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...
International Nuclear Information System (INIS)
The mechanical behavior of a silicon crystal under bending is investigated. For a crystal of length 30 mm and thickness 3 mm, to achieve the specified bend angle of 0.64 mrad, the appropriate angle of the aluminum punches is 0.96 mrad
Dispersion suppressors with bending
Energy Technology Data Exchange (ETDEWEB)
Garren, A.
1985-10-01
Dispersion suppressors of two main types are usually used. In one the cell quadrupole focussing structure is the same as in normal cells but some of the dipoles are replaced by drifts. In the other, the quadrupole strengths and/or spacings are different from those of the normal cells, but the bending is about the same as it is in the cells. In SSC designs to date, dispersion suppressors of the former type have been used, consisting of two cells with bending equivalent to one. In this note a suppressor design with normal bending and altered focussing is presented. The advantage of this scheme is that circumference is reduced. The disadvantages are that additional special quadrupoles must be provided (however, they need not be adjustable), and the maximum beta values within them are about 30% higher than the cell maxima.
1980-01-01
The very particular lattice of the AA required 2 types of dipole (bending magnets; BLG, long and narrow; BST, short and wide). The BLG had a steel length of 4.70 m, a good field width of 0.24 m, and a weight of about 70 t. Jean-Claude Brunet inspects the lower half of a BLG. For the BST magnets see 7811105 and 8006036.
Thiria, Benjamin
2010-01-01
Wing flexibility governs the flying performance of flapping wing flyers. Here we use a self-propelled flapping-wing model mounted on a "merry-go-round" to investigate the effect of wing compliance on the propulsive efficiency of the system. Our measurements show that the elastic nature of the wings can lead not only to a substantial reduction of the consumed power, but also to an increment of the propulsive force. A scaling analysis using a flexible plate model for the wings points out that, for flapping flyers in air, the time-dependent shape of the elastic bending wing is governed by the wing inertia. Based on this prediction, we define the ratio of the inertial forces deforming the wing to the elastic restoring force that limits the deformation as the 'elasto-inertial number'. Our measurements with the self-propelled model confirm that it is the appropriate structural parameter to describe flapping flyers with flexible-wings.
Energy Technology Data Exchange (ETDEWEB)
Courant, E.D. [Brookhaven National Lab., Upton, NY (United States); Garren, A.
1985-10-01
The phase shifting trombones considered up to now for SSC application consisted of sets of evenly spaced quadrupoles separated by drift spaces. One such trombone was placed between a dispersion suppressor and a crossing insertion, so that the trombone had zero dispersion. With such trombones, it is possible to change {beta}{sup *} at constant tune, or to change the tunes by several units without altering the cell phase advances in the arcs. An objection to the above type of phase trombone is that it adds to the circumference, since no bending is included. This objection may or may not be valid depending on the potential usefulness of the drift spaces in them. In this note the authors show an alternative trombone design in which dipoles are included between the quadrupoles as in the normal arc cells. Since these trombones have dispersion, they are placed at the ends of the arcs, to be followed in turn by the dispersion suppressors and crossing insertions.
A Numerical Study of the Spring-Back Phenomenon in Bending with a Rebar Bending Machine
Chang Hwan Choi; Lawrence Kulinsky; Joon Soo Jun; Jin Ho Kim
2014-01-01
Recently, the rebar bending methodology started to change from field processing to utilizing rebar bending machines at plant sites prior to transport to the construction locations. Computerized control of rebar plant bending machines provides more accurate and faster bending of rebars than the low quality inefficient field processing alternative. The bending process involves plastic deformation of rebars, where bending stress beyond the yield point of the material is applied. When the bending...
Effect of bending pattern on finger joint bending strength
Directory of Open Access Journals (Sweden)
Džinčić Igor
2012-01-01
Full Text Available Limited information is available on end gluing hardwoods in contrast to softwoods, which have been extensively investigated. The objective of this study was to examine the influence of bending patern on bending strength of finger jointed beech wood. In structural uses finger jointing is finally the major method to end joint timber for the production of glue-laminated elements. There are no bending strength experimental results for finger-jointed hardwoods for investigations conducted in Serbia. Two finger jointed profiles were studied in accordance with DIN68140. The finger joints were made by side and by face of beam. Length jointed samples were loaded at the side and in the face. The obtained results led to the conclusion that the direction of load, gluing surface and the position of joint influence on the strength of continued longitudinal beams.
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.
Combustion engineering: steam generator tube bending practices
International Nuclear Information System (INIS)
The tube bending practices and procedures employed by Combustion Engineering (CE), when bending inconel tubing is discussed. CE has two different type tube geometries in the steam generator. The innermost tubes are 1800 U-bends while the majority of the tubes have two (2) 900 bends with a straight leg between these 900 bends. The first 18 rows have U-bends (2 1/2'' to 11''R), while the remaining tubes have the double 900 geometry. All double 900 bends are bent to a 10'' radius. This presentation will address the following important parameters necessary to achieve a high quality bent tube: fabrication requirements at the tube mill; tube bending equipment; tube bending operation; inspection and final preparation; and packaging
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
Wood bending using microwave heating
International Nuclear Information System (INIS)
This article presents a new technique of wood bending where microwave irradiation is used to heat and soften wet wood specimens. Compared to the traditional steaming procedure, this procedure offers many advantages : (i) as the heating occurs inside the specimen, complete softening is obtained very quickly; (ii) temperature can be easily controlled in order to obtain the best processing conditions; (iii) the benefit will be especially big in the case of large specimens whose pretreatment may take hours with steaming; (iv) in general, the applicability of wood bending is enlarged, i.e. new wood species and specimens with lower quality can endure larger deformations with a reduced loss. In the case where drastic strain levels are required, the forming and setting operations should be done inside the microwave oven, in order to take advantage of the additional ''mechano-sorptive'' flexibility appearing when wood dries under load
Bending stresses in Facetted Glass Shells
DEFF Research Database (Denmark)
Bagger, Anne; Jönsson, Jeppe; Almegaard, Henrik
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 and...
Bending and stretching of plates
Mansfield, E H; Hemp, W S
2014-01-01
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.
Elastic bending modulus of monolayer graphene
International Nuclear Information System (INIS)
An analytic formula is derived for the elastic bending modulus of monolayer graphene based on an empirical potential for solid-state carbon atoms. Two physical origins are identified for the non-vanishing bending stiffness of the atomically thin graphene sheet, one due to the bond-angle effect and the other resulting from the bond-order term associated with the dihedral angles. The analytical prediction compares closely with ab initio energy calculations. Pure bending of graphene monolayers into cylindrical tubes is simulated by a molecular mechanics approach, showing slight nonlinearity and anisotropy in the tangent bending modulus as the bending curvature increases. An intrinsic coupling between bending and in-plane strain is noted for graphene monolayers rolled into carbon nanotubes. (fast track communication)
Elastic bending modulus of monolayer graphene
Energy Technology Data Exchange (ETDEWEB)
Lu Qiang; Huang Rui [Department of Aerospace Engineering and Engineering Mechanics, University of Texas, Austin, TX 78712 (United States); Arroyo, Marino [Department of Applied Mathematics 3, LaCaN, Universitat Politecnica de Catalunya (UPC), Barcelona 08034 (Spain)
2009-05-21
An analytic formula is derived for the elastic bending modulus of monolayer graphene based on an empirical potential for solid-state carbon atoms. Two physical origins are identified for the non-vanishing bending stiffness of the atomically thin graphene sheet, one due to the bond-angle effect and the other resulting from the bond-order term associated with the dihedral angles. The analytical prediction compares closely with ab initio energy calculations. Pure bending of graphene monolayers into cylindrical tubes is simulated by a molecular mechanics approach, showing slight nonlinearity and anisotropy in the tangent bending modulus as the bending curvature increases. An intrinsic coupling between bending and in-plane strain is noted for graphene monolayers rolled into carbon nanotubes. (fast track communication)
Bending magnets design of cERL
International Nuclear Information System (INIS)
We are now constructing Compact Energy Recovery Linac (cERL) to start commissioning in March of 2013. We started constructing 35MeV, 10mA, 1loop design, and after step by step reinforcement, we will complete 245MeV, 100mA, and 2loop facility of cERL. We use 2 type bending magnets, sector type magnet and branch bend. Both magnets are trapezoid shape and bending radiuses are 1m, bending angles are 45degree. After constructing second loop, we use the branch bend to separate low energy electron to first loop and high energy electron to second loop. We report these two type bending magnets design of cERL. (author)
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...
Peeling, sliding, pulling and bending
Lister, John; Peng, Gunnar
2015-11-01
The peeling of an elastic sheet away from thin layer of viscous fluid is a simply-stated and generic problem, that involves complex interactions between the flow and elastic deformation on a range of length scales. Consider an analogue of capillary spreading, where a blister of injected viscous fluid spreads due to tension in the overlying elastic sheet. Here the tension is coupled to the deformation of the sheet, and thus varies in time and space. A key question is whether or not viscous shear stresses ahead of the blister are sufficient to prevent the sheet sliding inwards and relieving the tension. Our asymptotic analysis reveals a dichotomy between fast and slow spreading, and between two-dimensional and axisymmetric spreading. In combination with bending stresses and gravity, which may dominate parts of the flow but not others, there is a plethora of dynamical regimes.
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...
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...
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...
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.
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)...
49 CFR 192.313 - Bends and elbows.
2010-10-01
... 49 Transportation 3 2010-10-01 2010-10-01 false Bends and elbows. 192.313 Section 192.313... Lines and Mains § 192.313 Bends and elbows. (a) Each field bend in steel pipe, other than a wrinkle bend... tested either before or after the bending process. (c) Wrought-steel welding elbows and...
Bending stresses in Facetted Glass Shells
DEFF Research Database (Denmark)
Bagger, Anne; Jönsson, Jeppe; Almegaard, Henrik
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 and...
Measurement of irradiation creep in bending
International Nuclear Information System (INIS)
The major deformation modes in LMFBR fuel channels are bowing caused by neutron flux and temperature gradients and dilation due to stresses imposed by the flowing sodium. In both cases, the stress state of interest is bending. The bulk of irradiation creep data has been generated by simply loaded specimens such as tensile or biaxial pressurized tubes but it is questionable whether this data can be used to predict creep in bending. An irradiation creep experiment using beams loaded in primary bending has been designed to investigate this premise
Measurement of irradiation creep in bending. [LMFBR
Energy Technology Data Exchange (ETDEWEB)
McSherry, A.J.; Marshall, J.; Patel, M.R.
1980-01-31
The major deformation modes in LMFBR fuel channels are bowing caused by neutron flux and temperature gradients and dilation due to stresses imposed by the flowing sodium. In both cases, the stress state of interest is bending. The bulk of irradiation creep data has been generated by simply loaded specimens such as tensile or biaxial pressurized tubes but it is questionable whether this data can be used to predict creep in bending. An irradiation creep experiment using beams loaded in primary bending has been designed to investigate this premise.
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
A flexible sensor measuring displacement and bending
Nishijima, Takashi; Yamamoto, Akio; Higuchi, Toshiro
2009-04-01
This paper proposes a new sensor that is capable of measuring both linear displacement and bending. The sensor is designed to be used with an electrostatic film motor that features mechanical flexibility, but can also be used as an independent sensor. The sensor employs three-phase electrodes both in sliding and stationary parts and estimates displacement and bending from the change of the capacitance between the electrodes. The paper describes an equivalent capacitance-network model for the sensor. Based on the model, sensing principles for both displacement and bending are presented and analyzed. The analyses are experimentally verified using a prototype sensor. The experimental results show that the prototype sensor could measure both displacement and bending with little interference between them.
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.
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.
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
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.
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
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.
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)
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 ...
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.
Probing the elastic limit of DNA bending
Le, Tung T
2014-01-01
Many structures inside the cell such as nucleosomes and protein-mediated DNA loops contain sharply bent double-stranded (ds) DNA. Therefore, the energetics of strong dsDNA bending constitutes an essential part of cellular thermodynamics. Although the thermomechanical behavior of long dsDNA is well described by the worm-like chain (WLC) model, the length limit of such elastic behavior remains controversial. To investigate the energetics of strong dsDNA bending, we measured the opening rate of small dsDNA loops with contour lengths of 40-200 bp using Fluorescence Resonance Energy Transfer (FRET). From the measured relationship of loop stability to loop size, we observed a transition between two separate bending regimes at a critical loop size below 100 bp. Above this loop size, the loop lifetime decreased with decreasing loop size in a manner consistent with an elastic bending stress. Below the critical loop size, however, the loop lifetime became less sensitive to loop size, indicative of softening of the doub...
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...
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.
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.
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.
Irradiation creep of stainless steel in bending
International Nuclear Information System (INIS)
The development is described of a test to measure irradiation enhanced creep in bending of 20% cold-worked Type-316 stainless steel. The test will be irradiated in the experimental fast reactor EBR-II. The rationale used in design selection is described. The selected beam designs, the supportive tests in other stress states and the measurement techniques are described in detail. (Auth.)
Irradiation creep of stainless steel in bending
International Nuclear Information System (INIS)
The development is described of a test to measure irradiation enhanced creep in bending of 20% cold-worked Type-316 stainless steel. The test will be irradiated in the experimental fast reactor EBR-II. The rationale used in design selection is described. The selected beam designs, the supportive tests in other stress states and the measurement techniques are described in detail
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.
Oceanic Plate Bending Along the Manila Trench
Zhang, F.; Lin, J.; Zhan, W.
2014-12-01
We quantify along-trench variations in plate flexural bending along the Manila trench in the South China Sea. A 3-D interpreted flexural deformation surface of the subducting South China Sea Plate was obtained by removing from the observed bathymetry the effects of sediment loading, isostatically-compensated topography based on gravity modeling, age-related lithospheric thermal subsidence, and residual short-wavelength features. We analyzed flexural bending of 21 across-trench profile sections along the Manila trench and then calculated five best-fitting tectonic and plate parameters that control the flexural bending for each of the across-trench profile sections. Results of analysis revealed significant along-trench variations: The trench relief of the Manila trench varies from 0.8 to 2.2 km, trench-axis vertical loading (-V0) from -0.4x1012 to 1.21x1012 N/m, and axial bending moment (-M0) from 0.005x1017 to 0.6x1017 N. The effective elastic plate thickness seaward of the Manila outer-rise region (TeM) ranges from 30 to 40 km, while that trench-ward of the outer-rise (Tem) ranges from 11 to 30 km. This corresponds to a reduction in Te of 26-63% for the Manila trench. The transition from TeM to Tem occurs at a breaking distance of 50-120 km from the Manila trench axis. The axial vertical loading, bending moment, and the effective elastic thickness of the Manila trench are much smaller than the Mariana trench (Zhang et al., 2014). The contrast in the flexural bending between the Mariana and Manila trenches might be related to the difference in the ages of the subducting plates and other tectonic variables. Zhang, F., Lin, J., Zhan, W., 2014. Variations in oceanic plate bending along the Mariana trench, Earth Planet. Sci. Lett. 401, 206-214. doi: 10.1016/j.epsl.2014.05.032
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. ...
Quantitative Evaluation of Photoinduced Bending Speed of Diarylethene Crystals
Directory of Open Access Journals (Sweden)
Daichi Kitagawa
2015-11-01
Full Text Available We investigated photoinduced crystal bending behavior of various photochromic diarylethenes. In all the diarylethene derivatives we used in this work, the relationship between the initial photoinduced bending speed and the crystal thickness was well explained by the easy-handled Timoshenkoʼs bimetal model. Moreover, we proposed a quantitative analysis method to reveal the relationship between the bending speed and the molecular structure of diarylethenes. These results provide the quantitative evaluation method of the photoinduced crystal bending speed.
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...
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.
Development of Bend Sensor for Catheter Tip
Nagano, Yoshitaka; Sano, Akihito; Fujimoto, Hideo
Recently, a minimally invasive surgery which makes the best use of the catheter has been becoming more popular. In endovascular coil embolization for a cerebral aneurysm, the observation of the catheter's painting phenomenon is very important to execute the appropriate manipulation of the delivery wire and the catheter. In this study, the internal bend sensor which consists of at least two bending enhanced plastic optical fibers was developed in order to measure the curvature of the catheter tip. Consequently, the painting could be more sensitively detected in the neighborhood of the aneurysm. In this paper, the basic characteristics of the developed sensor system are described and its usefulness is confirmed from the comparison of the insertion force of delivery wire and the curvature of catheter tip in the experiment of coil embolization.
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.
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
Molecular Origin of Model Membrane Bending Rigidity
International Nuclear Information System (INIS)
The behavior of the bending modulus κ of bilayers in lamellar phases was studied by Small Angle X-ray Scattering technique for various nonionic CiEj surfactants. The bilayers are either unswollen and dispersed in water or swollen by water and dispersed in dodecane. For unswollen bilayers, the values of κ decrease with both an increase in the area per surfactant molecule and in the polar head length. They increase when the aliphatic chain length increases at constant area per surfactant molecule. Whereas for water-swollen membranes, the values of κ decrease as the content of water increases converging to the value of the single monolayer bending modulus. Such a behavior results from the decoupling of the fluctuations of the two surfactant membrane monolayers. Our results emphasize the determinant contribution of the surfactant conformation to κ
Molecular Origin of Model Membrane Bending Rigidity
Kurtisovski, Erol; Taulier, Nicolas; Ober, Raymond; Waks, Marcel; Urbach, Wladimir
2007-06-01
The behavior of the bending modulus κ of bilayers in lamellar phases was studied by Small Angle X-ray Scattering technique for various nonionic CiEj surfactants. The bilayers are either unswollen and dispersed in water or swollen by water and dispersed in dodecane. For unswollen bilayers, the values of κ decrease with both an increase in the area per surfactant molecule and in the polar head length. They increase when the aliphatic chain length increases at constant area per surfactant molecule. Whereas for water-swollen membranes, the values of κ decrease as the content of water increases converging to the value of the single monolayer bending modulus. Such a behavior results from the decoupling of the fluctuations of the two surfactant membrane monolayers. Our results emphasize the determinant contribution of the surfactant conformation to κ
Characterization and study of photonic crystal fibres with bends
International Nuclear Information System (INIS)
Analysis of a photonic crystal fibre (PRCF) with bends is presented. Using the versatile finite difference time domain method, the modal characteristics of the PCFs are found. Possibilities of employing PCFs with bends in sensing are discussed. It is found that a large evanescent field is present when the bend angle exceeds 45o
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
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.
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...
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.
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...
First multi-bend achromat lattice consideration
International Nuclear Information System (INIS)
The first proposed lattice for a ‘diffraction-limited light source’ is reported. This approach has now more or less been used for the MAX IV project. By the beginning of 1990, three third-generation synchrotron light sources had been successfully commissioned in Grenoble, Berkeley and Trieste (ESRF, ALS and ELETTRA). Each of these new machines reached their target specifications without any significant problems. In parallel, already at that time discussions were underway regarding the next generation, the ‘diffraction-limited light source (DLSR)’, which featured sub-nm rad electron beam emittance, photon beam brilliance exceeding 1022 and the potential to emit coherent radiation. Also, at about that time, a first design for a 3 GeV DLSR was developed, based on a modified multiple-bend achromat (MBA) design leading to a lattice with normalized emittance of ∊x = 0.5 nm rad. The novel feature of the MBA lattice was the use of seven vertically focusing bend magnets with different bending angles throughout the achromat cell to keep the radiation integrals and resulting beam emittance low. The baseline design called for a 400 m ring circumference with 12 straight sections of 6 m length. The dynamic aperture behaviour of the DLSR lattice was estimated to produce > 5 h beam lifetime at 100 mA stored beam current
The role of elasticity in slab bending
Fourel, Loic; Goes, Saskia; Morra, Gabriele
2014-11-01
studies showed that plate rheology exerts a dominant control on the shape and velocity of subducting plates. Here, we perform a systematic investigation of the role of elasticity in slab bending, using fully dynamic 2-D models where an elastic, viscoelastic, or viscoelastoplastic plate subducts freely into a purely viscous mantle. We derive a scaling relationship between the bending radius of viscoelastic slabs and the Deborah number, De, which is the ratio of Maxwell time over deformation time. We show that De controls the ratio of elastically stored energy over viscously dissipated energy and find that at De>10-2, substantially less energy is required to bend a viscoelastic slab to the same shape as a purely viscous slab with the same intrinsic viscosity. Elastically stored energy at higher De favors retreating modes of subduction via unbending, while trench advance only occurs for some cases with De 1, where most zones have low De 0.1. Slabs with Deviscosities or they may be yielding, in which case our De estimates may be underestimated by up to an order of magnitude, potentially pointing towards a significant role of elasticity in ˜60% of the subduction zones. In support of such a role of elasticity in subduction, we find that increasing De correlates with increasing proportion of larger seismic events in both instrumental and historic catalogues.
2010-11-24
... Jeffries, District Ranger, Bend-Fort Rock Ranger District, Red Oaks Square, 1230 NE. Third Street, Suite A...-Fort Rock Ranger District, Red Oaks Square, 1230 NE. Third Street, Suite A-262, Bend, Oregon 97701... Forest Service Bend/Ft. Rock Ranger District; Deschutes National Forest; Deschutes County, OR; West...
2013-01-22
... COMMISSION PPL Bell Bend, LLC; Combined License Application for Bell Bend Nuclear Power Plant; Exemption 1.0... Approvals for Nuclear Power Plants.'' This reactor is to be identified as Bell Bend Nuclear Power Plant... (RCOL) application for UniStar's Calvert Cliffs Nuclear Power Plant, Unit 3 (CCNPP3). The NRC...
2011-12-29
... 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 Nuclear... application is based upon the U.S. EPR reference COL (RCOL) application for UniStar's Calvert Cliffs...
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.
Standard test methods for bend testing of material for ductility
American Society for Testing and Materials. Philadelphia
2009-01-01
1.1 These test methods cover bend testing for ductility of materials. Included in the procedures are four conditions of constraint on the bent portion of the specimen; a guided-bend test using a mandrel or plunger of defined dimensions to force the mid-length of the specimen between two supports separated by a defined space; a semi-guided bend test in which the specimen is bent, while in contact with a mandrel, through a specified angle or to a specified inside radius (r) of curvature, measured while under the bending force; a free-bend test in which the ends of the specimen are brought toward each other, but in which no transverse force is applied to the bend itself and there is no contact of the concave inside surface of the bend with other material; a bend and flatten test, in which a transverse force is applied to the bend such that the legs make contact with each other over the length of the specimen. 1.2 After bending, the convex surface of the bend is examined for evidence of a crack or surface irregu...
Bending response of single layer MoS2
Xiong, Si; Cao, Guoxin
2016-03-01
Using molecular mechanics (or dynamics) simulations, three different approaches, including the targeted molecular mechanics, four-point bending and nanotube methods, are employed to investigate the bending response of single layer MoS2 (SLMoS2), among which four-point bending is the most accurate approach to determine the bending stiffness according to the continuum theory. It is found that when the bending curvature radius is large enough (e.g. >4 nm), three approaches will give the same bending stiffness of SLMoS2 and the bending behavior is isotropic for SLMoS2, whereas the nanotube method with small tubes (e.g. theory, the revised Stillinger-Weber (SW) and reactive empirical bond-order (REBO) potentials can give the reasonable bending stiffness of SLMoS2 (8.7-13.4 eV) as well as the effective deformed conformation. In addition, since the Mo-S bond deformation of SLMoS2 under bending is similar to that under in-plane tension/compression, the continuum bending theory can quite accurately predict the bending stiffness of SLMoS2 if a reasonable thickness of SLMoS2 is given. For SLMoS2, the reasonable thickness should be larger than the distance between its two S atomic planes and lower than the distance between two Mo atomic planes of bulk MoS2 crystal, e.g. 0.375-0.445 nm.
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.
Cricket antennae shorten when bending (Acheta domesticus L.
Directory of Open Access Journals (Sweden)
CatherineLoudon
2014-06-01
Full Text Available Insect antennae are important mechanosensory and chemosensory organs. Insect appendages, such as antennae, are encased in a cuticular exoskeleton and are thought to bend only between segments or subsegments where the cuticle is thinner, more flexible, or bent into a fold. There is a growing appreciation of the dominating influence of folds in the mechanical behavior of a structure, and the bending of cricket antennae was considered in this context. Antennae will bend or deflect in response to forces, and the resulting bending behavior will affect the sensory input of the antennae. In some cricket antennae, such as in those of Acheta domesticus, there are a large number (>100 of subsegments (flagellomeres that vary in their length. We evaluated whether these antennae bend only at the joints between flagellomeres, which has always been assumed but not tested. In addition we questioned whether an antenna undergoes a length change as it bends, which would result from some patterns of joint deformation. Measurements using light microscopy and SEM were conducted on both male and female adult crickets (Acheta domesticus with bending in four different directions: dorsal, ventral, medial and lateral. Bending occurred only at the joints between flagellomeres, and antennae shortened a comparable amount during bending, regardless of sex or bending direction. The cuticular folds separating antennal flagellomeres are not very deep, and therefore as an antenna bends, the convex side (in tension does not have a lot of slack cuticle to "unfold" and does not lengthen during bending. Simultaneously on the other side of the antenna, on the concave side in compression, there is an increasing overlap in the folded cuticle of the joints during bending. Antennal shortening during bending would prevent stretching of antennal nerves and may promote hemolymph exchange between the antenna and head.
Self-bending symmetric cusp beams
Gong, Lei; Liu, Wei-Wei; Ren, Yu-Xuan; Lu, Yao; Li, Yin-Mei
2015-12-01
A type of self-bending symmetric cusp beams with four accelerating intensity maxima is theoretically and experimentally presented. Distinguished from the reported regular polygon beams, the symmetric cusp beams simultaneously exhibit peculiar features of natural autofocusing and self-acceleration during propagation. Further, such beams take the shape of a fine longitudinal needle-like structure at the focal region and possess the strong ability of self-healing over obstacles. All these intriguing properties were verified experimentally. Particularly, the spatial profile of the reconstructed beam exhibits spatially sculpted optical structure with four siamesed curved arms. Thus, we anticipate that the structured beam will benefit optical guiding and optofluidics in surprising ways.
Self-bending symmetric cusp beams
Energy Technology Data Exchange (ETDEWEB)
Gong, Lei; Liu, Wei-Wei; Lu, Yao; Li, Yin-Mei, E-mail: liyinmei@ustc.edu.cn [Department of Optics and Optical Engineering, University of Science and Technology of China, Hefei, Anhui Province 230026 (China); Ren, Yu-Xuan [Department of Physics and Astronomy, San Francisco State University, San Francisco, California 94132 (United States)
2015-12-07
A type of self-bending symmetric cusp beams with four accelerating intensity maxima is theoretically and experimentally presented. Distinguished from the reported regular polygon beams, the symmetric cusp beams simultaneously exhibit peculiar features of natural autofocusing and self-acceleration during propagation. Further, such beams take the shape of a fine longitudinal needle-like structure at the focal region and possess the strong ability of self-healing over obstacles. All these intriguing properties were verified experimentally. Particularly, the spatial profile of the reconstructed beam exhibits spatially sculpted optical structure with four siamesed curved arms. Thus, we anticipate that the structured beam will benefit optical guiding and optofluidics in surprising ways.
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 ...
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 moduli of polymeric surfactant interfaces
Milner, S.T.; Witten, T. A.
1988-01-01
Our recent theory of the free energy and conformations of end-grafted polymer « brushes » is extended to polymers attached to curved surfaces. Several important systems, e.g., layers of polymeric surfactants or of strongly segregated diblock copolymers, can be well described as brushes. By expanding in powers of the curvature the free energy of a brush on a curved surface, the mean and Gaussian bending moduli may be obtained analytically. Results for K and K of monodisperse brushes are consis...
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.
Bending of light in quantum gravity.
Bjerrum-Bohr, N E J; Donoghue, John F; Holstein, Barry R; Planté, Ludovic; Vanhove, Pierre
2015-02-13
We consider the scattering of lightlike matter in the presence of a heavy scalar object (such as the Sun or a Schwarzschild black hole). By treating general relativity as an effective field theory we directly compute the nonanalytic components of the one-loop gravitational amplitude for the scattering of massless scalars or photons from an external massive scalar field. These results allow a semiclassical computation of the bending angle for light rays grazing the Sun, including long-range ℏ contributions. We discuss implications of this computation, in particular, the violation of some classical formulations of the equivalence principle. PMID:25723201
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.
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.
Nonlinear Bending Stiffness of Plates Clamped by Bolted Joints under Bending Moment
Naruse, Tomohiro; Shibutani, Yoji
Equivalent stiffness of plates clamped by bolted joints for designing should be evaluated according to not only the strength of bolted joints but also the deformation and vibration characteristics of the structures. When the applied external axial load or the bending moment is sufficiently small, the contact surfaces of the bolted joint are stuck together, and thus both the bolt and the clamped plates deform linearly. Although the sophisticated VDI 2230 code gives the appropriate stiffness of clamped plates for the infinitesimal deformation, the stiffness may vary nonlinearly with increasing the loading because of changing the contact state. Therefore, the present paper focuses on the nonlinear behaviour of the bending stiffness of clamped plates by using Finite Element (FE) analyses, taking the contact condition on bearing surfaces and between the plates into account. The FE models of the plates with thicknesses of 3.2, 4.5, 6.0 and 9.0 mm tightened with M8, 10, 12 and 16 bolts were constructed. The relation between bending moment and bending compliance of clamped plates is found to be categorized into three regions, namely, (i) constant compliance with fully stuck contact surfaces, (ii) transition showing the nonlinear compliance, and (iii) constant compliance with one-side contact surfaces. The mechanical models for these three regions are proposed and compared with FEM solutions. The prediction on the bounds of three regions is in a fairly good agreement except the case with smaller bolts and thicker plates.
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.
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.
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%.
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)...
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...
Compliance measurements of chevron notched four point bend specimen
Calomino, Anthony; Bubsey, Raymond; Ghosn, Louis J.
1994-01-01
The experimental stress intensity factors for various chevron notched four point bend specimens are presented. The experimental compliance is verified using the analytical solution for a straight through crack four point bend specimen and the boundary integral equation method for one chevron geometry. Excellent agreement is obtained between the experimental and analytical results. In this report, stress intensity factors, loading displacements and crack mouth opening displacements are reported for different crack lengths and different chevron geometries, under four point bend loading condition.
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 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...
Wide range pure bending strains of Nb3Sn wires
International Nuclear Information System (INIS)
Pure bending behavior of Nb3Sn wire over a wide range of bending has been characterized. A previously developed test device designed to apply variable bending strains to Nb3Sn strands using a beam style sample holder was used. Based on finite element and experimental investigations, two sample holder beams were developed to cover pure bending strains up to 1.25% for ITER-type Nb3Sn wires. These newly designed beams were optimized to apply consistent and uniform pure bending strains to Nb3Sn strands over the entire bending range. Their performance was evaluated by testing two ITER-type Nb3Sn wires including one internal tin and one bronze route. The internal tin strands experienced around 55% critical current degradation at 1.25% bending strain while the critical current of the bronze route strands were only reduced by 40%. Upon removal of the bending load, the internal tin wires experienced significant permanent degradation whereas the bronze route wires were completely reversible. These critical current results were evaluated and explained using an existing integrated model accounting for neutral axis shift, current transfer length, filament breakage and uniaxial strain release under pure bending loads. (paper)
A preliminary bending fatigue spectrum for steel monostrand cables
DEFF Research Database (Denmark)
Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.; Kotas, Agnieszka
2011-01-01
This paper presents the results of the experimental study on the bending fatigue resistance of high-strength steel monostrand cables. From the conducted fatigue tests in the high-stress, low-cycle region, a preliminary bending fatigue spectrum is derived for the estimation of monostrand cable...... 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 and...
Sorting of bed load sediment by flow in meander bends.
Parker, G.; Andrews, E.D.
1985-01-01
Equilibrium sorting of coarse mobile bed load sediment in meander bends is considered. A theory of two-dimensional bed load transport of graded material, including the effects of gravity on lateral slopes and secondary currents, is developed. This theory is coupled with a simple tratement of flow in bends, an analytically determined bend shape, and the condition of continuity of each grain size range in transport to describe sorting. The theory indicates that the locus of coarse sediment shifts from the inside bank to the outside bank near the bend apex, as is observed.-Authors
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
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).
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
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)
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.
On the gravitational seesaw and light bending
Accioly, Antonio; Shapiro, Ilya L
2016-01-01
Local gravitational theories with more than four derivatives are superrenormalizable, and also may be unitary in the Lee-Wick sense. It makes sense to study low-energy properties of these theories, e.g., identify observables which might be useful for experimental detection of higher derivatives. Using an analogy with neutrino Physics, we explore the possibility of a gravitational seesaw mechanism, in which several dimensional parameters of the same order of magnitude produce a hierarchy in the masses of propagating particles and make a relatively light degree of freedom detectable by frequency dependence in the gravitational light bending. It turns out that such a seesaw mechanism in the six- and more-derivative theories is unable to reduce the lightest mass more than in the simplest four-derivative model. Adding more derivatives can only make heavier masses even larger. This fact may be favorable for protecting the theory from instabilities, but makes experimental detection of higher derivatives more difficu...
Factors affecting U-bend cracking
International Nuclear Information System (INIS)
Stress corrosion cracking of alloy 600 in pure water is assumed to be the damaging process of a large number of small radius U-bends of PWR steam generators. The possible influencing parameters are reviewed. The determining factor is a too high level of stress arising from two main origins: residual stresses; and overstresses induced by the inner pressure in deformed cross sections. The latter have been assessed by two dimensional finite elements computation and by strain gages measurements. Stress corrosion tests in boiling MgCl2 sustain the previous results for outer surface overstresses. Geometrical characterizations were performed on: in service SG tubes by internal spherical gages; and laboratory samples by internal spherical gages, LVDT and ultrasonic measurements, cross sectioning
Ruggiero, Matteo Luca
2016-05-01
In the framework of f(T) gravity, we focus on a weak-field and spherically symmetric solution for the Lagrangian f(T) = T + αT2, where α is a small constant which parametrizes the departure from general relativity (GR). In particular, we study the propagation of light and obtain the correction to the general relativistic bending angle. Moreover, we discuss the impact of this correction on some gravitational lensing observables, and evaluate the possibility of constraining the theory parameter α by means of observations. In particular, on taking into account the astrometric accuracy in the Solar System, we obtain that |α|≤ 1.85 × 105m2; this bound is looser than those deriving from the analysis of Solar System dynamics, e.g. |α|≤ 5 × 10‑1m2 [L. Iorio, N. Radicella and M. L. Ruggiero, J. Cosmol. Astropart. Phys. 1508 (2015) 021, arXiv:1505.06996 [gr-qc].], |α|≤ 1.8 × 104m2 [L. Iorio and E. N. Saridakis, Mon. Not. R. Astron. Soc. 427 (2012) 1555, arXiv:1203.5781 [gr-qc].] or |α|≤ 1.2 × 102m2 [Y. Xie and X. M. Deng, Mon. Not. R. Astron. Soc. 433 (2013) 3584, arXiv:1312.4103 [gr-qc].]. However, we suggest that, since the effect only depends on the impact parameter, better constraints could be obtained by studying light bending from planetary objects.
On the accuracy of analyses for in-plane bending of smooth pipe bends with end constraints
International Nuclear Information System (INIS)
The accuracy of theoretical analyses for in-plane bending of smooth pipebends with end constraints is discussed and investigated with a view to explaining and reducing the differences between the major works. An earlier theory of the authors is improved to give more accurate answers for bends with rigid flanges. Flanged bends are then examined in some detail, quantifying for the first time the important influence of the flange rigidity on the bend flexibility and stresses. A summary of some finite element analyses is presented from which it is clear that further work is desirable. (orig.)
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)
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
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.
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
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^...
Revisit the anomalous bending elasticity of sharply bent DNA
Cong, Peiwen; Chen, Hu; van der Maarel, Johan R C; Doyle, Patrick S; Yan, Jie
2015-01-01
Several recent experiments have suggested that sharply bent DNA has a surprisingly high bending flexibility, but the cause is poorly understood. It has been demonstrated that excitation of flexible defects can explain the results; while whether such defects can be excited under the level of DNA bending in those experiments has remained unclear and been debated. Interestingly, due to experimental design DNA contained pre-existing nicks in nearly all those experiments, while the potential effect of nicks have never been considered. Here, using full-atom molecular dynamics (MD) simulations, we show that nicks promote DNA basepair disruption at the nicked sites which drastically reduced DNA bending energy. In the absence of nicks, basepair disruption can also occur, but it requires a higher level of DNA bending. Overall, our results challenge the interpretations of previous sharp DNA bending experiments and highlight that the micromechanics of sharply bent DNA still remains an open question.
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.
Limits of stability in supported graphene nanoribbons subject to bending
Korhonen, Topi; Koskinen, Pekka
2016-06-01
Graphene nanoribbons are prone to in-plane bending even when supported on flat substrates. However, the amount of bending that ribbons can stably withstand remains poorly known. Here, by using molecular dynamics simulations, we study the stability limits of 0.5-1.9-nm-wide armchair and zigzag graphene nanoribbons subject to bending. We observe that the limits for maximum stable curvatures are below ˜10 deg /nm in case the bending is externally forced and the limit is caused by buckling instability. Furthermore, it turns out that the limits for maximum stable curvatures are also below ˜10 deg /nm in case the bending is not forced and the limit arises only from the corrugated potential-energy landscape due to the substrate. Both of the stability limits lower rapidly when ribbons widen. These results agree with recent experiments and can be understood by means of transparent elasticity models.
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.
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
Product Evaluation In Elliptical Helical Pipe Bending
Directory of Open Access Journals (Sweden)
Wasantha Samarathunga
2013-10-01
Full Text Available This research proposes a computation approach to address the evaluation of end product machining accuracy in elliptical surfaced helical pipe bending using 6dof parallel manipulator as a pipe bender. The target end product is wearable metal muscle supporters used in build-to-order welfare product manufacturing. This paper proposes a product testing model that mainly corrects the surface direction estimation errors of existing least squares ellipse fittings, followed by arc length and central angle evaluations. This post-machining modelling requires combination of reverse rotations and translations to a specific location before accuracy evaluation takes place, i.e. the reverse comparing to pre-machining product modelling. This specific location not only allows us to compute surface direction but also the amount of excessive surface twisting as a rotation angle about a specified axis, i.e. quantification of surface torsion. At first we experimented three ellipse fitting methods such as, two least-squares fitting methods with Bookstein constraint and Trace constraint, and one non-linear least squares method using Gauss-newton algorithm. From fitting results, we found that using Trace constraint is more reliable and designed a correction filter for surface torsion observation. Finally we apply 2D total least squares line fitting method with a rectification filter for surface direction detection.
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.
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.
Bolted flanged connections with longitudinal bending moments: Experimental results
International Nuclear Information System (INIS)
Flanges in piping systems and on tall vertical pressure vessels such as columns or fractionators, are often subjected to external, longitudinal bending moments of considerable magnitude. In piping systems, such bending moments are usually caused by thermal expansion. On pressure vessel flanges, external bending moments are often the result of wind or seismic loadings. In the ASME Code, only Section III, the Nuclear Power Plant Code, Subsections NB, NC, and ND, contain design rules for external bending moments on flanges. In Subsections NB, NC, and ND, an empirical formula is given, expressing a longitudinal bending moment in bolted flanged connections in terms of an equivalent internal pressure to be added to the design pressure of the flange. Other sections of the ASME Code, in particular Section VIII, Divisions 1 and 2, also the ASME-ANSI Piping Codes, do not contain rules for such external, longitudinal bending moments. In previous papers by the same authors, it was shown that a single empirical expression to convert external bending moments to intemal pressure, cannot include the differences between the geometries of flanges of various sizes. An attempt was also made to analyse the stresses in the flange-bolt assembly due to extemal bending moments and to compare flange thicknesses thus obtained with thicknesses required using the equivalent design pressure, specified in Subsections NB, NC, and ND. The present paper reports the findings of a series of experiments on a pair of 100 mm, Class 10 (4 inch, Class 150) pipe flanges which were subjected to various combinations of intemal pressure and extemal longitudinal bending. Measured values are compared with a proposed analytic design method and with results using the empirical formula of the ASME Code, Section III
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...
Bends in nanotubes allow electric spin control and coupling
DEFF Research Database (Denmark)
Flensberg, Karsten; Marcus, Charles Masamed
2010-01-01
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.......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...
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)
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.
Influence of plywood grain direction on sandwich panel bending properties
Jaroslav Kljak; Mladen Brezović; Alan Antonović
2009-01-01
This paper investigates the influence of plywood grain direction on bending properties of a sandwich panel, as well as on stress distribution in each layer. Experimental sandwich panels (tnom= 29 mm) were made of two three-ply plywood panels and a rigid PVC core between them. Grain directions of plywood panels were between 0° and 90°, continuously raised by 15°. Seven models of sandwich panels were made. Bending properties of a sandwich panel was determined by three point bending method and s...
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.
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...
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.
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...
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...
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
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......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...
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.
Technique cuts time and cost of bending jacketed piping
Gardner, J. N.
1967-01-01
Technique uses a stiff medium in the annular space between inner and outer pipes of jacketed piping in transfer lines. The process eliminates splitting and welding and makes possible the use of standard pipe-bending tools.
Cylindrical Bending of Deformable Textile Rectangular Patch Antennas
Freek Boeykens; Hendrik Rogier; Luigi Vallozzi
2012-01-01
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 bend...
Species-specific patterns of DNA bending and sequence.
VanWye, J D; Bronson, E C; Anderson, J N
1991-01-01
Nucleotide sequences in the GenEMBL database were analyzed using strategies designed to reveal species-specific patterns of DNA bending and DNA sequence. The results uncovered striking species-dependent patterns of bending with more variations among individual organisms than between prokaryotes and eukaryotes. The frequency of bent sites in sequences from different bacteria was related to genomic A + T content and this relationship was confirmed by electrophoretic analysis of genomic DNA. How...
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.
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
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.
Power monitor miter bends for high-power microwave transmission
Energy Technology Data Exchange (ETDEWEB)
Doane, John, E-mail: doane@fusion.gat.com; Anderson, James; Grunloh, Howard; Wu, Wen
2015-04-15
Two miter bends are described for monitoring the power transmitted in an oversized corrugated wave-guide. One has an array of holes in its mirror that couples a small fraction of the incident power to a rectangular waveguide directly machined into the mirror. Millimeter-wave detectors on the outputs of this miter bend can respond very rapidly to the transmitted power, but the coupling is sensitive to the mode purity in the oversized waveguide. The other miter bend monitors the power by measuring the rise in temperature of the cooling water passing through the mirror. The mirror is well isolated from the miter bend housing to prevent heat from neighboring waveguides from reaching the mirror. The measurement requires about 200 s to reach steady state, but it is relatively insensitive to mode purity. The measurement does require knowledge of the input polarization. Thermo-mechanical analyses of the miter bends indicate that they are capable of reliable operation with 1.5 MW transmitted through them. High-power long-pulse 170 GHz tests of these miter bends at the Japan Atomic Energy Agency (JAEA) are described.
Influence of plywood grain direction on sandwich panel bending properties
Directory of Open Access Journals (Sweden)
Jaroslav Kljak
2009-06-01
Full Text Available This paper investigates the influence of plywood grain direction on bending properties of a sandwich panel, as well as on stress distribution in each layer. Experimental sandwich panels (tnom= 29 mm were made of two three-ply plywood panels and a rigid PVC core between them. Grain directions of plywood panels were between 0° and 90°, continuously raised by 15°. Seven models of sandwich panels were made. Bending properties of a sandwich panel was determined by three point bending method and stress in each layer was determined by using finite element method. Simulation models were developed with equal load conditions as applied during empirical measurement of bending properties of the sandwich panel. The research results show that grain direction has a great influence on bending properties of the sandwich panel, as well as on stress values in each layer. Results also indicate the importance of analyzing stress in each layer of plywood for the purpose of avoiding stress concentration in respective layers and for optimizing structural construction of the sandwich panel. Such stress analyses are not covered by standardized empirical methods for determining bending properties of sandwich panels.
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.
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...
2013-12-24
... as described in 78 FR 4465 (January 22, 2013). On April 12, 2013, PPL submitted Revision 4 to the COL... Bend Nuclear Power Plant (BBNPP), in Luzerne County, Pennsylvania (Agencywide Documents Access...
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.
Validity of fracture toughness determined with small bend specimens
International Nuclear Information System (INIS)
This report considers the validity of fracture toughness estimates obtained with small bend specimens in relation to fracture toughness estimates obtained with large specimens. The study is based upon the analysis and comparison of actual test results. The results prove the validity of the fracture toughness determined based upon small bend specimens, especially when the results are only used to determine the fracture toughness transition temperature To. In this case the possible error is typically less than 5 deg C and at most 10 deg C. It can be concluded that small bend specimens are very suitable for the estimation of fracture toughness in the case of brittle fracture, provided the results are corrected for statistical size effects. (orig.). (20 refs., 17 figs.)
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.
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.
Single crystal plasticity with bend-twist modes
Elkhodary, Khalil I.; Bakr, Mohamed A.
2015-06-01
In this work a formulation is proposed and computationally implemented for rate dependent single crystal plasticity, which incorporates plastic bend-twist modes that arise from dislocation density based poly-slip mechanisms. The formulation makes use of higher order continuum theory and may be viewed as a generalized micromechanics model. The formulation is then linked to the burgers and Nye tensors, showing how their material rates are derivable from a newly proposed third-rank tensor Λp, which incorporates a crystallographic description of bend-twist plasticity through selectable slip-system level constitutive laws. A simple three-dimensional explicit finite element implementation is outlined and employed in three simulations: (a) bi-crystal bending; (b) tension on a notched single crystal; and (c) the large compression of a microstructure to induce the plastic buckling of secondary phases. All simulation are transient, for computational expediency. The results shed light on the physics resulting from dynamic inhomogeneous plastic deformation.
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.
What bends wide-angle tailed radio sources
International Nuclear Information System (INIS)
The authors discuss the mechanism responsible for bending WAT sources. The actual bending of the radio tails results from an interaction between the intracluster medium (ICM) and the extended radio plasma. Pressure gradients within the ICM will distort the plasma flow from linearity. Such pressure gradients could be seen as asymmetries in the X-ray emission produced by the hot cluster gas. Unlike the large-scale structure, the inner X-ray emission has an anisotropic, egg-shape near the cD with the excess between the radio tails. The origin of this gas anisotropy and its implications for the bending of the 3C465 tails are briefly considered using four models. (Auth.)
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
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.
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 into a...
Photomechanical Bending of Azobenzene-Based Photochromic Molecular Fibers
Directory of Open Access Journals (Sweden)
Riku Matsui
2013-03-01
Full Text Available Microfibers composed of azobenzene-based photochromic amorphous molecular materials, namely low molecular-mass photochromic materials with a glass-forming property, could be fabricated. These fibers were found to exhibit mechanical bending motion upon irradiation with a laser beam. In addition, the bending direction could be controlled by altering the polarization direction of the irradiated light without changing the position of the light source or the wavelength of the light. In-situ fluorescence observation of mass transport induced at the surface of the fiber doped with CdSe quantum dots suggested that the bending motions were related with the photoinduced mass transport taking place near the irradiated surface of the fiber.
Qualification of a motorized scanner for feeder bend inspection
International Nuclear Information System (INIS)
This paper will review the qualification of the Inspection System based on the motorized feeder bend-cracking crawler designed by IREQ and the inspection procedure COG-JP-4107- V43 developed by Hydro-Quebec and New-Brunswick Power. The mechanization of the inspection was necessary to address new concerns found after the discovery in 2003 of cracks on second bends and also the finding that several removed cracked bends had additional incipient OD cracks on the extrados. This document describes the apparatus, procedure and test-results that support the adequacy of the inspection system to meet the inspection specifications and the CSA N285.4 Standard. A review of the qualification process is included. A particular aspect of the work is the emphasis set on detecting OD flaws. Field results from PLGS and G-2 outages will be addressed. (author)
In situ heat treatment of U-bends: Final report
International Nuclear Information System (INIS)
Row 1 nuclear steam generator tubes of mill annealed Alloy 600 tubing were stress relief annealed at 14500F for 15 minutes using a special internally placed flexible electrical resistance heater. The U-bends were strained to simulate differential thermal expansion stresses and tested for primary water stress corrosion cracking (PWSCC) resistance in two reference accelerated test environments (6800F high purity water and 7500F superheated steam), both of which contained hydrogen partial pressures. Prototypical axial throughwall cracking at the extrados of the irregular U-bend transition tangent was produced in base line, non-stress relieved U-bends, while no throughwall cracking occurred in any stress relieved sample. An improvement in PWSCC resistance due to this stress relief of at least a factor of 30 can be inferred for the 7/8 in. tubing material that was of a highly PWSCC susceptible heat. The 3/4 in. tubing material, which was more resistant to PWSCC in the mill annealed condition, exhibited an inferred factor in PWSCC resistance, due to the 14500F stress relief, or at least 11. The program identified and qualified a lower temperature, shorter time, stress relief cycle of 13000F for five minutes. Accelerated PWSCC testing in 7500F steam indicated that 7/8 in. OD U-bends stress relieved at 13000F for five minutes exhibit a resistance to PWSCC that is at least 100 times greater than as-bent samples that were readily cracked in the steam exposures. It is concluded that in-situ stress relief of mill annealed Alloy 600 nuclear steam generator U-bends is highly beneficial in reducing, or possibly eliminating, PWSCC at the U-bend tangent points where instances of PWSCC have been documented in operating plants. 10 refs., 44 figs., 16 tabs
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
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.
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
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...
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.
Axisymmetrical bending of circular plates with eccentric stiffeners
International Nuclear Information System (INIS)
Small deflection bending theory of stiffened circular plates with uniformly spaced radial and circunferential ribs is presented. Equilibrium differential equations for the axisymmetric case, in terms of the displacements u and w of the middle surface of the plate are derived, and their general solutions are found. Closed form solutions for the circular plate with uniformly distributed bending moments along its edge are given for the special case in which geometrical and elastic properties of the ribs are constant and equal along both radial and circunferential directions. (Author)
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.
Origin of bending in uncoated microcantilever - Surface topography?
International Nuclear Information System (INIS)
We provide direct experimental evidence to show that difference in surface topography on opposite sides of an uncoated microcantilever induces bending, upon exposure to water molecules. Examination on opposite sides of the microcantilever by atomic force microscopy reveals the presence of localized surface features on one side, which renders the induced stress non-uniform. Further, the root mean square inclination angle characterizing the surface topography shows a difference of 73° between the opposite sides. The absence of deflection in another uncoated microcantilever having similar surface topography confirms that in former microcantilever bending is indeed induced by differences in surface topography
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
Influence of bending test configuration on cracking behavior of FRC
DEFF Research Database (Denmark)
Finazzi, Silvia; Paegle, Ieva; Fischer, Gregor;
2014-01-01
(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......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...
Test Equal Bending by Gravity for Space and Time
Sweetser, Douglas
2009-05-01
For the simplest problem of gravity - a static, non-rotating, spherically symmetric source - the solution for spacetime bending around the Sun should be evenly split between time and space. That is true to first order in M/R, and confirmed by experiment. At second order, general relativity predicts different amounts of contribution from time and space without a physical justification. I show an exponential metric is consistent with light bending to first order, measurably different at second order. All terms to all orders show equal contributions from space and time. Beautiful minimalism is Nature's way.
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
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.
Photoacoustic elastic bending in thin film—Substrate system
International Nuclear Information System (INIS)
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
Enhanced resolution of long-period grating bend sensor
DEFF Research Database (Denmark)
Glavind, Lars; Gao, S; Cook, K; Canning, J; Skipper, BF; Luo, Y; Peng, G; Kristensen, M
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...
Electrical Reliability of a Film-Type Connection during Bending
Directory of Open Access Journals (Sweden)
Ryosuke Mitsui
2015-10-01
Full Text Available With the escalating demands for downsizing and functionalizing mobile electronics, flexible electronics have become an important aspect of future technologies. To address limitations concerning junction deformation, we developed a new connection method using a film-type connector that is less than 0.1 mm thick. The film-type connector is composed of an organic film substrate, a UV-curable adhesive that deforms elastically under pressure, and electrodes that are arranged on the adhesive. The film-type connection relies on a plate-to-plate contact, which ensures a sufficient contact area. The electrical reliability of the film-type connection was investigated based on changes in the resistance during bending at curvature radii of 70, 50, 25, 10, 5, and 2.5 mm. The connection was bent 1000 times to investigate the reproducibility of the connector’s bending properties. The tests showed that no disconnections occurred due to bending in the vertical direction of the electrode, but disconnections were observed due to bending in the parallel direction at curvature radii of 10, 5, and 2.5 mm. In addition, the maximum average change in resistance was less than 70 milliohms unless a disconnection was generated. These results support the application of the new film-type connection in future flexible devices.
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…
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
Ultrathin 90-degree sharp bends for spoof surface plasmon polaritons
DEFF Research Database (Denmark)
Yang, Yihao; Chen, Hongsheng; Xiao, Sanshui; Mortensen, N. Asger; Zhang, Jingjing
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 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
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.
Optimal semi-active damping of cables with bending stiffness
Boston, C.; Weber, F.; Guzzella, L.
2011-05-01
The problem of optimal semi-active damping of cables with bending stiffness is investigated with an evolutionary algorithm. The developed damping strategy is validated on a single strand cable with a linear motor attached close to the anchor position. The motor is operated in force feedback mode during free decay of cable vibrations, during which time the decay ratios of the cable modes are measured. It is shown from these experiments that the damping ratios predicted in simulation are close to those measured. The semi-active damping strategy found by the evolutionary algorithm is very similar in character to that for a cable without bending stiffness, being the superposition of an amplitude-dependent friction and negative stiffness element. However, due to the bending stiffness of the cable, the tuning of the above elements as a function of the relevant cable parameters is greatly altered, especially for damper positions close to a fixed end anchor, where the mode shape depends strongly on bending stiffness. It is furthermore demonstrated that a semi-active damper is able to dissipate significantly more energy for a cable with simply supported ends compared to fixed ends due to larger damper strokes and thereby increased energy dissipation in the device.
Cylindrical Bending of a Plate on an Elastic Foundation
Czech Academy of Sciences Publication Activity Database
Gronát, Petr
Ostrava : VŠB - Technical University of Ostrava, 2011, C376-C393. ISBN 978-80-248-2257-0 R&D Projects: GA ČR GAP101/10/1230 Institutional research plan: CEZ:AV0Z20760514 Keywords : elastic foundation * cylindrical bending Subject RIV: JI - Composite Materials
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.
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.
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...
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
Study of transmission properties for waveguide bends by use of a circular photonic crystal
Xiao, Sanshui; Qiu, Min
2005-01-01
We study the transmission properties for the waveguide bends composed by a circular photonic crystal. Two types (Y and U type) of the waveguide bends utilizing the circular photonic crystal are studied. It has been shown, compared with the conventional photonic crystal waveguide bends, transmission properties for these bends can be significantly improved. Over a 6.4% bandwidth, less than 1-dB loss/bend are observed. U bent waveguide, i.e., $180^o$ bend, can be easily realized with low loss us...
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...
Novel low-loss 60° bends in photonic crystal waveguides
DEFF Research Database (Denmark)
Thorhauge, Morten; Frandsen, Lars Hagedorn; Borel, Peter Ingo; Harpøth, Anders; Zhuang, Y. X.; Kristensen, Martin; Bogaerts, W; Dumon, P; Baets, Roel; Wiaux, V; Wouters, J; Beckx, S
2004-01-01
A novel type of 60 degree photonic crystal waveguide bend has been designed, simulated and fabricated in silicon-on-insulator material utilizing deep ultraviolet lithography. Loss-free bending has been observed in certain wavelength regions.......A novel type of 60 degree photonic crystal waveguide bend has been designed, simulated and fabricated in silicon-on-insulator material utilizing deep ultraviolet lithography. Loss-free bending has been observed in certain wavelength regions....
Local and Global Light Bending in Einstein's and Other Gravitational Theories
Ehlers, J.; Rindler, W.
1997-01-01
To remedy a certain confusion in the literature, we stress the distinction between local and global light bending. Local bending is a purely kinematic effect between mutually accelerating reference frames tracking the same signal, and applies via Einstein's equivalence principle exactly and equally in Newton's, Einstein's, Nordström's and other gravitational theories, independently of all field equations. Global bending, on the other hand, arises as an integral of local bending and depends cr...
Emittance dilution through coherent energy spread generation in bending systems
International Nuclear Information System (INIS)
For a bunched beam, coherent energy spread generated within a bending system may couple to the transverse (bending) plane coordinates through the chromatic transfer functions of the particular beamline - even an achromatic beamline. The resulting transverse emittance dilution is dependent on the magnitude of the energy spread, its generation rate along the beamline, and the beamline's chromatic transfer functions. The coherent energy spread may be due to resistive-wall wakefields or coherent synchrotron radiation. For specific beamlines, such as a periodic arc or wiggler, the longitudinal-to-transverse coupling is minimal and, in ideal cases, completely suppressed resulting in reduction or cancellation of all transverse emittance dilution effects. This is of particular interest for micro-bunch transport or compression systems such as exist in future FEL or linear collider projects
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 $H(t)$.
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.
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.
Coupled Torsional and Bending Vibrations of Actively Controlled Drillstrings
YIGIT, A. S.; CHRISTOFOROU, A. P.
2000-06-01
The dynamics of actively controlled drillstrings is studied. The equations of motion are derived using a lumped parameter model in which the coupling between torsional and bending vibrations is considered. The model also includes the dynamics of the rotary drive system which contains the rotary table, the gearbox and an armature controlled DC motor. The interactions between the drillstring and the borehole which are considered, include the impacts of collars with the borehole wall as well as bit rotation-dependent weight and torque on bit (WOB and TOB). Simulation results obtained by numerically solving the equations of motion are in close qualitative agreement with field and laboratory observations regarding stick-slip oscillations. A linear quadratic regulator (LQR) controller is designed based on a linearized model and is shown to be effective in eliminating this type of oscillations. It is also shown that for some operational parameters the control action may excite large bending vibrations due to coupling with the torsional motion.
An approach to the hot bending process simulation
International Nuclear Information System (INIS)
An approach to the simulation of the thermal shaping or bending of large steel sheets, by ABAQUS/Standard code, will be presented. A thermal source representation, which can produce a temperature distribution, adequate to the processes which must be considered, has been set up. Some problems connected with the hot sheet shaping or bending process simulation have been approached and calculations have been executed in order to single out how to perform the sheet heating, so that the required sheet shape may be obtained. The results for one reference model for different source situations and one heating line, object of the first phase of the analyses performed, will be presented and discussed. The work will be presented at the 8th International Abaqus Users' Conference at Paris, 31 May - 2 June 1995
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.
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.
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.
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
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...
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...... the bend angle. We also demonstrate splitting and combining of two SPP line-defect modes in a 20-mum-long Y junction....
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...
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.
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...
Analysis of the optical Viscometer utilizing bend lost of fiber
Czech Academy of Sciences Publication Activity Database
Fedorchenko, Alexander I.; Stachiv, Ivo
Perth : Technical Digest, 2010 - (Wlodarsky, W.; Faraone, L.; Kalantar-Zadeh, K.; Matthews, G.), s. 67-68 ISBN 978-1-74052-208-3. [International meeting on Chemical Sensors /13./ IMC -13. Perth (AU), 11.07.2010-14.07.2010] R&D Projects: GA AV ČR(CZ) IAA200760801 Institutional research plan: CEZ:AV0Z20760514 Keywords : viscosity * bend loss of the fibe * resonance Subject RIV: BK - Fluid Dynamics
Buoyancy, bending, and seismic visibility in deep slab stagnation
Bina, Craig R.; Kawakatsu, Hitoshi; Suetsugu, D.; Bina, C.; Inoue, T.; Wiens, D.; Jellinek, M.
2010-11-01
The petrological consequences of deep subhorizontal deflection ("stagnation") of subducting slabs should affect both apparent seismic velocity structures and slab morphology. We construct kinematic thermal models of stagnant slabs and perform thermodynamic modeling of the consequent perturbation of high-pressure phase transitions in mantle minerals, focusing upon Japan as our study area. We calculate associated thermo-petrological buoyancy forces and bending moments which (along with other factors such as viscosity variations and rollback dynamics) may contribute to slab deformation. We consider effects of variations in depth of stagnation, post-stagnation dip angle, phase transition sharpness, transition triplication due to multiple intersection of geotherms with phase boundaries, and potential persistence of metastable phases due to kinetic hindrance. We also estimate seismic velocity anomalies, as might be imaged by seismic tomography, and corresponding seismic velocity gradients, as might be imaged by receiver-function analysis. We find that buoyant bending moment gradients of petrological origin at the base of the transition zone may contribute to slab stagnation. Such buoyancy forces vary with the depth at which stagnation occurs, so that slabs may seek an equilibrium slab stagnation depth. Metastable phase bending moment gradients further enhance slab stagnation, but they thermally decay after ∱/4600•700 km of horizontal travel, potentially allowing stagnant slabs to descend into the lower mantle. Stagnant slabs superimpose zones of negative velocity gradient onto a depressed 660-km seismic discontinuity, affecting the seismological visibility of such features. Seismologically resolvable details should depend upon both stagnation depth and the nature of the imaging technique (travel-time tomography vs. boundary-interaction phases). While seismic tomography appears to yield images of stagnant slabs, discontinuity topography beneath Japan resolved by
Mathematical aspects of bending of plates with transverse shear deformation
International Nuclear Information System (INIS)
The boundary integral equation method is applied to investigate the existence and uniqueness of regular solutions of a two-dimensional theory of bending of plates with transverse shear deformation. The stress function technique is then used to obtain the general analytic solution of the equilibrium equations and to elucidate the physical meaning of the mathematical restrictions arising in the analysis of the model. (orig.)
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...
Strength of arch-shaped members in bending and shear
Campana, Stefano; Fernández Ruiz, Miguel; Muttoni, Aurelio
2014-01-01
Arch-shaped members are widely used for construction of tunnels, bridges, silos and shells. These members are not typically provided with transverse reinforcement and may thus have a brittle behaviour at failure. When subjected to bending or shear, traditional design methods used for straight members are not applicable due to deviation forces developing at the curved chords carrying compression and tension, which is not always accounted in design codes. In this paper, two experimental series ...
[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...
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.
Bending and Focusing with Plasmas and Crystals - Potential and Challenges
Zimmermann, F
2013-01-01
This talk review the potential of plasmas and crystals for focusing and bending high-energy charged particle beams. It covers topics like plasma lenses, plasma wigglers, plasma dipoles, crystal channeling & reflection, radiation in crystals, crystal accelerators, crystalline beams and ultimate limitations. Past, ongoing or required R&D efforts are highlighted. Invited presentation at EuCARD'13 "Visions for the Future of Particle Accelerators," CERN, 11 June 2013.
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.
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.
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.
Effects of large bending deflections on blade flutter limits
Energy Technology Data Exchange (ETDEWEB)
Kallesoee, Bjarne Skovmose; Hartvig Hansen, Morten
2008-04-15
The coupling of bending and torsion due to large blade bending are assumed to have some effects of the flutter limits of wind turbines. In the present report, the aeroelastic blade model suggested by Kallesoee, which is similar to a second order model, is used to investigate the aeroelastic stability limits of the RWT blade with and without the effects of the large blade deflection. The investigation shows no significant change of the flutter limit on the rotor speed due to the blade deflection,whereas the first edgewise bending mode becomes negatively damped due to the coupling with blade torsion which causes a change of the effective direction of blade vibration. These observations are confirmed by nonlinear aeroelastic simulations using HAWC2. This work is part of the UpWind project funded by the European Commission under the contract number SES6-CT-2005-019945 which is gratefully acknowledged. This report is the deliverable D2.3 of the UpWind project. (au)
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.
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.
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
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.
A rotary piezoelectric actuator using longitudinal and bending hybrid transducer
Directory of Open Access Journals (Sweden)
Yingxiang Liu
2012-12-01
Full Text Available A rotary piezoelectric actuator using bolt-clamped type transducer with double driving feet is proposed in this study. The first-order longitudinal and fourth-order bending vibration modes are superimposed in the actuator to produce elliptical movements on the driving tips. Longitudinal PZT and bending PZT are clamped between the exponential shape horns and the flange by bolts. The vibration shape changes of the actuator are presented to give a clear explanation of its working principle. Several structural parameters of the exponential shape horn are selected and adjusted to accomplish the tuning process of the longitudinal and bending resonance frequencies. The input impedance and vibration characteristics are calculated by using FEM method; the gained results verify the feasibility of the proposed actuator. After the fabrication of a prototype, its vibration characteristics are measured by using a scanning laser Doppler vibrometer; the tested results are in good agreement with the FEM calculated results. The mechanical output performance experiments state that the prototype achieves a maximum speed of 129 r/min and a maximum torque of 1.5 Nm.
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 ...
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.)
Brightness of synchrotron radiation from undulators and bending magnets
International Nuclear Information System (INIS)
We consider the maximum of the Wigner distribution (WD) of synchrotron radiation (SR) fields as a possible definition of SR source brightness. Such figure of merit was originally introduced in the SR community by Kim. The brightness defined in this way is always positive and, in the geometrical optics limit, can be interpreted as maximum density of photon flux in phase space. For undulator and bending magnet radiation from a single electron, the WD function can be explicitly calculated. In the case of an electron beam with a finite emittance the brightness is given by the maximum of the convolution of a single electron WD function and the probability distribution of the electrons in phase space. In the particular case when both electron beam size and electron beam divergence dominate over the diffraction size and the diffraction angle, one can use a geometrical optics approach. However, there are intermediate regimes when only the electron beam size or the electron beam divergence dominate. In this asymptotic cases the geometrical optics approach is still applicable, and the brightness definition used here yields back once more the maximum photon flux density in phase space. In these intermediate regimes we find a significant numerical disagreement between exact calculations and the approximation for undulator brightness currently used in literature. We extend the WD formalism to a satisfactory theory for the brightness of a bending magnet. We find that in the intermediate regimes the usually accepted approximation for bending magnet brightness turns out to be inconsistent even parametrically.
Effect of Bend Curvature Ratio on Flow Pattern at a Mixing Tee after a 90 Degree Bend
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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.
Directory of Open Access Journals (Sweden)
Hamid Ahmadi
2015-01-01
Full Text Available Fatigue life of tubular joints in offshore structures is significantly influenced by the degree of bending (DoB. The DoB exhibits considerable scatter calling for greater emphasis in accurate determination of its governing probability distribution which is a key input for the fatigue reliability analysis of a tubular joint. Although the tubular X-joints are commonly found in offshore jacket structures, as far as the authors are aware, no comprehensive research has been carried out on the probability distribution of the DoB in tubular X-joints. In the present paper, results of parametric equations available for the calculation of the DoB have been used to develop probability distribution models for the DoB in the chord member of tubular X-joints subjected to four types of bending loads. Based on a parametric study, a set of samples was prepared and density histograms were generated for these samples using Freedman-Diaconis method. Twelve different probability density functions (PDFs were fitted to these histograms. In each case, Kolmogorov-Smirnov test was used to evaluate the goodness of fit. Finally, after substituting the values of estimated parameters for each distribution, a set of fully defined PDFs have been proposed for the DoB in tubular X-joints subjected to bending loads.
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.
Reversible Bending Fatigue Testing on Zry-4 Surrogate Rods
International Nuclear Information System (INIS)
Testing high-burnup spent nuclear fuel (SNF) presents many challenges in areas such as specimen preparation, specimen installation, mechanical loading, load control, measurements, data acquisition, and specimen disposal because these tasks are complicated by the radioactivity of the test specimens. Research and comparison studies conducted at Oak Ridge National Laboratory (ORNL) resulted in a new concept in 2010 for a U-frame testing setup on which to perform hot-cell reversible bending fatigue testing. Subsequently, the three-dimensional finite element analysis and the engineering design of components were completed. In 2013 the ORNL team finalized the upgrade of the U-frame testing setup and the integration of the U-frame setup into a Bose dual linear motor test bench to develop a cyclic integrated reversible-bending fatigue tester (CIRFT). A final check was conducted on the CIRFT test system in August 2013, and the CIRFT was installed in the hot cell in September 2013 to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The fatigue responses of Zircaloy-4 (Zry-4) cladding and the role of pellet pellet and pellet clad interactions are critical to SNF vibration integrity, but such data are not available due to the unavailability of an effective testing system. While the deployment of the developed CIRFT test system in a hot cell will provide the opportunity to generate the data, the use of a surrogate rod has proven quite effective in identifying the underlying deformation mechanism of an SNF composite rod under an equivalent loading condition. This paper presents the experimental results of using surrogate rods under CIRFT reversible cyclic loading. Specifically, monotonic and cyclic bending tests were conducted on surrogate rods made of a Zry-4 tube and alumina pellet inserts, both with and without an epoxy bond
Reversible Bending Fatigue Testing on Zry-4 Surrogate Rods
Energy Technology Data Exchange (ETDEWEB)
Wang, Jy-An John [ORNL; Wang, Hong [ORNL; Bevard, Bruce Balkcom [ORNL; Howard, Rob L [ORNL
2014-01-01
Testing high-burnup spent nuclear fuel (SNF) presents many challenges in areas such as specimen preparation, specimen installation, mechanical loading, load control, measurements, data acquisition, and specimen disposal because these tasks are complicated by the radioactivity of the test specimens. Research and comparison studies conducted at Oak Ridge National Laboratory (ORNL) resulted in a new concept in 2010 for a U-frame testing setup on which to perform hot-cell reversible bending fatigue testing. Subsequently, the three-dimensional finite element analysis and the engineering design of components were completed. In 2013 the ORNL team finalized the upgrade of the U-frame testing setup and the integration of the U-frame setup into a Bose dual linear motor test bench to develop a cyclic integrated reversible-bending fatigue tester (CIRFT). A final check was conducted on the CIRFT test system in August 2013, and the CIRFT was installed in the hot cell in September 2013 to evaluate both the static and dynamic mechanical response of SNF rods under simulated loads. The fatigue responses of Zircaloy-4 (Zry-4) cladding and the role of pellet pellet and pellet clad interactions are critical to SNF vibration integrity, but such data are not available due to the unavailability of an effective testing system. While the deployment of the developed CIRFT test system in a hot cell will provide the opportunity to generate the data, the use of a surrogate rod has proven quite effective in identifying the underlying deformation mechanism of an SNF composite rod under an equivalent loading condition. This paper presents the experimental results of using surrogate rods under CIRFT reversible cyclic loading. Specifically, monotonic and cyclic bending tests were conducted on surrogate rods made of a Zry-4 tube and alumina pellet inserts, both with and without an epoxy bond.
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
Design of optimal chamfered bends in Rectangular Substrate Integrated Waveguide
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Rahali Bochra
2011-07-01
Full Text Available Recently, has emerged a new technology, substrate integrated waveguide (SIW, it has been applied successfully to the conception of planar compact components for the microwave and millimeter waves applications. Our study concerns the analysis of right bends of rectangular waveguides under SIW technology by the HFSS code, in order to simulate different chamfrain positions, through the analysis of the transmission coefficient S21. In order to reduce losses of the performance, it is usual to chamfrain the external wall of the waveguide. Thus, through this modeling, we have confirmed the optimal position of the chamfrain. A good agreement between HFSS simulations and reference results has been obtained.
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 .
Reflection of bending Waves from Border of the Plate
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Belubekyan M.V.
2010-03-01
Full Text Available To problems of the reflection of the bending waves from flat border of the ambience dedicated to the multiple studies. Relatively little works are connected with questions of the reflection curved waves from flat edge of the thin plate. In this work happen to the decisions of the problem of the plate under different border condition. For partial case of the free edge, as limiting case of the absence of the reflected wave, is got decision of the problem localized curved variations.
Prevention of thermal bending of multilayered beams and plates
Yang, J. C. S.
1975-01-01
By adding an extra layer to multilayer beams or plates of different isotropic materials, it is possible to prevent the thermal bending of these materials. With the proper selection of thermoelastic properties the curvature produced prior to this addition would be eliminated. Several numerical examples are presented for various temperature distributions. A simple experiment was conducted, involving the addition of a brass strip to a bimetallic strip made of aluminum and steel at room temperature. The trimetal strip was placed in a furnace and remained straight for varying temperatures.
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.
Experimental investigations on dynamic effects in impact notch bending tests
International Nuclear Information System (INIS)
The dynamic behaviour of three point bending samples under impact stresses is examined experimentally. Various measuring processes, above all the shadow optics etching process are used. A quasi-static analysis is made by a simple spring/mass model to describe the stress behaviour quantitatively. Based on this, the dynamic effects in model experiments are measured quantitatively with dynamic correction functions and are discussed with reference to the wave processes in the sample. A systematic view of the effect of the many system parameters on the dynamic stress behaviour is obtained. Finally, examples show that the results of this model investigation can be transferred to other experimental conditions. (orig./HP)
BENDING ANALYSIS OF COMPOSITE PLATES USING HIGHER ORDER THEORY
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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.
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.
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.
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.
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?
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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%.
Radio occultation bending angle anomalies during tropical cyclones
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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.
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.
Bulk Shielding Calculation for 90 .deg. Bending Section of RISP
International Nuclear Information System (INIS)
The charge state of 238U beams with maximum intensity was 79+ among multi-charge states of 70+ to 89+, which were estimated by using LISE++ code. The bending section consists of twenty four quadrupoles, two dipoles, two two-cell type superconducting RF cavities and eleven slits. The complicated radiation environment is caused by the beam losses occurred normally during the stripping process and when the produced 238U beams are transported along the beam line. Secondary radiations generated by 238U beams irradiation are very important for predicting the prompt and residual doses and the radiation damage at the component. The production characteristics of neutron and photon from thin carbon and thick iron were studied to set up the shielding strategy. The dose estimation was done to the pre-designed the tunnel structure. In these calculations, major Monte Carlo codes, PHITS and FLUKA, were used. The present study provided information of shielding analysis for the 90 .deg. bending section of RISP facility. The source term was evaluated to determine fundamental parameter of the shielding analysis using PHITS and FLUKA codes. And the distribution of the dose rate at the outside of thick shielding wall was presented
Bending continuous structures with SMAs: a novel robotic fish design
International Nuclear Information System (INIS)
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.
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.
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.
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.
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
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.
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%.
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.
The effects of some factors on the impact bending strength of laminated veneer lumber
Directory of Open Access Journals (Sweden)
Bekir Cihad Bal
2012-11-01
Full Text Available In this study, the impact bending strengths and specific impact bending strengths were determined for solid wood and laminated veneer lumber (LVL produced from eucalyptus (Eucalyptus grandis W. Hill ex Maiden, poplar (Populus x euramericana I-214, and beech (Fagus orientalis L. woods using urea formaldehyde (UF, melamine urea formaldehyde (MUF, and phenol formaldehyde (PF adhesives. The tests were conducted in the flatwise and edgewise directions. In addition, specific impact bending strengths were calculated. Three-way ANOVA test results indicated that the effects of the species of tree and the direction of the load on the impact bending and specific impact bending were statistically significant. The type of adhesive was found to be insignificant. In addition, the results showed that impact bending strengths of solid beech and eucalyptus woods were greater than those of LVLs made of beech and eucalyptus, and no statistical differences were determined between solid poplar wood and LVL made of poplar.
Probing a label-free local bend in DNA by single-molecule Tethered Particle Motion
Brunet, Annaël; Chevalier, Sébastien; Destainville, Nicolas; Manghi, Manoel; Rousseau, Philippe; Salhi, Maya; Salomé, Laurence; Tardin, Catherine
2015-01-01
Being capable of characterizing DNA local bending is essential to understand thoroughly many biological processes because they involve a local bending of the double helix axis, either intrinsic to the sequence or induced by the binding of proteins. Developing a method to measure DNA bend angles that does not perturb the conformation of the DNA itself or the DNA-protein complex is a challenging task. Here, we propose a joint theory-experiment high throughput approach to rigorously measure such...
Probing a label-free local bend in DNA by single molecule tethered particle motion
Brunet, Annaël; Chevalier, Sébastien; Destainville, Nicolas; Manghi, Manoel; Rousseau, Philippe; Salhi, Maya; Salomé, Laurence; Tardin, Catherine
2015-01-01
Being capable of characterizing DNA local bending is essential to understand thoroughly many biological processes because they involve a local bending of the double helix axis, either intrinsic to the sequence or induced by the binding of proteins. Developing a method to measure DNA bend angles that does not perturb the conformation of the DNA itself or the DNA-protein complex is a challenging task. Here, we propose a joint theory-experiment high-throughput approach to rigorously measure such...
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...
International Nuclear Information System (INIS)
The effects of different misalignments of bending magnets with very small bending radius (ρ b = 180, in some cases 360 degree) are discussed. These magnets are represented by n segments. A method is given to calculate misalignments of a segment at any α b bend angle from the misalignments of the whole (rigid) magnet. This method is then used to calculate distorted closed orbits for the SXLS ring. 6 refs., 10 figs., 1 tab
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...
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
Contained Rupture in HeartMate II Outflow Graft Bend Relief Disconnection.
Chua, Kim Chai; Tan, Teing Ee; Lim, Chong Hee; Kerk, Ka Lee; Sivathasan, Cumaraswamy
2016-03-01
Thoratec recalled their HeartMate II ventricular assist device in March 2012 after some problems related to disconnection of the bend relief. Abrasion on the pump outflow graft caused by a disconnected bend relief is rare. We report the case of a 49-year-old man in whom a disconnected bend relief caused a puncture in the outflow graft, resulting in a contained hematoma, requiring outflow graft replacement. PMID:25348159
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)
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 are not...
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 ...
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.
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.
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)
The evaluation of helical bending for steam generator in integral reactor
International Nuclear Information System (INIS)
An integral reactor in comparison with loop reactor is that all of major primary components are placed in reactor vessel. It is necessary of helical bending to be manufactured once-through steam generator in the integral reactor, On the other hand dimensions variation and introduced residual stress of the part of helical bend can be serious problem. We have executed the mock-up test of Titanium tube which is being considered integral steam generator for the sake of detecting the dimension variation and residual stress of bending part. In this paper, we present the bending properties of Titanium tube and applicable possibility in integral steam generator
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.
50-Ma initiation of Hawaiian-Emperor bend records major change in Pacific plate motion.
Sharp, Warren D; Clague, David A
2006-09-01
The Hawaiian-Emperor bend has played a prominent yet controversial role in deciphering past Pacific plate motions and the tempo of plate motion change. New ages for volcanoes of the central and southern Emperor chain define large changes in volcanic migration rate with little associated change in the chain's trend, which suggests that the bend did not form by slowing of the Hawaiian hot spot. Initiation of the bend near Kimmei seamount about 50 million years ago (MA) was coincident with realignment of Pacific spreading centers and early magmatism in western Pacific arcs, consistent with formation of the bend by changed Pacific plate motion. PMID:16946069
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.
The Cosmological Constant and the Gravitational Light Bending
Biressa, Tolu
2011-01-01
The solution of the null non-radial geodesic in a Schwarzschild-de Sitter background is revisited. The gravitational bending of a light ray is affected by the cosmological constant, in agreement with the findings of some previous investigations. The present study confirms that the leading correction term depends directly not only on the cosmological constant but also on the impact parameter and on the angular distance to the source. Using the resulting lens equation, the projected mass of the lens was estimated for several systems displaying Einstein rings. Corrections on masses due to the cosmological constant are, on the average, of the order of 2%, indicating that they are not completly negligible for lens systems at cosmological distances.
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.
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.
Dynamic hysteretic sensing model of bending-mode Galfenol transducer
Energy Technology Data Exchange (ETDEWEB)
Cao, Shuying, E-mail: shuying-cao@hebut.edu.cn; Zheng, Jiaju; Sang, Jie; Zhang, Pengfei; Wang, Bowen; Huang, Wenmei [Province-Ministry Joint Key Laboratory of Electromagnetic Field and Electrical Apparatus Reliability, Hebei University of Technology, Tianjin 300130 (China)
2015-05-07
A dynamic hysteretic sensing model has been developed to predict the dynamic responses of the magnetic induction, the stress, and the output voltage for a bending-mode Galfenol unimorph transducer subjected simultaneously to acceleration and bias magnetic field. This model is obtained by coupling the hysteretic Armstrong model and the structural dynamic model of the Galfenol unimorph beam. The structural dynamic model of the beam is founded based on the Euler-Bernouli beam theory, the nonlinear constitutive equations, and the Faraday law of electromagnetic induction. Comparisons between the calculated and measured results show the model can describe dynamic nonlinear voltage characteristics of the device, and can predict hysteretic behaviors between the magnetic induction and the stress. Moreover, the model can effectively analyze the effects of the bias magnetic field, the acceleration amplitude, and frequency on the root mean square voltage of the device.
Dynamic hysteretic sensing model of bending-mode Galfenol transducer
International Nuclear Information System (INIS)
A dynamic hysteretic sensing model has been developed to predict the dynamic responses of the magnetic induction, the stress, and the output voltage for a bending-mode Galfenol unimorph transducer subjected simultaneously to acceleration and bias magnetic field. This model is obtained by coupling the hysteretic Armstrong model and the structural dynamic model of the Galfenol unimorph beam. The structural dynamic model of the beam is founded based on the Euler-Bernouli beam theory, the nonlinear constitutive equations, and the Faraday law of electromagnetic induction. Comparisons between the calculated and measured results show the model can describe dynamic nonlinear voltage characteristics of the device, and can predict hysteretic behaviors between the magnetic induction and the stress. Moreover, the model can effectively analyze the effects of the bias magnetic field, the acceleration amplitude, and frequency on the root mean square voltage of the device
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
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...
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).
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.
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.
Homogenization of long fiber reinforced composites including fiber bending effects
DEFF Research Database (Denmark)
Poulios, Konstantinos; Niordson, Christian Frithiof
2016-01-01
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...
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.
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.
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
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.
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.
Employment of concentrated-hardsphere- suspension pad for V-bending of thin strip
Directory of Open Access Journals (Sweden)
T. Ohashi
2008-12-01
Full Text Available Purpose: Authors have suggested employment of dilatant fluid for metal forming tools, and report an applicationon v-bending of thin stainless steel strips in this paper.Design/methodology/approach: An alumina concentrated hard-sphere suspension is employed as dilatant fluid forforming. The authors evaluate the suspension with backward extrusion test. Then, the authors try to bend SUS304stainless strip with 0.25 mm thickness and 30 mm width on the pad of the suspension with a v-bend punch.Findings: Behaviour of the suspension is revealed in backward extrusion test. Migration of water takesimportant role in it. In v-bending test, including acute angle bending, the authors bend the strip with only thev-bend punch and the alumina concentrated hard-sphere suspension pad successfully. It is thought that formingload is less than with general polyurethane tools.Research limitations/implications: Spring-back in partial bending, which is similar to the suggested process,is larger than in bottoming and coining with dies and bending with polyurethane tools. Therefore, the authorsare going to evaluate the spring-back in the suggested process in further study.Practical implications: Polyurethane pad is used in bending process generally because of advantageous pointsin easy-design, and safe from scratch. However it has disadvantageous points in its limited life and necessity oflarge forming load. The alumina concentrated hard-sphere suspension can be employed for such the pad withunlimited life. In addition, such the dilatant fluid can be applied on other metal forming process as easy tool.Originality/value: Employing dilatant fluid for forming tools is new idea. Authors try v-bending with analumina concentrated hard-sphere suspension.
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.
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...
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.
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
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.
A SENSOR AND A METHOD FOR DETERMINING THE DIRECTION AND THE AMPLITUDE OF A BEND
DEFF Research Database (Denmark)
2000-01-01
-period fibre gratings (LPG), in which the intrinsic properties of the fibre and the bend sensitivity of LPG is utilised. In a preferred embodiment, the connection between the Core Concentricity Error (CCE) of the fibre and the LPG in the asymmetric bend behaviour results in coupling resonance between the core...
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
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...
Cross talk between bending, twisting, and buckling modes of three types of microcantilever sensors
Jeon, Sangmin; Braiman, Yehuda; Thundat, Thomas
2004-11-01
Microcantilevers generally deflect in three ways: bending, twisting, and buckling. Among these, the accurate measurement of bending is essential for atomic force microscopy imaging and sensing applications. However, it was found that the bending of certain cantilevers can be coupled with twisting and buckling of the cantilever. In this article, cross talk between bending and twisting modes of microcantilevers of three different designs such as rectangular, triangular, and piezoresistive cantilevers is described. For the experiments, a thermal stress was applied to the rectangular and triangular cantilevers, and a Lorentz force was exerted on the triangular and the piezoresistive cantilevers. While the bending of the rectangular cantilever induced a negligible amount of twisting when heated, the triangular cantilevers showed nonlinear twisting responses during bending. This nonlinear response of the triangular cantilever was attributed to the variations in the spring constants between the two legs. When a Lorentz force was exerted on the triangular cantilevers, coupling of the bending and twisting modes depended on the direction of a magnetic field. For the piezoresistive cantilevers, a Lorentz force induced the in-phase buckling which accompanied both the bending and twisting modes.
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...
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.
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 Influence of Cyclic Loading on Ultimate Bending Strength of Beech Solid and Laminated Wood
Directory of Open Access Journals (Sweden)
Milan Gaff
2014-09-01
Full Text Available This work investigates the influence of cyclic loading of beech solid and laminated wood of various thicknesses on ultimate bending strength (ultimate flexural strength σp during bending in radial direction. For identification of ultimate bending strength, the static bending test with three-point loading was used. The ultimate bending strength was detected on testing samples that were not cyclically loaded and the results were compared with other results obtained from samples that were cyclically loaded. The results of this work show that the influence of cyclic loading on values of ultimate bending strength for solid and laminated wood is not significant. Thickness influence is a significant factor for both tested materials. The results show that the increase of thickness causes the decrease of ultimate bending strength. In our opinion, the decrease of ultimate bending strength is not caused by the sample thickness but by different sample lengths. With the increase of the sample length, the influence of inhomogeneous wood properties also increases.
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
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 .
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)
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.
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
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
-reported social support was categorized into low, moderate, and high levels. Multi-adjusted logistic regressions estimated the association between forward bending and LBPi and the effect modification by social support. RESULTS: Forward bending and LBPi were not significantly associated but modified by social......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...... support. 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...
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.
Bending strain study of Bi-2223/Ag tapes using Hall sensor magnetometry
International Nuclear Information System (INIS)
The influence of room temperature bending on critical current (Ic) of Bi-2223/Ag tapes is studied by Hall sensor magnetometry, four-point method and scanning electron microscopy. Hall sensor magnetometry allows one to assess tape homogeneity and the amount of mechanical damage caused by bending. The microstructure of the Bi-2223 ceramic is found to strongly affect the tape behavior under bending strain. In a tape with moderate Ic = 6.1 A at 77 K and a porous ceramic core, crack propagation took place normal to the Ag-ceramic interface, whereas in tapes with dense core, Ic above 10 A at 77 K, cracks propagated in the tape plane. In monofilamentary tapes core homogeneity correlated with good bending strain performance. In multifilamentary tapes crack propagation between filaments was prohibited by the Ag matrix, thus leading to enhanced strain tolerance. In the high Ic tapes studied, bending to 25 mm radius resulted in 1%--2% Ic degradation
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
Crack opening displacement of a through-wall crack in a plate subjected to bending load
International Nuclear Information System (INIS)
This study was performed in order to clarify crack opening displacement (COD) of through-wall cracks in a plate subjected to bending load. The former COD evaluation methods were mainly developed corresponding to tensile load, but there has been nothing that has been developed corresponding to bending load. Therefore, the authors evaluated CODs of the through-wall cracks in plates which were subjected to a bending load using finite element method (FEM) analyses, and proposed a simplified COD evaluation method accounting for both tensile and bending loads. The proposed method is useful for leakage evaluation at a crack opening of an elbow crown or in the vicinity of the coolant surface of a vessel in which the bending stress is relatively large
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.
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.
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
Giammanco, Chiara H; Kramer, Patrick L; Yamada, Steven A; Nishida, Jun; Tamimi, Amr; Fayer, Michael D
2016-01-28
The population relaxation of carbon dioxide dissolved in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2) was investigated using polarization-selective ultrafast infrared pump-probe spectroscopy and two-dimensional infrared (2D IR) spectroscopy. Due to the coupling of the bend with the asymmetric stretch, excitation of the asymmetric stretch of a molecule with a thermally populated bend leads to an additional peak, a hot band, which is red-shifted from the main asymmetric absorption band by the combination band shift. This hot band peak exchanges population with the main peak through the gain and loss of bend excitation quanta. The isotropic pump-probe signal originating from the unexcited bend state displays a fast, relatively small amplitude, initial growth followed by a longer time scale exponential decay. The signal is analyzed over its full time range using a kinetic model to determine both the vibrational lifetime (the final decay) and rate constant for the loss of the bend energy. This bend relaxation manifests as the fast initial growth of the stretch/no bend signal because the hot band (stretch with bend) is "over pumped" relative to the ground state equilibrium. The nonequilibrium pumping occurs because the hot band has a larger transition dipole moment than the stretch/no bend peak. The system is then prepared, utilizing an acousto-optic mid-infrared pulse shaper to cut a hole in the excitation pulse spectrum, such that the hot band is not pumped. The isotropic pump-probe signal from the stretch/no bend state is altered because the initial excited state population ratio has changed. Instead of a growth due to relaxation of bend quanta, a fast initial decay is observed because of thermal excitation of the bend. Fitting this curve gives the rate constant for thermal excitation of the bend and the lifetime, which agree with those determined in the pump-probe experiments without frequency
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.
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.
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.
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.
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.
Service water corrosion control at River Bend Station
International Nuclear Information System (INIS)
Service water systems are demanding more engineering, operations, and maintenance attention than ever before. Problems affecting service water systems have become more complex and more frequent due to increased environmental restrictions and unique concerns such as asiatic clams. Proven corrosion inhibitors like chromates are no longer permitted for discharge to the environment. Treatment program choices available to control biofouling, reduce corrosion, and prevent deposition and fouling are limited. The result is treatment programs which are less effective and which create an environment for Microbiological Influenced Corrosion (MIC). Once accelerated corrosion begins, a complex program of system design, water treatment, corrosion/deposition monitoring, inspection, repair, and operation may be necessary to restore the system. Such a program, necessitated by initial operating experience, is now in place at River Bend Station. Our experience is not unique. Both the Electric Power Research Institute and the Nuclear Regulatory Commission have initiated programs to address service water system problems, which include accelerated corrosion, deposition and fouling, degradation of heat exchanger performance and MIC
Prediction and Theory Evaluation: The Case of Light Bending
Brush, Stephen G.
1989-12-01
Is a theory that makes successful predictions of new facts better than one that does not? Does a fact provide better evidence for a theory if it was not known before being deduced from the theory? These questions can be answered by analyzing historical cases. Einstein's successful prediction of gravitational light bending from his general theory of relativity has been presented as an important example of how ``real'' science works (in contrast to alleged pseudosciences like psychoanalysis). But, while this success gained favorable publicity for the theory, most scientists did not give it any more weight than the deduction of the advance of Mercury's perihelion (a phenomenon known for several decades). The fact that scientists often use the word ``prediction'' to describe the deduction of such previously known facts suggests that novelty may be of little importance in evaluating theories. It may even detract from the evidential value of a fact, until it is clear that competing theories cannot account for the new fact.
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
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...
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)
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
Optical diffraction for measurements of nano-mechanical bending.
Hermans, Rodolfo I; Dueck, Benjamin; Ndieyira, Joseph Wafula; McKendry, Rachel A; Aeppli, Gabriel
2016-01-01
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. PMID:27255427
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
Boyle, Jason M; Liu, Jianbo; Anderson, Scott L
2009-04-23
A large set of quasi-classical trajectories were calculated at the PBE1PBE/6-311G** level of theory, in an attempt to understand the mechanistic origins of the large, mode-specific enhancement of the O-transfer reaction by NO2+ bending vibration and the surprisingly large suppressing effect of bending angular momentum. The trajectories reproduce the magnitude of the absolute reaction cross section, and also get the dependence of reactivity on NO2+ vibrational state, and the vibrational state dependent scattering behavior qualitatively correct. Analysis of the trajectories shows that the bending effect is not simply a consequence of enhanced reactivity in bent geometries but, rather, that excitation of bending motion allows reaction in a wider range of orientation angles, even if the NO2+ is not bent at the onset of the collisional interaction. There is a strong interplay between NO2+ bending and transient charge transfer during the collisions. Such charge transfer enhances reactivity, but only if the reactants are oriented correctly. PMID:19182967
Xia, Xingda; Yang, Bingchu; Zhang, Xiang; Zhou, Conghua
2015-07-01
Bending is usually used to test durability of flexible transparent and conductive films. Due to the large stress incurred by this technique, bending has always been observed to deteriorate conductance of electrodes such as indium tin oxide film. In contrast, we here demonstrate that bending could be used to improve conductance of silver nanowire-based flexible transparent and conductive films. The enhanced conductance is due to improved contact between nanowires, which was favored by the hydrogen bond formed between residential polyvinylpyrrolidone (PVP) on silver nanowire and TiOx nanoparticles pre-coated on the substrate. The enhanced conductance was found to be affected by bending direction; bending towards the substrate not only yielded quicker decrease in sheet resistance, but also showed better film conductance than bending towards the nanowires. Then, with assistance of surface modification of substrate and ultra-long silver nanowires (averaged at 124 μm, maximum at 438 μm), optoelectronic performance of 90.2% (transmittance at 550 nm) and 12.5 Ω sq-1 (sheet resistance) has been achieved by bending. Such performance was better than commercialized flexible ITO films, and even competed with that obtained from thermal annealing at temperature of 200 °C. Moreover, Fourier transfer infrared (FTIR) spectroscopy study showed strong coordination between C=O (heterocyclic ring of PVP) and silver atoms, showing obvious capping behavior of PVP on silver nanowires.
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
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.
Bending Characteristics of Foldable Touch Display Panel with a Protection Structure Design
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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.
Experimental study on improvement effect of guide wall to water flow in bend of spillway chute.
Zhang, Qinghua; Diao, Yanfang; Zhai, Xingtao; Li, Shuning
2016-01-01
In order to improve water flow in a bend of a spillway chute using a guide wall, modeling experiments with or without a guide wall under conditions of three different bend axial radii, three chute bottom slopes and three flow rates were carried out in this study. Two indexes were calculated, which are the improved water surface uniformity and the reduced rate of water surface difference in concave and convex banks of the cross-section. The results show that: (1) setting a guide wall in a bend can improve water flow in the bend because it increased the water surface uniformity of the cross-section and reduced the water surface difference in the concave and convex banks; (2) the smaller the bend axial radius, the better the water surface improvement effect will be using a guide wall; (3) the steeper the bottom slope, the more cross-sections with less water surface difference; and (4) flow rates have a great influence on water surface improvement in the bend, and the guide wall can improve water flow obviously when the water depth in the starting section of the bend is lower than the height of the guide wall. This study has important implications in engineering design of guide walls. PMID:26877052
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.
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
Drabik, Dominik; Przybyło, Magda; Chodaczek, Grzegorz; Iglič, Aleš; Langner, Marek
2016-02-01
Lipid bilayer is the main constitutive element of biological membrane, which confines intracellular space. The mechanical properties of biological membranes may be characterized by various parameters including membrane stiffness or membrane bending rigidity, which can be measured using flicker noise spectroscopy. The flicker noise spectroscopy exploits the spontaneous thermal undulations of the membrane. The method is based on the quantitative analysis of a series of microscopic images captured during thermal membrane fluctuations. Thus, measured bending rigidity coefficient depends on the image quality as well as the selection of computational tools for image processing and mathematical model used. In this work scanning and spinning disc confocal microscopies were used to visualize fluctuating membranes of giant unilamellar vesicles. The bending rigidity coefficient was calculated for different acquisition modes, using different fluorescent probes and different image processing methods. It was shown that both imaging approaches gave similar bending coefficient values regardless of acquisition time. Using the developed methodology the effect of fluorescent probe type and aqueous phase composition on the value of the membrane bending rigidity coefficient was measured. Specifically it was found that the bending rigidity coefficient of DOPC bilayer in water is smaller than that determined for POPC membrane. It has been found that the POPC and DOPC bending rigidities coefficient in sucrose solution was lower than that in water. Fluorescence imaging makes possible the quantitative analysis of membrane mechanical properties of inhomogeneous membrane. PMID:26615919
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
Axial forces and bending moments in the loaded rabbit tibia in vivo
Directory of Open Access Journals (Sweden)
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.
2011-04-26
..., Recreation Team Leader, Bend-Fort Rock Ranger District, Red Oaks Square, 1230 NE Third Street Suite A-262... Forest Service Bend/Ft. Rock Ranger District; Deschutes National Forest; Deschutes County, Oregon; Mt... Federal Register. ADDRESSES: Send written comments to Shane Jeffries, District Ranger, Bend-Fort...
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.
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
Determination of creep parameters from three-point bending test with C-shape specimen
International Nuclear Information System (INIS)
In this paper the creep parameters for a Norton law material are determined from the creep bending tests data by an elliptical arc shape specimen. According to the ideal time-dependent beam theory, the creep coefficient B and creep exponent are derived as a function of the applied load and displacement rate. Finite element simulations of the elliptical arc specimen bending creep are also carried out to validate the feasibility and accuracy of the proposed approach. Our work will contribute to a better understanding to derive creep parameters from creep bending test and extend its application for the milli/micro scale miniature specimen
Mcm1p-Induced DNA Bending Regulates the Formation of Ternary Transcription Factor Complexes
Lim, Fei-Ling; Hayes, Andrew; West, Adam G; Pic-Taylor, Aline; Darieva, Zoulfia; Morgan, Brian A; Oliver, Stephen G.; Sharrocks, Andrew D.
2003-01-01
The yeast MADS-box transcription factor Mcm1p plays an important regulatory role in several diverse cellular processes. In common with a subset of other MADS-box transcription factors, Mcm1p elicits substantial DNA bending. However, the role of protein-induced bending by MADS-box proteins in eukaryotic gene regulation is not understood. Here, we demonstrate an important role for Mcm1p-mediated DNA bending in determining local promoter architecture and permitting the formation of ternary trans...
Waveguide Bend of 90° in Two-Dimensional Triangular Lattice Silicon Photonic Crystal Slabs
International Nuclear Information System (INIS)
We design and realize a 90° waveguide bend in two-dimensional triangular lattice silicon photonic crystal slabs by connecting linear waveguides along the orthogonal Γ – K and Γ – M directions. A pass band of 70 nm is realized by optimizing the geometry of the Γ – M waveguide. The connection region of the waveguide bend is optimized to improve the transmission efficiency of infrared light through the two different kinds of waveguides. The transmission efficiency of an optimized single bend is about 75% in simulation and 45% in measurement. (fundamental areas of phenomenology (including applications))
The influence of the bending process on the critical current of high-Tc superconducting tapes
International Nuclear Information System (INIS)
The results of measurements of the influence of bending strain up to 1% on the current-voltage characteristics of high Tc superconducting tapes of Bi-2223 type are presented. Theoretical explanation of this effect, taking into account the creation of mechanical micro-cracks inside the filaments during bending, is discussed. The mechanism leading to the variation of the current-voltage characteristics and the decrease of the critical current as a result of the bending strain is considered taking into account the superposition of the percolation and flux creep effects. The critical current anisotropy in high temperature superconducting tapes in this model is also predicted
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.
EFFECTS OF TEMPERATURE ON THE BENDING PERFORMANCE OF WOOD-BASED PANELS
Jianhui Zhou; Chuanshuang Hu; Shuofei Hu; Hong Yun; Guifen Jiang,; Shikang Zhang
2012-01-01
The effect of temperature in the range from 25 ºC to 175 ºC on the bending performance of plywood and medium density fiberboard (MDF) has been studied with the ultimate purpose of optimizing the post-processing using radio frequency heating and improving the quality of the final products. Static 3-point bending tests were conducted on a universal testing machine inside a computer-controlled chamber. Results show that the bending strength (MOR) and modulus of elasticity (MOE) of plywood and MD...
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
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...
fMRI-compatible registration of jaw movements using a fiber-optic bend sensor
MacIntosh, Bradley J.; Graham, Simon J.
2010-01-01
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 recordi...
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.
Creep of uranium dioxide: bending test and mechanical behaviour
International Nuclear Information System (INIS)
These PhD work in the frame of Pellet-Cladding Interactions studies, in the fuel assemblies of nuclear plants. Electricite de France (EDF) must well demonstrate and insure the integrity of the cladding. For that purpose, the viscoplastic behaviour of the nuclear fuel has to be known and, if possible, controlled. This PhD work aimed to characterize the creep of uranium dioxide, in conditions of transient power regime. First, a literature survey on mechanical behaviour of UO2 revealed that the ceramic was essentially studied with compressive tests, and that its creep behaviour is characterized by two domains, depending on the stress level. To estimate the loadings in a fuel pellet, EDF and CEA developed specific global codes. A simulation during a power ramp allowed the order of magnitude of the loadings in the pellet to be determined (temperature, thermal gradients, strains, strain rate...). The stress calculation using a finite element simulation requires the identification of behaviour laws, able to describe the behaviour under small strains, low strain rates, and under tensile stresses. Starting from this observation, three point bending method has been chosen to test the uranium dioxide. As, for representativeness reasons, testing specimens cut in actual fuel pads was required in our study; a ten millimeters span has been used. For this study, a specific three-point testing device has been developed, that can tests specimens up to 2 000 C in a controlled atmosphere (Ar + 5% H2). A special care has been taken for the measurement of the deflexion of the sample, which is measured using a laser beam, that allow an accuracy of ±2μm to be reached at high temperature. Specimens with 0,5 to 1 mm thickness have been tested using this jig. A Norton's law describe, with respective stress exponent and activation energy values of 1.73 and 540 kJ.mole-1, provided a good description of the stationary creep rate. Then, the mechanical behaviour of the fuel has been modeled
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.
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
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.
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.
International Nuclear Information System (INIS)
Selected data showing typical macroscopic residual stress distributions in U-bent Inconel 600 and 90 degrees bends in Incoloy 800 are presented. The results indicate regions of both high magnitude tension and compression in the longitudinal direction around the circumference of the bends at the apex. The microscopic residual stress, or percent plastic strain and macroscopic residual distributions in the surface of cross-roll straightened and ground Inconel 600 tubing are described. The results indicate a compressive surface layer accompanied by a yield strength gradient from 90 ksi at the surface to 30 ksi at a depth of 0.003 in
International Nuclear Information System (INIS)
I-V characterization of commercial multi-filamentary Magnesium Di-Boride (MgB2) wire of diameter 0.83 mm were studied in cryocooler based self-field characterization system under both react and bent mode and bent and react mode for a range of temperature 6 K - 25 K. This study is of practical technical relevance where the heat treatment of the superconducting wire makes the sample less flexible for winding in magnet and in other applications. There are limited reported data, available on degradation of MgB2 wire with bending induced strain in react and wind and wind and react method. In the present work the bending diameter were varied from 80 mm to 20 mm in the interval of 10 mm change of bending diameter and for each case critical current (Ic) of the strand is measured for the above range of temperature. An ETP copper made customized sample holder for mounting the MgB2 strand was fabricated and is thermally anchored to the cooling stage of the cryocooler. It is seen from the experimental data that in react and bent mode the critical current degrades from 105 A to 87 A corresponding to bending diameter of 80 mm and 20 mm respectively. The corresponding bending strain was analytically estimated and compared with the simulation result. It is also observed that in react and bent mode, the degradation of the transport property of the strand is less as compared to react and bent mode. For bent and react mode in the same sample, the critical current (Ic) was measured to be ∼145 A at 15 K for bending diameter of 20 mm. Apart from studying the bending induced strain on MgB2 strand, the tensile test of the strand at RT was carried out. The electrical characterizations of the samples were accompanied by the microstructure analyses of the bent strand to examine the bending induced degradation in the grain structure of the strand. All these experimental findings are expected to be used as input to fabricate prototype MgB2 based magnet. (author)
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...
Measurements of emittance growth through the achromatic bend at the BNL Accelerator Test Facility
International Nuclear Information System (INIS)
Measurements of emittance growth in a high peak current beam as it passes through an achromatic double bend are summarized. Experiments were performed using the ATF at Brookhaven National Laboratory by X.J. Wang and D. Kehne as a collaboration resulting from the proposal attached at the end of the document. The ATF consists off an RF gun (1 MeV), two sections of linac (40-75 MeV), a diagnostic section immediately following the linac, a 20 degree bend magnet, a variable aperture slit at a high dispersion point, 5 quadrupoles, then another 20 degree bend followed by another diagnostic section. The TRANSPORT deck describing the region from the end of the linac to the end of the diagnostic line following the achromatic bends is attached to the end of this document. Printouts of the control screens are also attached
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.
Stress Corrosion Cracking of Basalt/Epoxy Composites under Bending Loading
Shokrieh, Mahmood M.; Memar, Mahdi
2010-04-01
The purpose of this research is to study the stress corrosion behavior of basalt/epoxy composites under bending loading and submerged in 5% sulfuric acid corrosive medium. There are limited numbers of research in durability of fiber reinforced polymer composites. Moreover, studies on basalt fibers and its composites are very limited. In this research, mechanical property degradation of basalt/epoxy composites under bending loading and submerged in acidic corrosive medium is investigated. Three states of stress, equal to 30%, 50% and 70% of the ultimate strength of composites, are applied on samples. High stress states are applied to the samples to accelerate the testing procedure. Mechanical properties degradation consists of bending strength, bending modulus of elasticity and fracture energy of samples are examined. Also, a normalized strength degradation model for stress corrosion condition is presented. Finally, microscopic images of broken cross sections of samples are examined.
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 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.
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.
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.
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.
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.
Influence of coherent twin boundaries on three-point bending of gold nanowires
International Nuclear Information System (INIS)
In the present work we elucidate the deformation mechanisms of twinned Au nanowires (NWs) under three-point bending by means of molecular dynamics simulations. We further investigate the effects of twin boundary orientation, NW diameter and twin boundary spacing on the mechanical properties and deformation behaviors of NWs. Our simulation results reveal that dislocation slip, twin boundary associated mechanisms and deformation twinning work in parallel in the heterogeneous localized plastic deformation of twinned Au NWs under bending. The dislocation–twin boundary interactions can be significantly altered by changing the twin boundary orientation as well as the bending direction. Furthermore, the NW diameter and twin boundary spacing strongly influence the competition between individual deformation mechanisms, which in turn leads to extrinsic and intrinsic size effects on the strength and the bending ductility of the NWs. (paper)
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.
75 FR 54381 - Charles M. Russell National Wildlife Refuge and UL Bend National Wildlife Refuge, MT
2010-09-07
... wild ungulates and responsible synthetic methods such as farming and tree planting. Wildlife-dependent... Register (72 FR 68174, December 4, 2007). Charles M. Russell and UL Bend NWRs encompass nearly 1.1...
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...
Effects of kinesio taping on lumbopelvic-hip complex kinematics during forward bending.
Kim, Soo-Yong; Kang, Min-Hyeok; Kim, Eui-Ryong; Kim, Gyoung-Mo; Oh, Jae-Seop
2015-03-01
[Purpose] The aim of this study was to investigate the effect of kinesio taping (KT) on the kinematics of the lumbo-pelvic-hip complex during forward bending by individuals with reduced hamstring extensibility. [Subjects] Eighteen males with reduced hamstring extensibility were randomly assigned to one of two groups:, the hamstring KT group (n=9), or the sham KT group (n=9). [Methods] The kinematics of the lumbopelvic-hip complex during lumbar forward bending was measured using a motion capture system before and after applying KT. [Results] The angle of lumbar flexion during late lumbar forward bending increased significantly post-KT compared to pre-KT measurements in the hamstring KT group. [Conclusion] These findings suggest that KT does not directly affect an individual's movement during lumbar forward bending. PMID:25931760
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 longrange development of the Division, by identifying and...
Irradiation creep in bending of cold-worked AISI 316 stainless steel at low neutron fluence
International Nuclear Information System (INIS)
The results from the first and second interim examinations of a test to measure irradiation creep in bending of 20 percent cold-worked AISI 316 stainless steel are presented. These low-fluence results indicate that irradiation creep in bending exhibits a larger primary creep component of the total strain as compared with creep in biaxial pressurized tubes of the same heat of material, but the secondary creep rates in the two cases appear to be similar. The data also indicate that the bending strains have a linear fluence and stress dependency, and strains measured on beams fabricated parallel to and transverse to the direction of cold work are similar, indicating that material texture anisotropy does not effect irradiation creep in bending. 6 refs
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.
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...
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.
Rousset, G; Charbonnier, F; Lepoutre, F.
1983-01-01
The calculation of the thermoelastic bending of thin plates shows that this effect can dominate the photoacoustic effect with thermally thick samples. An application of this calculation to thermal diffusivity measurements is given.
Yao, Bao-guo; Zhang, Shan; Yang, Yun-juan; Zhang, De-pin
2016-01-01
A new test method and a measurement system was proposed and developed to evaluate the bending and twisting properties of textile fabrics. The measurement system and the test method is based on the mechanical device, sensors and microelectronics and simulates the dynamic process during the fabric is bent and twisted. The virtual instrument based system can measure the dynamic changes of the signals due to the bending and twisting loads. Derived from the test data, a series of indices are defined to characterize the bending and twisting properties. The test and evaluation method, the experiments and the test results are reported. The analysis of the variance for intra-laboratory test was performed to determine the precisions of the test method and the measurement system. The measurement system provides a method for objective measurement and evaluation of bending and twisting properties of textile fabrics.
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
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...
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.
Reliability studies on printed conductors on flexible substrates under cyclic bending
Happonen, T. (Tuomas)
2016-01-01
Abstract This thesis investigates the reliability of printed conductors on flexible substrates under cyclic bending. The topic is approached by studying the effects of several key design parameters on the bending lifetime of printed conductors under dynamic loading. In this thesis, the test specimens with various cross-sectional geometries were printed on different plastic and paper substrates. The test samples were fabricated with two printing methods, silk screen and roll-to-roll pri...
Axial forces and bending moments in the loaded rabbit tibia in vivo
Reifenrath Janin; Gottschalk Daniel; Angrisani Nina; Besdo Silke; Meyer-Lindenberg Andrea
2012-01-01
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. T...
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...
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.
Impact of bending strain on critical current of second generation 344 YBCO high Tc coated conductor
International Nuclear Information System (INIS)
Second generation YBCO coated conductor has been characterized under various bending stresses. The down slope of the critical current with increasing strain has been supported by the SEM analysis of the tape. The tensile as well as flexural strength of the tape also have been determined experimentally at room temperature. The stress profile of the critically bend strip has been analyzed in ANSYS and the maximum stress on the YBCO strip in the operating condition has been quantified. (author)
Mass transfer coefficient factor in pipe bend - 3 D CFD analysis
International Nuclear Information System (INIS)
In power industries Flow Accelerated Corrosion (FAC) has been a concern for pipe wall thinning where high velocity fluid at elevated temperatures is used. Even straight pipes are found to have non uniform corrosion and this is enhanced in junctions such as bends, orifices etc. Mass transfer coefficient (MTC) which defines the amount of corrosion changes from its value in straight pipe (with same fluid parameters) for flow in bends, orifice etc due to changes in velocity profile in axial direction. In this paper, 3 D computational fluid dynamics (CFD) simulation is carried out for an experiment on 58° bend angle and 2D bend radius circular carbon steel pipe carrying water at 120°C under neutral pH conditions. The turbulent model K-ω with shear stress transport was used for this purpose. The mass transfer boundary layer (MTBL) thickness δmtbl depends on Schmidt number (Sc), as δmtbl ∼ δh/(Sc1/3). MTBL is significantly smaller than hydrodynamic boundary layer δh for large Sc, hence boundary layer meshing was carried out deep into δmtbl. Uniform velocity was applied at the inlet. The flow velocity was 3 m/s at room temperature while the experimental fluid velocity was 7 m/s. Lower value of fluid velocity is chosen due to the limitations of grid size since it depends inversely on fluid velocity. The ratio of MTC in bend to straight pipe is not strongly dependent on Sc. CFD simulation at lower temperature is sufficient to get approximate MTC in bends. The ratio of the mass transfer coefficient at some locations in bend to the straight pipe coefficient (MTCR) is determined through simulation. The MTC increased in the extrados of the bend towards the outlet. (author)
Transport and deposition of spherical microparticles with single-shell in a 90 degree bend
Directory of Open Access Journals (Sweden)
Chen Zhen-Hua
2015-01-01
Full Text Available Theoretical investigation on particle transport in a 90 degree bend was carried out. The finite volume method was used to simulate the flow field in the bend pipe, and one-way coupled Lagrangian method was used to calculate the trajectory and deposition efficiency of microparticles. The unique relationship between the irreversible deposition efficiency and radius ratio of single-shell microparticle was given finally.
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
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...
Modelling of current distribution in Nb3Sn multifilamentary strands subjected to bending
Miyoshi, Y.; Zhou, C.; van Lanen, E. P. A.; Dhallé, M. M. J.; Nijhuis, A.
2012-05-01
In Nb3Sn cable-in-conduit conductors (CICCs), strands follow complex trajectories that result in a periodic bending strain acting on the strands upon electromagnetic loading and thermal contraction. Such a periodic bending strain leads to degradation of the overall transport performance of a CICC. Aiming for a better understanding and quantitative correlation between strand degradation and CICC test results, a detailed strand model is essential in combination with accurate intra-strand resistance data, the spatial filament strain distribution, and the associated filament crack distribution. Our novel numerical strand model is a 3D network of resistors including superconducting filaments, normal matrix elements, and an outer stabilizing shell or inner core. Along the strand length, matrix elements have Ohmic resistance, there is a filament-to-matrix contact resistance (Rfm) between filaments and matrix elements, while superconducting filaments have a power-law voltage-current (VI) characteristic with critical current (Ic) and an n-value described by the ITER Nb3Sn strain scaling law based on measured strand data. The model simulates the VI characteristic in a periodic bending experiment and provides the associated spatial potential distribution. The VI characteristics representing the low- and high-resistivity limits (LRL and HRL) are identified for periodic and uniform axial bending. The voltage level for the current transfer regime depends on the strand internal resistivities, i.e. the filament-to-matrix contact and the matrix resistivity, the twist pitch and the bending wavelength. The simulation results show good agreement against Ic degradation, as experimentally measured by the TARSIS facility, versus the assessed peak bending strain. In addition we discuss different methods for determining the applied peak bending strain. The model provides a basis to find a practical relationship between a strand’s VI characteristic and the periodic bending strain, as well
Modelling of current distribution in Nb3Sn multifilamentary strands subjected to bending
International Nuclear Information System (INIS)
In Nb3Sn cable-in-conduit conductors (CICCs), strands follow complex trajectories that result in a periodic bending strain acting on the strands upon electromagnetic loading and thermal contraction. Such a periodic bending strain leads to degradation of the overall transport performance of a CICC. Aiming for a better understanding and quantitative correlation between strand degradation and CICC test results, a detailed strand model is essential in combination with accurate intra-strand resistance data, the spatial filament strain distribution, and the associated filament crack distribution. Our novel numerical strand model is a 3D network of resistors including superconducting filaments, normal matrix elements, and an outer stabilizing shell or inner core. Along the strand length, matrix elements have Ohmic resistance, there is a filament-to-matrix contact resistance (Rfm) between filaments and matrix elements, while superconducting filaments have a power-law voltage–current (VI) characteristic with critical current (Ic) and an n-value described by the ITER Nb3Sn strain scaling law based on measured strand data. The model simulates the VI characteristic in a periodic bending experiment and provides the associated spatial potential distribution. The VI characteristics representing the low- and high-resistivity limits (LRL and HRL) are identified for periodic and uniform axial bending. The voltage level for the current transfer regime depends on the strand internal resistivities, i.e. the filament-to-matrix contact and the matrix resistivity, the twist pitch and the bending wavelength. The simulation results show good agreement against Ic degradation, as experimentally measured by the TARSIS facility, versus the assessed peak bending strain. In addition we discuss different methods for determining the applied peak bending strain. The model provides a basis to find a practical relationship between a strand’s VI characteristic and the periodic bending strain, as
Effects of kinesio taping on lumbopelvic-hip complex kinematics during forward bending
Kim, Soo-Yong; Kang, Min-Hyeok; Kim, Eui-ryong; Kim, Gyoung-Mo; Oh, Jae-Seop
2015-01-01
[Purpose] The aim of this study was to investigate the effect of kinesio taping (KT) on the kinematics of the lumbo-pelvic-hip complex during forward bending by individuals with reduced hamstring extensibility. [Subjects] Eighteen males with reduced hamstring extensibility were randomly assigned to one of two groups:, the hamstring KT group (n=9), or the sham KT group (n=9). [Methods] The kinematics of the lumbopelvic-hip complex during lumbar forward bending was measured using a motion captu...
Vibrational relaxation of the H2O bending mode in liquid water.
Larsen, Olaf F A; Woutersen, Sander
2004-12-22
We have studied the vibrational relaxation of the H(2)O bending mode in an H(2)O:HDO:D(2)O isotopic mixture using infrared pump-probe spectroscopy. The transient spectrum and its delay dependence reveal an anharmonic shift of 55+/-10 cm(-1) for the H(2)O bending mode, and a value of 400+/-30 fs for its vibrational lifetime. PMID:15606231
Vibrational relaxation of the H2O bending mode in liquid water
Larsen, Olaf F. A.; Woutersen, Sander
2004-12-01
We have studied the vibrational relaxation of the H2O bending mode in an H2O:HDO:D2O isotopic mixture using infrared pump-probe spectroscopy. The transient spectrum and its delay dependence reveal an anharmonic shift of 55±10 cm-1 for the H2O bending mode, and a value of 400±30 fs for its vibrational lifetime.
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 ...
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...
fMRI-compatible registration of jaw movements using a fiber-optic bend sensor
Directory of Open Access Journals (Sweden)
Bradley J MacIntosh
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.
fMRI-Compatible Registration of Jaw Movements Using a Fiber-Optic Bend Sensor.
Sörös, Peter; Macintosh, Bradley J; Tam, Fred; Graham, Simon J
2010-01-01
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 two 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. PMID:20463865
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...
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...
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.
EFFECT OF ADHESIVE TYPE ON THE BENDING MOMENT CAPACITY OF MITER FRAME CORNER JOINTS
Directory of Open Access Journals (Sweden)
Suat Altun
2010-05-01
Full Text Available The bending moment capacity was studied under the diagonal tensile and compression loadings of miter corner joints with dovetail fitting in frames made with medium density fiberboard (MDF. The influence of the type of adhesive in the joints with dovetail fitting on bending moment capacity under diagonal tensile and compression loading were considered, and the joints without adhesive were compared. A total of 80 each miter frame corner joint specimens with dovetail fitting were made. Polyvinyl acetate (PVAc, polyurethane (PU, and cyanoacrylate (CA adhesives were used, and 20 specimens were prepared without adhesive (WA with dovetail fitting. MDF was used as a frame material, as in normal practice. The specimens were subjected to diagonal tensile and compression loadings in accordance with ASTM-D 143-94. The data were analyzed statistically. The highest bending moment capacity under diagonal tensile loading (46.09 Nm was obtained in the specimens bonded with CA adhesive and the highest bending moment capacity under diagonal compression loading (72.04 Nm was obtained in the specimens glued with PVAc adhesive. Other than this, since there is no difference between these and the unbonded joints, the PU adhesive was not effective in increasing the bending moment capacity under diagonal tensile loading, and the PU and CA adhesives were not effective in increasing the bending moment capacity under diagonal compression loadings.
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.)
"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.
Evaluation of the physical characteristic of Cerro bend blocks used for radiation therapy
International Nuclear Information System (INIS)
In Radiation Therapy, the sparing of normal tissues can be performed using either multi-leaf collimators or Cerro bend blocks. The current work focuses on the physical characteristics of Cerro bend blocks including attenuation coefficient, effective penumbra width and isodose curves undulation in penumbral regions. Materials and Methods: All measurements were performed using a dual energy linac and the Cerro bend blocks designed and fabricated using a commercial Cerro bend material. Data were collected using a calibrated ionization chamber as well as EDR2 films. Results: The results showed that the attenuation coefficient was found to be 0.4475 and 0.4276 cm-1 for photon beams 6 MV and 15 MV, respectively, and a potential air bubble with a diameter greater than 3 mm affects beam attenuation significantly. The optimum Cerro bend block width was found to be around 16 mm. The isodose curves scalloping achieved for secondary collimator jaws, were also similar. Conclusion: If Cerro bend blocks are used as a basic method to protect normal tissues, its physical characteristics will be recommended to be taken into account comprehensively.
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.
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
International Nuclear Information System (INIS)
Highlights: ► A simplified plastic collapse assessment procedure for pipe bends with a local thin area is proposed. ► Conditions under combined internal pressure and external in-plane bending moment are considered. ► The procedure is using the p–M diagram method (pressure ratio and external bending moment ratio). ► The p–M diagram is derived from the reference stresses based on the Tresca theory. ► The plastic collapse loads are ascertained by results of the full scale testing with pipe bends and FEA. - Abstract: Pipe bends are common elements in piping systems such as power or process piping, and local thinning typically occurs on pipe bends due to erosion and/or corrosion. Therefore, it is important to establish the plastic collapse condition for pipe bends having a local thin area (LTA) under combined internal pressure and external bending moment. In this paper, a simplified plastic collapse assessment procedure in the p–M (internal pressure ratio and external bending moment ratio) diagram method for pipe bends with a local thin area simultaneously subjected to internal pressure, p, and external in-plane bending moment, M, due to earthquake, etc., is proposed, which is based on the reference stresses derived from the Tresca theory under a three axes condition. The plastic collapse loads derived from the proposed p–M diagram method are ascertained by comparing with the results of experimental testing with full-scale pipe bends and those of FEA for the same sized pipe bends with an LTA having various dimensions as well.
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.
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.
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
Energy Technology Data Exchange (ETDEWEB)
Shiheido, Hirokazu, E-mail: shiheido@ak.med.kyoto-u.ac.jp; Shimizu, Jun
2015-02-20
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 (BEND3{sub 56–58}, 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
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
Optimization of bending sequence in roll forming using neural network and genetic algorithm
International Nuclear Information System (INIS)
In the roll forming process, the bending sequence plays a major role in the product quality. The optimal bending sequence results in the smallest number of passes and the flawless process. This paper presents a new optimization procedure of bending sequence in a roll forming process. The multilayer perceptron is used to build the neural network (NN), which models the variation of longitudinal strain in process while the genetic algorithm (GA) is employed to optimize the bending sequence. The data used for training the network is automatically obtained by the integration between CAD and CAE. The values of peak longitudinal strains are maximized while the number of passes is reduced to the smallest and the constraint conditions being set on the maximal longitudinal strain to avoid buckling. The overbending at final pass after spring back is also considered in this paper. Two roll forming processes are optimized in order to prove applicability and efficiency of the optimization procedure. This method maintains the longitudinal strain less than the buckling limit, whereas reducing the number of passes to the smallest. Thus, the advantages of the proposed method show the high applicability in designing and optimizing the bending sequence in the roll forming process
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.
Bending rigidity of transition metal dichalcogenide monolayers from first-principles
Lai, Kang; Zhang, Wei-Bing; Zhou, Fa; Zeng, Fan; Tang, Bi-Yu
2016-05-01
Due to the presence of a sizeable direct band gap, three-atom-thick transition metal dichalcogenide (TMDC) monolayers have been suggested as important candidates for flexible electronic and optoelectronic devices recently. The in-plane elasticity of TMDC monolayers has been investigated extensively, however, little is known about their bending rigidity. Here, we have determined bending rigidities of single-layer MX2 (M = Mo, W; X = S, Se) by fitting the energetics of single wall nanotubes from first-principles to the Helfrich Hamiltonian for the configurational energy of membranes. This parameter-free approach can avoid the controversy induced by ambiguous definition of the thickness of monolayers, which are required in the empirical determination of bending rigidity using classical shell theory. The obtained direction-dependent bending rigidities of single-layer MoS2 are 9.10 and 9.61 eV along the armchair and zigzag directions, which are larger than that estimated using shell theory but similar to the previous analytic formula based on an empirical potential. Moreover, the relative magnitude of bending rigidities for different TMDCs are found to be MoS2 theory. Further analysis indicates that this inconsistence can be understood by a competition mechanism between two-dimensional elastic modulus of monolayers and the structural relaxation of nanotubes.
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.
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.
Low-loss sharp bends in low contrast polymer hybrid metallic waveguides
Sefunc, M. A.; van de Meent, W.; Coenen, A. R.; Pace, A.; Dijkstra, M.; García-Blanco, S. M.
2015-02-01
Surface plasmons polaritons have drawn significant attention in recent years not only thanks to their capability of confining the field in the dielectric/metal interface, but also thanks to their potential to produce highly efficient thermooptical or electro-optical devices such as modulators and switches due to the presence of the metal layer amidst the electromagnetic field. However, the high confinement comes at the cost of high propagation losses due to the metal's highly absorptive nature at visible and near-IR wavelengths. In order for plasmonic devices to find a widespread use in integrated optics, an advantage over dielectric waveguides needs to be found that justifies their utilization. In this work, we present an application in which metallic waveguides perform better than their dielectric counterparts. By adding a thin metallic layer underneath the waveguide core, the total bend losses (dB/90° are reduced with respect to the bend losses of the equivalent dielectric structure without the metallic layer for a range of radii from 35 µm down to 1 µm. The results show a dramatic reduction of total bend losses in TE-polarization with values as low as 0.02 dB/90° bend for radii between 6 and 13 µm. The mechanism for the reduction of bend losses is the shielding action of the metal layer, which prevents the field to leak into the substrate. In this paper, both detailed theoretical calculations as well as experimental results for SU-8 channel waveguides will be presented.
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.
Behavior of concrete filled FRP tubes under fully reversed cyclic bending
International Nuclear Information System (INIS)
Concrete filled Fiber Reinforced Polymer (FRP) tubes (CFFT) are currently being used as piles in corrosive marine applications and as columns in bridge piers, and could be used in overhead sign structures. CFFTs provide a non-corrosive alternative to conventional materials. Studies conducted on CFFTs in the past decade have been mostly focused on the short-term monotonic behavior of this system in bending and under axial loads, with hardly any information available on their fatigue behavior. In this paper the details of a research program that was conducted to address this issue and its results are presented. The program included the testing of two full-scale specimens under reversed cyclic bending. The program also included the testing of several coupons, cut from the tubes in tension-tension fatigue. The full scale tests showed that CFFTs seem to have a relatively short fatigue life under bending moments of 40% and higher of their ultimate static bending moment capacities and that strains and deflections tend to increase gradually during cyclic bending indicating a stiffness degradation behavior. The coupon test showed that rapid stiffness degradation occurs initially then reduces due to the cracking of matrix in the hoop layers and that a fatigue life of millions of cycles could be reached for stresses less than 30% of the ultimate tensile stress. (author)
Mechanical failure of anodized aluminum under three and four-point bending tests
International Nuclear Information System (INIS)
Highlights: • We study the flexural behavior of anodic oxide layers formed on aluminum. • Three and four-point bending tests were used as techniques. • Changing the beam configuration will change the flexural response. - Abstract: In this work, three and four-point bending tests were adopted as methods for characterizing anodized aluminum beams in a sulfuric acid bath. The failure behavior of sandwich beams having aluminum oxide face sheets and aluminum core were tested. In so doing, many configurations were adopted by anodizing aluminum beams on one and both sides to investigate faces in place of tension and compression. Bending tests showed different behaviors. When the oxide was only on the top side of the beam (working in compression) a slight sudden decrease of the load was observed. This fact was absent on beams with oxide layers working in tensile. The bending behavior of sandwich beams was similar to those with oxide on top sides but with much higher loads. The mechanical failure of the oxide was mainly caused by its failure when it is placed in compression beneath the loading rollers. Finally, a morphological study of the aluminum oxide layers after bending tests was conducted by optical microscopy
Measurement of developing turbulent flow in a U-bend of circular cross-section
International Nuclear Information System (INIS)
Hot-wire measurements of the full mapping of the velocity and Reynolds stress components are reported for developing turbulent flow in a strongly curved 180 deg pipe and its tangents. A slanted wire is rotated into 6 orientations and the voltage outputs from wires are combined to obtain the mean velocity and Reynolds stress components. The strength of secondary flow reaches up to the 28% of bulk mean velocity. The strong counter-rotating vortex pair induced by the transverse pressure gradient and centrifugal force imbalance grows up to θ = 67.5 .deg. into the bend. But the vortex pair breaks down into two cell pattern after θ=90 .deg. Core vortex formation and reversal of secondary flow direction along the bend symmetry plane is cleanly found in the secondary vector plot. At θ=67.5 .deg. and θ = 90 .deg. into bend a large 'trough' develops in the longitudinal velocity toward the inside of the bend due to the breakdown of secondary flow. In the bend, the mean longitudinal velocity component changes little after θ=90 .deg., but secondary flow never achieves fully-developed state. Similar behaviors are observed in the radial and circumferential stresses
Tensile and bending mechanical properties of bulk superconductors at room temperature
International Nuclear Information System (INIS)
Tensile and 3-point bending tests of specimens cut from an Y123 and a Gd123 bulk superconductors fabricated by using the modified QMG (Quench and Melt Growth) process were carried out at room temperature. The mechanical properties obtained by two testing method were compared. The average values of the Young's modulus obtained by tensile tests, 122 GPa for Y123 and 109 GPa for Gd123, were lower than those obtained by bending tests, 132 and 117 GPa, respectively. The average values of the tensile strength, 39 MPa for Y123 and 42 MPa for Gd123, were also lower than those of the bending strength, 74 MPa and 71 MPa, respectively. There was no appreciable difference between the Weibull coefficient for the tensile strength and that for the bending strength, 6.9, in Gd123. On the other hand, the coefficient for the bending strength, 17.6, was significantly higher than that for the tensile strength, 6.8, in Y123
International Nuclear Information System (INIS)
Local and overall transport critical current IC and n-value at 77 K of multifilamentary Bi2223-composite tape were studied under applied tensile and bending strains. The IC and n-value of the local elements constituting of the overall sample and those of the overall sample were measured for the voltage probe distances 10 and 60 mm, respectively. The local IC as well as n-value varied along the sample length under both tensile and bending strains, while the critical current reduction process under the tensile strain was quite different from that under bending one; a big difference in damage among the local elements was found under tensile strain but not under bending one. While the damage process was different between the tensile and bending strains, the relation of overall IC and n-value to the local ones was described comprehensively by the voltage summation model. From the analysis of the experimentally observed critical current-applied strain relation of the local elements, the variation of the critical current determining factor 'fracture strain-residual strain' along the sample length was revealed
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
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.
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
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.
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.
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.
International Nuclear Information System (INIS)
During the first experiment of the experimental group E21 - behaviour of crack growth of piping components at operating pressure and cyclic bending load in a corrosive medium - performed within phase III of the HDR Safety Program a pipe bend made of ferritic material 20 MnMoNi 5 5 was the object investigated. During the test incipient cracks were generated by cyclic bending on the inner surface around the bend flanks. In various phases of the test characterized by sinoidal and sawtooth modes of loading and different load frequencies (1 cycle per minute and 1 cycle per 15 minutes) the cracks were further extended. At the end of the phase cyclic testing the maximum crack depth of the macrocrack embedded in a crack field was approx. 21 mm. In the final load test with monotonously rising bending moment the pipe bend failed in the form of a leak. (author)
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
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.
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.
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...
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.
International Nuclear Information System (INIS)
The induction heating bending process, which has been recently applied to nuclear piping, can generate residual stresses due to thermomechanical mechanism during the process. This residual stress is one of the crack driving forces that have important effects on crack initiation and propagation. However, previous studies have focused only on geometric shape variations such as the change in thickness and ovality. Moreover, very few studies are available on the effects of process variables on residual stresses. This study investigated the effects of process variables on the residual stress distributions of induction heating bended austenitic stainless steel (316 series) piping using parametric finite element analysis. The results indicated that the heat generation rate and feed velocity have significant effects on the residual stresses whereas the moment and bending angle have insignificant effects
Bend-Bounded Path Intersection Graphs: Sausages, Noodles, and Waffles on a Grill
Chaplick, Steven; Jelínek, Vít; Kratochvíl, Jan; Vyskočil, Tomáš
2012-01-01
In this paper we study properties of intersection graphs of k-bend paths in the rectangular grid. A k-bend path is a path with at most k 90 degree turns. The class of graphs representable by intersections of k-bend paths is denoted by B_k-VPG. We show here that for every fixed k, B_k-VPG is a proper subset of B_{k+1}-VPG and that recognition of graphs from B_k-VPG is NP-complete even when the input graph is given by a B_{k+1}-VPG representation. We also show that the class B_k-VPG (for k>0) i...
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.
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
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.
Characterization of Human Rib Biomechanical Responses due to Three-Point Bending.
Kalra, Anil; Saif, Tal; Shen, Ming; Jin, Xin; Zhu, Feng; Begeman, Paul; Yang, King H; Millis, Scott
2015-11-01
In the elderly population, rib fracture is one of the most common injuries sustained in motor vehicle crashes. The current study was conducted to predict the biomechanical fracture responses of ribs with respect to age, gender, height, weight and percentage of ash content. Three-point bending experiments were conducted on 278 isolated rib samples extracted from 82 cadaver specimens (53 males and 29 females between the ages of 21 and 87 years) for 6th and 7th levels of ribs. Statistical analyses were carried out to identify differences based on age and gender. It was found that, in comparison to males, females had significantly lower values for maximum bending moments, slopes of bending moment-angle curves, and average cortical-bone thickness (pcrash conditions. Hence, rib-material properties, which are dependent on strain rate, and are needed for wholebody finite element models representing different populations, still require more research. PMID:26660742
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.