been recognized as an important mechanism of change in the path of the channel. Meander bend cutoffs can develop by the progressive migration of an elongated bend onto itself, which forms a neck cutoff, or by the erosion of a new channel across the neck of the bend, which is known as a chute cutoff. River cutoffs affect channel navigation, and form meander scars and oxbow lakes in river floodplains, which are important habitats for riparian ecosystems. The importance of cutoff processes in meander dynamics is well established, but the effects of cutoffs on overall sediment flux are poorly characterized. Here we use aerial imagery, global positioning system mapping and measurements of channel bathymetry to estimate the amount of sediment released by two chute cutoffs on the Wabash River in the Midwestern USA. We find that each event triggered the rapid delivery of sediment into the river, at rates that are one to five orders of magnitude larger than those produced by lateral migration of individual bends. We find that much of this material was deposited immediately downstream, at the confluence of the Wabash and Ohio rivers, which led to significant changes in channel morphology. This sedimentation ultimately impeded barge traffic and necessitated extensive dredging.
Material development for grade X80 heavy-wall hot induction bends
Energy Technology Data Exchange (ETDEWEB)
Wang Xu [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); CNPC Bohai Petroleum Equipment Manufacture Co. Ltd., Qingxian 062658 (China); Xiao Furen, E-mail: frxiao@ysu.edu.cn [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); Fu Yanhong [CNPC Bohai Petroleum Equipment Manufacture Co. Ltd., Qingxian 062658 (China); Chen Xiaowei [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China); CNPC Bohai Petroleum Equipment Manufacture Co. Ltd., Qingxian 062658 (China); Liao Bo, E-mail: cyddjyjs@263.net [Key Laboratory of Metastable Materials Science and Technology, College of Materials Science and Engineering, Yanshan University, Qinhuangdao 066004 (China)
2011-12-15
Highlights: Black-Right-Pointing-Pointer The new material for X80 heavy wall thickness hot induction bend was designed. Black-Right-Pointing-Pointer The continuous cooling transformation (CCT) diagrams were determined. Black-Right-Pointing-Pointer The steel adapts to manufacture of X80 heavy-wall thickness hot induction bend. Black-Right-Pointing-Pointer The optimum manufactural processes were obtained. Black-Right-Pointing-Pointer The bending temperature is about 990 Degree-Sign C, and tempering is about 600 Degree-Sign C. - Abstract: A new steel for grade X80 heavy wall thickness hot induction bends was designed based on the chemical compositions of commercial X80 steels in this work. Then, its continuous cooling transformation (CCT) diagram was determined with Gleeble-3500 thermo-mechanical simulator. Furthermore, the effects of heat treatment technology on its microstructure and mechanical property were investigated, and the technology parameters of the heat treatment were optimized. The results show that the acicular ferrite and/or bainite transformations are promoted, the polygonal ferrite and pearlite transformation are restrained, because proper amount of alloying elements were added into the new steel. Therefore, the strength of this new steel is improved markedly, even if the cooling rate is lower, which ensure the higher strength distribution along cross section of the heavy wall thickness. It is significant for the manufacture of grade X80 heavy wall thickness hot induction bends in the second West-to-East gas transportation pipeline project of China.
Development of a system to monitor laryngeal movement during swallowing using a bend sensor.
Directory of Open Access Journals (Sweden)
Qiang Li
Full Text Available BACKGROUND: Swallowing dysfunction (also known as dysphagia, which results in a deterioration of nutritional intake, slows rehabilitation and causes aspiration pneumonia, is very common following neurological impairments. Although videofluorographic (VF examination is widely used for detecting aspiration, an objective and non-invasive method for assessing swallowing function has yet to be established because of a lack of adequate devices and protocols. In this paper, a bend sensor whose resistance is altered by bending was introduced to monitor swallowing-related laryngeal movement. METHODS: Six healthy male volunteers were recruited in the present study. Specific time points on the signal waveform produced by the bend sensor were defined to describe laryngeal movement by differential analysis. Additionally, the physiological significance of the obtained waveform was confirmed by analyzing the sequential correlations between the signal waveform from the bend sensor and hyoid bone kinetics simultaneously recorded by VF. RESULTS: Seven time points were successfully defined on the signal waveform to reference laryngeal movement. Each time point was well correlated with certain VF events, with evidence of no significant time lags, and there were positive correlations between waveform time points and matched VF events. Furthermore, obvious similarities were noticed between the duration of each phase on the signal waveform and the duration of the matched hyoid bone activity. CONCLUSIONS: The present monitoring system using a bend sensor might be useful for observing the temporal aspects of laryngeal movement during swallowing, and it was well coordinated with hyoid bone movement.
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
The nonlinear dynamic behavior of a rubbing rotor system was studied with a mathematical model established with the eccentricity and interaction between bending and torsional vibrations taken into consideration.The nonlinear vibrational response of a rubbing rotor was analyzed using numerical integral,spectroscopic analysis and Poince mapping method,which made it possible to have better understanding of the vibrational characteristics of partial rubbing and complete circular rubbing rotors.The numerical results reveal the response of torsional vibration mainly takes a form of suporchronous motion,and its frequency decreases as the rotational speed increases when partial rubbing occurs,and the response of torsional vibration is synchronous when complete circular rubbing occurs.The comparison of the dynamics of rubbing rotors with and without the interaction between bending and torsional vibrations shows the interaction between bending and torsional vibrations advances the rotational speed,at which the response of bending vibration changes from a synchronous motion into a quasi-periodic motion,and the interaction between bending and torsional vibrations reduces stability of the rubbing rotor.
Impact compressive and bending behaviour of rocks accompanied by electromagnetic phenomena.
Kobayashi, Hidetoshi; Horikawa, Keitaro; Ogawa, Kinya; Watanabe, Keiko
2014-08-28
It is well known that electromagnetic phenomena are often observed preceding earthquakes. However, the mechanism by which these electromagnetic waves are generated during the fracture and deformation of rocks has not been fully identified. Therefore, in order to examine the relationship between the electromagnetic phenomena and the mechanical properties of rocks, uniaxial compression and three-point bending tests for two kinds of rocks with different quartz content, granite and gabbro, have been carried out at quasi-static and dynamic rates. Especially, in the bending tests, pre-cracked specimens of granite were also tested. Using a split Hopkinson pressure bar and a ferrite-core antenna in close proximity to the specimens, both the stress-strain (load-displacement) curve and simultaneous electromagnetic wave magnitude were measured. It was found that the dynamic compressive and bending strengths and the stress increase slope of both rocks were higher than those observed in static tests; therefore, there is a strain-rate dependence in their strength and stress increase rate. It was found from the tests using the pre-cracked bending specimens that the intensity of electromagnetic waves measured during crack extension increased almost proportionally to the increase of the maximum stress intensity factor of specimens. This tendency was observed in both the dynamic and quasi-static three-point bending tests for granite. PMID:25071241
Stress relaxation and recovery behaviour of composite orthodontic archwires in bending.
Zufall, S W; Kusy, R P
2000-02-01
The viscoelastic behaviour of prototype composite orthodontic archwires was evaluated using a bend stress relaxation test. Archwires having 10 different volume fractions of reinforcement were subjected to constant bending radii in a water bath at 37 degrees C for time periods of up to 90 days. The wires were subsequently released and left unconstrained for the same testing conditions. Creep-induced changes in the unconstrained bending radii of the wires were measured at specific times during both phases (stress relaxation and recovery) of the test. The statistical analysis showed that stress relaxation behaviour was strongly correlated with the archwire reinforcement level. The final relaxation varied, with decreasing reinforcement, from 2 to 8 per cent. Archwire recovery was not correlated with reinforcement level, and revealed a final viscous loss of only 1 per cent. The relaxed elastic moduli in bending of the composite wires were similar to the elastic moduli in bending of several conventional orthodontic archwire materials. Losses that were associated with the viscoelastic behaviour varied with decreasing reinforcement level from 1.2 to 1.7 GPa. Because these modulus losses were minimal, each archwire retained sufficient resilience to be applicable to the early and intermediate stages of orthodontic treatment. PMID:10721240
Bending behavior of double-row stabilizing piles with constructional time delay
Institute of Scientific and Technical Information of China (English)
Yang YU; Yue-quan SHANG; Hong-yue SUN
2012-01-01
The bending behavior of double-row stabilizing plies is associated with the constructional time delay (CTD),which can be defined as the time interval between the installations of the front stabilizing pile and the rear stabilizing pile.This paper investigates the effect of CTD on the bending moments of double-row stabilizing piles and a method for determining the optimal CTD is proposed.The stabilizing pile is modeled as a cantilever pile embedded in the Winkler elastic foundation.A triangular distributed earth pressure is assumed on the pile segment in the sliding layer.The front stabilizing pile and the rear stabilizing pile are connected by a beam with pinned joints.The analytical solutions of bending moments on the front and the rear stabilizing piles are derived and the accuracy of bending moment solutions is validated by comparing the tensile strain measured from the Hongyan landslide project,Taizhou,Zhejiang,China.It is concluded that CTD has a significant influence on the bending moments of double-row stabilizing piles.An optimal CTD can be obtained when the maximum tensile stress in the front stabilizing pile is equal to that in the rear stabilizing pile,which is 1.4 months for the Hongyan landslide project.
Simulation of dilute pneumatic conveying with different types of bends by CFD-DEM
International Nuclear Information System (INIS)
Bends are one of the most commonly used facilities to change flow direction in pneumatic conveying. It is important to understand the effect of the bend to the gas-solid flow structures in a pneumatic conveying system. CFD-DEM is one of powerful methods to study the fundamentals of gas-solid flow, as it takes the particle-particle and particle-wall collisions into account. But the time consumption is one of major limitations for its application. In this paper, a three-dimensional CFD-DEM model which ignores the effect of void fraction to the gas phase is used to simulate the dilute gas-solid flow. Gas-solid flows in different types of bends including horizontal-vertical, vertical-horizontal and horizontal-horizontal 90° bends are studied. The present CFD-DEM model is verified by compared the rope structure with the result for traditional CFD-DEM model in horizontal-vertical case. Compared the particle rope dispersion in different types of bends, the rope disperses more quickly in the vertical-horizontal case than others, and the solid flow structure is the most complicated in the horizontal- horizontal case. As their various solid flow structures, the collision data of three cases also seem different
International Nuclear Information System (INIS)
The bending of rod fuel elements in gas-cooled fast reactors under the action of temperature gradients radiation-induced swelling non-uniform over the perimeter of fuel cans is evaluated. It is pointed out that the radiation-induced swelling gives the main contribution to the bending of fuel elements. Calculated data on the bending of the corner fuel element in the assembly of the fast reactor with dissociating gas coolant are given. With the growth of temperature difference over the perimeter, the bending moment and deformation increase, resulting in the increase of axial stresses. The obtained data give the basis for accounting the stresses connected with thermal and radiation bending when estimating serviceability of fuel elements in gas cooled fast reactors. Fuel element bending must be also taken into account when estimating the thermal hydrualic properties
Sutherland, H. J.
The load spectrum unposed upon a horizontal-axis wind turbine blade is typically decomposed into two primary bending moments; flap and edgewise bending. The critical fatigue loads (stress cycles) imposed on the blade may not be on one of these axes, especially if die two bending loads are in-phase with one another. To quantify the correlation of these two bending moments and determine the impact of this correlation on off-axis fatigue loads, an extensive data set for a typical wind turbine blade is examined. The results are compared using their respective cycle count matrices. These results illustrate that the harmonic components of die principal bending stresses are correlated, and that the random components are not. The analysis techniques described in the paper provide the turbine designer with a spectral technique for combining primary bending spectra into off-axis fatigue loads.
The effect of applied stress on damage mode of 3D C/C composites under bend-bend fatigue loading
Institute of Scientific and Technical Information of China (English)
LIAO XiaoLing; LI HeJun; XU WenFeng; LI KeZhi
2007-01-01
The bend-bend fatigue behavior of 3D integral braided carbon/carbon composites (3D C/C) was examined. Fatigue test was conducted under load control at a sinusoidal frequency of 10 Hz to obtain stress-fracture cycles (S-N) relationship. The fatigue limit of the C/C was found to be 203 MPa (92% of the static flexural strength), the lag loops of fatigue load-displacement were transformed from elasticity to anelasticity and the flexibility of specimens were enhanced with increase in applied stress. It is revealed that the interfacial sliding abrasion played an important role in the fatigue failure process, and the extent and speed of sliding abrasion were controlled by the level of applied stress.
The effect of applied stress on damage mode of 3D C/C composites under bend-bend fatigue loading
Institute of Scientific and Technical Information of China (English)
2007-01-01
The bend-bend fatigue behavior of 3D integral braided carbon/carbon composites (3D C/C) was examined. Fatigue test was conducted under load control at a sinu-soidal frequency of 10 Hz to obtain stress-fracture cycles (S-N) relationship. The fatigue limit of the C/C was found to be 203 MPa (92% of the static flexural strength), the lag loops of fatigue load-displacement were transformed from elasticity to anelasticity and the flexibility of specimens were enhanced with increase in applied stress. It is revealed that the interfacial sliding abrasion played an important role in the fatigue failure process, and the extent and speed of sliding abrasion were con-trolled by the level of applied stress.
Energy Technology Data Exchange (ETDEWEB)
Mang, F.; Herion, S.; Bucak, O. [Univ. of Karlsruhe (Germany)
1994-12-31
This paper presents first results of calculations according to the finite element method for uniplanar K-joints with gap. The investigations cover thin-walled rectangular hollow sections of commonly used dimensions and manufacture. The employed finite element model has been optimized and checked carefully in a research program sponsored by the Deutsche Forschungsgemeinschaft DFG (Research foundation of German government) dealing with multiplanar K-joints with gap. Compared to previous investigations, the influence of axial load, in-plane bending moments (IPB) and out-of-plane bending moments (OPB) are considered separately. With these models, parametric studies have been carried out to make statements on the strain concentration factors SNCF in terms of the geometric parameters {beta} = b{sub 1}/b{sub 0}; {tau} = t{sub 1}/t{sub 0} and gap g. As far as possible, graphs are given.
Energy Technology Data Exchange (ETDEWEB)
Herion, S.; Mang, F. [Univ. of Karlsruhe (Germany)
1994-12-31
This paper presents the most significant results of a comprehensive parametric study on multiplanar K-joints. In this study, which is part of a pH. D. work, the influence of axial load, in-plane bending moments (IPB) and out-of-plane bending moments (OPB) are considered separately. For each type of loading, symmetric load vectors have been assumed and the most unfavorable assumption has been investigated. On this basis and in dependence of the geometric parameters {beta} = b{sub 1}/b{sub 0}, {tau} = t{sub 1}/t{sub 0}, 2{gamma} = b{sub 1}/t{sub 0}, SNCF diagrams and formulae for the design of multiplanar K-joints with gap made of RHS are given.
Van Erps, Jürgen; Debaes, Christof; Nasilowski, Tomasz; Watté, Jan; Wojcik, Jan; Thienpont, Hugo
2008-03-31
We present the design of a low bending loss hole-assisted fiber for a 180?-bend fiber socket application, including a tolerance analysis for manufacturability. To this aim, we make use of statistical design methodology, combined with a fully vectorial mode solver. Two resulting designs are presented and their performance in terms of bending loss, coupling loss to Corning SMF-28 standard telecom fiber, and cut-off wavelength is calculated.
Strength Behavior of High Strength R/C Columns under Biaxial Bending-Shear and Varying Axial Load
MIZOGUCHI, Mitsuo; Arakawa, Takashi; ARAI, Yasuyuki
1991-01-01
Twelve short square R/C columns using high-strength concrete were tested to examine the effects of biaxial bending-shear force and varying axial load on the shear and flexural strength behavior. The columns were cyclically deflected either along their transverse principal axis to produce uniaxial bending-shear or along their diagonal to produce biaxial bending-shear. For columns failing in flexure, the experimental results were found to be in close agreement with the computed values given by ...
Over-leg Bending Test for Mixed-mode I/II Interlaminar Fracture in Composite Laminates
Szekrényes, András; UJ, József
2007-01-01
Abstract In this work the over-leg bending (OLB) specimen is developed for mixed-mode I/II delamination characterization in composites. The traditional single-leg bending (SLB) specimen is modified by introducing the load eccentrically between the two supports of a three-point bending setup. The modified configuration is analyzed by using linear beam theories. The theories of transverse shear, Winkler-Paste...
New optical method for measuring the bending elasticity of lipid bilayers
Minetti, C.; Vitkova, V.; Dubois, F.; Bivas, I.
2016-02-01
The knowledge of the elasticity of lipid bilayer structures is fundamental for new developments in biophysics, pharmacology and biomedical research. Lipid vesicles are readily prepared in laboratory conditions and employed for studying the physical properties of lipid membranes. The thermal fluctuation analysis of the shape of lipid vesicles (or flicker spectroscopy) is one of the experimental methods widely used for the measurement of the bending modulus of lipid bilayers. We present direct phase measurements performed on dilute vesicular suspensions by means of a new optical method exploiting holographic microscopy. For the bending constant of phosphatidylcholine bilayers we report the value of 23kBT in agreement with values previously measured by micropipette aspiration, electrodeformation and flicker spectroscopy of giant lipid vesicles. The application of this novel approach for the evaluation of the bending elasticity of lipid membranes opens the way to future developments in the phase measurements on lipid vesicles for the evaluation of their mechanical constants.
Quasi-static and dynamical bending of a cantilever poroelastic beam
Institute of Scientific and Technical Information of China (English)
YANG Yi; LI Li; YANG Xiao
2009-01-01
Based on the theory of porous media, the quasi-static and dynamical bending of a cantilever poroelastic beam subjected to a step load at its free end is investigated, and the influences of its permeability on bending deformation is examined.The initial boundary value problems for dynamical and quasi-static responses are solved with the Laplace transform technique,and the deflections, the bending moments of the solid skeleton and the equivalent couples of the pore fluid pressure are shown in figures. It is shown that the dynamical and quasi-static behavior of the saturated poroelastic beam depends closely on the permeability conditions at the beam ends. Under the different permeability conditions, the deflections of the beam may oscillate or not. The Mandel-Cryer effect also exists in liquid-saturated poroelastic beams.
A method for controlling the bending of wells in the plane of a layer
Energy Technology Data Exchange (ETDEWEB)
Levkovich, P.E.; Savich, N.S.
1980-07-17
A method is presented for the control of the bending of wells in a plane of a layer in the process of boring, based on the determination of the magnitude of the bending of the supply column, is characterized in that for the purpose of increasing the reliability of the control, the magnitude of the forces of the supply is measured between the tangential elements of the supply column and the drive mechanism at the segments diametrically opposite in respect to the vertical plane passing along the longitudinal axis of the column, and according to the forces of the drive at these part, the direction and the magnitude of the bending of the supply column are judged.
Correlation of in-plane bending test and FEA results for thin-walled elbows
International Nuclear Information System (INIS)
The objective of this study is to validate a finite element analysis (FEA) simulation methodology to predict the global behavior of thin-walled elbows subjected to in-plane bending. Two in-plane closing mode bending tests and one in-plane opening mode bending test were conducted on 2'' schedule 10 elbows, and a nonlinear FEA procedure was used to simulate the tests. A detailed FEA study was carried out to determine the relative importance of weld size and location, measured wall thicknesses, and original cross-section dimensions on the reconciliation results. When the weld bead was included in the analysis, the reconciliation results for load-displacement behavior and some of the strain measurements were excellent. For those cases in which the strain measurements reconciliations were not so good, a possible explanation is provided
Bending in laminas of NFPR: type of reinforcement, fracture and properties
Directory of Open Access Journals (Sweden)
Mirtânia Antunes Leão
2011-03-01
Full Text Available Natural fiber reinforced plastics (NFRP have awakened considerable interest in the area of polymer composites, because of the need to develop new, environmentally friendly materials. One of the most complex ways of manufacturing this type of material is in the form of ultrathin laminar layers; however, this process hinders mechanical testing, mainly three and four-point bending. The present investigation faces this challenge and shows the influence of parameters, such as the grammage of reinforcing fabric and lamination process, on strength, stiffness and fracture characteristics for three-point bending in this type of structural element. The industrially manufactured laminas were composed of orthophthalic polyester resin reinforced with licuri fibers. Macromechanical and micromechanical analyses were conducted in the study of fracture characteristics for all the parameters. The mechanical behavior in the three-point bending of the laminar composite showed that the use of licuri fiber to obtain natural fiber-based plastic is completely viable.
Olender, Gavin; Pfeifer, Ronny; Müller, Christian W; Gösling, Thomas; Barcikowski, Stephan; Hurschler, Christof
2011-05-01
Nitinol is a promising biomaterial based on its remarkable shape changing capacity, biocompatibility, and resilient mechanical properties. Until now, very limited applications have been tested for the use of Nitinol plates for fracture fixation in orthopaedics. Newly designed fracture-fixation plates are tested by four-point bending to examine a change in equivalent bending stiffness before and after shape transformation. The goal of stiffness alterable bone plates is to optimize the healing process during osteosynthesis in situ that is customized in time of onset, percent change as well as being performed non-invasively for the patient. The equivalent bending stiffness in plates of varying thicknesses changed before and after shape transformation in the range of 24-73% (p values inertia. PMID:21286815
Dynamic investigation of twist-bend coupling in a wind turbine blade
DEFF Research Database (Denmark)
Luczak, M.; Manzato, S.; Peeters, B.;
2011-01-01
This paper presents some results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study in static and dynamic domains on the bend-twist coupling in the full scale section of a wind turbine blade structure. The main goal of the conducted...... research is to confirm experimentally the numerical prediction of modification of the dynamic and static properties of a wind turbine blade. The bend-twist coupling was implemented by adding angled UD (UniDirectional) layers on the suction and pressure side of the blade. Static and dynamic tests were...... performed on a section of the full scale wind turbine blade provided by VestasWind Systems A/S. The results are presented and compared with the measurements of the original and modified blade. Comparison analysis confirmed that UD layers introduce measurable bend-twist couplings, which was not present...
Effects of texture on shear band formation in plane strain tension/compression and bending
DEFF Research Database (Denmark)
Kuroda, M.; Tvergaard, Viggo
2007-01-01
In this study, effects of typical texture components observed in rolled aluminum alloy sheets on shear band formation in plane strain tension/compression and bending are systematically studied. The material response is described by a generalized Taylor-type polycrystal model, in which each grain...... model analysis. Third, shear band developments in plane strain pure bending of a sheet specimen with the typical textures are studied. Regions near the surfaces in a bent sheet specimen are approximately subjected to plane strain tension or compression. From this viewpoint, the bendability of a sheet...... specimen may be evaluated, using the knowledge regarding shear band formation in plane strain tension/compression. To confirm this and to encompass overall deformation of a bent sheet specimen, including shear bands, finite element analyses of plane strain pure bending are carried out, and the predicted...
Strength Characteristics of OSB in Bending – Difference between Upper and Lower Panel Faces
Directory of Open Access Journals (Sweden)
Martin Böhm
2011-06-01
Full Text Available This article is focused on evaluating the differences between the upper and lower faces of OSB/3 – Superfinish in the course of bending stress. OSB is a material manufactured from wood chips of a large surface area, irregular shape and unequal length, which are partly randomly distributed and at the same time not perfectly oriented. Differences regarding the content of OSB surface layers cause unequal properties, which can be demonstrated, especially under bending load. The measurements made show that OSB positioned with upper face downwards in the course of the bending test are capable of withstanding a higher load, and reaching an evidentially lower deflection, compared to those with lower face downwards.
Akbar, Fathan
2016-01-01
In this paper we examine more deeply about the bending mechanism of rod-shaped fireworks which burned from the free end. We derived new analytic equations. Surprisingly, we obtained the bending patterns are similar to the cornu spiral. With a few simple steps we proved that positions of points throughout the fireworks are given by Fresnel integrals, C(x) and S(x), which are generally found in phenomena of electromagnetic wave diffraction. Although we deeply discussed bending of fireworks rods, however the proposed method is likely to explain any phenomena in nature related to an evolving length scale associated with some material that becomes progressively stiff or dry, such as the growth of resin exuded from trees.
Exploring the cylindrical photo-bending shape in polydomain nematic glass
Xuan, Chen; Huo, Yongzhong
2016-01-01
This paper explores different photo-bending shapes in polydomain nematic glass. The motivation is to explain the phenomenon in experiment [1] under polarized light in which a nematic film curls into an circular arc, like part of a cylindrical surface. Polarized light triggers photo-isomerization and therefore makes liquid crystals (LCs) contract along their directors. We apply the Sachs limit to homogenize the deformation of polydomain LC glass. Photo-strain can be either contraction or expansion through the material. Bending shapes can be anticlastic, bowl-shaped and cylindrical affected by Poisson ratio and illumination intensity. An explanation for the cylindrical bend and ways to observe other shapes are given in a parameter plane.
Breather statics and dynamics in Klein-Gordon chains with a bend.
Cuevas, J; Kevrekidis, P G
2004-05-01
In this paper, we examine a nonlinear model with an impurity emulating a bend. We justify the geometric interpretation of the model and connect it with earlier work on models including geometric effects. We focus on both the bifurcation and stability analysis of the modes that emerge as a function of the strength of the bend angle, but we also examine dynamical effects including the scattering of mobile localized modes (discrete breathers) off of such a geometric structure. The potential outcomes of such numerical experiments (including transmission, trapping within the bend as well as reflection) are highlighted and qualitatively explained. Such models are of interest both theoretically in understanding the interplay of breathers with curvature, but also practically in simple models of photonic crystals or of bent chains of DNA.
Polarization-independent self-collimating bends and beam splitters in photonic crystals
Institute of Scientific and Technical Information of China (English)
Xiaopeng Shen; Kui Han; Xianqing Yang; Yifeng Shen; Haipeng Li; Gang Tang; Zhitian Guo
2007-01-01
Polarization independent bends and beam splitters for transverse electric (TE) and transverse magnetic (TM) polarizations have been demonstrated in two-dimensional (2D) photonic crystals (PhCs). In virtuel of equi-frequency contour analysis and finite-difference time-domain calculations, self-collimation behaviors for TE- and TM-polarizations are achieved at the same frequency. Simulation results show a 90-degree bend with 90% efficiency and beam splitters with about 96% total efficiency for both TE- and TMpolarizations, where the light is self-guided by the self-collimation effect. Such bends and beam splitters are expected to play important roles in optical devices where polarization insensitivity is needed.
The Faraday Pavilion: activating bending in the design and analysis of an elastic gridshell
DEFF Research Database (Denmark)
Nicholas, Paul; Lafuente Hernandez, Elisa; Gengnagel, Christoph
2013-01-01
This paper reports the architectural and engineering design, and construction, of The Faraday Pavilion, a GFRP elastic gridshell with an irregular grid topology. Gridshell structures are self-formed through an erection process in which they are elastically deformed, and the prediction and steering...... of this aspect becomes a central part of both architectural and engineering design processes. While there are existing architectural approaches to determining the geometry of other kinds of form-active structure, as well as new engineering approaches to the simulation of bending active structures, a fast...... and light-weight design approach to bending active structures is not currently developed. In this paper, we introduce an approach to the architectural design of a bending active structure whereby the shell form and grid topology are determined by simulation. Particular features are that the grid topology...
Elasticity of randomly diluted honeycomb and diamond lattices with bending forces.
Liarte, Danilo B; Stenull, O; Mao, Xiaoming; Lubensky, T C
2016-04-27
We use numerical simulations and an effective-medium theory to study the rigidity percolation transition of the honeycomb and diamond lattices when weak bond-bending forces are included. We use a rotationally invariant bond-bending potential, which, in contrast to the Keating potential, does not involve any stretching. As a result, the bulk modulus does not depend on the bending stiffness κ. We obtain scaling functions for the behavior of some elastic moduli in the limits of small [Formula: see text], and small [Formula: see text], where [Formula: see text] is an occupation probability of each bond, and [Formula: see text] is the critical probability at which rigidity percolation occurs. We find good quantitative agreement between effective-medium theory and simulations for both lattices for [Formula: see text] close to one. PMID:27023434
Transport and deposition of nanoparticles in bend tube with circular cross-section
Institute of Scientific and Technical Information of China (English)
Peifeng Lin; Jianzhong Lin
2009-01-01
Transport and deposition of nanoparticles in bend tube with circular cross-section were simulated numerically for different Reynolds numbers and Dean numbers.A finite-volume code and the SIMPLE scheme were used to solve the equations.The results show that the distribution of nanoparticle concentration is symmetrical with respect to the top and bottom sides of the tube.The diameter of the nanoparticles has a weak effect on the distribution of nanoparticle concentration.The maximum and minimum of the deposition enhancement factor occur near the outside and inside walls of the bend tube,respectively.The higher the Reynolds number is,the shorter is the time for nanoparticle deposition.The bend curvature radius has a slight effect on the deposition enhancement factor.
Jin, LiMin; Yao, Yao; Yu, YiMin; Rotich, Gideon; Sun, BaoZhong; Gu, BoHong
2014-03-01
This paper reports the structural effects of three-dimensional (3-D) angle-interlock woven composite (3DAWC) undergoing three-point bending cyclic loading from experimental and finite element analysis (FEA) approaches. In experiment, the fatigue tests were conducted to measure the bending deflection and to observe the damage morphologies. By the FEA approach, a micro-structural unit-cell model of the 3DAWC was established at the yarn level to simulate the fatigue damage. The stress degradation at the loading condition of constant deformation amplitude was calculated to show the degradation of mechanical properties. In addition, the stress distribution, fatigue damage evolution and critical damage regions were also obtained to qualitatively reveal the structural effects and damage mechanisms of the 3DAWC subjected to three-point bending cyclic loading.
Prediction and measurement of composite tube twist and bending due to thermal loading
Bluth, A. Marcel; Tucker, James R.; Thompson, Troy
2013-09-01
Composite materials are applied in precision optical metering structures because of their low thermal expansion properties in concert with high specific stiffness. Twisting and bending of long composite tubes, such as the secondary mirror support structure for the JWST telescope, requires control and verification. A stochastic modeling method was applied that simulates the manufacturing process variability and estimates ranges for expected twist and bend over the tube length from ambient to cryogenic temperatures. A development strut for the JWST secondary mirror support structure was fabricated and a metrology system was designed and implemented that measured the bend and twist response from ambient to 30 K. Modeling methods and predictions are outlined. The test metrology and results are summarized, along with a comparison between test and prediction.
Stress Distribution on Sandwich Structure with Triangular Grid Cores Suffered from Bending Load
Directory of Open Access Journals (Sweden)
Cui Xu
2015-01-01
Full Text Available Triangular grid reinforced by carbon fiber/epoxy (CF/EP was designed and manufactured. The sandwich structure was prepared by gluing the core and composite skins. The mechanical properties of the sandwich structure were investigated by the finite element analysis (FEA and three-point bending methods. The calculated bending stiffness and core shear stress were compared to the characteristics of a honeycomb sandwich structure. The results indicated that the triangular core ultimately failed under a bending load of 11000 N; the principal stress concentration was located at the loading region; and the cracks occurred on the interface top skin and triangular core. In addition, the ultimate stress bearing of the sandwich structure was 8828 N. The experimental results showed that the carbon fiber reinforced triangular grid was much stiffer and stronger than the honeycomb structure.
International Nuclear Information System (INIS)
The fuel handling operating rules exclude any accidental risk. However in the framework of the PRECCI R and D project, the bending of a spent fuel assembly resulting from its locking during a translation displacement is taken into account. This enabled us to develop an approach based on experiments and calculations that allows us to simulate the behaviour of an assembly under such loading. This study was carried out in CEA laboratories with the funding and the technical support of EDF. A three points bending test on a spent fuel rod segment was performed at the Laboratory for Mechanical Behaviour of Irradiated Materials (LCMI). From the experimental strength-displacement curve, a maximum failure strain, a maximum failure curvature and an equivalent constitutive equation were determined. CAST3M modelling of the fuel rod taking into account the elasto-plastic behaviour of the clad and the cracking of the UO2 fuel pellets was verified by the experimental results. Consequently, the identification of the respective contributions of the clad and of the pellets to the rod global behaviour was made possible. A two dimensional assembly with beam elements was modelled with CAST3M. The properties of the beams modelling the different parts of the assembly (top and bottom nozzle, grids) were chosen and adjusted according to their materials (zirconium alloys, steel) in order to obtain stiffness, tensile and shear behaviour, sliding and holding functions close to the experimental ones. Assembly bending calculations were performed. In order to obtain a rod integrity estimator, their maximum calculated strains and curvatures as a function of the bending angles can be compared to the failure experimental ones. (authors)
Effect of Induction Heat Bending Process on the Properties of ASME SA106 Gr. C Carbon Steel Pipes
Energy Technology Data Exchange (ETDEWEB)
Kim, Ki Tae; Kim, Young Sik [Andong National University, Andong (Korea, Republic of); Chang, Hyun Young; Oh, Young Jin [KEPCO Engineering and Construction Company, Seongnam (Korea, Republic of); Sung, Gi Ho [R and D Center, Busan (Korea, Republic of)
2015-04-15
Recently, the bending process is greatly applied to fabricate the pipe line. Bending process can reduce welding joints and then decrease the number of inspection. Thus, the maintenance cost will be reduced. Induction heat bending process is composed of bending deformation by repeated local heat and cooling. By this thermal process, corrosion properties and microstructure can be affected. This work focused on the effect of induction heating bending process on the properties of ASME SA106 Gr. C low carbon steel pipes. Microstructure analysis, hardness measurements, and immersion corrosion test were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. Hardness was measured using a Rockwell B scale. Induction heat bending process has influenced upon the size and distribution of ferrite and pearlite phases which were transformed into finer structure than those of base metal. Even though the fine microstructure, every bent area showed a little lower hardness than that of base metal. It is considered that softening by the bending process may be arisen. Except of I2, intrados area, the others showed a similar corrosion rate to that of base metal. But even relatively high rate of intrados area was very low and acceptable. Therefore, it is judged that induction heat bending process didn't affect boric acid corrosion behaviour of carbon steel.
Control of Reversible Self-Bending Behavior in Responsive Janus Microstrips.
Oh, Myung Seok; Song, Young Shin; Kim, Cheolgyu; Kim, Jongmin; You, Jae Bem; Kim, Taek-Soo; Lee, Chang-Soo; Im, Sung Gap
2016-04-01
Here, we demonstrate a simple method to systematically control the responsive self-bending behavior of Janus hydrogel microstrips consisting of a polymeric bilayer with a high modulus contrast. The Janus hydrogel microstrips could be easily fabricated by a simple micromolding technique combined with an initiated chemical vapor deposition (iCVD) coating, providing high flexibility in controlling the physical and chemical properties of the microstrips. The fabricated Janus hydrogel microstrip is composed of a soft, pH-responsive polymer hydrogel layer laminated with a highly cross-linked, rigid thin film, generating a geometric anisotropy at a micron scale. The large difference in the elastic moduli between the two layers of the Janus microstrips leads to a self-bending behavior in response to the pH change. More specifically, the impact of the physical and chemical properties of the microstrip on the self-bending phenomena was systematically investigated by changing the thickness and composition of two layers of the microstrip, which renders high controllability in bending of the microstrips. The curvature of the Janus microstrips, formed by self-bending, highly depends on the applied acidity. A reversible, responsive self-bending/unbending exhibits a perfect resilience pattern with repeated changes in pH for 5 cycles. We envision that the Janus microstrips can be engineered to form complex 3D microstructures applicable to various fields such as soft robotics, scaffolds, and drug delivery. The reliable responsive behaviors obtained from the systematic investigation will provide critical information in bridging the gap between the theoretical mechanical analysis and the chemical properties to achieve micron-scale soft robotics. PMID:26974225
Semi-analytical solution of groundwater flow in a leaky aquifer system subject to bending effect
Yu, Chia-Chi; Yang, Shaw-Yang; Yeh, Hund-Der
2013-04-01
SummaryThe bending of aquitard like a plate due to aquifer pumping and compression is often encountered in many practical problems of subsurface flow. This reaction will have large influence on the release of the volume of water from the aquifer, which is essential for the planning and management of groundwater resources in aquifers. However, the groundwater flow induced by pumping in a leaky aquifer system is often assumed that the total stress of aquifer maintains constant all the time and the mechanical behavior of the aquitard formation is negligible. Therefore, this paper devotes to the investigation of the effect of aquitard bending on the drawdown distribution in a leaky aquifer system, which is obviously of interest in groundwater hydrology. Based on the work of Wang et al. (2004) this study develops a mathematical model for investigating the impacts of aquitard bending and leakage rate on the drawdown of the confined aquifer due to a constant-rate pumping in the leaky aquifer system. This model contains three equations; two flow equations delineate the transient drawdown distributions in the aquitard and the confined aquifer, while the other describes the vertical displacement in response to the aquitard bending. For the case of no aquitard bending, this new solution can reduce to the Hantush Laplace-domain solution (Hantush, 1960). On the other hand, this solution without the leakage effect can reduce to the time domain solution of Wang et al. (2004). The results show that the aquifer drawdown is influenced by the bending effect at early time and by the leakage effect at late time. The results of sensitivity analysis indicate that the aquifer compaction is sensitive only at early time, causing less amount of water released from the pumped aquifer than that predicted by the traditional groundwater theory. The dimensionless drawdown is rather sensitive to aquitard's hydraulic conductivity at late time. Additionally, both the hydraulic conductivity and
Anton, Steven R; Erturk, Alper; Inman, Daniel
2012-06-01
The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads.
Distributed force probe bending model of critical dimension atomic force microscopy bias
Ukraintsev, Vladimir A.; Orji, Ndubuisi G.; Vorburger, Theodore V.; Dixson, Ronald G.; Fu, Joseph; Silver, Rick M.
2013-04-01
Critical dimension atomic force microscopy (CD-AFM) is a widely used reference metrology technique. To characterize modern semiconductor devices, small and flexible probes, often 15 to 20 nm in diameter, are used. Recent studies have reported uncontrolled and significant probe-to-probe bias variation during linewidth and sidewall angle measurements. To understand the source of these variations, tip-sample interactions between high aspect ratio features and small flexible probes, and their influence on measurement bias, should be carefully studied. Using theoretical and experimental procedures, one-dimensional (1-D) and two-dimensional (2-D) models of cylindrical probe bending relevant to carbon nanotube (CNT) AFM probes were developed and tested. An earlier 1-D bending model was refined, and a new 2-D distributed force (DF) model was developed. Contributions from several factors were considered, including: probe misalignment, CNT tip apex diameter variation, probe bending before snapping, and distributed van der Waals-London force. A method for extracting Hamaker probe-surface interaction energy from experimental probe-bending data was developed. Comparison of the new 2-D model with 1-D single point force (SPF) model revealed a difference of about 28% in probe bending. A simple linear relation between biases predicted by the 1-D SPF and 2-D DF models was found. The results suggest that probe bending can be on the order of several nanometers and can partially explain the observed CD-AFM probe-to-probe variation. New 2-D and three-dimensional CD-AFM data analysis software is needed to take full advantage of the new bias correction modeling capabilities.
Anton, Steven R; Erturk, Alper; Inman, Daniel
2012-06-01
The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads. PMID:22711404
Shen, I. Y.
1995-05-01
This paper is to develop a mathematical model to predict bending, twisting, and axial vibration response of a composite beam with intelligent constrained layer (ICL) or active constrained layer (ACL) damping treatments. In addition, preliminary experiments are conducted on composite beams to evaluate this new technique. The ICL composite beam model is obtained by integrating the existing ICL composite plate model proposed by Shen. When the plate width (along the x-axis) is much smaller than the plate length (along the y-axis), integration of the ICL composite plate equations and linearization of displacement fields with respect to x leads to a set of equations that couples bending, tosional, and axial vibrations of a composite beam. The equations of motion and associated boundary conditions are normalized and rearranged in a state-space matrix form, and the vibration response is predicted through the distributed transfer function method developed by Yang and Tan. A numerical example is illustrated on a composite beam with bending-torsion coupling stiffness. Numerical results show that ICL damping treatments may or may not reduce coupled bending and torsional vibrations of a composite beam simultaneously. When the deflection is fed back to actuate the ICL damping treatment, a sensitivity analysis shows that only those vibration modes with significant bending response are suppressed simultaneously with their torsional components. In the preliminary experiments, two different ICL setups are tested on a composite beam without bending-torsion coupling. Damping performance of both ICL setups agrees qualitatively with existing mathematical models and experimental results obtained from other researchers. The damping performance, however, is not optimized due to the availability of materials and their dimensions in the laboratory. An optimization strategy needs to be developed to facilitate design of ACL damping treatments with maximized damping performance.
Anharmonic effects in the optical and acoustic bending modes of graphene
Ramírez, R.; Chacón, E.; Herrero, C. P.
2016-06-01
The out-of-plane fluctuations of carbon atoms in a graphene sheet have been studied by means of classical molecular dynamic simulations with an empirical force field as a function of temperature. The Fourier analysis of the out-of-plane fluctuations often applied to characterize the acoustic bending mode of graphene is extended to the optical branch, whose polarization vector is perpendicular to the graphene layer. This observable is inaccessible in a continuous elastic model of graphene but it is readily obtained by the atomistic treatment. Our results suggest that the long-wavelength limit of the acoustic out-of-plane fluctuations of a free layer without stress is qualitatively similar to that predicted by a harmonic model under a tensile stress. This conclusion is a consequence of the anharmonicity of both in-plane and out-of-plane vibrational modes of the lattice. The most striking anharmonic effect is the presence of a linear term, ωA=vAk , in the dispersion relation of the acoustic bending band of graphene at long wavelengths (k →0 ). This term implies a strong reduction of the amplitude of out-of-plane oscillations in comparison to a flexural mode with a k2 dependence in the long-wavelength limit. Our simulations show an increase of the sound velocity associated to the bending mode, as well as an increase of its bending constant, κ , as the temperature increases. Moreover, the frequency of the optical bending mode, ωO(Γ ), also increases with the temperature. Our results are in agreement with recent analytical studies of the bending modes of graphene using either perturbation theory or an adiabatic approximation in the framework of continuous layer models.
Diameter-dependent bending dynamics of single-walled carbon nanotubes in liquids
Fakhri, Nikta; Tsyboulski, Dmitri A.; Cognet, Laurent; Weisman, R. Bruce; Pasquali, Matteo
2009-01-01
By relating nanotechnology to soft condensed matter, understanding the mechanics and dynamics of single-walled carbon nanotubes (SWCNTs) in fluids is crucial for both fundamental and applied science. Here, we study the Brownian bending dynamics of individual chirality-assigned SWCNTs in water by fluorescence microscopy. The bending stiffness scales as the cube of the nanotube diameter and the shape relaxation times agree with the semiflexible chain model. This suggests that SWCNTs may be the archetypal semiflexible filaments, highly suited to act as nanoprobes in complex fluids or biological systems. PMID:19706503
Jesudoss Hynes, N. Rajesh; Nagaraj, P.; Vivek Prabhu, M.
Joining of metal with ceramics has become significant in many applications, because they combine properties like ductility with high hardness and wear resistance. By friction welding technique, alumina can be joined to mild steel with AA1100 sheet of 1mm thickness as interlayer. In the present work, investigation of the effect of friction time on interlayer thickness reduction and bending strength is carried out by factorial design. By using ANOVA, a statistical tool, regression modeling is done. The regression model predicts the bending strength of welded ceramic/metal joints accurately with ± 2% deviation from the experimental values.
The Eddington's Eclispe and a Possible Replica of the Experiment of Light Bending
Sigismondi, Costantino
2015-01-01
The success of the first measurement of the light bending by the solar gravitational field is due to the particular stellar field during the Eddington's 1919 total eclipse of the Sun, near the Hyades, giving the opportunity to measure the gravitational bending of the light to the astronomers in two expeditions in Brazil, Sobral, and on the Principe Island in the Atlantic Ocean. The geometrical properties of this field and another field in Leo are discussed in view of repeating this experiment of General Relativity with SOHO satellite data in the context of the International Year of Light 2015.
The quantitative check-measure of the bend strain parameters of the rotating components
Institute of Scientific and Technical Information of China (English)
李文华; 乔中涛
2002-01-01
Based on the principle of the electric-magnetic check-measure, this paper puts forward a new technology and method that use the magnetic marks to check and measure the dynamic physical parameters such as angle speed, bending strain,stress and bending moment. The principles of the check-measure and the dealing and exchanging technology about signals have been demonstrated and the rotating components have been made up. The timely and quantitative check-measure of the dynamic physical parameters during the component in working has been realized by using computer control.
Coil End Parts Development Using BEND and Design for MQXF by LARP
Energy Technology Data Exchange (ETDEWEB)
Yu, Miao [Fermilab; Ambrosio, G. [Fermilab; Bermudez, S. Izquierdo [CERN; Bossert, R. [Fermilab; Ferracin, P. [CERN; Krave, S. [Fermilab
2016-09-06
End parts are critical components for saddle-shaped coils. They have a structural function where the cables are deformed in order to cross over the magnet aperture. Based on the previous design of the US LARP program for 90 mm aperture quadrupoles (TQ/LQ) and 120 mm aperture quadrupoles (HQ/LHQ) using BEND, the coil ends of the low-β quadruples (MQXF) for the HiLumi LHC upgrade were developed. This paper shows the design of the MQXF coil ends, the analysis of the coil ends during the coil fabrication, the autopsy analysis of the coil ends and the feedback to BEND parameters.
A Study on Viscoelastic Fluid Flow in a Square-Section 90-Degrees Bend
Institute of Scientific and Technical Information of China (English)
Mizue Munekata; Kazuyoshi Matsuzaki; Hideki Ohba
2003-01-01
It is well known that the drag-reducing effect is obtained in a surfactant solution flow in a straight pipe. We investigate about a viscoelastic fluid flow such as a surfactant solution flow in a square-section 90° bend. In the experimental study, drag-reducing effect and velocity field in a surfactant solution flow are investigated by measurements of wall pressure loss and LDV measurements. For the numerical method, LES with FENE-P model is used in the viscoelastic fluid flow in the bend. The flow characteristics of viscoelastic fluid are discussed compared with that of a Newtonian fluid.
Bonding Interface and Bending Deformation of Al/316LSS Clad Metal Prepared by Explosive Welding
Guo, Xunzhong; Fan, Minyu; Wang, Liuan; Ma, Fuye
2016-06-01
The morphology, elemental distribution, and phase analysis of the bonding interface were investigated by means of SEM, EDS, and XRD to evaluate the interface bonding properties of Al/316LSS clad metal prepared by explosive welding method. Furthermore, the micro-hardness and bending properties were also investigated. The results indicated that the linear and wavy bonding interfaces coexisted and intermetallic phases were present in the local interfacial zone. Moreover, the micro-hardness value at the bonding interface with intermetallic phases was higher than that at the interface without any intermetallic phases. In addition, bulk metal compounds could easily lead to the generation of micro-cracks during the bending forming process.
Subrahmanyam, K. B.; Kaza, K. R. V.; Brown, G. V.; Lawrence, C.
1986-01-01
The coupled bending-bending-torsional equations of dynamic motion of rotating, linearly pretwisted blades are derived including large precone, second degree geometric nonlinearities and Coriolis effects. The equations are solved by the Galerkin method and a linear perturbation technique. Accuracy of the present method is verified by comparisons of predicted frequencies and steady state deflections with those from MSC/NASTRAN and from experiments. Parametric results are generated to establish where inclusion of only the second degree geometric nonlinearities is adequate. The nonlinear terms causing torsional divergence in thin blades are identified. The effects of Coriolis terms and several other structurally nonlinear terms are studied, and their relative importance is examined.
Analysis of pipe mitred bends using beam models - by finite element method
International Nuclear Information System (INIS)
The formulation of a recently proposed displacement based straight pipe element for the analysis of pipe mitred bends is summarized in this work. The element kinematics includes axial, bending, torsional and ovalisation displacements, all varying cubically along the axis of the element. Interaction effects between angle adjoined straight pipe section are modeled including the appropriate additional strain terms in the stiffness matrix formulation and by using a penalty procedure to enforce continuity of pipe skin flexural rotations at the common helical edge. The element model capabilities are ilustrated in some sample analysis and the results are compared with other available experimental, analytical or more complex numerical models. (Author)
Investigation of Structural Behavior due to Bend-Twist Couplings in Wind Turbine Blades
Fedorov, Vladimir; Dimitrov, Nikolay Krasimirov; Berggreen, Christian; Krenk, Steen; Branner, Kim; Berring, Peter
2010-01-01
One of the problematic issues concerning the design of future large composite wind turbine blades is the prediction of bend-twist couplings and torsion behaviour. The current work is a continuation of a previous work [1,2], and it examines different finite element modelling approaches for predicting the torsional response of the wind turbine blades with built-in bend-twist couplings. Additionally, a number of improved full-scale tests using an advanced bi-axial servo-hydraulic load control ha...
Experimental study on centrifugal concrete-filled steel tubes under bending and torsion
Institute of Scientific and Technical Information of China (English)
金伟良; 曲晨; 于弋
2003-01-01
A real-size experiment on 11 tubes was done to study the performance of centrifugal concrete-filled steel tubes under bending and torsion. This paper first introduces the relevant operating method, equipment, subjects and processes. The factors that affect deformation and stiffness and the break mechanism under different loading were studied. Experimental stress analysis showed that the values of practical critical stress of steel tubes accorded well with the MISES Yielding Rule. The correlative equation (on the bearing capacity of a structural member under bending and torsion) deduced in this study may provide valuable reference for the design of this structural member.
Kamardin, Kamilia; Rahim, Mohamad Kamal A.; Hall, Peter S.; Samsuri, Noor Asmawati; Latef, Tarik Abdul; Ullah, Mohammad Habib
2016-04-01
Textile artificial magnetic conductor (AMC) waveguide jacket for transmission enhancement between on-body antennas is proposed. Transmission characteristics between antennas with different orientations and placements are studied. Significant transmission enhancement is observed for all tested positions. Bending and wetness measurements are also conducted. Bending is found not to give significant effect to the antennas and AMC performance, while wetness yields severe performance distortion. However, the original performance is retrieved once the antennas and AMC dried. The proposed AMC jacket will act as a new approach for efficient wearable body-centric communications.
A Temperature Sensor Based on a Polymer Optical Fiber Macro-Bend
Joseba Zubia Zaballa; Jon Arrue; Carmen Vázquez García; Alberto Tapetado Moraleda
2013-01-01
The design and development of a plastic optical fiber (POF) macrobend temperature sensor is presented. The sensor has a linear response versus temperature at a fixed bend radius, with a sensitivity of 〖1.92.10〗^(-3) 〖(°C) 〗^(-1) . The sensor system used a dummy fiber-optic sensor for reference purposes having a resolution below 0.3 °C. A comprehensive experimental analysis was carried out to provide insight into the effect of different surrounding media on practical macro-bend POF sensor imp...
International Nuclear Information System (INIS)
We have experimentally demonstrated the guiding, bending, and splitting of electromagnetic (EM) waves in highly confined waveguides built around three-dimensional layer-by-layer photonic crystals by removing a single rod. Full transmission of the EM waves was observed for straight and bended waveguides. We also investigated the power splitter structures in which the input EM power could be efficiently divided into the output waveguide ports. The experimental results, dispersion relation and photon lifetime, were analyzed with a theory based on the tight-binding photon picture. Our results provide an important tool for designing photonic crystal based optoelectronic components
Estimating Young’s Modulus of Materials by a New Three-Point Bending Method
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Xiaohu Zeng
2014-01-01
Full Text Available A new test method based on the three-point bending test is put forward to measure Young’s modulus of materials. The simplified mechanical model is established to make theoretical derivation. This method has not only the advantages of simple specimen preparation and convenient loading device, but also higher precision than the traditional three-point bending method. The method is adopted to obtain Young’s modulus of the aluminum alloy 2024. The feasibility of the method has been demonstrated by comparisons with the corresponding results obtained from the finite element method and experiment method. And the influence of contact friction on the test accuracy is analyzed.