WorldWideScience

Sample records for bend tests

  1. Wire and Cable Cold Bending Test

    Science.gov (United States)

    Colozza, Anthony

    2010-01-01

    One of the factors in assessing the applicability of wire or cable on the lunar surface is its flexibility under extreme cold conditions. Existing wire specifications did not address their mechanical behavior under cold, cryogenic temperature conditions. Therefore tests were performed to provide this information. To assess this characteristic 35 different insulated wire and cable pieces were cold soaked in liquid nitrogen. The segments were then subjected to bending and the force was recorded. Any failure of the insulation or jacketing was also documented for each sample tested. The bending force tests were performed at room temperature to provide a comparison to the change in force needed to bend the samples due to the low temperature conditions. The results from the bending tests were plotted and showed how various types of insulated wire and cable responded to bending under cold conditions. These results were then used to estimate the torque needed to unroll the wire under these low temperature conditions.

  2. Thermal Analysis of Bending Under Tension Test

    DEFF Research Database (Denmark)

    Ceron, Ermanno; Martins, Paulo A.F.; Bay, Niels

    2014-01-01

    during testing is similar to the one in the production tool. A universal sheet tribo-tester has been developed, which can run multiple tests automatically from coil. This allows emulating the temperature increase as in production. The present work performs finite element analysis of the evolution...... and distribution of temperature in the bending under tension test by making use of boundary conditions and calibration values directly measured from experiments. The overall methodology combines 2D and 3D models of the bending under tension test with steady state and transient thermal and thermo......-mechanical procedures. Results show that the proposed methodology applied to a single stroke can effectively and accurately predict the interface temperature in the test tool, thus avoiding the otherwise required thousands of thermo-mechanical FEM analyses of temperature development during testing before thermal steady...

  3. 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.

  4. Monitoring thermoplastic composites under cyclic bending tests

    Science.gov (United States)

    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.

  5. Bamboo Taper Effect on Third Point Loading Bending Test

    OpenAIRE

    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...

  6. A numerical investigation of the continuous bending under tension test

    NARCIS (Netherlands)

    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

  7. GFRP Bar: Determining Tensile Strength with Bending Test

    OpenAIRE

    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...

  8. Influence of bending test configuration on cracking behavior of FRC

    DEFF Research Database (Denmark)

    Finazzi, Silvia; Paegle, Ieva; Fischer, Gregor;

    2014-01-01

    This paper describes an investigation of the influence of the testing configuration for Fiber Reinforced Concrete in bending and aims at evaluating the influence of the test configuration details on the characterization of the material. Two different types of FRC, Steel Fiber Reinforced Concrete...... (SFRC) and Engineered Cementitious Composites (ECC), were tested and are described in this study. The materials were chosen so that one of them would be strain hardening (ECC) and the other tension softening (SFRC). Notched and un-notched three- and four-point bending tests were carried out to determine...... the flexural load-deformation response of FRC. This research focuses particularly on the influence of the appearance and depth of the notch on the cracking behavior of FRC. For this purpose, several specimens, both un-notched and notched with different depths of the notch (25 mm and 45 mm), were tested...

  9. 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.

  10. Pressure and bending tests on fibreglass augmented steel technology pipes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Qishi; Ozkan, Istemi F. [C-FER Technologies, Edmonton, Alberta, (Canada); Salama, Mamdouh M. [ConocoPhillips Company, Houston, Texas, (United States)

    2010-07-01

    The economic manufacture of large diameter high pressure pipelines is a challenge. The FAST-PipeTM concept is fabricated from a steel liner hoop-wound with non-impregnated fibreglass stands. This report presents the qualification results of the FAST-PipeTM concept. The qualification testing program studied the effects of external environment (frozen/thawed cycle), load duration and the wrap thickness on the burst and bending capacity of the FAST-PipeTM concept. Burst and pressure-bend tests were performed under different conditions and for different thickness of fibreglass. The values obtained were compared to those from unwrapped pipes. It also established FAST-PipeTM behaviour in several loading scenarios using the FEA model. The burst tests results showed that freezing temperatures do not have an impact on the pressure capacity of FAST-PipeTM. The results of the tests showed the effectiveness of dry fibreglass wrap in increasing the internal pressure capacity of the pipe.

  11. 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

  12. Evaluation of ultimate tensile strength using Miniature Disk Bend Test

    Science.gov (United States)

    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.

  13. 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...

  14. 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.

  15. 16 CFR Figure 1 to Part 1512 - Bicycle Front Fork Cantilever Bending Test Rig

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Bicycle Front Fork Cantilever Bending Test Rig 1 Figure 1 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS... Fork Cantilever Bending Test Rig EC03OC91.070...

  16. Bending Under Tension Test with Direct Friction Measurement

    DEFF Research Database (Denmark)

    Andreasen, Jan Lasson; Olsson, David Dam; Chodnikiewicz, K.;

    2006-01-01

    A special Bending-Under-Tension (BUT) transducer has been developed in which friction around the tool radius can be directly measured when drawing a plane sheet strip around a cylindrical tool-pin under constant back tension. The front tension, back tension and torque on the tool-pin are all meas...... in drawing of stainless steel showing the influence of varying process conditions and the performance of different lubricants.......A special Bending-Under-Tension (BUT) transducer has been developed in which friction around the tool radius can be directly measured when drawing a plane sheet strip around a cylindrical tool-pin under constant back tension. The front tension, back tension and torque on the tool-pin are all...... measured directly, thus enabling accurate measurement of friction and direct determination of lubricant film breakdown for varying normal pressure, sliding speed, tool radius and tool preheat temperature. The transducer is applied in an experimental investigation focusing on limits of lubrication...

  17. Standard Practice for Making and Using U-Bend Stress-Corrosion Test Specimens

    CERN Document Server

    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...

  18. Flexural strength of dental composite restoratives: comparison of biaxial and three-point bending test.

    Science.gov (United States)

    Chung, S M; Yap, A U J; Chandra, S P; Lim, C T

    2004-11-15

    This study compared two test methods used to evaluate the flexural strength of resin-based dental composites. The two test methods evaluated were the three-point bending test4 and the biaxial flexural test. Materials used in this investigation were from the same manufacturer (3M ESPE) and included microfill (A110), minifill (Z100 and Filtek Z250), polyacid modified (F2000), and flowable [Filtek Flowable (FF)] composites. Flexural strength was determined with the use of both test methods after 1 week of conditioning in water at 37 degrees C. Data were analyzed with the use of an ANOVA/Scheffe test and an independent-samples t test at significance level 0.05. Mean flexural strength (n = 7) ranged from 66.61 to 147.21 and 67.27 to 182.81 MPa for three-point bending and ball-on-three-ball biaxial test methods, respectively. In both test methods, Z100 was significantly stronger than all other composites evaluated. In the three-point bending test, flexural strength of Z250 was significantly higher than A110, F2000 and FF, and FF was significantly stronger than A110 and F2000. The biaxial test method arrived at the same conclusions except that there was no significant difference between Z250 and FF. Pearson's correlation revealed a significantly (p bending test. PMID:15386492

  19. Comparison of ring compression testing to three point bend testing for unirradiated ZIRLO cladding

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2015-04-01

    Safe shipment and storage of nuclear reactor discharged fuel requires an understanding of how the fuel may perform under the various conditions that can be encountered. One specific focus of concern is performance during a shipment drop accident. Tests at Savannah River National Laboratory (SRNL) are being performed to characterize the properties of fuel clad relative to a mechanical accident condition such as a container drop. Unirradiated ZIRLO tubing samples have been charged with a range of hydride levels to simulate actual fuel rod levels. Samples of the hydrogen charged tubes were exposed to a radial hydride growth treatment (RHGT) consisting of heating to 400°C, applying initial hoop stresses of 90 to 170 MPa with controlled cooling and producing hydride precipitates. Initial samples have been tested using both a) ring compression test (RCT) which is shown to be sensitive to radial hydride and b) three-point bend tests which are less sensitive to radial hydride effects. Hydrides are generated in Zirconium based fuel cladding as a result of coolant (water) oxidation of the clad, hydrogen release, and a portion of the released (nascent) hydrogen absorbed into the clad and eventually exceeding the hydrogen solubility limit. The orientation of the hydrides relative to the subsequent normal and accident strains has a significant impact on the failure susceptability. In this study the impacts of stress, temperature and hydrogen levels are evaluated in reference to the propensity for hydride reorientation from the circumferential to the radial orientation. In addition the effects of radial hydrides on the Quasi Ductile Brittle Transition Temperature (DBTT) were measured. The results suggest that a) the severity of the radial hydride impact is related to the hydrogen level-peak temperature combination (for example at a peak drying temperature of 400°C; 800 PPM hydrogen has less of an impact/ less radial hydride fraction than 200 PPM hydrogen for the same thermal

  20. Correlation of in-plane bending test and FEA results for thin-walled elbows

    International Nuclear Information System (INIS)

    The objective of this study is to validate a finite element analysis (FEA) simulation methodology to predict the global behavior of thin-walled elbows subjected to in-plane bending. Two in-plane closing mode bending tests and one in-plane opening mode bending test were conducted on 2'' schedule 10 elbows, and a nonlinear FEA procedure was used to simulate the tests. A detailed FEA study was carried out to determine the relative importance of weld size and location, measured wall thicknesses, and original cross-section dimensions on the reconciliation results. When the weld bead was included in the analysis, the reconciliation results for load-displacement behavior and some of the strain measurements were excellent. For those cases in which the strain measurements reconciliations were not so good, a possible explanation is provided

  1. Analysis of five-point bending test for multilayer surfacing system on orthotropic steel bridge

    NARCIS (Netherlands)

    Li, J.; Scarpas, A.; Tzimiris, G.; Kasbergen, C.; Hofman, R.; Voskuilen, J.

    2013-01-01

    The French five-point bending test (5PBT) provides a laboratory scale test that allows studying the fatigue resistance of surfacing systems on orthotropic steel deck bridges (OSDB). The surfacing structure for OSDB in the Netherlands consists mostly of multilayer system: top porous asphalt layer, gu

  2. Modelling the double cantilever beam test with bending moments by using bilinear discontinuous cohesive laws

    DEFF Research Database (Denmark)

    Valvo, Paolo S.; Sørensen, Bent F.; Toftegaard, Helmuth Langmaack

    2015-01-01

    A theoretical model of the double cantilever beam tests with bending moments (DCB-UBM) is presented. The specimen is modelled as the assemblage of two laminated beams connected by a cohesive interface. It is assumed that the traction-separation laws – i.e. the relationships between the interfacial...

  3. Design, Manufacture and Testing of A Bend-Twist D-Spar

    Energy Technology Data Exchange (ETDEWEB)

    Ong, Cheng-Huat; Tsai, Stephen W.

    1999-06-01

    Studies have indicated that an adaptive wind turbine blade design can significantly enhance the performance of the wind turbine blade on energy capture and load mitigation. In order to realize the potential benefits of aeroelastic tailoring, a bend-twist D-spar, which is the backbone of a blade, was designed and fabricated to achieve the objectives of having maximum bend-twist coupling and fulfilling desirable structural properties (031 & GJ). Two bend-twist D-spars, a hybrid of glass and carbon fibers and an all-carbon D-spar, were fabricated using a bladder process. One of the D-spars, the hybrid D-spar, was subjected to a cantilever static test and modal testing. Various parameters such as materials, laminate schedule, thickness and internal rib were examined in designing a bend-twist D-spar. The fabrication tooling, the lay-up process and the joint design for two symmetric clamshells are described in this report. Finally, comparisons between the experimental test results and numerical results are presented. The comparisons indicate that the numerical analysis (static and modal analysis) agrees well with test results.

  4. Bending Test of a Variable-Stiffness Fiber-Reinforced Composite Cylinder

    NARCIS (Netherlands)

    Blom, A.W.; Rassaian, M.; Stickler, P.B.; Gürdal, Z.

    2010-01-01

    Two carbon-fiber-reinforced composite cylinders were tested in bending. One cylinder, the baseline cylinder, consisted of 0º, 90º and ±45º plies, whereas the other cylinder, called the variable-stiffness cylinder, contained plies with fiber orientations that varied in the circumferential direction,

  5. Elasticity and yield strength of pentagonal silver nanowires: In situ bending tests

    Energy Technology Data Exchange (ETDEWEB)

    Vlassov, Sergei, E-mail: vlassovs@ut.ee [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Riia 142, 51014 Tartu (Estonia); Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Polyakov, Boris [Institute of Solid State Physics, University of Latvia, Kengaraga 8, LV-1063 Riga (Latvia); Dorogin, Leonid M.; Antsov, Mikk [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Riia 142, 51014 Tartu (Estonia); Mets, Magnus; Umalas, Madis; Saar, Rando [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Lõhmus, Rünno; Kink, Ilmar [Institute of Physics, University of Tartu, Riia 142, 51014 Tartu (Estonia); Estonian Nanotechnology Competence Centre, Riia 142, 51014 Tartu (Estonia)

    2014-02-14

    This paper reports in situ mechanical characterization of silver nanowires (Ag NWs) inside a scanning electron microscope using a cantilevered beam bending technique. Measurements consisted in controlled bending of a cantilevered NW by the tip of an atomic force microscope glued to the force sensor. Relatively high degree of elasticity followed by either plastic deformation or fracture was observed in bending experiments. Experimental data were numerically fitted into the model based on the elastic beam theory and values of Young modulus and yield strength were extracted. Measurements were performed on twenty Ag NWs with diameters from 76 nm to 211 nm. Average Young modulus and yield strength were found to be 90 GPa and 4.8 GPa respectively. In addition, fatigue tests with several millions of cycles were performed and high fatigue resistance of Ag NWs was demonstrated. - Highlights: • Mechanical properties of pentagonal silver nanowires were measured. • Cantilevered beam bending technique was used. • Measurements were performed inside a scanning electron microscope. • Young's modulus and yield point were calculated. • Both plastic deformation and fracture of nanowires were observed.

  6. The use of experimental bending tests to more accurate numerical description of TBC damage process

    Science.gov (United States)

    Sadowski, T.; Golewski, P.

    2016-04-01

    Thermal barrier coatings (TBCs) have been extensively used in aircraft engines to protect critical engine parts such as blades and combustion chambers, which are exposed to high temperatures and corrosive environment. The blades of turbine engines are additionally exposed to high mechanical loads. These loads are created by the high rotational speed of the rotor (30 000 rot/min), causing the tensile and bending stresses. Therefore, experimental testing of coated samples is necessary in order to determine strength properties of TBCs. Beam samples with dimensions 50×10×2 mm were used in those studies. The TBC system consisted of 150 μm thick bond coat (NiCoCrAlY) and 300 μm thick top coat (YSZ) made by APS (air plasma spray) process. Samples were tested by three-point bending test with various loads. After bending tests, the samples were subjected to microscopic observation to determine the quantity of cracks and their depth. The above mentioned results were used to build numerical model and calibrate material data in Abaqus program. Brittle cracking damage model was applied for the TBC layer, which allows to remove elements after reaching criterion. Surface based cohesive behavior was used to model the delamination which may occur at the boundary between bond coat and top coat.

  7. Four-point bending test of the Bauschinger effect in prestrained IF steel thin sheet

    Energy Technology Data Exchange (ETDEWEB)

    Kato, Hiroyuki, E-mail: hkato@eng.hokudai.ac.jp [Mechanical and Space Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Sasaki, Kazuaki [Mechanical and Space Engineering, Hokkaido University, Sapporo 060-8628 (Japan); Mori, T. [National Defense Academy, Yokosuka 239-0811 (Japan)

    2015-08-26

    The Bauschinger effect in a 1 mm thick sheet of interstitial free (IF) steel was examined by tensile testing (prestraining) and subsequent four-point bending. The effect was absent when the prestrain was below 4% and was present when the prestrain was above 4%. The Bauschinger effect parameter determined the elastic back stress which developed after prestraining. The occurrence of back stress coincided with the development of dislocation cell structures, observed with transmission electron microscopy.

  8. Strength testing methods for high polymer base composite materials. 3. Bending test method; Kobunshi kifukugozai no kyodo shikenho - III. Mage shikenho

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, H. [Science Univ. of Tokyo (Japan)

    1998-05-15

    In the second generation report of 1982 fiscal year, most of testing methods at that time are included. For bending test, not only the bending testing method of hard plastics in ISO 178-1975, that of woven glass roving reinforced plastics in ISO 3597-1971, that of hard plastics in JIS K7203-1982, and that of plastics and electrical insulating materials in ASTM D790-80, but also private companies` specifications as well as BS, DIN, NF and so forth are recorded. In this paper, to avoid duplication with them, those established after them are describe. In JIS K7055-1987 established in following of JIS K7203, only glass fiber reinforced plastics is limited to specify the three points bending (A method) and the four points bending (B method). In JIS K7074-1988, a bending testing method of carbon fiber reinforced plastics is specified. As a research on bending test, stress distribution at bending test, effect of insert material, simple bending, compression bending and so on are conducted. 15 refs., 9 figs., 3 tabs.

  9. Four-point Bend Testing of Irradiated Monolithic U-10Mo Fuel

    Energy Technology Data Exchange (ETDEWEB)

    Rabin, B. H. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lloyd, W. R. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schulthess, J. L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wright, J. K. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lind, R. P. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Scott, L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Wachs, K. M. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-03-01

    This paper presents results of recently completed studies aimed at characterizing the mechanical properties of irradiated U-10Mo fuel in support of monolithic base fuel qualification. Mechanical properties were evaluated in four-point bending. Specimens were taken from fuel plates irradiated in the RERTR-12 and AFIP-6 Mk. II irradiation campaigns, and tests were conducted in the Hot Fuel Examination Facility (HFEF) at Idaho National Laboratory (INL). The monolithic fuel plates consist of a U-10Mo fuel meat covered with a Zr diffusion barrier layer fabricated by co-rolling, clad in 6061 Al using a hot isostatic press (HIP) bonding process. Specimens exhibited nominal (fresh) fuel meat thickness ranging from 0.25 mm to 0.64 mm, and fuel plate average burnup ranged from approximately 0.4 x 1021 fissions/cm3 to 6.0 x 1021 fissions/cm3. After sectioning the fuel plates, the 6061 Al cladding was removed by dissolution in concentrated NaOH. Pre- and post-dissolution dimensional inspections were conducted on test specimens to facilitate accurate analysis of bend test results. Four-point bend testing was conducted on the HFEF Remote Load Frame at a crosshead speed of 0.1 mm/min using custom-designed test fixtures and calibrated load cells. All specimens exhibited substantially linear elastic behavior and failed in a brittle manner. The influence of burnup on the observed slope of the stress-strain curve and the calculated fracture strength is discussed.

  10. Effect of fluoride mouth rinses on various orthodontic archwire alloys tested by modified bending test: An in vitro study

    Directory of Open Access Journals (Sweden)

    Kamna Srivastava

    2012-01-01

    Full Text Available Objective: Fluorides can cause corrosion and degradation in mechanical properties of commonly used archwires by forming hydrofluoric acid HF and causing disruption of protective titanium oxide layer. Hence, the aim of this study was to assess the change in load deflection characteristics of Ni-Ti, Cu Ni-Ti, S.S, and β-Ti wires on immersing in fluoride mouth rinses of two types- Phosflur and neutral NaF mouth rinse utilizing a modified bending test and comparing it to control. Materials and Methods: Round preformed wires were immersed in 10 ml of control and test solution (Phosflur and S-Flo mouth rinse for 1.5 hours and incubated at 37°C. Modified bending test was carried out to evaluate load-deflection characteristics of different wires using Instron. Analysis of variance (ANOVA was applied to determine if statistically significant difference exist among the mean load values obtained at various deflections in control and test solutions. Results: There was no statistically significant reduction in load deflection characteristics of Ni-Ti, copper Ni-Ti, β-Ti, and S.S wires on immersing in Phosflur mouth rinse and neutral sodium fluoride mouth rinses as compared to control at 2.5 and 1 mm of deflection in unloading phase. Conclusion: Phosflur and a neutral sodium fluoride mouth rinse did not affect the mechanical bending properties of Ni-Ti, copper Ni-Ti, B-Ti, and SS wires in in vitro conditions.

  11. Effect of nondestructive testing of laminations on the bending properties of glulam beams made from louro-vermelho (Sextonia rubra

    Directory of Open Access Journals (Sweden)

    Ricardo Faustino Teles

    2010-03-01

    Full Text Available This work aims to assess the bending properties of glued laminated timber beams (glulam manufactured with species red louro (Sextonia rubra. Laminations were nondestructively tested using the transverse vibration method (EMlam. Then 10 glulam beams were manufactured and tested in static bending according to ASTM D 198 standard, having modulus of elasticity (EM, modulus of rupture (fM, and bending moment (M determined. The finished beams were also tested by the transverse vibration method (EMvt. It was noted that the EMvt value was only 2% lower than the EM value. Using laminations with a high modulus of elasticity did allow effective gain in stiffness. Therefore, results indicate that the transverse vibration method is a valid, reliable technique both for testing glulam laminations and for assessing stiffness in finished beams. Bending properties in glulam beams were influenced by the stiffness of constituent laminations.

  12. PROJECT, MANUFACTURING AND QUALIFICATION OF MACHINE TO ROTARY BENDING OF NITI SUPERELASTIC WIRES IN FATIGUE TESTS

    Directory of Open Access Journals (Sweden)

    William Marcos Muniz Menezes

    2014-03-01

    Full Text Available In this work it was developed a rotating bending apparatus for fatigue tests of superelastic NiTi wires, and other materials with high elasticity. It was evaluated the performance, robustness, operability, and reliability through testing of 1 mm thick stainless steel wires. This device is mounted on a steel frame and features semiautomatic rotation speed control, time and testing bath temperature for sample immersion. The equipment qualification tests were performed controlling the following parameters: deformation of the wire, power level and ambient temperature. The results indicated lower discrepancies for the following parameters evaluated: number of cycles in fatigue life, rotation speed, the bath temperature and arc angle of rupture. Besides the reliability, the robustness and operability of the equipment also meet the purpose of the research as evidenced by the small number of failures in the qualification tests and calibration.

  13. Four-Point Bending Strength Testing of Pultruded Fiberglass Composite Wind Turbine Blade Sections

    Energy Technology Data Exchange (ETDEWEB)

    Musial, W.; Bourne, B; Hughes, S; Zuteck, M. D. (MDZ Consulting)

    2001-07-10

    The ultimate strength of the PS Enterprises pultruded blade section was experimentally determined under four-point bending at the National Renewable Energy Laboratory. Thirteen 8-foot long full-scale blade segments were individually tested to determine their maximum moment carrying capability. Three airfoil-bending configurations were tested: high- and low-pressure skin buckling, and low pressure skin buckling with foam interior reinforcement. Maximum strain was recorded for each sample on the compressive and tensile surfaces of each test blade. Test data are compared to the results of three analytical buckling prediction methods. Based on deviations from the linear strain versus load curve, data indicate a post-buckling region. High-pressure side buckling occurred sooner than low-pressure side buckling. The buckling analyses were conservative for both configurations, but high-pressure side buckling in particular was substantially under-predicted. Both high- and low-pressure buckling configurations had very similar failure loads. These results suggests that a redundant load path may be providing strength to the section in the post-buckling region, making the onset of panel buckling a poor predictor of ultimate strength for the PS Enterprises pultrusion.

  14. Creep of Sn-9Zn as Measured by a Bending Test Method

    Institute of Scientific and Technical Information of China (English)

    WEI Xiuqin; LIAO Fuping; HUANG Huizhen; ZHOU Lang

    2011-01-01

    A bending creep setup was introduced and its feasibility to evaluate creep behavior of materials was experimentally verified on pure Sn. Thereby, the creep ofeutectic Sn-9Zn was studied.It was identified that high and low stress regimes exist in the creep of Sn-9Zn, and in both stress regimes, the data obtained well fit the modified equation of Norton power law. Parameters n and Q in the modified Norton equation obtained are very closed to those reported by other researchers by means of conventional tensile creep tests. The mechanisms governing the creep deformation of Sn-9Zn in both stress regimes were also discussed.

  15. Potential of acoustic emissions from three point bending tests as rock failure precursors

    Institute of Scientific and Technical Information of China (English)

    Agioutantis Z.; Kaklis K.; Mavrigiannakis S.; Verigakis M.; Vallianatos F.; Saltas V.

    2016-01-01

    Development of failure in brittle materials is associated with microcracks, which release energy in the form of elastic waves called acoustic emissions. This paper presents results from acoustic emission mea-surements obtained during three point bending tests on Nestos marble under laboratory conditions. Acoustic emission activity was monitored using piezoelectric acoustic emission sensors, and the potential for accurate prediction of rock damage based on acoustic emission data was investigated. Damage local-ization was determined based on acoustic emissions generated from the critically stressed region as scat-tered events at stresses below and close to the strength of the material.

  16. Operation corrosion test of austenitic steel bends for supercritical coal boilers

    Directory of Open Access Journals (Sweden)

    Cizner J.

    2016-03-01

    Full Text Available Corrosion tests of both annealed and not annealed bends of HR3C and S304H steels in operation conditions of black and brown coal combustion boilers in EPRU and EDE. After a long-term exposure, the samples were assessed gravimetrically and metallographically. The comparison of annealed and unannealed states showed higher corrosion rates in the annealed state; corrosion of the sample surface did not essentially differ for compression and tensile parts of the beams. Detailed assessment of both steels is described in detail in this study.

  17. Tension and Bending Testing of an Integral T-Cap for Stitched Composite Airframe Joints

    Science.gov (United States)

    Lovejoy, Andrew E.; Leone, Frank A., Jr.

    2016-01-01

    The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is a structural concept that was developed by The Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body aircraft configuration. An important design feature required for assembly is the integrally stitched T-cap, which provides connectivity of the corner (orthogonal) joint between adjacent panels. A series of tests were conducted on T-cap test articles, with and without a rod stiffener penetrating the T-cap web, under tension (pull-off) and bending loads. Three designs were tested, including the baseline design used in large-scale test articles. The baseline had only the manufacturing stitch row adjacent to the fillet at the base of the T-cap web. Two new designs added stitching rows to the T-cap web at either 0.5- or 1.0-inch spacing along the height of the web. Testing was conducted at NASA Langley Research Center to determine the behavior of the T-cap region resulting from the applied loading. Results show that stitching arrests the initial delamination failures so that the maximum strength capability exceeds the load at which the initial delaminations develop. However, it was seen that the added web stitching had very little effect on the initial delamination failure load, but actually decreased the initial delamination failure load for tension loading of test articles without a stiffener passing through the web. Additionally, the added web stitching only increased the maximum load capability by between 1% and 12.5%. The presence of the stiffener, however, did increase the initial and maximum loads for both tension and bending loading as compared to the stringerless baseline design. Based on the results of the few samples tested, the additional stitching in the T-cap web showed little advantage over the baseline design in terms of structural failure at the T-cap web/skin junction for the current test articles.

  18. CAST3M modelling of a spent fuel assembly bending during a handling accident Rod failure risk evaluation from the experimental results of spent fuel rod bending test

    International Nuclear Information System (INIS)

    The fuel handling operating rules exclude any accidental risk. However in the framework of the PRECCI R and D project, the bending of a spent fuel assembly resulting from its locking during a translation displacement is taken into account. This enabled us to develop an approach based on experiments and calculations that allows us to simulate the behaviour of an assembly under such loading. This study was carried out in CEA laboratories with the funding and the technical support of EDF. A three points bending test on a spent fuel rod segment was performed at the Laboratory for Mechanical Behaviour of Irradiated Materials (LCMI). From the experimental strength-displacement curve, a maximum failure strain, a maximum failure curvature and an equivalent constitutive equation were determined. CAST3M modelling of the fuel rod taking into account the elasto-plastic behaviour of the clad and the cracking of the UO2 fuel pellets was verified by the experimental results. Consequently, the identification of the respective contributions of the clad and of the pellets to the rod global behaviour was made possible. A two dimensional assembly with beam elements was modelled with CAST3M. The properties of the beams modelling the different parts of the assembly (top and bottom nozzle, grids) were chosen and adjusted according to their materials (zirconium alloys, steel) in order to obtain stiffness, tensile and shear behaviour, sliding and holding functions close to the experimental ones. Assembly bending calculations were performed. In order to obtain a rod integrity estimator, their maximum calculated strains and curvatures as a function of the bending angles can be compared to the failure experimental ones. (authors)

  19. Bend Testing of Silicon Microcantilevers from 21°C to 770°C

    Science.gov (United States)

    Armstrong, David E. J.; Tarleton, Edmund

    2015-12-01

    The measurement of mechanical properties at the microscale is of interest across a wide range of engineering applications. Much recent work has demonstrated that micropillar compression can be used to measure changes in flow properties at temperatures up to 600°C. In this work, we demonstrate that an alternative microscale bend testing geometry can be used to measure elastic, plastic, and fracture behavior up to 770°C in silicon. We measure a Young's modulus value of 130 GPa at room temperature, which is seen to drop with increasing temperature to ≈125 GPa. Below 500°C, no failure is seen up to elastic strains of 3%. At 530°C, the microcantilever fractures in a brittle fashion. At temperatures of 600°C and above plastic deformation is seen before brittle fracture. The yield stresses at these temperatures are in good agreement with literature values measured using micropillar compression.

  20. Flexibility of Burned Al2O3-C Due to Bending Tests at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Simple three-point bending test at ambient tempera-ture characterized the mechanical behavior of burned Al2O3-C refractories before and after thermal shock in association with the processing parameters (graphite con-tent and coking temperature,etc.).The results showed that non-linear plastic-elastic behavior under load lower than cold modulus of rupture (CMOR) Was registered in all specimens and real linear elastic behavior could be identified after the first load.The total deformation could be divided into two parts,plastic and elastic areas.The graphite content and joint bonding system of carbon and ceramic phases were responsible for mechanical behavior of Al2O3-C refractories.

  1. Determination of Concrete Fracture Parameters from a Three-Point Bending Test

    Institute of Scientific and Technical Information of China (English)

    张君; 刘骞

    2003-01-01

    The mechanical behavior within the processing zone of concrete material can be well described by the crack bridging performance. The material properties related to the crack bridging are cracking strength, tensile strength, and the stress-crack width relationship. In general, the cracking strength is lower than the tensile strength of concrete. Crack propagation is governed by the cracking strength. This paper presents a method to determine the above material parameters from a three-point bending test. In the experiment, a pre-notched beam is used. Corresponding values of load, crack mouth opening displacement, and load point displacement are simultaneously recorded. From experimentally determined load-crack mouth opening displacement curves, the above-mentioned crack bridging parameters are deduced by a numerical procedure. The method can be used to evaluate the influence of coarse aggregate and cementitious matrix strength on the stress-crack width relationship, tensile strength, and fracture energy of concrete.

  2. Load-to-failure bending test of wood composite beams connected by gang nail

    Directory of Open Access Journals (Sweden)

    A.V. Karelskiy

    2015-03-01

    Full Text Available The results of a bending test of wood composite beams connected by gang nail are presented in this paper. Two types of wood composite beams fracture were observed: brittle and ductile. In addition, a numerical model of wood composite beams was produced and the results of the numerical investigations were analyzed. Compliance of connection «gang nail – wood» was considered by means of input elements with a reduced modulus of elasticity in the numerical model. Then the theoretical and experimental results of stress and strain state of a composite beam with gang nail were compared. The conclusion was made about the efficiency of gang nail application for increased shear resistance of wood composite structures not only for reinforcement but also for production of new beam structures.

  3. Numerical Modeling for Hole-Edge Cracking of Advanced High-Strength Steels (AHSS) Components in the Static Bend Test

    Science.gov (United States)

    Kim, Hyunok; Mohr, William; Yang, Yu-Ping; Zelenak, Paul; Kimchi, Menachem

    2011-08-01

    Numerical modeling of local formability, such as hole-edge cracking and shear fracture in bending of AHSS, is one of the challenging issues for simulation engineers for prediction and evaluation of stamping and crash performance of materials. This is because continuum-mechanics-based finite element method (FEM) modeling requires additional input data, "failure criteria" to predict the local formability limit of materials, in addition to the material flow stress data input for simulation. This paper presents a numerical modeling approach for predicting hole-edge failures during static bend tests of AHSS structures. A local-strain-based failure criterion and a stress-triaxiality-based failure criterion were developed and implemented in LS-DYNA simulation code to predict hole-edge failures in component bend tests. The holes were prepared using two different methods: mechanical punching and water-jet cutting. In the component bend tests, the water-jet trimmed hole showed delayed fracture at the hole-edges, while the mechanical punched hole showed early fracture as the bending angle increased. In comparing the numerical modeling and test results, the load-displacement curve, the displacement at the onset of cracking, and the final crack shape/length were used. Both failure criteria also enable the numerical model to differentiate between the local formability limit of mechanical-punched and water-jet-trimmed holes. The failure criteria and static bend test developed here are useful to evaluate the local formability limit at a structural component level for automotive crash tests.

  4. Development of pure bending testing methods for advanced composite materials. Senshin fukugo zairyo no mage shikenho ni okeru jun mage hoshiki no kento

    Energy Technology Data Exchange (ETDEWEB)

    Iwai, H.; Uemura, M. (Nihon Univ., Tokyo (Japan). College of Industrial Technology); Uemura, S. (Fuji Heavy Industries Ltd., Tokyo (Japan))

    1994-04-15

    Advanced composite materials are strongly anisotropic and have high strength, high rigidity and many other fracture mechanisms, hence they show shortcomings such as generation of local fracture due to stress concentration at the point immediately below the loading point in case of application of the widely-used 3-point and 4-point bending tests, indicating their unsuitableness for the bending fracture test by the axial stress. In this article, bending testing methods of advanced composite materials, which can load the pure bending stress with no stress concentration, nor shearing stress component in the entire testing region, have been developed by test manufacturing a jig for pure bending. As a result of the experiment, no fracture due to local stress concentration like the 3-point and 4-point bending tests has occurred, the obtained bending strength has been more than 30% higher than that obtained by the 3-point and 4-point bending and a constant value has been obtained irrespective of its span. Also concerning the elastic coefficient obtained by this pure bending testing methods, the constant value has been obtained irrespective of span and plate thickness. Regarding the developed bending jigs, there are the sliding frame (SF) type and the rack and pinion (RP) type. For the SF and RP1 types, correction is required, but the RP2 type requires no correction. 3 refs., 15 figs.

  5. Mechanical Parameters and Post-Cracking Behaviour of HPFRC according to Three-Point and Four-Point Bending Test

    Directory of Open Access Journals (Sweden)

    Francesco Bencardino

    2013-01-01

    Full Text Available High performance fibre reinforced concrete (HPFRC is a modern structural material with a high potential and with an increasing number of structural applications. Structural design of HPFRC elements is based on the post-cracking residual strength provided by fibre reinforcement, and for structural use, a minimum mechanical performance of HPFRC must be guaranteed. To optimize the performance of HPFRC in structural members, it is necessary to establish the mechanical properties and the post-cracking and fracture behaviour in a univocal and reliable way. The best test methodology to evaluate the post-cracking and toughness properties of HPFRC is the beam bending test. Two different types of configurations are proposed: the three-point and the four-point bending tests. The overall focus of this paper is to evaluate the mechanical properties and the post-cracking and fracture behaviour of HPFRC, using the two different standard test procedures. To achieve these aims, plain and fibre concrete specimens were tested. All the test specimens were extensively instrumented to establish the strength properties, crack tip and crack mouth opening displacement, and post-cracking behaviour. The results of the two types of bending tests were critically analysed and compared to identify and highlight the differing effects of the bending load configurations on the mechanical parameters of HPFRC material.

  6. Haptic Evaluation of the Prickle of Fabrics:Axial Compression Bending Tests On Ramie Fibers

    Institute of Scientific and Technical Information of China (English)

    刘宇清; 韩露; 于伟东

    2004-01-01

    Although smoothness, softness, and stiffness determine the physical and mechanical behavior of a fabric and the subjective assessment of quality when it is handled, the perceived comfort of clothing is more important to consumers. The sensations perceived from the contact of clothing with the skin can greatly influence our over-all state of comfort and one aspect of this is the unpleasant skin sensation of prickle. Surface prickle of fabrics can be a factor limiting the use of the coarser types of ramie in apparel. And the mechanical stimulus of fabric-evoked prickle underlies our discomfort to fabrics independent in the majority of cases of any chemical or the atopic status of the individual. It is known that the prickle of fabric can be reduced by fabric-finishing treatments, but the assessment of fabric prickle is often done subjectively. This is time consuming, and it is difficult to obtain reliable and reproducible results, since variability between subjects in their sensitivity to prickle, such as skin mechanical properties, effective density of nociceptors and the mood state of the individual. In order to find an objective method of measuring the physical properties of the stiff fiber ends protruding from the fabrics to predict prickle, axial compression bending tests were examined by using single ramie fiber. By comparing analysis, it is found that the critical compressing load (Pcr), the bending modulus (E) are the important parameters. The relationship of the critical load (Pcr) with the length of fiber (L) and the fineness of fiber (Nt) has been investigated.

  7. Three-Point Bending Tests of Zirconia Core/Veneer Ceramics for Dental Restorations

    Directory of Open Access Journals (Sweden)

    Massimo Marrelli

    2013-01-01

    Full Text Available Introduction. The mechanical strength and the surface hardness of commercially available yttrium-doped zirconia were investigated. Furthermore, a comparative study of eight different ceramic veneers, to be used for the production of two-layered all-ceramic restorative systems, was carried out. Materials and Methods. Four types of zirconia specimens were analyzed, according to a standard ISO procedure (ISO 6872. Besides, two-layered zirconia-veneer specimens were prepared for three-point bending tests. Results. A strong effect of the surface roughness on the mechanical strength of zirconia specimens was observed. Finally, a comparative study of eight commercially available veneering ceramics shows different modes of failure between the selected veneers. Conclusion. The results indicate that close attention should be paid to the preparation of zirconia-based crowns and bridges by CAD/CAM process, because surface roughness has an important effect on the mechanical strength of the material. Finally, the results of the mechanical tests on two-layered specimens represent an important support to the choice of the veneering ceramic.

  8. Design and validation of bending test method for characterization of miniature pediatric cortical bone specimens.

    Science.gov (United States)

    Albert, Carolyne I; Jameson, John; Harris, Gerald

    2013-02-01

    Osteogenesis imperfecta is a genetic disorder of bone fragility; however, the effects of this disorder on bone material properties are not well understood. No study has yet measured bone material strength in humans with osteogenesis imperfecta. Small bone specimens are often extracted during routine fracture surgeries in children with osteogenesis imperfecta. These specimens could provide valuable insight into the effects of osteogenesis imperfecta on bone material strength; however, their small size poses a challenge to their mechanical characterization. In this study, a validated miniature three-point bending test is described that enables measurement of the flexural material properties of pediatric cortical osteotomy specimens as small as 5 mm in length. This method was validated extensively using bovine bone, and the effect of span/depth aspect ratio (5 vs 6) on the measured flexural properties was examined. The method provided reasonable results for both Young's modulus and flexural strength in bovine bone. With a span/depth ratio of 6, the median longitudinal modulus and flexural strength results were 16.1 (range: 14.4-19.3)GPa and 251 (range: 219-293)MPa, respectively. Finally, the pilot results from two osteotomy specimens from children with osteogenesis imperfecta are presented. These results provide the first measures of bone material strength in this patient population.

  9. Three Point Bending Test of Human Femoral Tissue: An Essay in Ancient and Modern Bones

    Science.gov (United States)

    González-Bárcenas, L. A.; Trejo-Camacho, H.; Suárez-Estrella, I.; Heredia, A.; Magaña, C.; Bucio, L.; Orozco, E.

    2003-09-01

    Some procedures for characterising the mechanical properties of femur diaphysis are reviewed here. We have used the three point bending test to measure the relative rupture modulus of ancient healthy human tissues (1250, 800, 614, and 185 years BP) as well as recent bones. The maximum resistance to fracture was measured applying a force (by a wedge) over the femoral inner surface. The maximum rupture strength was about 150 MPa for recent bone and decreased as the antiquity increased. The typical anisotropy that is observed in this kind of tissues is due to the anisotropical orientation of fibres as well as the textured orientation of the apatite crystals over the collagen fibres. Therefore we found that ancient bones show less fracture strength probably due to an abiotic crystal growth phenomenon during the diagenesis process. By LVSEM analysis we have found that in recent samples the fracture surface is irregular due to the crosslinking interactions between the collagen molecules, in comparison with the ancient samples, where a smooth surface is clearly appreciated as the antiquity of the sample increases. The results reported here strongly suggest that these composites should contain a fibrillar phase as a matrix constituted mainly by a natural polymer (i.e. collagen, cellulose, etc.). Moreover, this composite must have a minimum rupture strength of about 150 MPa.

  10. Test research on cold bend of {phi}1219 mm x 22 mm X80 longitudinally submerged-arc welded line pipes

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Chi; Lingkang, Ji; Yinglai, Liu; Peng, Wang [China National Petroleum Corporation (CNPC), Xi' an (China). Tubular Goods Research Center

    2009-07-01

    The tests of cold bend of {phi}1219 mm x 22 mm X80 longitudinally submerged-arc welded line pipes were done to research the effects of cold bend processes on the configuration and property of X80 steel pipe in this paper. In the filed bend tests, the six kinds radius of curvature consist of 18D, 20D, 24D, 28D, 35D and 47D (D is the diameter of steel pipe) were adopted. The results of welding seam non-destructive and macrograph examination show that the effect of bending process on the quality of welding seam is not obvious. The appearance inspections show that the serious distortions occur on the bend pipes of 18D and 20D radius of curvature. The mechanical property tests results indicate that the change of the transverse tensile property, toughness and hardness of cold bend pipes manufactured by various radius of curvature compare with the mother pipe are smaller. The change of longitudinal tensile property is bigger. Compared with the mother pipe, the yield strength and yield ratio in inner arc of bend pipe decrease, but those in outer arc of bend pipe increase. The longitudinal tensile curves in different sampling locations of bend pipe exhibit a rather large difference. (author)

  11. Numerical Analysis of AHSS Fracture in a Stretch-bending Test

    Science.gov (United States)

    Luo, Meng; Chen, Xiaoming; Shi, Ming F.; Shih, Hua-Chu

    2010-06-01

    Advanced High Strength Steels (AHSS) are increasingly used in the automotive industry due to their superior strength and substantial weight reduction advantage. However, their limited ductility gives rise to numerous manufacturing issues. One of them is the so-called `shear fracture' often observed on tight radii during stamping processes. Since traditional approaches, such as the Forming Limit Diagram (FLD), are unable to predict this type of fracture, efforts have been made to develop failure criteria that can predict shear fractures. In this paper, a recently developed Modified Mohr-Coulomb (MMC) ductile fracture criterion[1] is adopted to analyze the failure behavior of a Dual Phase (DP) steel sheet during stretch bending operations. The plasticity and ductile fracture of the present sheet are fully characterized by the Hill'48 orthotropic model and the MMC fracture model respectively. Finite Element models with three different element types (3D, shell and plane strain) were built for a Stretch Forming Simulator (SFS) test and numerical simulations with four different R/t ratios (die radius normalized by sheet thickness) were performed. It has been shown that the 3D and shell element models can accurately predict the failure location/mode, the upper die load-displacement responses as well as the wall stress and wrap angle at the onset of fracture for all R/t ratios. Furthermore, a series of parametric studies were conducted on the 3D element model, and the effects of tension level (clamping distance) and tooling friction on the failure modes/locations were investigated.

  12. Comparison of the bending performance of solid and cannulated spinal pedicle screws using finite element analyses and biomechanical tests.

    Science.gov (United States)

    Shih, Kao-Shang; Hsu, Ching-Chi; Hou, Sheng-Mou; Yu, Shan-Chuen; Liaw, Chen-Kun

    2015-09-01

    Spinal pedicle screw fixations have been used extensively to treat fracture, tumor, infection, or degeneration of the spine. Cannulated spinal pedicle screws with bone cement augmentation might be a useful method to ameliorate screw loosening. However, cannulated spinal pedicle screws might also increase the risk of screw breakage. Thus, the purpose of this study was to investigate the bending performance of different spinal pedicle screws with either solid design or cannulated design. Three-dimensional finite element models, which consisted of the spinal pedicle screw and the screw's hosting material, were first constructed. Next, monotonic and cyclic cantilever bending tests were both applied to validate the results of the finite element analyses. Finally, both the numerical and experimental approaches were evaluated and compared. The results indicated that the cylindrical spinal pedicle screws with a cannulated design had significantly poorer bending performance. In addition, conical spinal pedicle screws maintained the original bending performance, whether they were solid or of cannulated design. This study may provide useful recommendations to orthopedic surgeons before surgery, and it may also provide design rationales to biomechanical engineers during the development of spinal pedicle screws. PMID:26208430

  13. Analysis of the discontinuous Petrov-Galerkin method with optimal test functions for the Reissner-Mindlin plate bending model

    KAUST Repository

    Calo, Victor M.

    2014-01-01

    We analyze the discontinuous Petrov-Galerkin (DPG) method with optimal test functions when applied to solve the Reissner-Mindlin model of plate bending. We prove that the hybrid variational formulation underlying the DPG method is well-posed (stable) with a thickness-dependent constant in a norm encompassing the L2-norms of the bending moment, the shear force, the transverse deflection and the rotation vector. We then construct a numerical solution scheme based on quadrilateral scalar and vector finite elements of degree p. We show that for affine meshes the discretization inherits the stability of the continuous formulation provided that the optimal test functions are approximated by polynomials of degree p+3. We prove a theoretical error estimate in terms of the mesh size h and polynomial degree p and demonstrate numerical convergence on affine as well as non-affine mesh sequences. © 2013 Elsevier Ltd. All rights reserved.

  14. Interlamellar cracking of thermal barrier coatings with TGOs by non-standard four-point bending tests

    International Nuclear Information System (INIS)

    Highlights: → A non-standard modified four-point bending specimen is adopted for delamination test. → Typical failure mode of the TBC system with TGO layer is demonstrated. → Fracture toughness of 8YSZ on a cold-sprayed MCrAlY coating is evaluated theoretically. - Abstract: This work concerns the failure mode and fracture toughness of plasma-sprayed 8 wt% yttria-stabilized zirconia (8YSZ) deposited on a cold-sprayed MCrAlY bond coat (BC) after thermal oxidation. Upon high-temperature exposure, a thermally grown oxide (TGO) layer was formed along the interface between the BC layer and YSZ ceramic coating layer through oxidation of the bond coat. By utilizing a non-standard modified four-point bending specimen, in conjunction with fractured surface examinations by scanning electron microscope and energy disperse spectroscope, the failure mode of this thermal barrier coating (TBC) system has been checked experimentally. It is shown that delamination cracks firstly initiate at the YSZ/BC interface edge, and then propagate along a wavy path near the interface, not only through the TBC but also within the TGO and along the interlamellar interfaces. Through a theoretical analysis of the bending specimen, the fracture toughness of this TBC system, in terms of strain energy release rate, has been determined from the load-displacement curves which were recorded during the tests.

  15. Experimental investigation of fatigue behavior of carbon fiber composites using fully-reversed four-point bending test

    Science.gov (United States)

    Amiri, Ali

    Carbon fiber reinforced polymers (CFRP) have become an increasingly notable material for use in structural engineering applications. Some of their advantages include high strength-to-weight ratio, high stiffness-to-weight ratio, and good moldability. Prediction of the fatigue life of composite laminates has been the subject of various studies due to the cyclic loading experienced in many applications. Both theoretical studies and experimental tests have been performed to estimate the endurance limit and fatigue life of composite plates. One of the main methods to predict fatigue life is the four-point bending test. In most previous works, the tests have been done in one direction (load ratio, R, > 0). In the current work, we have designed and manufactured a special fixture to perform a fully reversed bending test (R = -1). Static four-point bending tests were carried out on three (0°/90°)15 and (± 45°)15 samples to measure the mechanical properties of CFRP. Testing was displacement-controlled at the rate of 10 mm/min until failure. In (0°/90°)15 samples, all failed by cracking/buckling on the compressive side of the sample. While in (± 45°)15 all three tests, no visual fracture or failure of the samples was observed. 3.4 times higher stresses were reached during four-point static bending test of (0° /90°)15 samples compared to (± 45°)15. Same trend was seen in literature for similar tests. Four-point bending fatigue tests were carried out on (0° /90°)15 sample with stress ratio, R = -1 and frequency of 5 Hz. Applied maximum stresses were approximately 45%, 56%, 67%, 72% and 76% of the measured yield stress for (0° /90°)15 samples. There was visible cracking through the thickness of the samples. The expected downward trend in fatigue life with increasing maximum applied stress was observed in S-N curves of samples. There appears to be a threshold for ‘infinite’ life, defined as 1.7 million cycles in the current work, at a maximum stress of about

  16. Load-displacement measurement and work determination in three-point bend tests of notched or precracked specimens

    Science.gov (United States)

    Buzzard, R. J.; Fisher, D. M.

    1978-01-01

    Suggestions for testing of notched or cracked three-point bend specimens are presented that (1) correct displacement measurement errors resulting from misalignment between the load applicator and specimen; (2) account for coincidental strains not associated with the work of crack extension; (3) simplify record analysis and processing; and (4) extend displacement gage range without sacrifice of sensitivity or accuracy. These testing details are particularly applicable to procedures in which the crack extension force J(I) is determined from the work done on the specimen.

  17. Mode I Critical Stress Intensity Factor of Medium - Density Fiberboard Obtained by Single-Edge - Notched Bending Test

    Directory of Open Access Journals (Sweden)

    Hiroshi Yoshihara

    2014-06-01

    Full Text Available The Mode I critical stress intensity factor (KIc obtained by single-edge-notched bending (SENB tests of medium-density fiberboard (MDF was experimentally analyzed. In the SENB test, the critical load for crack propagation (Pc was determined from the relationship between load/loading-line displacement and load/crack opening displacement (COD. A double cantilever beam (DCB test was also conducted and the results were compared with those of SENB tests. The value of Mode I critical stress intensity factor was obtained by introducing an additional crack length, when the crack length ranged from 0.5 to 0.7 times the depth of the specimen. This range coincided well with that used to derive the appropriate KIc value in the single-edge-notched tension (SENT test, which was conducted using the specimens with a similar confi guration cut from the MDF panel used in this study.

  18. Effects of strain and strain rate on electronic behavior of metal surfaces under bending and tension tests

    International Nuclear Information System (INIS)

    Surface electronic behavior of MEMS and NEMS can be characterized using the Kelvin probe technique by measurements of work function (WF). However, the physical mechanism responsible for such electronic behavior of a surface subjected to mechanical loading has not been completely understood. In this study, changes in WF of copper and aluminum with respect to strain and strain rate under bending and tension tests were measured using a scanning Kelvin probe. The results showed that plastic strain and strain rate can decrease WF although elastic strain may lead to complex changes in WF, which can be explained well using the electrostatic energy model on dislocation density.

  19. The Role of Home Bleaching Agent on the Fracture Toughness of Resin Composites Using Four-Point Bending Test

    Directory of Open Access Journals (Sweden)

    Ghazvini Ferooz M

    2014-09-01

    Full Text Available Statement of Problem: Resin composites are a common type of tooth coloured restorative materials. These materials are brittle and their major shortcomings are sensitivity to flaws and defects, low tensile strength, and susceptibility to catastrophic failure.The role of home bleaching agents on the fracture toughness of resin composites using four-point bending test is scanty. Objectives: To compare the fracture toughness (KIc of resin composites on a fourpoint bending test and to assess the effect of distilled water and a home bleaching agent on the resistance of the materials to fracture. Materials and Methods: seventy-two bar-shaped specimens were prepared from three materials: Rok (SDI, Estelite (Tokuyama, and Vit-l-escence (Ultradent and divided into three groups. Two groups were assigned as “control” and conditioned in distilled water at 37oC for 24 hours or 21 days, respectively. The specimens in the third group (treatment were stored in distilled water for 21 days and bleached using Polanight (SDI for 2 hours daily. For each material, a total of 24 disc-shaped specimens were prepared and after each time interval loaded in a four-point bending test using a universal testing machine with a crosshead speed of 0.5 mm/m. The maximum load to specimen failure was recorded and the KIc was calculated. Results: Statistical analysis using two-way ANOVA showed a significant relationship between materials and treatment (P<0.05. Tukey’s test showed that after 24 hours of immersion in distilled water, KIc was not significantly different between materials; Rok revealed the highest value followed by Estelite and Vit-l-escence. The bleaching agent significantly decreased the KIc values of Estelite and Rok while it did not affect that of Vita-l-escence. Immersion in distilled water for all resin composites caused a significant decrease in KIc. Conclusion: The fracture toughness of the resin composites was affected by the bleaching agent and 21day

  20. Bending testing and characterization of surrogate nuclear fuel rods made of Zircaloy-4 cladding and aluminum oxide pellets

    Science.gov (United States)

    Wang, Hong; Wang, Jy-An John

    2016-10-01

    Behavior of surrogate nuclear fuel rods made of Zircaloy-4 (Zry-4) cladding with alumina pellets under reversed cyclic bending was studied. Tests were performed under load or moment control at 5 Hz. The surrogate rods fractured under moment amplitudes greater than 10.16 Nm with fatigue lives between 2.4 × 103 and 2.2 × 106 cycles. Fatigue response of Zry-4 cladding was characterized by using flexural rigidity. Degradation of flexural rigidity was shown to depend on the moment and the prefatigue condition of specimens. Pellet-to-pellet interface (PPI), pellet-to-cladding interface (PCI), and pellet condition affect surrogate rod failure. Both debonding of PPI/PCI and pellet fracturing contribute to surrogate rod bending fatigue. The effect of sensor spacing on curvature measurement using three-point deflections was studied; the method based on effective gauge length is effective in sensor spacing correction. The database developed and the understanding gained in this study can serve as input to analysis of SNF (spent nuclear fuel) vibration integrity.

  1. Over-leg Bending Test for Mixed-mode I/II Interlaminar Fracture in Composite Laminates

    OpenAIRE

    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...

  2. Analysis of a bending test on a full-scale PWR hot leg elbow containing a surface crack

    Energy Technology Data Exchange (ETDEWEB)

    Delliou, P. le [Electricite de France, EDF, 77 - Moret-sur-Loing (France). Dept. MTC; Julisch, P.; Hippelein, K. [Stuttgart Univ. (Germany). Staatliche Materialpruefungsanstalt; Bezdikian, G. [Electricite de France, EDF, 92 - Paris la Defense (France). Direction Production Transport

    1998-11-01

    EDF, in co-operation with Framatome, has conducted a large research programme on the mechanical behaviour of thermally aged cast duplex stainless steel elbows, which are part of the main primary circuit of French PWR. One important task of this programme consisted of testing a full-scale PWR hot leg elbow. The elbow contained a semi-elliptical circumferential notch machined on the outer surface of the intrados as well as casting defects located on the flanks. To simulate the end-of-life condition of the component regarding material toughness, it had undergone a 2400 hours ageing heat treatment at 400 C. The test preparation and execution, as well as the material characterization programme, were committed to MPA. The test was conducted under constant internal pressure and in-plane bending (opening mode) at 200 C. For safety reasons, it took place on an open air-site: the Meppen military test ground. At the maximum applied moment (6000 kN.m), the notch did not initiate. This paper presents the experimental results and the fracture mechanics analysis of the test, based on finite element calculations. (orig.)

  3. Measurement and Analysis on SAW Pipe Guided Bend Test%埋弧焊管导向弯曲变形测量与分析

    Institute of Scientific and Technical Information of China (English)

    曾德胜; 王彬

    2014-01-01

    对埋弧焊管的导向弯曲试验进行了理论分析,得到其应变公式,并计算了最大应变。将不同试样尺寸下钢材的断后伸长率,按Oliver公式换算到同一个标准条件下进行了比较。建立了弯曲应变判断公式来分析弯曲不合的基本原因。通过实际测量方法对弯曲试样的母材、热影响区和焊缝的应变进行了测量和分析,认为焊接接头的塑性一般足以满足导向弯曲试验要求。通过分析弯曲不合钢管酸洗样的显微照片,认为焊趾微裂纹是弯曲不合的主要原因。%In this article, the theoretical analysis of SAW pipe guided bend test was carried out, its strain formula was obtained, and the maximum strain was calculated. The percentage elongations after fracture of steel material under different sample size were compared, according to Oliver formula conversion to the same standard condition. It established a bend strain judging formula to find the basic reason of bend failure. By the method of actual measurement, the strain on bend specimens of parent metal, heat affected zone and weld was measured and analyzed, the result showed that the plasticity of welded jointer enough to meet the requirements of guided bend test. Through analyzing the micrograph of pickling sample of bend disqualified pipe, it considers that the microcrack in weld toe is the main reason of the bend disqualified test.

  4. Technical report on the fatigue crack Growth Benchmark based on CEA pipe bending tests

    International Nuclear Information System (INIS)

    In order to improve the estimation methods of surface crack propagation through the thickness of components, CEA has proposed a benchmark to members of the IAGE WG, sub-group on Integrity of metal components and structures. The subject is a simple configuration of a pipe containing an axisymmetric notch and submitted to a cyclic bending load. An experimental data-set form CEA was used to validate three issues in the topic of Leak Before Break. - Crack initiation, - Crack propagation through the thickness, - Crack penetration. All material and geometrical data which are necessary for the simulation were given in the proposal, including experimental results. Due to the peculiar complexity of the problem, it was decided to focus the work on methodologies comparison so as to allow participants to tune up parameters and adjust their models and tools. This report presents all estimations performed by the participants and collected by CEA. They are compared to the experimental results. An analysis of the used procedures is also proposed. This, associated with the study of the accuracy of different methodologies, leads to comments and recommendations on the analysis of fatigue crack growth. The participation in the first step was important: nine participants have proposed analyses, sometimes parametric analysis to estimate crack growth. Results sorted out three estimation methods groups that give results in accordance with experimental ones (these three groups are based on a strain range evaluation and the fatigue curve of the material): - The use of an elastic stress at the notch tip and a fatigue notch concentration factor to determine the strain range. - The use of a KI (or elastic F.E. calculation) and a Neuber rule for the estimation of the strain range at a characteristic distance from the crack tip. - The direct calculation of the strain range at the characteristic distance by an elastic plastic F.E. calculation. Only 4 participants have proposed an estimate of the

  5. Progress Letter Report on Bending Fatigue Test System Development for Spent Nuclear Fuel Vibration Integrity Study (Out-of-cell fatigue testing development - Task 2.4)

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jy-An John [ORNL; Wang, Hong [ORNL; Cox, Thomas S [ORNL; Baldwin, Charles A [ORNL; Bevard, Bruce Balkcom [ORNL

    2013-08-01

    Vibration integrity of high burn-up spent nuclear fuel in transportation remains to be a critical component of US nuclear waste management system. The structural evaluation of package for spent fuel transportation eventually will need to see if the content or spent fuel is in a subcritical condition. However, a system for testing and characterizing such spent fuel is still lacking mainly due to the complication involved with dealing radioactive specimens in a hot cell environment. Apparently, the current state-of-the-art in spent fuel research and development is quite far away from the delivery of reliable mechanical property data for the assessment of spent fuels in the transport package evaluation. Under the sponsorship of US NRC, ORNL has taken the challenge in developing a robust testing system for spent fuel in hot cell. An extensive literature survey was carried out and unique requirements of such testing system were identified. The U-frame setup has come to the top among various designs examined for reverse bending fatigue test of spent fuel rod. The U-frame has many features that deserve mentioned here: Easy to install spent fuel rod in test; Less linkages than in conventional bending test setup such as three-point or four-point bending; Target the failure mode relevant to the fracture of spent fuel rod in transportation by focusing on pure bending; The continuous calibrations and modifications resulted in the third generation (3G) U-frame testing setup. Rigid arms are split along the LBB axis at rod sample ends. For each arm, this results in a large arm body and an end piece. Mating halves of bushings were modified into two V-shaped surfaces on which linear roller bearings (LRB) are embedded. The rod specimen is installed into the test fixture through opening and closing slide end-pieces. The 3G apparently has addressed major issues of setup identified in the previous stage and been proven to be eligible to be further pursued in this project. On the other

  6. Procedure of crack resistance estimation for steels from results of standard tensile and impact bend tests

    International Nuclear Information System (INIS)

    Dependences binding minimal level of the static crack resistance, yield point and reduced test temperature Ttest-TB50 are plotted according to the results obtained from test of various structural steels. The given dependences permit suggesting a simple method to calculate static crack resistance by the yield point of steel and critical temperature, corresponding to 50 % viscous component in the fracture of standard impact specimens of the Charpy type. This method has been used to calculate temperature dependences of crack resistance and choice of optimal composition for cold-resistant cast steel

  7. Study Of Ceramic-Polymer Composites Reliability Based On The Bending Strength Test

    Directory of Open Access Journals (Sweden)

    Walczak Agata

    2015-11-01

    Full Text Available In this paper the reliability assessment of structural reliability of the selected light-cured dental composites based on the biaxial flexural strength test results has been presented. A two-parameter Weibull distribution was applied as a reliability model in order to estimate probability of strength maintenance in the analysed population. Weibull distribution parameters were interpreted as a characteristic material strength (scale parameter and structural reliability parameter in terms of ability to maintain strength by each of specimen from the general population (shape parameter. 20 composite specimens underwent strength tests, including 2 “flow” type composites and 2 standard composites (with typical filler content. “Flow” type composites were characterized with lower characteristic strength and higher structural reliability comparing to other studied composites.

  8. Mechanical characterization of C{sub 60} whiskers by MEMS bend testing

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, M P; Lucyszyn, S [Optical and Semiconductor Devices Group, Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, London, SW7 2AZ (United Kingdom)], E-mail: s.lucyszyn@imperial.ac.uk

    2009-04-01

    Little has been published on the mechanical characteristics of C{sub 60} whiskers, due to the inherent difficulties in physically mounting such small test samples. Earlier reported results suggested Young's modulus values of 32 and 54 GPa, with 130 and 160 micron diameter C{sub 60} nanowhiskers, respectively, using compressive deformation techniques. In our work, an experimental bespoke silicon-based microelectromechanical system has been developed to extract an other value. 1th as been found, through parameter extraction techniques, that a Young's modulus of only {approx} 2 GPa is obtained with a C{sub 60} whisker having a diameter of 4 microns. By including the previously published data points, there is now strong evidence to suggest an inverse proportionality relationship between the Young's modulus and the diameter of a C{sub 60} whisker.

  9. Non-standard coupled extensional and bending bias tests for planar pantographic lattices. Part II: comparison with experimental evidence

    Science.gov (United States)

    Turco, Emilio; Barcz, Katarzyna; Rizzi, Nicola Luigi

    2016-10-01

    In dell'Isola et al. (Zeitschrift für Angewandte Math und Physik 66(6):3473-3498, 2015, Proc R Soc Lond A Math Phys Eng Sci 472(2185):1-23, 2016) pantographic sheets are proposed as a basic constituent for a novel metamaterial. In Part I, see Turco et al. (Zeitschrift für Angewandte Math und Physik, doi: 10.1007/s00033-016-0713-4, 2016), two different numerical models are applied in order to design an experimental setup aimed to prove the effectiveness of introduced concept. The aim of this paper is to prove that the Hencky-type model introduced for planar pantographic sheets allows for the correct prediction, in a large range of imposed displacements, of the experimental measurements concerning specimens undergoing coupled bending and extensional deformations. The four-parameter numerical model introduced is shown to have a large range of applicability: Indeed without changing the values of the material parameters previously attributed in simple extensional tests to a specific specimen by a best-fit procedure, it is possible to forecast its behavior in all the considered type of imposed deformations. The measurements performed include the determination of reactive forces exerted by used hard devices, and the numerical modeling is able to predict very carefully quantitatively and qualitatively also this complex aspect of phenomenology, where previously attempted models seem to have failed.

  10. Estimation of Fracture Toughness of Anisotropic Rocks by Semi-Circular Bend (SCB) Tests Under Water Vapor Pressure

    Science.gov (United States)

    Kataoka, M.; Obara, Y.; Kuruppu, M.

    2015-07-01

    In order to investigate the influence of water vapor pressure in the surrounding environment on mode I fracture toughness ( K Ic) of rocks, semi-circular bend (SCB) tests under various water vapor pressures were conducted. Water vapor is one of the most effective agents which promote stress corrosion of rocks. The range of water vapor pressure used was 10-2 to 103 Pa, and two anisotropic rock types, African granodiorite and Korean granite, were used in this work. The measurement of elastic wave velocity and observation of thin sections of these rocks were performed to investigate the microstructures of the rocks. It was found that the distribution of inherent microcracks and grains have a preferred orientation. Two types of specimens in different orientations, namely Type-1 and Type-3, were prepared based on the anisotropy identified by the differences in the elastic wave velocity. K Ic of both rock types was dependent on the water vapor pressure in the surrounding environment and decreased with increasing water vapor pressure. It was found that the degree of the dependence is influenced by the orientation and density of inherent microcracks. The experimental results also showed that K Ic depended on the material anisotropy. A fracture process was discussed on the basis of the geometry of fractures within fractured specimens visualized by the X-ray computed tomography (CT) method. It was concluded that the dominant factor causing the anisotropy of K Ic is the distribution of grains rather than inherent microcracks in these rocks.

  11. Damage Characterization of Glass/Epoxy Composite Under Three-Point Bending Test Using Acoustic Emission Technique

    Science.gov (United States)

    Pashmforoush, Farzad; Fotouhi, Mohamad; Ahmadi, Mehdi

    2012-07-01

    Acoustic emission (AE) technique is an efficient non-destructive method for detection and identification of various damage mechanisms in composite materials. Discrimination of AE signals related to different damage modes is of great importance in the use of this technique. For this purpose, integration of k-means algorithm and genetic algorithm (GA) was used in this study to cluster AE events of glass/epoxy composite during three-point bending test. Performing clustering analysis, three clusters with separate frequency ranges were obtained, each one representing a distinct damage mechanism. Furthermore, time-frequency analysis of AE signals was performed based on wavelet packet transform (WPT). In order to find the dominant components associated with different damage mechanisms, the energy distribution criterion was used. The frequency ranges of the dominant components were then compared with k-means genetic algorithm (KGA) outputs. Finally, SEM observation was utilized to validate the results. The obtained results indicate good performance of the proposed methods in the damage characterization of composite materials.

  12. Bending behavior of lapped plastic ehv cables

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, G H; Muller, A C

    1980-01-01

    One of the factors delaying the development of lapped polymeric cables has been their reputed poor bending characteristics. Complementary programs were begun at BNL several years ago to mathematically model the bending of synthetic tape cables and to develop novel plastic tapes designed to have moduli more favorable to bending. A series of bend tests was recently completed to evaluate the bending performance of several tapes developed for use in experimental superconducting cables. The program is discussed and the results of the bend tests are summarized.

  13. Study of the temperature dependence of the mechanical characteristics of the steels GX 5 CrNi 13 4 and GGG 40 in tensile and bending tests

    International Nuclear Information System (INIS)

    This report addresses the results of the study of the temperature dependence of the mechanical characteristics of two cast materials. Diagrams show the yield point and the tensile strength of the steel GX 5 CrNi 13 4 - as determined from the bending test. For the material GGG 40 we tested the yield point and the tensile strength in unnotched tensile specimens and also the yield point and strength in bending tests with differently notched notched-bar impact bend test specimens as a function of temperature. The steel GX 4 CrNi 13 4 exhibits very good toughness to temperatures of -1960C without any indication of a drop, whereas the GGG 40 casting exhibits a sharp drop in toughness between -130 and -1750C. This embrittlement is virtually independent of the notch sharpness, which is also expressed by the shape of the fracture toughness-temperature curve. Only below about -1400C can valid K/sub IC/ values be determined, since above this temperature the sharp increase in toughness makes an exact K/sub IC/ determination impossible. 33 figs., 15 tabs

  14. A general mixed mode fracture mechanics test specimen: The DCB-specimen loaded with uneven bending moments

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Jørgensen, K.; Jacobsen, T.K.;

    2004-01-01

    A mixed mode specimen is proposed for fracture mechanics characterisation of adhesive joints, laminates and multilayers. The specimen is a double cantilever beam specimen loaded with uneven bending moments at the two free beams. By varying the ratiobetween the two applied moments, the full mode...

  15. SEM in situ laboratory investigations on damage growth in GFRP composite under three-point bending tests

    DEFF Research Database (Denmark)

    Zhou, Hong Wei; Mishnaevsky, Leon; Brøndsted, Povl;

    2010-01-01

    Glass fiber-reinforced polymer (GFRP) composites are widely used in low-weight constructions. SEM (scanning electron microscopy) in situ experiments of damage growth in GFRP composite under three-point bending loads are carried out. By summarizing the experimental results of three groups of samples...

  16. Design and fabrication of a bending rotation fatigue test rig for in situ electrochemical analysis during fatigue testing of NiTi shape memory alloy wires

    Energy Technology Data Exchange (ETDEWEB)

    Neelakantan, Lakshman [Ruhr-Universitaet Bochum, Institute for Materials, 44801 Bochum (Germany); Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras, 600 036 Chennai (India); Zglinski, Jenni Kristin; Eggeler, Gunther [Ruhr-Universitaet Bochum, Institute for Materials, 44801 Bochum (Germany); Frotscher, Matthias [Ruhr-Universitaet Bochum, Institute for Materials, 44801 Bochum (Germany); CORTRONIK GmbH, 18119 Rostock-Warnemuende (Germany)

    2013-03-15

    The current investigation proposes a novel method for simultaneous assessment of the electrochemical and structural fatigue properties of nickel-titanium shape memory alloy (NiTi SMA) wires. The design and layout of an in situ electrochemical cell in a custom-made bending rotation fatigue (BRF) test rig is presented. This newly designed test rig allows performing a wide spectrum of experiments for studying the influence of fatigue on corrosion and vice versa. This can be achieved by performing ex situ and/or in situ measurements. The versatility of the combined electrochemical/mechanical test rig is demonstrated by studying the electrochemical behavior of NiTi SMA wires in 0.9% NaCl electrolyte under load. The ex situ measurements allow addressing various issues, for example, the influence of pre-fatigue on the localized corrosion resistance, or the influence of hydrogen on fatigue life. Ex situ experiments showed that a pre-fatigued wire is more susceptible to localized corrosion. The synergetic effect can be concluded from the polarization studies and specifically from an in situ study of the open circuit potential (OCP) transients, which sensitively react to the elementary repassivation events related to the local failure of the oxide layer. It can also be used as an indicator for identifying the onset of the fatigue failure.

  17. Design and fabrication of a bending rotation fatigue test rig for in situ electrochemical analysis during fatigue testing of NiTi shape memory alloy wires

    Science.gov (United States)

    Neelakantan, Lakshman; Zglinski, Jenni Kristin; Frotscher, Matthias; Eggeler, Gunther

    2013-03-01

    The current investigation proposes a novel method for simultaneous assessment of the electrochemical and structural fatigue properties of nickel-titanium shape memory alloy (NiTi SMA) wires. The design and layout of an in situ electrochemical cell in a custom-made bending rotation fatigue (BRF) test rig is presented. This newly designed test rig allows performing a wide spectrum of experiments for studying the influence of fatigue on corrosion and vice versa. This can be achieved by performing ex situ and/or in situ measurements. The versatility of the combined electrochemical/mechanical test rig is demonstrated by studying the electrochemical behavior of NiTi SMA wires in 0.9% NaCl electrolyte under load. The ex situ measurements allow addressing various issues, for example, the influence of pre-fatigue on the localized corrosion resistance, or the influence of hydrogen on fatigue life. Ex situ experiments showed that a pre-fatigued wire is more susceptible to localized corrosion. The synergetic effect can be concluded from the polarization studies and specifically from an in situ study of the open circuit potential (OCP) transients, which sensitively react to the elementary repassivation events related to the local failure of the oxide layer. It can also be used as an indicator for identifying the onset of the fatigue failure.

  18. Studi Eksperimen perbandingan Laju Korosi pada Plat ASTM (American Society For Testing and Material A36 dengan Menggunakan Variasi Sudut Bending

    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.

  19. Finite element method for the simulation of impact tests on large-size bending test specimens of a pressure vessel steel

    International Nuclear Information System (INIS)

    Impact tests have been made on 3-point bending test specimens of the size 495x90x45 mm3 of a pressure vessel steel in order to verify the experimentally determined J-integral and the crack propagation Δa by the numerical finite element method. The model uses the impact hammer as the point mass, the contact area as the elastic spring, and the specimen as a two-dimensional FE model, and assumes a plane stress. The calculations have been made with explicit time integration, taking into account dynamic effects. The measured time curve of the hammer load in the initial phase could not be reproduced with the statically determined elastic-plastic stress-strain relation. Modelling is achievable assuming a viscoplastic material model with a fluid parameter γ = 100 s-1. With a strong entire deformation of the specimen being given, the measured hammer impact could be explained assuming a friction with a friction coefficient of 0.7. About 10 to 15% of the hammer impact energy is taken up at the bearing points, and considering this percentage, the experimental data and the numerically derived J(Δα) curve almost agree. After about 5 mm of crack propagation, the calculated J-integral increasingly depends on the integration area. This is assumed to be due to the fact that the energy density becomes explicitly dependent on position as a result of relieving processes. (orig.)

  20. 舵机弯矩电动加载测试系统的设计%Design of Motor-Driven Bending Moment Loading Test System

    Institute of Scientific and Technical Information of China (English)

    周军; 刘光辉; 周凤岐; 张佼龙

    2011-01-01

    针对舵机测试需求,设计了一种弯矩电动加载测试系统.系统以直流电机为执行元件能够实现几百到几万牛力加载,介绍了系统的工作原理和机械结构,分析计算了弯矩加载对其他力矩加载的干扰和系统影响,从测试技术要求上论证了方案的可行性.最后进行了理论分析和研究,建立了加载系统的数学模型,基于PID控制算法,进行了计算机仿真.仿真结果表明,能够满足系统预定的性能指标要求.%To meet the requirements to current rudder motor test, the bending moment loading test system is designed. The system can achieve a few hundred to tens of thousands of N force output with DC motor driven. Based on an introduction to the structure and principle of electrical loading system, and the calculation of disturbance on torque from bending moment, the test system design is feasible to meet rudder motor test requirements. A mathematical model of the system is established to analyze and to computer simulate with PID control arithmetic. Simulation results indicated that the performance of the motor-driven bending moment loading test system is competent for rudder motor test.

  1. Friction and bending forces evaluation of AISI 304 DDQ steel sheet forming by bending tests under deep-drawing multiaxial stresses; Evaluacion de la fuerza de doblado y de friccion en el conformado de chapa de acero inoxidable AISI 304 DDQ mediante ensayos de doblado en condiciones multiaxiales de embuticion

    Energy Technology Data Exchange (ETDEWEB)

    Coello, J.; Miguel, V.; Ferrer, C.; Calatayud, A.; Martinez, A.

    2012-11-01

    Die radius is a critical area from the viewpoint of friction in forming processes. Moreover the sheet, that has been previously deformed in flange area, suffers bending and unbending stresses. Then, die-sheet contact in die radius must be especially considered in order to guarantee the suitable lubrication conditions. In the present work, a test method is carried out for evaluating an AISI 304 DDQ steel under similar conditions to those existing in the die radius area and that, usually, are not really reproduced in traditional bending under tensions tests. Deformation under pure shear condition, the bending and the radius angle have been established as variables of the tests. Results allow to obtain the apparent pressure sheet-bending tool, that increases with bending angle and decreases with tool radius. This last variable is the most significant while the bending angle has lesser influence. Although experimental results present some concordances with values obtained by analytical methods, some corrections must be considered in them in order to improve the theoretical values. (Author) 18 refs.

  2. Effect of dexamethasone on mandibular bone biomechanics in rats during the growth phase as assessed by bending test and peripheral quantitative computerized tomography.

    Science.gov (United States)

    Bozzini, Clarisa; Champin, Graciela; Alippi, Rosa M; Bozzini, Carlos E

    2015-04-01

    Long-term glucocorticoid administration to growing rats induces osteopenia and alterations in the biomechanical behavior of the bone. This study was performed to estimate the effects of dexamethasone (DTX), a synthetic steroid with predominant glucocorticoid activity, on the biomechanical properties of the mandible of rats during the growth phase, as assessed by bending test and peripheral quantitative computed tomographic (pQCT) analysis. The data obtained by the two methods will provide more precise information when analyzed together than separately. Female rats aged 23 d (n=7) received 500μg.kg-1 per day of DXT for 4 weeks. At the end of the treatment period, their body weight and body length were 51.3% and 20.6% lower, respectively, than controls. Hemimandible weight and area (an index of mandibular size) were 27.3% and 9.7% lower, respectively. The right hemimandible of each animal was subjected to a mechanical 3-point bending test. Significant weakening of the bone, as shown by a correlative impairment of strength and stiffness, was observed in experimental rats. Bone density and cross-sectional area were measured by pQCT. Cross-sectional, cortical and trabecular areas were reduced by 20% to 30% in the DTX group, as were other cortical parameters, including the bone density, mineral content and cross-sectional moment of inertia. The "bone strength index" (BSI, the product of the pQCT-assessed xCSMI and vCtBMD) was 56% lower in treated rats, which compares well with the 54% and 52% reduction observed in mandibular strength and stiffness determined through the bending test. Data suggest that the corticosteroid exerts a combined, negative action on bone geometry (mass and architecture) and volumetric bone mineral density of cortical bone, which would express independent effects on both cellular (material quality) and tissue (cross-sectional design) levels of biological organization of the skeleton in the species.

  3. An Experimental Investigation of Transverse Tension Fatigue Characterization of IM6/3501-6 Composite Materials Using a Three-Point Bend Test

    Science.gov (United States)

    Peck, Ann W.

    1998-01-01

    As composites are introduced into more complex structures with out-of-plane loadings, a better understanding is needed of the out-of-plane, matrix-dominated failure mechanisms. This work investigates the transverse tension fatigue characteristics of IM6/3501 composite materials. To test the 90 degree laminae, a three-point bend test was chosen, potentially minimizing handling and gripping issues associated with tension tests. A finite element analysis was performed of a particular specimen configuration to investigate the influence of specimen size on the stress distribution for a three-point bend test. Static testing of 50 specimens of 9 different sized configurations produced a mean transverse tensile strength of 61.3 Mpa (8.0 ksi). The smallest configuration (10.2 mm wide, Span-to-thickness ratio of 3) consistently exhibited transverse tensile failures. A volume scale effect was difficult to discern due to the large scatter of the data. Static testing of 10 different specimens taken from a second panel produced a mean transverse tensile strength of 82.7 Mpa (12.0 ksi). Weibull parameterization of the data was possible, but due to variability in raw material and/or manufacturing, more replicates are needed for greater confidence. Three-point flex fatigue testing of the smallest configuration was performed on 59 specimens at various levels of the mean static transverse tensile strength using an R ratio of 0.1 and a frequency of 20 Hz. A great deal of scatter was seen in the data. The majority of specimens failed near the center loading roller. To determine whether the scatter in the fatigue data is due to variability in raw material and/or the manufacturing process, additional testing should be performed on panels manufactured from different sources.

  4. Numerical Investigation of Dynamic Rock Fracture Toughness Determination Using a Semi-Circular Bend Specimen in Split Hopkinson Pressure Bar Testing

    Science.gov (United States)

    Xu, Y.; Dai, F.; Xu, N. W.; Zhao, T.

    2016-03-01

    The International Society for Rock Mechanics (ISRM) has suggested a notched semi-circular bend technique in split Hopkinson pressure bar (SHPB) testing to determine the dynamic mode I fracture toughness of rock. Due to the transient nature of dynamic loading and limited experimental techniques, the dynamic fracture process associated with energy partitions remains far from being fully understood. In this study, the dynamic fracturing of the notched semi-circular bend rock specimen in SHPB testing is numerically simulated for the first time by the discrete element method (DEM) and evaluated in both microlevel and energy points of view. The results confirm the validity of this DEM model to reproduce the dynamic fracturing and the feasibility to simultaneously measure key dynamic rock fracture parameters, including initiation fracture toughness, fracture energy, and propagation fracture toughness. In particular, the force equilibrium of the specimen can be effectively achieved by virtue of a ramped incident pulse, and the fracture onset in the vicinity of the crack tip is found to synchronize with the peak force, both of which guarantee the quasistatic data reduction method employed to determine the dynamic fracture toughness. Moreover, the energy partition analysis indicates that simplifications, including friction energy neglect, can cause an overestimation of the propagation fracture toughness, especially under a higher loading rate.

  5. Conversion of fracture toughness testing values from small scale three point bending test specimens to small scale yielding state (SSY) by elastic-plastic stress analysis; Murtumissitkeyden laskeminen pienen taivutuspalkin kokeesta

    Energy Technology Data Exchange (ETDEWEB)

    Ikonen, K. [Technical Research Centre of Finland, Espoo (Finland). Nuclear Engineering Lab.

    1993-07-01

    The report describes the work performed for achieving readiness to calculate fracture toughness dependence on dimension effects and loading conditions in fracture test specimens and real structures. In the report two- and three-dimensional computer codes developed and calculational methods applied are described. One of the main goals is to converse fracture toughness from small scale three point bending test specimens to case of a depth crack in plane strain i.e. to small scale yielding state (SSY) by numerical elastic-plastic stress analysis. Thickness effect of a test specimens and effect of a crack depth are separately investigated. Tests of three point bending specimens with and without sidegrooves and curved crack front are numerically simulated and experimental and computed results are compared. J-integral is calculated along crack front and also from force-deflection dependence of the beam. For the analyses the computing system was thoroughly automatized. Measuring capacity of three point bending test specimens was tried to evaluate. (orig.) (7 refs., 54 figs.).

  6. Bend Properties of Sapphire Fibers at Elevated Temperatures. 1; Bend Survivability

    Science.gov (United States)

    Morscher, Gregory N.; Sayir, Haluk

    1995-01-01

    The effect of temperature on the bend radius that a c-axis-oriented sapphire fiber can withstand was determined for fibers of various diameter. Bend stress rupture tests were performed for times of 1-100 h and temperatures of 300-1700 C. Fibers would survive the bend test undeformed, would fracture or would deform. The bend survival radius was determined to be the radius above which no fibers fractured or deformed for a given time-temperature treatment. It was found that the ability of fibers to withstand curvature decreases substantially with time and increasing temperature and that fibers of smaller diameter (46-83 micron) withstood smaller bend radii than would be expected from just a difference in fiber diameter when compared with the bend results of the fibers of large diameter (144 micron). This was probably due to different flaw populations, causing high temperature bend failure for the tested sapphire fibers of different diameters.

  7. Non-standard coupled extensional and bending bias tests for planar pantographic lattices. Part I: numerical simulations

    Science.gov (United States)

    Turco, Emilio; Barcz, Katarzyna; Pawlikowski, Marek; Rizzi, Nicola Luigi

    2016-10-01

    In dell'Isola et al. (Zeitschrift für Angewandte Math und Physik 66(6):3473-3498, 2015, Proc R Soc Lond A Math Phys Eng Sci 472(2185), 2016), the concept of pantographic sheet is proposed. The aim is to design a metamaterial showing: (i) a large range of elastic response; (ii) an extreme toughness in extensional deformation; (iii) a convenient ratio between toughness and weight. However, these required properties must coexist with non-detrimental mechanical characteristics in the presence of other kinds of imposed displacements. The aim of this paper is to prove via numerical simulations that pantographic sheets may effectively resist to coupled bending and extensional deformations. The four-parameter model introduced shows its versatility as it is able to encompass all the considered types of (large) deformations. The numerical integration scheme which we use is based on the same concepts exploited in Turco et al. (Zeitschrift für Angewandte Math und Physik 67(4):1-28, 2016): They prove that the Hencky-type discretization is very efficient also in nonlinear large deformations and large displacements regimes. In Part II of this paper, we will show that the used models are very effective to describe experimental evidence.

  8. Experimental Test of Data Analysis Methods from Staggered Pair X-ray Beam Position Monitors at Bending Magnet Beamlines

    International Nuclear Information System (INIS)

    Different methods have been proposed to calculate the vertical position of the photon beam centroid from the four blade currents of staggered pair X-ray beam position monitors (XBPMs) at bending magnet beamlines since they emerged about 15 years ago. The original difference-over-sum method introduced by Peatman and Holldack is still widely used, even though it has been proven to be rather inaccurate at large beam displacements. By systematically generating bumps in the electron orbit of the ANKA storage ring and comparing synchronized data from electron BPMs and XBPM blade currents, we have been able to show that the log-ratio method by S. F. Lin, B.G. Sun et al. is superior (meaning the characteristic being closer to linear) to the ratio method, which in turn is superior to the difference over sum method. These findings are supported by simulations of the XBPM response to changes of the beam centroid. The heuristic basis for each of the methods is investigated. The implications on using XBPM readings for orbit correction are discussed

  9. A general mixed mode fracture mechanics test specimen: The DCB-specimen loaded with uneven bending moments

    Energy Technology Data Exchange (ETDEWEB)

    Soerensen, B.F.; Joergensen, K.; Oestergaard, R.C. [Risoe National Lab., Materials Dept., Roskilde (Denmark); Jacobsen, T.K. [LM Glasfiber A/S, Lunderskov (Denmark)

    2004-03-01

    A mixed mode specimen is proposed for fracture mechanics characterisation of adhesive joints, laminates and multilayers. The specimen is a double cantilever beam specimen loaded with uneven bending moments at the two free beams. By varying the ratio between the two applied moments, the full mode mixity range from pure mode I to pure mode II can be generated for the same specimen geometry. The specimen allows stable crack growth. In case of large scale crack bridging, mixed mode cohesive laws can be obtained by a J integral based approach. As a preliminary example, fracture of adhesive joints between two glass-fibre laminates was studied. The mixed mode fracture resistance increased with increasing crack length due to fibre cross over bridging, eventually reaching a steady-state level (R-curve behaviour). The steady-state fracture toughness level increased with increasing tangential crack opening displacement. Cohesive stresses were determined by a J integral approach. The deducted shear stress was found to be relative high ({approx} = 20 MPa) in comparison with the normal stress ({approx} = 1 MPa). (au)

  10. Research on residual bending capacities of used wood members based on the correlation between non-destructive testing results and the mechanical properties of wood

    Institute of Scientific and Technical Information of China (English)

    Jin ZHANG; Qing-feng XU; Yi-xiang XU; Ming ZHANG

    2015-01-01

    To quantitatively assess the residual strength of wood members after rot and infestation using non-destructive testing (NDT), the multi-point Resistograph method was applied to test six used wood beams with initial imperfections. Each wood beam was then divided into a shorter segment for mechanical tests and a longer one for bending capacity tests. With the help of finite element analysis using ANSYS, bending capacity is predicted by taking account of the initial imperfections. Results show that there is a significant correlation between drill resistance values and strengths for small specimens. Therefore, the strengths of wood at other measurement points may be obtained through drill resistance values. The beams showed a near linear behaviour up to the maximum load with poor ductility performance in bending capacity tests. It can also be found that the effects of initial imperfec-tions on failure modes and ultimate loads are significant. The lateral side of specimen BA1 has serious infestation and the bottom of BA2 has a long longitudinal crack, the ultimate bearing capacities of these specimens are respectively only 67.6%and 64.8%of BA3, which has fewer cracks. BB1 and BB3 have knots at the bottom and their ultimate bearing capacities are respectively 83.9%and 81.0%of BB2, which has fewer cracks as well. Furthermore, there is quite good agreement between test results and numerical prediction using strength values obtained by NDT results. Therefore, the bending capacity of used wood beams can be obtained using NDT, which can provide the basis for the protection and retrofitting of wood structures.%题目:基于无损检测与木材力学性能相关性的既有木构件剩余抗弯承载力研究  目的:利用无损检测的方法,定量评估经腐朽和虫蛀后的既有木构件的剩余抗弯承载力。  方法:1.通过对木材小试件进行阻抗仪检测试验和材性试验,建立木材阻力值与抗压/抗拉强度

  11. 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.

  12. Moisture Absorption/Desorption Effects on Flexural Property of Glass-Fiber-Reinforced Polyester Laminates: Three-Point Bending Test and Coupled Hygro-Mechanical Finite Element Analysis

    Directory of Open Access Journals (Sweden)

    Xu Jiang

    2016-08-01

    Full Text Available Influence of moisture absorption/desorption on the flexural properties of Glass-fibre-reinforced polymer (GFRP laminates was experimentally investigated under hot/wet aging environments. To characterize mechanical degradation, three-point bending tests were performed following the ASTM test standard (ASTM D790-10A. The flexural properties of dry (0% Mt/M∞, moisture unsaturated (30% Mt/M∞ and 50% Mt/M∞ and moisture saturated (100% Mt/M∞ specimens at both 20 and 40 °C test temperatures were compared. One cycle of moisture absorption-desorption process was considered in this study to investigate the mechanical degradation scale and the permanent damage of GFRP laminates induced by moisture diffusion. Experimental results confirm that the combination of moisture and temperature effects sincerely deteriorates the flexural properties of GFRP laminates, on both strength and stiffness. Furthermore, the reducing percentage of flexural strength is found much larger than that of E-modulus. Unrecoverable losses of E-modulus (15.0% and flexural strength (16.4% for the GFRP laminates experiencing one cycle of moisture absorption/desorption process are evident at the test temperature of 40 °C, but not for the case of 20 °C test temperature. Moreover, a coupled hygro-mechanical Finite Element (FE model was developed to characterize the mechanical behaviors of GFRP laminates at different moisture absorption/desorption stages, and the modeling method was subsequently validated with flexural test results.

  13. 减振器活塞杆侧向弯曲疲劳试验机构设计%Design on Lateral Bending Fatigue Test Mechanism of Piston Rod in Shock Absorber

    Institute of Scientific and Technical Information of China (English)

    孙晓帮; 杨晓琦; 杨殿旭; 王国东

    2014-01-01

    在介绍减振器活塞杆侧向弯曲疲劳试验原理的基础上,设计出实现活塞杆侧向弯曲试验功能的曲柄连杆双弹簧机构,并确定了关键功能参数。试验结果表明,该试验机构能满足直径小于25 mm的活塞杆侧向弯曲疲劳试验。%Based on introducing the principle on lateral bending fatigue test of piston rod in shock absorber, crank connecting rod double spring mechanism was designed to implement function of lateral bending test of piston rod, and key function parameters were determined. Experimental results show that this mechanism can meet lateral bending fatigue test of piston rod whose diameter is less than 32mm.

  14. Miniaturized disk bend test-a new technique for monitoring the changes of mechanical properties of structural materials operating in extreme conditions

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Method of Miniaturized Disk Bend Test (MDBT) originally designed for the tests of irradiated materials is a convenient technique for monitoring the degradation of mechanical properties of structural materials operating in extreme conditions. A small size of specimens (disks with 3 mm in diameter and 0.1-0.3 mm in thickness) as well as possibility to use the standard equipments for tension and/or pressure tests allow minimizing the financial charge for application of this method in practice and enable to keep up in the real time with (watch on) the changes of materials mechanical properties induced by the effect of unfavorable environment. Wide application of MDBT or other methods for miniaturized specimen tests does possible to inspect on the fly the changes of strength and ductility of the materials, and, of the expense of it, to prevent an alert conditions caused by the materials degradation, for instance, catastrophic embrittlement.In the paper, methodical aspects of MDBT technique application for estimation of structural materials mechanical properties have been considered. By the example of own results and literature data, the possibilities of MDBT method are demonstrated as well as the correlation of obtained from this technique parameters with the standard mechanical properties such as strength, yield stress and ductility of metals.

  15. The evaluation of dynamic cracking resistance of chosen casting alloys in the aspect of the impact bending test

    Directory of Open Access Journals (Sweden)

    J.Sadowski

    2008-10-01

    Full Text Available The increase of quality and durability of produced casting alloys can be evaluated on the base of material tests performed on a high level. One of such modern test methods are tests of the dynamic damage process of materials and the evaluation on the base of obtained courses F(f, F(t of parameters of dynamic cracking resistance KId, JId, performed with the usage of instrumented Charpy pendulums. In the paper there was presented the evaluation of dynamic cracking resistance parameters of casting alloys such as: AK12 aluminum alloy, L20G cast steel and spheroid cast iron. The methodology of the evaluation of that parameters was described and their change as well, for the AK12 alloy with the cold work different level, L20G cast steel cooled from different temperatures in the range +20oC -60oC, and for the spheroid cast iron in different stages of treatment i.e. raw state, after normalization, spheroid annealing and graphitizing annealing.Obtained parameters of dynamic cracking resistance KId, JId of tested casting alloys enabled to define the critical value of the ad defect that can be tolerated by tested castings in different work conditions with impact loadings.

  16. An evaluation of the sandwich beam in four-point bending as a compressive test method for composites

    Science.gov (United States)

    Shuart, M. J.; Herakovich, C. T.

    1978-01-01

    The experimental phase of the study included compressive tests on HTS/PMR-15 graphite/polyimide, 2024-T3 aluminum alloy, and 5052 aluminum honeycomb at room temperature, and tensile tests on graphite/polyimide at room temperature, -157 C, and 316 C. Elastic properties and strength data are presented for three laminates. The room temperature elastic properties were generally found to differ in tension and compression with Young's modulus values differing by as much as twenty-six percent. The effect of temperature on modulus and strength was shown to be laminate dependent. A three-dimensional finite element analysis predicted an essentially uniform, uniaxial compressive stress state in the top flange test section of the sandwich beam. In conclusion, the sandwich beam can be used to obtain accurate, reliable Young's modulus and Poisson's ratio data for advanced composites; however, the ultimate compressive stress for some laminates may be influenced by the specimen geometry.

  17. Evaluation of constraint methodologies applied to a shallow-flaw cruciform bend specimen tested under biaxial loading conditions

    International Nuclear Information System (INIS)

    A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a prototypic, far-field. out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for RPV materials. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies. namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness, the conventional maximum principal stress criterion indicated no effect

  18. Semiconductor laser beam bending

    OpenAIRE

    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...

  19. Fracture assessment of HSST Plate 14 shallow-flaw cruciform bend specimens tested under biaxial loading conditions

    Energy Technology Data Exchange (ETDEWEB)

    Bass, B.R.; McAfee, W.J.; Williams, P.T.; Pennell, W.E.

    1998-06-01

    A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow, surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a far-field, out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for an RPV material. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies, namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness; the conventional maximum principal stress criterion indicated no effect. A three-parameter Weibull model based on the hydrostatic stress criterion is shown to correlate the experimentally observed biaxial effect on cleavage fracture toughness by providing a scaling mechanism between uniaxial and biaxial loading states.

  20. Fracture assessment of HSST Plate 14 shallow-flaw cruciform bend specimens tested under biaxial loading conditions

    International Nuclear Information System (INIS)

    A technology to determine shallow-flaw fracture toughness of reactor pressure vessel (RPV) steels is being developed for application to the safety assessment of RPVs containing postulated shallow surface flaws. Matrices of cruciform beam tests were developed to investigate and quantify the effects of temperature, biaxial loading, and specimen size on fracture initiation toughness of two-dimensional (constant depth), shallow, surface flaws. The cruciform beam specimens were developed at Oak Ridge National Laboratory (ORNL) to introduce a far-field, out-of-plane biaxial stress component in the test section that approximates the nonlinear stresses resulting from pressurized-thermal-shock or pressure-temperature loading of an RPV. Tests were conducted under biaxial load ratios ranging from uniaxial to equibiaxial. These tests demonstrated that biaxial loading can have a pronounced effect on shallow-flaw fracture toughness in the lower transition temperature region for an RPV material. The cruciform fracture toughness data were used to evaluate fracture methodologies for predicting the observed effects of biaxial loading on shallow-flaw fracture toughness. Initial emphasis was placed on assessment of stress-based methodologies, namely, the J-Q formulation, the Dodds-Anderson toughness scaling model, and the Weibull approach. Applications of these methodologies based on the hydrostatic stress fracture criterion indicated an effect of loading-biaxiality on fracture toughness; the conventional maximum principal stress criterion indicated no effect. A three-parameter Weibull model based on the hydrostatic stress criterion is shown to correlate the experimentally observed biaxial effect on cleavage fracture toughness by providing a scaling mechanism between uniaxial and biaxial loading states

  1. Thin-slice fiber pushout and specimen bending in metallic matrix composite tests. [sapphire-TiAl,sapphire-NiAl

    Energy Technology Data Exchange (ETDEWEB)

    Rhyne, E.P.; Hellmann, J.R.; Galbraith, J.M.; Koss, D.A. (Pennsylvania State Univ., University Park, PA (United States). Center for Advanced Materials)

    1995-02-15

    Both the degree of strengthening and the crack growth resistance of fiber-reinforced composites are sensitive to the shear behavior at the fiber-matrix interface. It is shown in this work that composites containing optically transparent fibers can be metal backplated using photolithographic techniques to provide a support with a hole size matching the fiber diameter. Results from sapphire-reinforced metal matrix composites in thin-slice fiber pushout tests indicate that the interfacial shear strength values are the same regardless of whether the specimen was supported by the metal backplate or by a hole 1.6 times the fiber diameter or by a groove 2 times the fiber diameter.

  2. Bend me, shape me

    CERN Multimedia

    2002-01-01

    A Japanese team has found a way to bend and shape silicon substrates by growing a thin layer of diamond on top. The technique has been proposed as an alternative to mechanical bending, which is currently used to make reflective lenses for X-ray systems and particle physics systems (2 paragraphs).

  3. Creep of uranium dioxide: bending test and mechanical behaviour; Etude du fluage du dioxyde d'uranium: caracterisation par essais de flexion et modelisation mecanique

    Energy Technology Data Exchange (ETDEWEB)

    Colin, Ch

    2003-09-01

    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 UO{sub 2} 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% H{sub 2}). 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 {+-}2{mu}m 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

  4. Performance monitoring of large-scale autonomously healed concrete beams under four-point bending through multiple non-destructive testing methods

    Science.gov (United States)

    Karaiskos, G.; Tsangouri, E.; Aggelis, D. G.; Van Tittelboom, K.; De Belie, N.; Van Hemelrijck, D.

    2016-05-01

    Concrete is still the leading structural material due to its low production cost and great structural design flexibility. Although it is distinguished by such a high durability and compressive strength, it is vulnerable in a series of ambient and operational degradation factors which all too frequently result in crack formation that can adversely affect its mechanical performance. The autonomous healing system, using encapsulated polyurethane-based, expansive, healing agent embedded in concrete, is triggered by the crack formation and propagation and promises material repair and operational service life extension. As shown in our previous studies, the formed cracks on small-scale concrete beams are sealed and repaired by filling them with the healing agent. In the present study, the crack formation and propagation in autonomously healed, large-scale concrete beams are thoroughly monitored through a combination of non-destructive testing (NDT) methods. The ultrasonic pulse velocity (UPV), using embedded low-cost and aggregate-size piezoelectric transducers, the acoustic emission (AE) and the digital image correlation (DIC) are the NDT methods which are comprehensively used. The integrated ultrasonic, acoustic and optical monitoring system introduces an experimental configuration that detects and locates the four-point bending mode fracture on large-scale concrete beams, detects the healing activation process and evaluates the subsequent concrete repair.

  5. 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

  6. Test on Bending Performance of Recycled Concrete Composite Beams%再生混凝土叠合梁受弯力学性能试验研究

    Institute of Scientific and Technical Information of China (English)

    肖建庄; 高歌; 徐亚玲; 范氏鸾

    2012-01-01

    设计了3根再生混凝土叠合梁,受拉钢筋配筋率分别为0.5%、1.0%、1.5%,预制部分采用普通混凝土,叠合部分采用100%再生粗骨料取代率的再生混凝土.另外设计了1根整浇梁,全部采用再生粗骨料取代率的再生混凝土.通过受弯性能试验,得到挠度和裂缝发展规律以及破坏特征.运用Ansys软件对叠合梁进行了非线性有限元分析.试验结果和数值分析表明,再生混凝土叠合梁的受弯力学性能和普通混凝土梁受弯性能接近,其受弯承载力可采用普通混凝土梁的计算方法进行计算.采用再生混凝土的弹性模量,利用现有规范GB 50010-2002短期刚度计算公式得到的挠度,需乘以0.8的修正系数后才适用于再生混凝土叠合梁.%Three recycled concrete composite beams with tensile reinforcement ratios of 0. 5%, 1. 0%, 1. 5% are respectively designed. The prefabricated part uses conventional concrete while the cast-in-place part uses recycled concrete. In order to compare with the conventional concrete beam, a conventional concrete beam is also designed in which the replacement ratio of the recycled coarse aggregate is 100%. The midpoint deflections, ultimate loads, the distribution of the cracks, and failure characteristics have been obtained during the bending test. The non-linear finite element analysis is carried out by the software of Ansys. The experiment results and numerical analysis show that the recycled concrete composite beams behave similarly as the conventional concrete beams, the theory and design method applied to the conventional concrete beams can also be suitable to the recycled concrete composite beams. The deflection calculated according to the GB 50010-002 can still be applied to the recycled concrete composite beams after mordified by a factor 0. 8.

  7. 用热弯实验方法决定导电薄膜的热膨胀系数%DETERMINING THERMAL EXPANSION COEFFICIENT OF CONDUCTIVE THIN FILM BY THERMAL BEND TEST

    Institute of Scientific and Technical Information of China (English)

    沈为; 彭立华; 李伟; 邓泽贤

    2001-01-01

    研究了热-力载荷下薄膜/基板复合梁的弯曲问题,导出了薄膜的热膨胀系数与试样表面的温度和变形之间的关系式;提出一种测量导电薄膜的热膨胀系数的方法,并用热弯实验测SnO2膜的热膨胀系数.%The bending problem of thin film/substrate composite subjected to thermal load is studied. The relation between the thermal expansion coefficient of conductive thin films, temperature and deformation of specimen surfaces is derived in this paper. Based on the findings, a method for measuring the thermal expansion coefficient of conductive thin films is developed. The thermal expansion coefficient of conductive thin films has been measured by applying the method in a thermal bend test.

  8. A transparent bending-insensitive pressure sensor

    Science.gov (United States)

    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.

  9. A transparent bending-insensitive pressure sensor.

    Science.gov (United States)

    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.

  10. Bending rigidity of composite resin coating clasps.

    Science.gov (United States)

    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

  11. 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...

  12. Study on the Ultra High Cycle Bending Vibration Fatigue Test of Titanium Alloys%钛合金超高周弯曲振动疲劳性能试验

    Institute of Scientific and Technical Information of China (English)

    申景生; 李全通; 吴晓峰; 高潮; 刘青川

    2011-01-01

    Based on the three-point bending method, an ultra high cycle bending vibration fatigue system is developed and the design method of fatigue test specimens is introduced too. The S - N curve of titanium alloy TC17 is determined by the ultra high cycle dissymmetrical bending fatigue system (20 kHz). The result shows that when stress ratio(R) is -1, the S - N curve of titanium alloy TC17 is a continuously declining curve, The specimens continue to fail over 107 stress cycles. In 107 weeks time, the samples don' t happen the fatigue damage, so it does not exist in the traditional sense fatigue limit.%在三点弯曲超高周疲劳试验的基础上,开发了悬臂梁式弯曲振动超高周疲劳试验系统,并介绍了疲劳试验试片的设计方法.利用超高周弯曲疲劳试验系统(20 kHz)测定了钛合金TC17的S-N曲线,结果表明,当应力比R=-1时TC17钛合金的S-N曲线是一条连续下降型曲线,在107周次以后,试样仍未发生疲劳破坏,不存在传统意义上的疲劳极限.

  13. Spring back evaluation by bending under tension tests in conditions of multiaxial stresses corresponding to deep drawing processes. Application to AISI 304 DDQ stainless steel sheet; Evaluacion del springback mediante ensayos de doblado bajo tension en condiciones de multiaxialidad tipicas de los procesos de embuticion profunda. Aplicacion a chapa de acero inoxidable AISI 304 DDQ

    Energy Technology Data Exchange (ETDEWEB)

    Miguel, V.; Coello, J.; Martinez, A.; Calatayud, A.

    2013-09-01

    In this paper, a methodology has been developed for evaluating the spring back of AISI 304 DDQ stainless steel sheet based on a bending under tension test. The main difference of the methodology herein carried out is that tests are made under the multiaxial stresses state that take place in deep drawing processes. This affects to the level of stress value in the test and to the hardening state of the sheet. Springback evaluation has been done in two different areas. Bending area has been evaluated from elastic recovery ratio defined as the ratio between the bending radius after and before bending. Bending and unbending extreme has been studied from the measured curvature radius in this area and taking into account the geometric equivalence of the test with the drawing cups process. Results found allow to state that drawing ratio or deformation ratio have a negligible influence on the springback into the range of values experimented here. Bending radius has hardly influence as well while bending angle is the most significant variable. The results obtained are compared to those measured in deep-drawn cups, finding a great agreement. (Author)

  14. 基于虚拟仪器的减振器活塞杆侧向弯曲疲劳试验系统%Lateral dynamic bending fatigue test system of piston rod in shock absorber based on virtual instruments

    Institute of Scientific and Technical Information of China (English)

    孙晓帮; 王天利; 张忠洋; 谢佳茵

    2011-01-01

    Lateral dynamic bending fatigue test system of piston rod based on virtual instruments is developed by using LabVIEW and data acquisition device of NI Corporatior.In the system,slider-crank connecting rod dual spring mechanism is drived by motor to provide piston rods sinusoidal excitation,data acquisitionsystem tests the waveforms of exciting force,and records the fiexiblelifes.The experiment results indicate the test system has the characteristics of convenient use,stable test precision,and are satisfied with piston rods the diameter of which are not more than 32mm in dynamic bending fatigue test.%结合LabVIEW软件和NI公司的数据采集设备,开发出基于虚拟仪器的活塞杆侧向弯曲疲劳试验系统.在该系统中,驱动电机带动曲柄连杆滑块双弹簧机构对活塞杆施加正弦激振力,数据采集系统检测激振力波形,并记录弯曲疲劳寿命.试验结果表明,该试验系统具有使用方便、测试精度稳定的特点,能满足直径不大于32mm的活塞杆弯曲疲劳试验.

  15. Bending Behavior and Ductility Test of High Performance Steel Beam Based on Hybrid Design%基于混合设计的高性能钢梁抗弯性能及延性试验

    Institute of Scientific and Technical Information of China (English)

    王春生; 段兰; 王继明; 郑丽

    2012-01-01

    基于混合设计的理念,采用中国产高性能钢HPS 485W和普通结构钢Q235,加工制造了6片混合设计工字形钢梁,在跨中单点加载,研究试验梁的抗弯承载能力、变形特征及最终的破坏形态。试验结果表明:腹板屈曲强度和试验梁侧向支撑刚度对试验梁的极限承载力、延性和失效形式有显著影响;试验梁的抗弯承载力主要由翼缘提供,但抗弯延性主要受腹板控制,承载力下降阶段受腹板屈曲强度影响显著;采用厚实截面设计的高性能钢梁可以达到全截面塑性,在有效的侧向限位下高性能钢梁具有很好的延性。试验结果与理论计算结果的对比表明,塑性弯矩理论计算结果与试验值吻合较好。%Based on the concept of hybrid design,6 I-beams were designed and fabricated by high performance steel HPS 485W for flanges and steel Q235 for webs.In the bending test,these simple supported welding beams were loaded at mid-span.After the test,flexural capacity,deformation characteristics and the ultimate failure mode were analyzed during the whole experimental process.Test results show that web bucking strength and the rigidity of lateral bracing significantly affect the ultimate capacity,ductility and failure mode of tested beams.Flexural capacity is mainly contributed by flanges,and ductility is primarily affected by web.The descending stage of the bending capacity is controlled by the web bucking strength.It can be concluded that HPS beam with compact section has good plastic bending behavior and good ductility under effective lateral bracing system.Comparison between test result and theoretical calculation shows good coincidence between theoretical plastic moment and bending process in the test.

  16. Numerical and Experimental Analysis on Seven-Point Bending Test of Integrated Composite Panels%复合材料整体加筋板的七点弯曲试验与数值分析

    Institute of Scientific and Technical Information of China (English)

    叶强; 夏翔; 肖闪闪; 陈普会; 李新翔; 柴亚南

    2011-01-01

    研究了复合材料整体加筋板七点弯曲试验的失效表征同题.在有限元分析的基础上,设计了七点弯曲试件和试验夹具.在试验研究和有限元计算的基础上,对七点弯曲试验的失效机理进行了讨论分析.通过对一系列七点弯曲试验模型的分析,获得了复合材料加筋板典型部位的失效包线,并给出了失效表征方法.最后给出了指导复合材料整体加筋板结构细节设计的建议.%The failure characterization is studied for the seven-point bending tests of integrated composite panels. The specimen and fixture of seven-point bending test are designed based on the finite element analysis. Furthermore, the failure mechanisms of the specimen are discussed based on the test results and the finite element simulations. The failure envelop of the typical structural details is obtained and the method is presented for the failure characterization of the specimen by numerically simulating a series of seven-point bending test models. Finally, some suggestions are proposed for the detailed design of integrated stiffened composite panels.

  17. 金属材料弯曲试验压头位移与角度关系的程序编制%Programming of the Relationship between Head Displacement and Angular in Metallic Materials Bending Test

    Institute of Scientific and Technical Information of China (English)

    陈彦恒; 张超平; 朱永超

    2014-01-01

    In the test, the steel raw materials and reinforced flash butt welding requires bending test. In the current, the most commonly used method is visual measurement, so it may inevitably produce some errors. So this paper developed a application program for the relationship between the head displacement and angular according to the relevant provisions in "Metallic Materials Bending Test Method"GB/T232-2010, which improved the seriousness and accuracy of test.%钢筋原材和钢筋闪光对焊在试验检测中需要进行抗弯试验,目前常用的角度量测方法为目测,为此不可避免产生一些误差。为此本文根据《金属材料弯曲试验法》GB/T232-2010相关规定编制了试验压头行程与角度关系的应用程序,提高了试验检测的严肃性和准确度。

  18. 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.

  19. A Method to Identify the Load of Accelerate Bending Fatigue Testing%一种确定加速弯曲疲劳试验载荷的方法

    Institute of Scientific and Technical Information of China (English)

    唐振国; 张跃春; 左晃

    2015-01-01

    For reducing the development time and cost,this article used the concrete reducer as an example to come up with a method to identify the load of accelerated bending fatigue testing.According to the experiment load spectrum of reducer and considered the law of actual load between each drive disk assembly,then using multilevel equivalent load method to deduced the equivalent load bending of each gears and got the load of accelerate bending fatigue testing through the method of linear hardening.MASTA software showed that the damage rate of consistency in two kinds of load conditions was great.%为缩短多级多工况传动装置研发周期,降低研发成本,文章以混凝土减速器为例,提出了一种确定加速弯曲疲劳试验载荷的方法.根据减速器的实测载荷谱,考虑传动部件之间实际载荷作用规律,采用多级等效载荷法,推导出各个齿轮的弯曲等效载荷并通过线性强化方法最终获得加速弯曲疲劳试验载荷.采用MASTA软件验算结果表明,各齿轮在两种载荷状态下损伤率一致性很好.

  20. 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.

  1. Finite Element Analysis for Bending Process of U-Bending Specimens

    Energy Technology Data Exchange (ETDEWEB)

    Park, Won Dong; Bahn, Chi Bum [Pusan National University, Busan (Korea, Republic of)

    2015-10-15

    ASTM G30 suggests that the applied strain can be calculated by dividing thickness by a bend radius. It should be noted, however, that the formula is reliable under an assumption that the ratio of thickness to bend radius is less than 0.2. Typically, to increase the applied stress/strain, the ratio of thickness to bend radius becomes larger than 0.2. This suggests that the estimated strain values by ASTM G30 are not reliable to predict the actual residual strain state of the highly deformed U-bend specimen. For this reason, finite element analysis (FEA) for the bending process of Ubend specimens was conducted by using a commercial finite element analysis software ABAQUS. ver.6.14- 2;2014. From the results of FEA, PWSCC initiation time and U-bend specimen size can be determined exactly. Since local stress and strain have a significant effect on the initiation of PWSCC, it was inappropriate to apply results of ASTM G30 to the PWSCC test directly. According to results of finite element analysis (FEA), elastic relaxation can cause inaccuracy in intended final residual stress. To modify this inaccuracy, additional process reducing the spring back is required. However this additional process also may cause uncertainty of stress/strain state. Therefore, the U-bending specimen size which is not creating uncertainty should be optimized and selected. With the bending radius of 8.3 mm, the thickness of 3 mm and the roller distance of 32.6 mm, calculated maximum stress and strain were 670 MPa and 0.21, respectively.

  2. 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.

  3. Inelastic Deformation Analysis of Aluminum Bending Members

    Institute of Scientific and Technical Information of China (English)

    CHENG Ming; SHI Yongjiu; WANG Yuanqing

    2006-01-01

    Aluminum alloys are typical nonlinear materials, and consequently bending members made of this material exhibit a nonlinear behavior. Most design codes do not pay much attention to such deformations and adopt a simple linear analysis for the calculation of deflections. This paper presents an investigation of the nonlinear deformation of aluminum bending members using the finite-element analysis (FEA). The plastic adaptation coefficient, which can be used to limit the residual deflection, is introduced, and the influence of residual deflection is investigated. A method for evaluating the plastic adoption coefficient is proposed. This paper also shows the load-deflection curve of aluminum bending members and the influence of several parameters. A semi-empirical formula is derived, and some numerical examples are given by FEA. The coefficients of the semi-empirical formula are modified by the FEA results using the nonlinear fitting method. Based on these results, two improved design methods for strength and deformation of aluminum bending members are proposed. Through the comparison with test data, these methods are proved to be suitable for structural design.

  4. 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.

  5. Regulation of transcription by synthetic DNA-bending agents.

    Science.gov (United States)

    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

  6. Development of a hybrid dome composed of glued-laminated timbers and steel cables. (Part 3). ; Bending tests of the glulam joint. Daidanmen shuseizai to cable ni yoru hybridter dot dome kozo no kaihatsu. 3. ; Daidanmen shuseizai setsugobu no mage saika jikken

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, N.; Tsubota, H.; Maruyama, N.; Kobayashi, H. (Kajima Corp., Tokyo (Japan))

    1991-10-31

    As a part of the development of the large scale hybrid dome (140 m in diameter, 49 m in height) composed of glued-laminated timbers (glulam) and steel cables, bending tests of full-size glulam joints with steel plates and bolts were conducted to evaluate the bending moment capacity of the joint. As a result, the observed ultimate bending moment capacities of all the joint specimens were larger than the designed ones, and all the specimens failed with splits in the glulam along bolt rows in a tensile zone due to either strong or weak-axial bending. Adhesive enhanced the bending rigidity of the joint in the weak axis, relaxing slightly radical failure. The specific bolt was subjected to tensile force through bending in the strong axis, while all the bolts equally subjected to tensile force in the weak axis. It was rational to design wooden joints by applying the AIJ (Architectural Institute of Japan) standard under the appropriate assumption of the force distribution among members of a bolt group. 2 refs., 11 figs., 2 tabs.

  7. Advanced device for testing the electrical behavior of conductive coatings on flexible polymer substrates under oscillatory bending: comparison of coatings of sputtered indium-tin oxide and poly3,4ethylenedioxythiophene

    International Nuclear Information System (INIS)

    A special device was designed and set up to investigate the electrical behavior of conductive layers on flexible substrates under oscillatory bending. The resistance of conductive coatings can be measured during various oscillatory bending conditions. The bending radius, the amplitude and the frequency can be set to well-defined values. Furthermore, the setup allows us to apply tensile or compressive stress to the coating as well as both stresses alternately. Thus, various bending loads occurring in printable electronics applications can be simulated to investigate the electrical reliability of conductive coatings. In addition, it is possible to simulate different environmental conditions during oscillatory bending by running the device in an environmental chamber. Characterizations of the electrical behavior under oscillatory bending were carried out on commercially available polyethyleneterephthalate (PET) films sputtered with indium-tin oxide (ITO) and coated with poly3,4ethylenedioxythiophene (PEDOT). For coatings of sputtered ITO, a dramatic increase of the resistance is observed for bending radii smaller than 14 mm due to cracks spanning the whole sample width. The higher the amplitude, the more pronounced is the increase of the resistance. Coatings of PEDOT show high stability under oscillatory bending. There is no change in resistance observed for all bending radii and amplitudes applied over a large number of cycles

  8. Rock bending creep and disturbance effects

    Institute of Scientific and Technical Information of China (English)

    付志亮; 郑颖人; 刘元雪

    2008-01-01

    The bending creep and its disturbance effects of red sandstone rock beam and oil shale rock beam were studied by adopting the self-developed gravitation level style rock creep test machine and bending creep test system,and the constitutive equations were established.It is found that fracture morphology of rock beams under no disturbance load is regular,cracking position of fractures is on part of loading concentration,the crack starts from a neutral plane.However,fracture morphology of rock beams under disturbance load is irregular,cracking position of fractures deviates from a neutral plane.Delayed instability of rock beam occurs for some time under constant disturbance load.When disturbance load is beyond a certain range,suddenly instability of occurs rock beam in a certain time.The results show that there is a guiding significance for creep stability in the geotechnical engineering fields.

  9. Sheet Bending using Soft Tools

    Science.gov (United States)

    Sinke, J.

    2011-05-01

    Sheet bending is usually performed by air bending and V-die bending processes. Both processes apply rigid tools. These solid tools facilitate the generation of software for the numerical control of those processes. When the lower rigid die is replaced with a soft or rubber tool, the numerical control becomes much more difficult, since the soft tool deforms too. Compared to other bending processes the rubber backed bending process has some distinct advantages, like large radius-to-thickness ratios, applicability to materials with topcoats, well defined radii, and the feasibility of forming details (ridges, beads). These advantages may give the process exclusive benefits over conventional bending processes, not only for industries related to mechanical engineering and sheet metal forming, but also for other disciplines like Architecture and Industrial Design The largest disadvantage is that also the soft (rubber) tool deforms. Although the tool deformation is elastic and recovers after each process cycle, the applied force during bending is related to the deformation of the metal sheet and the deformation of the rubber. The deformation of the rubber interacts with the process but also with sheet parameters. This makes the numerical control of the process much more complicated. This paper presents a model for the bending of sheet materials using a rubber lower die. This model can be implemented in software in order to control the bending process numerically. The model itself is based on numerical and experimental research. In this research a number of variables related to the tooling and the material have been evaluated. The numerical part of the research was used to investigate the influence of the features of the soft lower tool, like the hardness and dimensions, and the influence of the sheet thickness, which also interacts with the soft tool deformation. The experimental research was focused on the relation between the machine control parameters and the most

  10. Experimental verification of a weak zone model for timber in bending

    DEFF Research Database (Denmark)

    Källsner, B.; Ditlevsen, Ove Dalager; Salmela, K.

    1997-01-01

    In order to verify a stochastic model for the variation of bending strength within and between structural timber members, tests with long members subjected to constant bending moment have been performed. The span with constant moment contained between five and nine weak zones, i.e. zones with a c......In order to verify a stochastic model for the variation of bending strength within and between structural timber members, tests with long members subjected to constant bending moment have been performed. The span with constant moment contained between five and nine weak zones, i.e. zones...... with a cluster of knots. In a previous investigation test specimens, each containing one weak zone, have been tested in bending separately. Based on these tests a hierarchical model with two levels was formulated. The test results show that the bending strength of the long timber members on the average is 5...

  11. Parallel monostrand stay cable bending fatigue

    DEFF Research Database (Denmark)

    Winkler, Jan Pawel

    This dissertation investigates the bending fatigue response of high-strength steel monostrands and multistrand stay cables to cyclic transverse deformations. Increasing bridge stock numbers and a push for longer cable-supported span lengths have led to an increased number of reported incidents...... of damage and replacement of bridge stay cables due to wind and traffic-induced fatigue. The understanding of fatigue mechanisms in most steel structures is well established. However, in the case of cables composed of steel strands, many important aspects related with bending fatigue remain to be clarified....... The thesis starts with a literature review of the state-of-the-art in the fields of stay cable fatigue testing and cable fatigue resistance. The study helped to systemize the understanding of the fatigue characteristics of bridge cables subjected to cyclic transverse displacements, failure mechanisms...

  12. Materials Reliability Program: Environmental Fatigue Testing of Type 304L Stainless Steel U-Bends in Simulated PWR Primary Water (MRP-137)

    Energy Technology Data Exchange (ETDEWEB)

    R.Kilian

    2004-12-01

    Laboratory data generated in the past decade indicate a significant reduction in component fatigue life when reactor water environmental effects are experimentally simulated. However, these laboratory data have not been supported by nuclear power plant component operating experience. In recent comprehensive review of laboratory, component and structural test data performed through the EPRI Materials Reliability Program, flow rate was identified as a critical variable that was generally not considered in laboratory studies but applicable in plant operating environments. Available data for carbon/low-alloy steel piping components suggest that high flow is beneficial regarding the effects of a reactor water environment. Similar information is lacking for stainless steel piping materials. This report documents progress made to date in an extensive testing program underway to evaluate the effects of flow rate on the corrosion fatigue of 304L stainless steel under simulated PWR primary water environmental conditions.

  13. Size and deformation limits to maintain constraint in K{sub Ic} and J{sub c} testing of bend specimens

    Energy Technology Data Exchange (ETDEWEB)

    Koppenhoefer, K.C.; Dodds, R.H. Jr. [Illinois Univ., Urbana, IL (United States). Dept. of Civil Engineering

    1995-10-01

    The ASTM Standard Test Method for Plane-Strain Fracture Toughness of metallic Materials (E399-90) restricts test specimen dimensions to insure the measurement of highly constrained fracture toughness values (K{sub Ic}). These requirements insure small-scale yielding (SSY) conditions at fracture, and thereby the validity of linear elastic fracture mechanics. Recently, Dodds and Anderson have proposed a less restrictive size requirement for cleavage fracture toughness measured in terms of the J-integral (J{sub c}), as given by a, b, B {ge} 200 J{sub c}/{sigma}{sub 0}. The size requirement proposed by Dodds and Anderson increases the applicability of fracture toughness experiments by expanding the range of conditions over which fracture toughness data meeting SSY conditions can be reliably measured. This investigation compares the proposed size requirement with that of ASTM Standard Test Method E399 and, by comparison with published experimental data for various alloys, provides validation of the new requirements.

  14. FY 2013 Summary Report: Post-Irradiation Examination of Zircaloy-4 Samples in Target Capsules and Initiation of Bending Fatigue Testing for Used Nuclear Fuel Vibration Integrity Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Howard, Richard H [ORNL; Yan, Yong [ORNL; Wang, Jy-An John [ORNL; Ott, Larry J [ORNL; Howard, Rob L [ORNL

    2013-10-01

    This report documents ongoing work performed at Oak Ridge National Laboratory (ORNL) for the Department of Energy, Office of Fuel Cycle Technology Used Fuel Disposition Campaign (UFDC), and satisfies the deliverable for milestone M2FT-13OR0805041, “Data Report on Hydrogen Doping and Irradiation in HFIR.” This work is conducted under WBS 1.02.08.05, Work Package FT-13OR080504 ST “Storage and Transportation-Experiments – ORNL.” The objectives of work packages that make up the S&T Experiments Control Account are to conduct the separate effects tests (SET) and small-scale tests that have been identified in the Used Nuclear Fuel Storage and Transportation Data Gap Prioritization (FCRD-USED-2012-000109). In FY 2013, the R&D focused on cladding and container issues and small-scale tests as identified in Sections A-2.9 and A-2.12 of the prioritization report.

  15. Application of non contact video gauge in bending loading test%非接触式位移/应变视频测量系统在弯曲试验中的应用

    Institute of Scientific and Technical Information of China (English)

    梁芳; 黄志强; 白桦

    2014-01-01

    在弯曲梁试验中运用了非接触式位移/应变视频测量系统,对其跨中挠度及梁侧混凝土应变进行测量,同时使用应变片在梁的另一侧测量应变,与视频测量法进行对比。结果表明:两种仪器测得的应变的相对误差能够满足测量需要。在本试验的基础上而且非接触式位移/应变视频测量系统在试验前无需花费时间去贴应变片,测量结束后整个试验过程都被记录下来,可供以后研究。%The paper compares the measure results by non contact video gauge and strain gauges in bending loading test. The non contact video gauge don't need to stick the strain gauges, and can record the entire test process.

  16. An Investigation on the Relationship between Breaking Loads and Deflections in Three Points Bending Test of Camshaft%凸轮轴三点弯曲断裂载荷与挠度的关系研究

    Institute of Scientific and Technical Information of China (English)

    沈保罗; 李莉; 高致文; 张昊

    2012-01-01

    使用WE-500型液压式万能拉伸试验机测定了IAE6半激冷合金铸铁凸轮轴的三点弯曲断裂载荷,研究了其三点弯曲断裂载荷和挠度之间的关系.研究表明:(1)不同炉次的凸轮轴的三点弯曲断裂载荷存在一定的分散性;(2)凸轮轴的三点弯曲断裂载荷与挠度之间存在正相关关系,凸轮轴中含有适量碳化物对其强度和挠度都是有益的.%The breaking load in three points bending test of the 1AE6 semi-chilled alloyed cast iron camshaft was determined by using WE-500 model hydraulic universal tensile test machine and thereby the relationship between its breaking loads and ite defections was; investigated. The resuit showed: (a )There was some dispersivity existing in the three point bonding breaking loads of camshafts of different melting heats; (b)There was a positive correlation existing between the breaking loads and deflections, and a proper amount of carbide contained in the camshaft was beneficial to both its strength and deflection.

  17. Optimization on 135º Orthosis Bending and Springback of Q345 Steel Plate Based on Contrast Test%基于对比试验的Q345钢135º矫正法折弯及回弹优化

    Institute of Scientific and Technical Information of China (English)

    刘佳灏; 杜勇; 薛克敏; 张恒光; 田耀江; 姚嘉炜; 葛自良

    2015-01-01

    目的:针对自由回弹采用的补偿法寻找最优解过程繁杂,结果不稳定这一问题,寻找更为有效的折弯方式。方法利用Pearson相关系数和灰色系统理论,采用对比实验,以16 mm厚Q345钢为研究对象,选择凸模圆角、摩擦因数及矫正量为变量,回弹角与最大成形力为目标函数,求得工艺参数对回弹角的关联系数。再对优化的参数组合进行有限元模拟验证。结果矫正法回弹控制效果远远优于自由折弯模具的回弹控制效果。结论将优化获得的工艺参数进行有限元模拟验证,指导设计、试模,成形质量得到明显提高,对实际生产具有显著的指导意义。%This paper explored more effective bending method targeting at the problem of complex process and unstable results by the compensating method for calculation of the free springback. This paper adopted the comparison test using Pearson related coefficients and the gray system theory. The test took the Q345 steel of 16 mm thickness as the research subject to obtain the correlation coefficient of the processing parameters to the springback angle, taking punch radius, friction coefficient and rectification as the variables and springback angle and maximum forming force as the objective functions. The FEM simulation was used to verify the optimized parameter combination. The springback control effect by the orthosis method was much better than that by the free bending mold. The FEM verification showed the design and the die trial with the opti-mized processing parameters can improve the forming quality and had significant guidance for practical production.

  18. A New Kind of Bend Sensor

    Institute of Scientific and Technical Information of China (English)

    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.

  19. Development of a hybrid dome composed of glued-laminated timbers and steel cables. (Part 4). ; Bending and buckling tests on compled glulam beams. Daidanmen shuseizai to cable ni yoru hybridter dot dome kozo no kaihatsu. 4. ; Kumitate shuseizai buzai no mage jikken oyobi zakutsu jikken

    Energy Technology Data Exchange (ETDEWEB)

    Kobayashi, H.; Tsubota, H.; Maruyama, N.; Sasaki, N. (Kajima Corp., Tokyo (Japan))

    1991-10-31

    As a part of the development of the large scale hybrid dome (140 m in diameter, 49 m in height) composed of glued-laminated timbers (glulam) and steel cables, bending and buckling tests were conducted on coupled glulam beams. As the result of bending tests, every specimen offered a sufficient bending capacity for the allowable stress calculated by AIJ (Architectural Institute of Japan) standard, and no bending stiffness of a strong axis specimen decreased in the absence of adhesive, while that of a weak one was greatly affected by how firmly main beams and spacer blocks were attached to each other. As the result of buckling tests, the effect of joints on buckling strength was negligible, and the buckling strength of beams was high enough to guarantee the safety of the dome. The buckling strength could be accurately estimated from the slenderness ratio of the main beam as adhesion assured nearly perfect attachment, and the effective slenderness ratios of beams without adhesive well corresponded to those calculated by AIJ standard. 2 refs., 9 figs., 5 tabs.

  20. Time-dependent Springback Tests and the Finite Element Exploration of DP600 after Bending%DP600弯曲变形滞后回弹试验及有限元探究

    Institute of Scientific and Technical Information of China (English)

    付泽; 鄂大辛

    2016-01-01

    To initially explore the time-dependent springback change law and reason of the blank at temperature. Different bending angels of three-point bending tests were taken of high strength steel sheet DP600,then the instantaneous springback angels and time-dependent springback angels for up to a mouth were measured at room temperature,meanwhile the finite element analogy analysis was proceeded with creep model of ABAQUS software. Time-dependent springback angels changed in a exponential growth law over time and finally trended to be stable. The correction coefficient k was introduced to the original creep model,the calculation result of the update model has good agreement with the experimental values. Stress distribution in the plate gradually flattened out. The release of residual stress is one kind of causes of the time-dependent springback.%目的:初步探索室温下板材弯曲滞后回弹的变化规律及产生原因。方法对DP600高强度钢板进行不同弯曲角的三点弯曲试验,在室温下测量卸载瞬时回弹及长达1个月的滞后回弹,同时应用ABAQUS软件中的蠕变模型类比进行有限元分析。结果滞后回弹角随时间大致呈指数规律增长,最后逐渐趋于稳定。在原有蠕变模型基础上引入一个修正系数k,改进模型的计算结果与实验值吻合较好;滞后回弹过程中板材内应力分布逐渐趋于平缓。结论残余应力的释放是驱动滞后回弹的一种原因。

  1. 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.

  2. 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.

  3. Hormonal regulation of gravitropic bending

    Science.gov (United States)

    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

  4. Effects of Bending Radii on the Characteristics of Flexible Organic Solar Cells Investigated by Impedance Analysis.

    Science.gov (United States)

    Kim, Hoonbae; Ye, Donghyun; Won, Beomhee; Yu, SeGi; Jung, Donggeun

    2016-05-01

    Flexible organic solar cells (OSCs) were fabricated on an indium-tin-oxide (ITO)/poly(ethylene terephthalate) (PET) substrate and were subjected to bending tests with various bending radii. We observed that the photovoltaic properties of the OSCs precipitously deteriorated at a bending radius ≤ 0.75 cm. In order to investigate the effects of the bending test, the changes in the surface morphology and the sheet resistance of the ITO-coated PET samples were investigated, and the photovoltaic properties of bent and unbent OSCs were evaluated. Thereafter, equivalent circuits for the OSCs were assumed and the change in their parameters, such as resistance and capacitance, was observed. PMID:27483935

  5. Investigation of structural behaviour due to bend-twist couplings in wind turbine blades

    DEFF Research Database (Denmark)

    Fedorov, Vladimir; Dimitrov, Nikolay Krasimiroy; Berggreen, Christian;

    2009-01-01

    The structural behaviour of a composite wind turbine blade with implemented bend-twist coupling is examined in this paper. Several shell finite element models of the blade have been developed and validated against full-scale tests. All shell models performed well for flap-wise bending, but perfor......The structural behaviour of a composite wind turbine blade with implemented bend-twist coupling is examined in this paper. Several shell finite element models of the blade have been developed and validated against full-scale tests. All shell models performed well for flap-wise bending...

  6. 一种用于测量鱼体材料粘弹性性质的弯曲变形试验机%On a Bending Test Machine used to Measure Viscoelastic Properties of Fish Material

    Institute of Scientific and Technical Information of China (English)

    王拓道; 贾来兵; 尹协振

    2011-01-01

    研究生物材料力学性质是生物力学的重要内容之一.测量材料粘弹性性质的传统方渗是单轴拉伸松弛或蠕变实验.与传统方法不同,为了测量鱼体材料粘弹性性质,本文设计了一种用于测量鱼体材料性质的弯曲变形试验机,通过模拟鱼体摆动,可以测得鱼体材料的储能模量、耗散模量、滞后相位角等参数.通过弹性体(铜片)和粘弹性体(橡胶)材料实验验证了该试验机的可靠性,并对鱼鳍进行了实验,计算出鱼鳍的粘弹性性质的各个参数.实验结果表明,实验测试系统可靠而且简单实用.%Mechanical property investigation of biological materials is one of the important branches of biomechanics. Traditionally, the uniaxial tensile test, relaxation or creep, are often used to study the viscoelastic properties of material. However, in order to measure the viscoelastic properties of fish material, a bending test machine was designed and its application is presented in this paper. Fish swing movement can be simulated based on this machine, angular displacement curve and moment of experimental samples were measured and then the storage modulus, loss modulus and phase angle of hysteresis were obtained. Experiment of elastic (copper) and viscoelastic (rubber) specimens was carried out to verify the reliability of this testing machine. Finally, experiment of fish fin was carried out and the parameters of its viscoelastic properties was obtained. Experimental results show that this test system is reliable, simple and practical.

  7. 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.

  8. Evolution Law of Parameters in Surface Crack Propagation Rate Test under Cantilever Bend Loading%悬臂弯曲加载表面裂纹扩展速率试验中各参量的变化规律

    Institute of Scientific and Technical Information of China (English)

    张亚军; 魏平安; 张利娟

    2013-01-01

    在悬臂弯曲加载方式下,采用逐级递增的六级名义应变控制模式,完成了三件10CrNiMo钢试样的低周疲劳表面裂纹扩展速率试验.试验数据处理结果表明:在每级名义应变控制下,位移和载荷的峰谷值是基本保持不变的,但随着名义应变级别的增加,位移和载荷的均值存在向负向增大的趋势;而在低名义应变级别控制下,应变峰谷值的变化规律和位移与载荷的峰谷值的变化规律相似,但随着名义应变级别的增加,应变的峰谷值和均值均存在向正向增大的趋势.分析认为,产生上述现象的原因主要和试样表面的残余应变有关.%Under cantilever bend loading,a test method of six-grade nominal strain from low to high gradually as controlling mode was adopted and low cycle fatigue surface crack propagation rate test of 10CrNiMo steel were performed in three pieces of specimens.The test data manifested that under the control of every grade nominal strain,the peak and valley values of displacement and force were invariable basically,and with increase of the nominal strain grade,the average values of displacement and force had a tendency of increase to negative direction,while under the control of low nominal strain,evolution law of the three values of strain were similar as those of displacement and force,but with increase of nominal strain grade,the peak and valley values of strain trended to enlarge to the positive direction.An analysis was carried out and the results showed the reason of above phenomena was relative to residual strain.

  9. Experimental method for determination of bending and torsional rigidities of advanced composite laminates

    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.

  10. Evaluation of cold bending and mechanical properties of helical (SAWH) and longitudinal (SAWL) seam pipes

    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)

  11. 下肢屈曲挤压实验对容量反应性评估%A new method for the assessment of volume responsiveness:the bending and pressing the lower extremities test

    Institute of Scientific and Technical Information of China (English)

    李向; 黄慧; 方金东; 方莉; 周兆杰; 张劲琼

    2016-01-01

    This study introduced a new method for the assessment of volume responsiveness:the bending and pressing the lower extremities test(BPLE-T). The BPLE-T can produce hemodynamic changes. Various hemodynamic parameters, such as systolic blood pressure( SBP) ,diastolic blood pressure( DBP) ,mean arterial pressure( MAP) ,central venous pres-sure(CVP),heart rate(HR),respiratory frequency(R),stroke volume(SV),and cardiac output(CO),can be determined via invasive or non-invasive monitoring techniques,and volume responsiveness can be evaluated based on changes in these parameters during the BPLE-T procedure. Moreover,this test relates to another concept:pressure reactivity. Evaluations of pressure reactivity can reveal the resistance status of the peripheral arterial system and thereby indicate whether a patient re-quires vasoactive drugs and/or how these drugs should be selectively administered. Thus,relative to other methods for asses-sing volume responsiveness,the BPLE-T is not only simple to utilize,non-invasive,and repeatable but also capable of simul-taneously evaluating both volume responsiveness and pressure reactivity.%介绍一种评估容量反应性的新方法:下肢屈曲挤压实验。通过有创或无创监测技术得到实验时血液动力学变化的参数,如收缩压( SBP)、舒张压( DBP)、平均动脉压( MAP)、中心静脉压( CVP)、心率( HR)、每搏输出量( SV)、心排血量( CO)等。根据这些参数在实验过程中的变量评估容量反应性。该实验得出另一个概念:压力反应性。对压力反应性的评估,可以了解外周动脉系统阻力状态,并据此评估患者是否需要或选择性地给予血管活性药物。下肢屈曲挤压实验简单、无创,评估容量反应性的同时可评估压力反应性。

  12. 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.

  13. 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.

  14. Bending and stretching of plates

    CERN Document Server

    Mansfield, E H; Hemp, W S

    1964-01-01

    The Bending and Stretching of Plates deals with elastic plate theory, particularly on small- and large-deflexion theory. Small-deflexion theory concerns derivation of basic equations, rectangular plates, plates of various shapes, plates whose boundaries are amenable to conformal transformation, plates with variable rigidity, and approximate methods. Large-deflexion theory includes general equations and some exact solutions, approximate methods in large-deflexion theory, asymptotic large-deflexion theories for very thin plates. Asymptotic theories covers membrane theory, tension field theory, a

  15. 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.

  16. 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.

  17. Contact and Bending Durability Calculation for Spiral-Bevel Gears

    Science.gov (United States)

    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.

  18. 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...

  19. 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.

  20. BENDING-SHEAR INTERACTION OF LONGITUDINALLY STIFFENED GIRDERS

    OpenAIRE

    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...

  1. [On fatigue bending strength of PMMA-specimen (author's transl)].

    Science.gov (United States)

    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

  2. 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

  3. Fresh-stem bending of silver fir and Norway spruce.

    Science.gov (United States)

    Lundström, Tor; Stoffel, Markus; Stöckli, Veronika

    2008-03-01

    The bending and growth characteristics of large fresh stems from four silver fir (Abies alba Mill.) and three Norway spruce (Picea abies (L.) Karst.) trees were studied. Twenty logs taken from different stem heights were subjected to four-point bending tests. From the bending test records, we calculated stress-strain curves, which accounted for detailed log taper, shear deformation and self weight. From these curves we determined, among other parameters, the modulus of elasticity (MOE), the modulus of rupture (MOR) and the work absorbed in bending (W). No significant differences were found between species for the wood properties examined. Values of MOE, MOR and W generally decreased with stem height, with MOR in the range of 43 to 59 MPa and MOE ranging from 10.6 to 15.6 GPa. These MOE values are twice or more those reported for stems of young Sitka spruce (Picea sitchensis (Bong.) Carr.) trees. Based on the radial growth properties measured in discs from the logs, we calculated predicted values of MOE and MOR for the stem cross section. The predictions of MOE were precise, whereas those of MOR were approximate because of a complex combination of different failure mechanisms. Methods to test and calculate MOE, MOR and W for the stems of living trees are discussed with the aim of improving analyses of tree biomechanics and assessments of forest stability protection.

  4. Static Fatigue of Optical Fibers in Bending

    Science.gov (United States)

    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

  5. 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)

  6. FACTORS INFLUENCING BENDING RIGIDITY OF SUBMERGED VEGETATION

    Institute of Scientific and Technical Information of China (English)

    WU Long-hua; YANG Xiao-li

    2011-01-01

    The bending rigidity of submerged vegetation is closely related with vegetative drag force.This work aims at determining the effects of flow conditions and characteristics of vegetation on the bending rigidity of submerged vegetation.Based on the dimensional analysis method,the factors influencing the bending rigidity of individual submerged vegetation were analyzed.The relationship between the relative bending rigidity and its influencing factors was investigated by experimental observation,and a relative bending rigidity expression for submerged vegetation was obtained by means of multiple linear regression method.The results show that the submerged vegetation has three states under different inflow conditions,and the each critical relative bending rigidity of individual submerged vegetation was determined for the different states of submerged vegetation.

  7. Minimum Membrane Bending Energies of Fusion Pores

    OpenAIRE

    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...

  8. Cyclic Testing on Rectangular Hollow Bridge Piers Under Axial Load and Biaxial Bending%双向压弯状态下矩形空心桥墩循环试验

    Institute of Scientific and Technical Information of China (English)

    韩强; 杜修力; 赵彦; 王利辉

    2013-01-01

    To investigate the seismic performance of reinforced concrete (RC) rectangular hollow bridge piers, cyclic testing on five well-confined specimens was performed under constant axial load and biaxial bending. The test variables included axial load ratio, longitudinal reinforcement ratio and lateral reinforcement ratio. The results show that these specimens are flexural failure modes; biaxial force and displacement hysteretic loops show significant stiffness and strength degradation, pinching effect and coupling interaction of the structural seismic resistances in both directions; the ductility coefficient, varying from 3. 5 to 5. 7, and the equivalent viscous damping ratio, varying from 0. 19 to 0. 26, can meet the requirements of seismic design; RC rectangular hollow bridge piers with configurations of lateral reinforcement subject to bi-directional earthquake components have excellent earthquake resistance, and can substitute for current hollow RC rectangular section configurations described in the Chinese Guideline for Seismic Design of Highway Bridges (JTG/T B02-01-2008); and the length of the plastic hinge region is found to approach one sixth of the the hollow RC rectangular bridge pier height for all specimen piers, which is far less than the currently specified minimum value in Chinese Guideline, so the length of plastic hinge region is more concentrated for RC rectangular hollow bridge piers.%为了研究水平双向地震作用下矩形空心桥墩的抗震性能,对约束良好但轴压比和纵向、横向配筋率不同的5个钢筋混凝土(RC)矩形空心桥墩在轴力和双向弯曲作用下的性能进行了循环试验研究.结果表明:试件破坏形态为桥墩底部形成塑性铰的弯曲形破坏,桥墩双向力-位移滞回曲线显示了双向压弯状态下RC矩形空心桥墩刚度和强度退化、捏拢效应以及2个水平方向抗震性能的相互影响;试件桥墩的延性系数在3.5~5.7之间,等效粘滞阻尼系数在0

  9. Bending of the looping heart: differential growth revisited.

    Science.gov (United States)

    Shi, Yunfei; Yao, Jiang; Xu, Gang; Taber, Larry A

    2014-08-01

    In the early embryo, the primitive heart tube (HT) undergoes the morphogenetic process of c-looping as it bends and twists into a c-shaped tube. Despite intensive study for nearly a century, the physical forces that drive looping remain poorly understood. This is especially true for the bending component, which is the focus of this paper. For decades, experimental measurements of mitotic rates had seemingly eliminated differential growth as the cause of HT bending, as it has commonly been thought that the heart grows almost exclusively via hyperplasia before birth and hypertrophy after birth. Recently published data, however, suggests that hypertrophic growth may play a role in looping. To test this idea, we developed finite-element models that include regionally measured changes in myocardial volume over the HT. First, models based on idealized cylindrical geometry were used to simulate the bending process in isolated hearts, which bend without the complicating effects of external loads. With the number of free parameters in the model reduced to the extent possible, stress and strain distributions were compared to those measured in embryonic chick hearts that were isolated and cultured for 24 h. The results show that differential growth alone yields results that agree reasonably well with the trends in our data, but adding active changes in myocardial cell shape provides closer quantitative agreement with stress measurements. Next, the estimated parameters were extrapolated to a model based on realistic 3D geometry reconstructed from images of an actual chick heart. This model yields similar results and captures quite well the basic morphology of the looped heart. Overall, our study suggests that differential hypertrophic growth in the myocardium (MY) is the primary cause of the bending component of c-looping, with other mechanisms possibly playing lesser roles.

  10. Multilevel light bending in nanoplasmonics

    Science.gov (United States)

    El Sherif, Mohamed H.; Ahmed, Osman S.; Bakr, Mohamed H.; Swillam, Mohamed A.

    2014-03-01

    Nanoplasmonic optical interconnects is proposed to mitigate challenges facing electronics integration. It provides fast and miniaturized data channel that overcome the diffraction limit. We present a three dimensional plasmonic coupler that vertically bends the light to multilevel circuit configurations. It exploits light guiding in nanoscale plasmonic slot waveguides (PSWs). A triangularly-shaped plasmonic slot waveguide rotator is introduced to attain such coupling with good efficiency over a wide bandwidth. Using this approach, light propagating in a horizontal direction is easily converted and coupled to propagate in the vertical direction and vice versa. The proposed configuration is further extended to the design of a multilayer power divider/combiner with ultra-compact footprint that guides the light to multiple channels. A detailed study of the triangular rotator is demonstrated with the analysis of multiple configurations. This structure is suitable for efficient coupling and splitting in multilevel nano circuit environment.

  11. Development of U-frame bending system for studying the vibration integrity of spent nuclear fuel

    Science.gov (United States)

    Wang, Hong; Wang, Jy-An John; Tan, Ting; Jiang, Hao; Cox, Thomas S.; Howard, Rob L.; Bevard, Bruce B.; Flanagan, Michelle

    2013-09-01

    A bending fatigue system developed to evaluate the response of spent nuclear fuel rods to vibration loads is presented. A U-frame testing setup is used for imposing bending loads on the fuel rod specimen. The U-frame setup consists of two rigid arms, side connecting plates to the rigid arms, and linkages to a universal testing machine. The test specimen's curvature is obtained through a three-point deflection measurement method. The tests using surrogate specimens with stainless steel cladding revealed increased flexural rigidity under unidirectional cyclic bending, significant effect of cladding-pellets bonding on the response of surrogate rods, and substantial cyclic softening in reverse bending mode. These phenomena may cast light on the expected response of a spent nuclear fuel rod. The developed U-frame system is thus verified and demonstrated to be ready for further pursuit in hot-cell tests.

  12. 46 CFR 56.80-5 - Bending.

    Science.gov (United States)

    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...

  13. Discontinious Galerkin formulations for thin bending problems

    NARCIS (Netherlands)

    Nguyen, T.D.

    2008-01-01

    A structural thin bending problem is essentially associated with a fourth-order partial differential equation. Within the finite element framework, the numerical solution of thin bending problems demands the use of C^1 continuous shape functions. Elements using these functions are challenging and di

  14. 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...

  15. 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...

  16. Bending of light in conformal Weyl gravity

    Science.gov (United States)

    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.

  17. 核电土建设备产品见证件弯曲试验钢筋断裂原因分析%Cause Analysis on Fracture of Steel Bar in Nuclear Power Civil Construction Product Witness Samples during Bend Testing

    Institute of Scientific and Technical Information of China (English)

    刘宏伟

    2011-01-01

    Steel bar longitudinal fracture occured during bend testing for nuclear power civil construction product witness samples.Fracture reason of the steel bar was analyzed by chemical compositions analysis, hardness testing, metallographic examination and impact test.The results show that the heat produced by welding heated the steel bar to the temperature producing second category tempering brittleness, and the cooling rate was too slow, so impurity elements segregated at the grain boundary, and resulted in weakening of the brittle grain boundary.So the product witness sample fractured at the steel bar along the longitudind direction during bend testing.%某核电土建设备产品见证件在弯曲试验时发生钢筋纵向断裂现象,采用化学成分分析、硬度检测、金相检验和冲击试验等方法对钢筋的断裂原因进行了分析.结果表明:由于产品焊接时的热量将钢筋加热到了产生第二类回火脆性的温度,加之焊后冷却速度过慢,使杂质元素在晶界处偏聚,造成晶界弱化而产生脆性,从而导致产品见证件在弯曲试验时于钢筋处纵向断裂.

  18. 49 CFR 195.212 - Bending of pipe.

    Science.gov (United States)

    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)...

  19. 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

  20. 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.

  1. 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.

  2. 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

  3. EFFECT OF DIVIDED CORE ON THE BENDING PERFORMANCES OF TEXTILE REINFORCED FOAM CORE SANDWICH COMPOSITES

    Directory of Open Access Journals (Sweden)

    ALPYILDIZ Tuba

    2016-05-01

    Full Text Available Sandwich composites are generally used in marine applications, wind turbines, space and aircraft vehicles due to their high bending rigidities in addition to their lighter weights. The objective of this study is to investigate the effect of divided foam core and interlayer sheet of glass fabric on the bending performances of sandwich composites which are manufactured with glass fabrics as the facesheets/interlayer sheets and PVC foam as the core material. Sandwich composites with single and divided core are manufactured and compared in terms of flexural behavious via three point bending tests. It is found that the bending performance is enhanced with the use of divided core and using divided core does not affect the behaviour of the sandwich composite against bending deformations. In the case of the plain core sandwich composite, dividing the core is advised for certain applications rather than perforating the core to increase the bending stiffness and strength of the textile reinforced sandwich composites because it is possible to purchase core with any thickness and there is no need for additional process such as perforation. The proposed application could enhance the bending performances without altering the weight and cost of the sandwich composites, which are preferred due to their higher bending rigidities in relation to their lighter weights.

  4. Bending Characteristics of Foldable Touch Display Panel with a Protection Structure Design

    Directory of Open Access Journals (Sweden)

    Hsien-Chie Cheng

    2015-01-01

    Full Text Available The study proposes and demonstrates an enhancement of a touch display panel (TDP through a polymer-based protection structure to achieve higher bendability and reliability. The bending performance of the TDP without or with the protection structure designs is addressed using three-dimensional geometry-nonlinear finite element analysis and mechanical testing. The elastic properties of the components in the TDP structure are derived from nanoindentation and uniaxial tensile/compressive testing. The calculated results are compared with each other and also against the experimental bending fatigue test data. At last, a design guideline and optimal factor setting for enhanced bending performance are sought through parametric FE analysis and Taguchi experimental design, respectively. The optimal design is compared with the original in terms of bending stress. The simulation results show that bending would create significant tensile and compressive bending stresses on the indium tin oxide/dielectric layers, which are the main cause of several commonly observed failures, such as thin film cracking and delamination, in a thin rigid film coating on a thick compliant substrate. It also turns out that a substrate with a lower stiffness has a better mechanical stability against bending stress.

  5. Bending strength of delaminated aerospace composites.

    Science.gov (United States)

    Kinawy, Moustafa; Butler, Richard; Hunt, Giles W

    2012-04-28

    Buckling-driven delamination is considered among the most critical failure modes in composite laminates. This paper examines the propagation of delaminations in a beam under pure bending. A pre-developed analytical model to predict the critical buckling moment of a thin sub-laminate is extended to account for propagation prediction, using mixed-mode fracture analysis. Fractography analysis is performed to distinguish between mode I and mode II contributions to the final failure of specimens. Comparison between experimental results and analysis shows agreement to within 5 per cent in static propagation moment for two different materials. It is concluded that static fracture is almost entirely driven by mode II effects. This result was unexpected because it arises from a buckling mode that opens the delamination. For this reason, and because of the excellent repeatability of the experiments, the method of testing may be a promising means of establishing the critical value of mode II fracture toughness, G(IIC), of the material. Fatigue testing on similar samples showed that buckled delamination resulted in a fatigue threshold that was over 80 per cent lower than the static propagation moment. Such an outcome highlights the significance of predicting snap-buckling moment and subsequent propagation for design purposes.

  6. Low Loss S-Bend Structure With Tapered Curved Waveguides

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    A novel S-bend with tapered curved waveguides is proposed. The normalized transmitted power is greater than the conventional bend with weakly guided waveguides. Small size and low loss can be reached by the proposed S-bend.

  7. Bending stresses in Facetted Glass Shells

    DEFF Research Database (Denmark)

    Bagger, Anne; Jönsson, Jeppe; Almegaard, Henrik

    2008-01-01

    A shell structure of glass combines a highly effective structural principle with a material of optimal permeability to light. A facetted shell structure has a piecewise plane geometry, and together the facets form an approximation to a curved surface. A distributed load on a plane-based facetted...... structure will locally cause bending moments in the loaded facets. The bending stresses are dependent on the stiffness of the joints. Approximate solutions are developed to estimate the magnitude of the bending stresses. A FE-model of a facetted glass shell structure is used to validate the expressions...

  8. Strength Behavior of High Strength R/C Columns under Biaxial Bending-Shear and Varying Axial Load

    OpenAIRE

    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 ...

  9. Problems with cryogenic operation of piezoelectric bending elements

    Science.gov (United States)

    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.

  10. 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

  11. 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

  12. Characterization of Optical Fiber Strength Under Applied Tensile Stress and Bending Stress

    Energy Technology Data Exchange (ETDEWEB)

    P.E. Klingsporn

    2011-08-01

    Various types of tensile testing and bend radius tests were conducted on silica core/silica cladding optical fiber of different diameters with different protective buffer coatings, fabricated by different fiber manufacturers. The tensile tests were conducted to determine not only the average fiber strengths at failure, but also the distribution in fracture strengths, as well as the influence of buffer coating on fracture strength. The times-to-failure of fiber subjected to constant applied bending stresses of various magnitudes were measured to provide a database from which failure times of 20 years or more, and the corresponding minimum bend radius, could be extrapolated in a statistically meaningful way. The overall study was done to provide an understanding of optical fiber strength in tensile loading and in applied bending stress as related to applications of optical fiber in various potential coizfgurations for weapons and enhanced surveillance campaigns.

  13. slice of a LEP bending magnet

    CERN Multimedia

    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.

  14. Slice of a LEP bending magnet

    CERN Multimedia

    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.

  15. Pipes under internal pressure and bending

    CERN Document Server

    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.

  16. 一种外掺新型引气剂的水泥胶砂抗折强度试验研究%A Study on the Bending Strength Test of Cement Mortar Added in a New Type of Air Entraining Agent

    Institute of Scientific and Technical Information of China (English)

    李铁军; 郭红兵

    2014-01-01

    In order to improve the mechanical property of cement mortar, admixtures are pro-posed to be put into cement mortar by adding air-entraining agent separately or mixing air en-training agent and water-reducing agent. The bending strength test of cement mortar has been done. The best model and the optimal dosage of air entraining agent in cement mortar have been determined for its optimal mechanical property. The result shows that the bending strength of cement mortar is significantly greater when air entraining agent and water-reducing agent are mixed. 2 # air-entraining agent has better effect in meeting the requirements of the bending strength of cement mortar.%为了提高水泥胶砂的力学性能,提出在水泥胶砂中掺加外加剂的方法,通过在水泥胶砂中单掺引气剂、复掺引气剂与减水剂两种途径,进行水泥胶砂抗折强度检测试验,对比确定水泥胶砂力学性能最优的引气剂型号及其最佳掺量。结果表明:引气剂与减水剂复掺时水泥胶砂的抗折强度明显大于引气剂单掺时水泥胶砂的抗折强度,2#引气剂最能满足水泥胶砂抗折强度要求。

  17. DYNAMIC BEHAVIOR OF BURIED BEND WITH THRUST RESTRAINT IN LIQUEFYING GROUND

    Science.gov (United States)

    Kawabata, Toshinori; Sawada, Yutaka; Mohri, Yoshiyuki; Ling, Hoe I.

    In this study, a shaking table test was carried out in order to discuss the dynamic behavior for the bend of pressure pipeline with a concrete block and thrust restraints using geogrids or gravels in liquefying ground. As a result, it was revealed that the concrete block was largely moved and the relative displacement between the bend and the adjacent pipe became large. On the other hand, it was proved that geogrids and gravels were very effective for the lateral resistance in liquefying ground. In addition, the relative displacement was small because of the same difference between the bend and the adjacent pipe.

  18. Analysis of the bending behaviour of flax based reinforcements used in shape forming

    CERN Document Server

    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.

  19. New Equation for Bending Development of Arbitrary Rods and Application to Palm Fronds Bending

    CERN Document Server

    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.

  20. 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.

  1. 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.)

  2. 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.

  3. 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.

  4. Nickel multilayers and their effects on bend fatigue strength of leads

    Institute of Scientific and Technical Information of China (English)

    LIU Feihua; WANG Zhanhua; SHEN Zhuoshen

    2004-01-01

    Nickel is commonly coated on the outer leads for T8 metal package. The leads electrodeposited by conventional dull or bright nickel over 5 μm at direct current from Watt bath are hard to pass the bend fatigue test for three times. Nickel electrodeposited at multi waveform current including direct current, single and double pulse from sulfamate bath can improve the bend fatigue strength of leads. Such nickel plating has a multilayer structure, its morphology of sublayers can be clearly seen in its cross section with SEM. The electrochemical study shows that these sublayers have different corrosion potentials. The bend fatigue test of leads with such plating for T8 metal package shows that the number of bend increases with the decrease of average current density of multi waveform, which can be attributed to the reduction of every sublayer thickness and the increase of layer numbers under the same condition of total thickness.

  5. Experimental Research and Numerical Simulation of Wing Boxes under Pure Bending Load

    OpenAIRE

    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...

  6. Coupling Lateral Bending and Shearing Mechanisms to Define Knee Injury Criteria for Pedestrian Safety

    OpenAIRE

    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...

  7. 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.

  8. 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)

  9. Sharp bends of phononic crystal surface modes

    Science.gov (United States)

    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.

  10. 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.

  11. Tunable thermoelectric properties in bended graphene nanoribbons

    Science.gov (United States)

    Chang-Ning, Pan; Jun, He; Mao-Fa, Fang

    2016-07-01

    The ballistic thermoelectric properties in bended graphene nanoribbons (GNRs) are systematically investigated by using atomistic simulation of electron and phonon transport. We find that the electron resonant tunneling effect occurs in the metallic-semiconducting linked ZZ-GNRs (the bended GNRs with zigzag edge leads). The electron-wave quantum interference effect occurs in the metallic-metallic linked AA-GNRs (the bended GNRs with armchair edge leads). These different physical mechanisms lead to the large Seebeck coefficient S and high electron conductance in bended ZZ-GNRs/AA-GNRs. Combined with the reduced lattice thermal conduction, the significant enhancement of the figure of merit ZT is predicted. Moreover, we find that the ZTmax (the maximum peak of ZT) is sensitive to the structural parameters. It can be conveniently tuned by changing the interbend length of bended GNRs. The magnitude of ZT ranges from the 0.15 to 0.72. Geometry-controlled ballistic thermoelectric effect offers an effective way to design thermoelectric devices such as thermocouples based on graphene. Project supported by the National Natural Science Foundation of China (Grant No. 61401153) and the Natural Science Foundation of Hunan Province, China (Grant Nos. 2015JJ2050 and 14JJ3126).

  12. Pure plate bending in couple stress theories

    CERN Document Server

    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 ...

  13. 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)

  14. Biomorphodynamic modelling of inner bank advance in migrating meander bends

    Science.gov (United States)

    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.

  15. Effect of Induction Heat Bending Process on the Properties of ASME SA106 Gr. C Carbon Steel Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ki Tae; Kim, Young Sik [Andong National University, Andong (Korea, Republic of); Chang, Hyun Young; Oh, Young Jin [KEPCO Engineering and Construction Company, Seongnam (Korea, Republic of); Sung, Gi Ho [R and D Center, Busan (Korea, Republic of)

    2015-04-15

    Recently, the bending process is greatly applied to fabricate the pipe line. Bending process can reduce welding joints and then decrease the number of inspection. Thus, the maintenance cost will be reduced. Induction heat bending process is composed of bending deformation by repeated local heat and cooling. By this thermal process, corrosion properties and microstructure can be affected. This work focused on the effect of induction heating bending process on the properties of ASME SA106 Gr. C low carbon steel pipes. Microstructure analysis, hardness measurements, and immersion corrosion test were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. Hardness was measured using a Rockwell B scale. Induction heat bending process has influenced upon the size and distribution of ferrite and pearlite phases which were transformed into finer structure than those of base metal. Even though the fine microstructure, every bent area showed a little lower hardness than that of base metal. It is considered that softening by the bending process may be arisen. Except of I2, intrados area, the others showed a similar corrosion rate to that of base metal. But even relatively high rate of intrados area was very low and acceptable. Therefore, it is judged that induction heat bending process didn't affect boric acid corrosion behaviour of carbon steel.

  16. Bending Capacity of Middle Joints of Upholstered Furniture Frames

    Directory of Open Access Journals (Sweden)

    Vasiliki Kamperidou, Vasileios Vasileiou

    2012-12-01

    Full Text Available This study evaluates the edgewise bending moment capacity of the four most frequently used middle joints in the upholstered furniture frames. The research included the following joints: Mortise and Tenon, double Dowel, Corner Blocks and double Gusset Plates, designed in the form of middle joints and made of beech and poplar solid wood. The test results indicated that regarding the edgewise bending force, the strongest middle joint was the double dowel joint made of beech wood (1896.9 N, while the respective joint made of poplar marked quite a low value of bending force (937.2 N. The strength of wooden corner blocks was proved to be quite powerful, made either of beech wood, poplar wood or the combination of the two wood species (beech: 1881.8 N, poplar: 1237.6 N, beech-poplar: 1783.6 N. The gusset plate joint made of beech resulted in weaker values (1378.2 N, compared to the dowel and corner block joints made of beech, whereas the same joint made of poplar demonstrated very satisfying values of edgewise bending force (1471.8 N. Finally, the mortise and tenon joint appeared to have the lowest strength, both in the case of beech (1306 N and poplar (634 N. The highest coeffi cient of elasticity (CE derived from double gusset plate joint, made of beech. All the joints showed good elasticity, except the mortise and tenon joint made of poplar, as well as, the dowel joint made of poplar, which recorded the lowest elasticity values of all. Generally, beech wood resulted in stronger and more elastic joints compared to poplar.

  17. Impact compressive and bending behaviour of rocks accompanied by electromagnetic phenomena.

    Science.gov (United States)

    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

  18. Relationship between pore structure and mechanical properties of ordinary concrete under bending fatigue

    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.

  19. How Does The Bone Shaft Geometry Affect its Bending Properties?

    Directory of Open Access Journals (Sweden)

    Kaveh P. Saffar

    2009-01-01

    Full Text Available In this research, ten fresh specimens of sheep tibiae were provided from slaughtered animals. Whole bone specimens were loaded in three-point bending according to standard wet bone test protocols. Mechanical properties were determined and compared with the results which were obtained from two dry bone tests. The results showed that fracture bending moment and bone extrinsic stiffness had significant relations with fracture cross-section dependent parameters (i.e., cross-section area and area moment of inertia. Where, fracture energy and ultimate strength did not have such a relation with these parameters. Finite element modeling of bone shaft was made with simplified geometry (neglecting cross-section variations along bone shaft in two steps: First, by elliptical cross-section and second, by circular cross-section, assuming linear elastic and isotropic properties for the specimens. Elastic (Young’s 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%.

  20. Estimating Young’s Modulus of Materials by a New Three-Point Bending Method

    Directory of Open Access Journals (Sweden)

    Xiaohu Zeng

    2014-01-01

    Full Text Available A new test method based on the three-point bending test is put forward to measure Young’s modulus of materials. The simplified mechanical model is established to make theoretical derivation. This method has not only the advantages of simple specimen preparation and convenient loading device, but also higher precision than the traditional three-point bending method. The method is adopted to obtain Young’s modulus of the aluminum alloy 2024. The feasibility of the method has been demonstrated by comparisons with the corresponding results obtained from the finite element method and experiment method. And the influence of contact friction on the test accuracy is analyzed.

  1. Demonstration model of LEP bending magnet

    CERN Multimedia

    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.

  2. Axisymmetric bending oscillations of stellar disks

    CERN Document Server

    Sellwood, J A

    1996-01-01

    Self-gravitating stellar disks with random motion support both exponentially growing and, in some cases, purely oscillatory axisymmetric bending modes, unlike their cold disk counterparts. A razor-thin disk with even a very small degree of random motion in the plane is both unstable and possesses a discrete spectrum of neutral modes, irrespective of the sharpness of the edge. Random motion normal to the disk plane has a stabilizing effect but at the same time allows bending waves to couple to the internal vibrations of the particles, which causes the formerly neutral modes to decay through Landau damping. Focusing first on instabilities, I here determine the degree of random motion normal to the plane needed to suppress global, axisymmetric, bending instabilities in a family of self-gravitating disks. As found previously, bending instabilities are suppressed only when the thickness exceeds that expected from a na\\"\\i ve local criterion when the degree of pressure support within the disk plane is comparable to...

  3. 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.

  4. 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.

  5. 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.

  6. Symmetric bends how to join two lengths of cord

    CERN Document Server

    Miles, Roger E

    1995-01-01

    A bend is a knot securely joining together two lengths of cord (or string or rope), thereby yielding a single longer length. There are many possible different bends, and a natural question that has probably occurred to many is: "Is there a 'best' bend and, if so, what is it?"Most of the well-known bends happen to be symmetric - that is, the two constituent cords within the bend have the same geometric shape and size, and interrelationship with the other. Such 'symmetric bends' have great beauty, especially when the two cords bear different colours. Moreover, they have the practical advantage o

  7. Spaceflight-induced bone loss alters failure mode and reduces bending strength in murine spinal segments.

    Science.gov (United States)

    Berg-Johansen, Britta; Liebenberg, Ellen C; Li, Alfred; Macias, Brandon R; Hargens, Alan R; Lotz, Jeffrey C

    2016-01-01

    Intervertebral disc herniation rates are quadrupled in astronauts following spaceflight. While bending motions are main contributors to herniation, the effects of microgravity on the bending properties of spinal discs are unknown. Consequently, the goal of this study was to quantify the bending properties of tail discs from mice with or without microgravity exposure. Caudal motion segments from six mice returned from a 30-day Bion M1 mission and eight vivarium controls were loaded to failure in four-point bending. After testing, specimens were processed using histology to determine the location of failure, and adjacent motion segments were scanned with micro-computed tomography (μCT) to quantify bone properties. We observed that spaceflight significantly shortened the nonlinear toe region of the force-displacement curve by 32% and reduced the bending strength by 17%. Flight mouse spinal segments tended to fail within the growth plate and epiphyseal bone, while controls tended to fail at the disc-vertebra junction. Spaceflight significantly reduced vertebral bone volume fraction, bone mineral density, and trabecular thickness, which may explain the tendency of flight specimens to fail within the epiphyseal bone. Together, these results indicate that vertebral bone loss during spaceflight may degrade spine bending properties and contribute to increased disc herniation risk in astronauts.

  8. 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.

  9. Overall Thermal Performance of Flexible Piping Under Simulated Bending Conditions

    Science.gov (United States)

    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.

  10. Microstructural and Microhardness Variation of Amorphous Fe78Si9B13 Alloy during Bend Stress Relaxation

    Institute of Scientific and Technical Information of China (English)

    Xifeng LI; Kaifeng ZHANG; Changli WANG; Wenbo HAN; Guofeng WANG

    2007-01-01

    The amorphous Fe78Si9B13 ribbons were bend stress relaxed at various temperature well below the crystallization temperature (Tx) for different time. The effect of pre-annealing on the subsequent bend stress relaxation was examined. The variation of the microstructure and microhardness during bend stress relaxation process was studied using X-ray diffraction (XRD), atomic force microscopy (AFM) and Vickers microhardness test,respectively. Curvature radius of the amorphous Fe78Si9B13 ribbons decreased with increase bend stress relaxation temperature and time. The microhardness of the stress relaxed specimens increased with time at 300℃ due to the forming of nanocrystals during bend stress relaxation. The pre-annealing reduced the decrease rate of the curvature radius of stress relaxed specimens.

  11. 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

  12. 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.

  13. Stress relaxation and recovery behaviour of composite orthodontic archwires in bending.

    Science.gov (United States)

    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

  14. Evaluation of the electromechanical properties in GdBCO coated conductor tapes under low cyclic loading and bending

    Science.gov (United States)

    Shin, Hyung-Seop; Gorospe, Alking; Bautista, Zhierwinjay; Dedicatoria, Marlon J.

    2016-01-01

    The effects of low cyclic loading on the critical current, I c, under uniaxial and transverse loadings, and bending deformations in GdBCO coated conductor (CC) tapes were evaluated. Under monotonic continuous bending deformation, CC tapes exhibit a high tolerance of I c up to the lowest bending diameter of 12 mm using the Goldacker bending test rig. However, when the CC tape was subjected to alternate tension-compression bending, a lower irreversible bending strain limit was measured. This was also observed when cyclic bending was applied to the CC tapes which showed a significant decrease in I c just after 10 cycles of alternate tension-compression bending at 20 mm bending diameter. Such different I c degradation behavior under different bending deformation procedures gave insight into the proper handling of CC tapes from manufacturing, coiling and up to operating conditions. In the case of uniaxial tension, when electromechanical properties of CC tape were evaluated by repeated loading based on a critical stress level obtained under monotonic loading, I c also did not show significant change in its degradation behavior up to the irreversible stress limit. The GdBCO CC tape adopted can allow cyclic loading up to 100 cycles without significant irreversible degradation below the monotonic irreversible limit. In the case of the transverse cyclic test, with regard to the large scattering of data especially in the tensile direction, a different cyclic loading procedure was established. For 10 repeated loadings, the mechanical and electromechanical properties of the GdBCO CC tapes showed similar values within the reversible range under the monotonic loading. I c degraded abruptly indicating that no delamination occurred at the REBCO film during the subcritical cyclic loading. Different fracture morphologies were observed under cyclic loading depicting branch-like patterns of the remaining REBCO layer on the substrate of the CC tape.

  15. When Blood Cells Bend: Understanding Sickle Cell Disease

    Science.gov (United States)

    ... 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. ...

  16. A preliminary bending fatigue spectrum for steel monostrand cables

    DEFF Research Database (Denmark)

    Winkler, Jan; Fischer, Gregor; Georgakis, Christos T.;

    2011-01-01

    service life expectancy. The presented preliminary bending fatigue spectrum of high-strength monostrands is currently unavailable in the published literature. The presented results provide relevant information on the bending mechanism and fatigue characteristics of monostrand steel cables in tension...

  17. The design of an agent to bend DNA.

    OpenAIRE

    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...

  18. Bending strength analysis of steel-composite submerged floating tunnels

    OpenAIRE

    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...

  19. 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.

  20. 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

  1. Oide Effect and Radiation in Bending Magnets

    CERN Document Server

    Blanco, Oscar; Bambade, Philip

    2014-01-01

    Including radiation effects during lattice design optimization is crucial in high energy accelerators. Oide effect and radiation in bending magnets are reviewed aiming to include them in the optical design process to minimize the IP beam size. The Oide double integral is expressed in simpler terms in order to speed up calculations, concluding in how longer quadrupoles with lower gradients may help reducing the Oide effect. Radiation in bending magnets is reviewed for linear lattices, generalizing to the case when the final dispersion is different from zero and making comparisons with theoretical results and particle tracking. An agreement between the theory, the implemented approximation included in MAPCLASS2 and the six-dimensional tracking in PLACET has been found.

  2. The first ANDES elements: 9-DOF plate bending triangles

    Science.gov (United States)

    Militello, Carmelo; Felippa, Carlos A.

    1991-01-01

    New elements are derived to validate and assess the assumed natural deviatoric strain (ANDES) formulation. This is a brand new variant of the assumed natural strain (ANS) formulation of finite elements, which has recently attracted attention as an effective method for constructing high-performance elements for linear and nonlinear analysis. The ANDES formulation is based on an extended parametrized variational principle developed in recent publications. The key concept is that only the deviatoric part of the strains is assumed over the element whereas the mean strain part is discarded in favor of a constant stress assumption. Unlike conventional ANS elements, ANDES elements satisfy the individual element test (a stringent form of the patch test) a priori while retaining the favorable distortion-insensitivity properties of ANS elements. The first application of this formulation is the development of several Kirchhoff plate bending triangular elements with the standard nine degrees of freedom. Linear curvature variations are sampled along the three sides with the corners as gage reading points. These sample values are interpolated over the triangle using three schemes. Two schemes merge back to conventional ANS elements, one being identical to the Discrete Kirchhoff Triangle (DKT), whereas the third one produces two new ANDES elements. Numerical experiments indicate that one of the ANDES element is relatively insensitive to distortion compared to previously derived high-performance plate-bending elements, while retaining accuracy for nondistorted elements.

  3. Hydrodynamic processes in sharp meander bends and their morphological implications

    NARCIS (Netherlands)

    Blanckaert, K.

    2011-01-01

    The migration rate of sharp meander bends exhibits large variance and indicates that some sharply curved bends tend to stabilize. These observations remain unexplained. This paper examines three hydrodynamic processes in sharp bends with fixed banks and discusses their morphological implications: se

  4. Superconducting beam bending magnets at CERN

    CERN Multimedia

    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

  5. Electron cooling device without bending magnets

    Science.gov (United States)

    Sharapa, A. N.; Shemyakin, A. V.

    1993-11-01

    The scheme of an axisymmetric electron cooling device without bending magnets is proposed. Solutions for the most important elements, i.e., a gun and a recuperator, are considered. The main characteristics of the recuperator of the Faraday cup type having a reflector and a gun with a ring emitter are explored. In the gun, the beam is formed, the diameter of which is 40 mm and the dimension of a disturbance region is several millimeters.

  6. AA, assembly of wide bending magnet

    CERN Multimedia

    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.

  7. Drag Reduction, from Bending to Pruning

    CERN Document Server

    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.

  8. Large deformation dynamic bending of composite beams

    OpenAIRE

    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...

  9. Effects of Induction Heat Bending Process on Microstructure and Corrosion Properties of ASME SA312 Gr.TP304 Stainless Steel Pipes

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Nam In; Kim, Young Sik [Andong National University, Andong (Korea, Republic of); Kim, Kyung Soo; Chang, Hyun Young; Park, Heung Bae; Sung, Gi Ho [KEPCO Engineering and Construction Company, Seongnam (Korea, Republic of); Sung, Gi Ho [R and D Center, Busan (Korea, Republic of)

    2015-06-15

    The usage of bending products recently have increased since many industries such as automobile, aerospace, shipbuilding, and chemical plants need the application of pipings. Bending process is one of the inevitable steps to fabricate the facilities. Induction heat bending is composed of compressive bending process by local heating and cooling. This work focused on the effect of induction heat bending process on the properties of ASME SA312 Gr. TP304 stainless steel pipes. Tests were performed for base metal and bended area including extrados, intrados, crown up, and down parts. Microstructure was analyzed using an optical microscope and SEM. In order to determine intergranular corrosion resistance, Double Loop Electrochemical Potentiokinetic Reactivation (DL-EPR) test and ASTM A262 practice A and C tests were done. Every specimen revealed non-metallic inclusion free under the criteria of 1.5i of the standard and the induction heat bending process did not affect the non-metallic inclusion in the alloys. Also, all the bended specimens had finer grain size than ASTM grain size number 5 corresponding to the grain sizes of the base metal and thus the grain size of the pipe bended by induction heat bending process is acceptable. Hardness of transition start, bend, and transition end areas of ASME SA312 TP304 stainless steel was a little higher than that of base metal. Intergranular corrosion behavior was determined by ASTM A262 practice A and C and DL-EPR test, and respectively step structure, corrosion rate under 0.3 mm/y, and Degree of Sensitization (DOS) of 0.001 - 0.075 % were obtained. That is, the induction heat bending process didn't affect the intergranular corrosion behavior of ASME SA312 TP304 stainless steel.

  10. More on the bending of light !

    CERN Document Server

    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...

  11. A preliminary study of bending stiffness alteration in shape changing nitinol plates for fracture fixation.

    Science.gov (United States)

    Olender, Gavin; Pfeifer, Ronny; Müller, Christian W; Gösling, Thomas; Barcikowski, Stephan; Hurschler, Christof

    2011-05-01

    Nitinol is a promising biomaterial based on its remarkable shape changing capacity, biocompatibility, and resilient mechanical properties. Until now, very limited applications have been tested for the use of Nitinol plates for fracture fixation in orthopaedics. Newly designed fracture-fixation plates are tested by four-point bending to examine a change in equivalent bending stiffness before and after shape transformation. The goal of stiffness alterable bone plates is to optimize the healing process during osteosynthesis in situ that is customized in time of onset, percent change as well as being performed non-invasively for the patient. The equivalent bending stiffness in plates of varying thicknesses changed before and after shape transformation in the range of 24-73% (p values inertia. PMID:21286815

  12. Prediction and measurement of composite tube twist and bending due to thermal loading

    Science.gov (United States)

    Bluth, A. Marcel; Tucker, James R.; Thompson, Troy

    2013-09-01

    Composite materials are applied in precision optical metering structures because of their low thermal expansion properties in concert with high specific stiffness. Twisting and bending of long composite tubes, such as the secondary mirror support structure for the JWST telescope, requires control and verification. A stochastic modeling method was applied that simulates the manufacturing process variability and estimates ranges for expected twist and bend over the tube length from ambient to cryogenic temperatures. A development strut for the JWST secondary mirror support structure was fabricated and a metrology system was designed and implemented that measured the bend and twist response from ambient to 30 K. Modeling methods and predictions are outlined. The test metrology and results are summarized, along with a comparison between test and prediction.

  13. Inverse modelling approach in 3-point bending for elasto- plastic material parameter identification of thin spring steel

    Science.gov (United States)

    Mertin, C.; Huse, K.; Hirt, G.

    2016-08-01

    Under process conditions such as bending of flat wire made from high strength spring steel, the occurring strains are many times higher than the maximum strains determined from uniaxial tensile tests. To determine the elasto-plastic material behaviour of high strength spring steel (X10CrNi18-8), an inverse modelling approach using a simple testing method is presented. A 3-point bending test with the resulting force-displacement measurements is used for the inverse analysis. The inverse approach is used for determining the Young's modulus and hardening parameters of the Ludwik-Hollomon's law for bending of high strength spring steel. FE simulations with the optimised material data meet the experimentally measured punch forces during bending. The optimised material data considerably enhances the springback prediction.

  14. 76 FR 81992 - PPL Bell Bend, LLC; Combined License Application for Bell Bend Nuclear Power Plant; Exemption

    Science.gov (United States)

    2011-12-29

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION PPL Bell Bend, LLC; Combined License Application for Bell Bend Nuclear Power Plant; Exemption 1.0..., Certifications, and Approvals for Nuclear Power Plants.'' This reactor is to be identified as Bell Bend...

  15. Tunable waveguide bends with graphene-based anisotropic metamaterials

    KAUST Repository

    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.

  16. An optical fiber Fabry-Perot flow measurement technology based on partial bend structure

    Science.gov (United States)

    Yang, Huijia; Jiang, Junfeng; Zhang, Xuezhi; Pan, Yuheng; Zhu, Wanshan; Zhou, Xiang; Liu, Tiegen

    2016-08-01

    An optical fiber Fabry-Perot (F-P) flow measurement technology is presented, which is based on partial bend structure. A 90° partial bend structure is designed to achieve the non-probe flow measurement with a pressure difference. The fluid simulation results of partial bend structure show that the error of the pressure difference is below 0.05 kPa during steady flow. The optical fiber F-P sensor mounted on the elbow with pressure test accuracy of 1% full scale is used to measure the fluid flow. Flow test results show that when the flow varies from 1 m3/h to 6.5 m3/h at ambient temperature of 25 °C, the response time is 1 s and the flow test accuracy is 4.5% of the F-P flow test system, proving that the F-P flow test method based on partial bend structure can be used in fluid flow measurement.

  17. 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.

  18. Composite failure prediction of π-joint structures under bending

    Science.gov (United States)

    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.

  19. Bending mechanics of the red-eared slider turtle carapace.

    Science.gov (United States)

    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

  20. Evolving efficiency of restraining bends within wet kaolin analog experiments

    Science.gov (United States)

    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.

  1. Bending strength of piezoelectric ceramics and single crystals for multifunctional load-bearing applications.

    Science.gov (United States)

    Anton, Steven R; Erturk, Alper; Inman, Daniel

    2012-06-01

    The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads.

  2. Bending strength of piezoelectric ceramics and single crystals for multifunctional load-bearing applications.

    Science.gov (United States)

    Anton, Steven R; Erturk, Alper; Inman, Daniel

    2012-06-01

    The topic of multifunctional material systems using active or smart materials has recently gained attention in the research community. Multifunctional piezoelectric systems present the ability to combine multiple functions into a single active piezoelectric element, namely, combining sensing, actuation, or energy conversion ability with load-bearing capacity. Quantification of the bending strength of various piezoelectric materials is, therefore, critical in the development of load-bearing piezoelectric systems. Three-point bend tests are carried out on a variety of piezoelectric ceramics including soft monolithic piezoceramics (PZT-5A and PZT-5H), hard monolithic ceramics (PZT-4 and PZT-8), single-crystal piezoelectrics (PMN-PT and PMN-PZT), and commercially packaged composite devices (which contain active PZT-5A layers). A common 3-point bend test procedure is used throughout the experimental tests. The bending strengths of these materials are found using Euler-Bernoulli beam theory to be 44.9 MPa for PMN-PZT, 60.6 MPa for PMN-PT, 114.8 MPa for PZT- 5H, 123.2 MPa for PZT-4, 127.5 MPa for PZT-8, 140.4 MPa for PZT-5A, and 186.6 MPa for the commercial composite. The high strength of the commercial configuration is a result of the composite structure that allows for shear stresses on the surfaces of the piezoelectric layers, whereas the low strength of the single-crystal materials is due to their unique crystal structure, which allows for rapid propagation of cracks initiating at flaw sites. The experimental bending strength results reported, which are linear estimates without nonlinear ferroelastic considerations, are intended for use in the design of multifunctional piezoelectric systems in which the active device is subjected to bending loads. PMID:22711404

  3. Microstructure-Based RVE Approach for Stretch-Bending of Dual-Phase Steels

    Science.gov (United States)

    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.

  4. Investigation of Structural Behavior due to Bend-Twist Couplings in Wind Turbine Blades

    OpenAIRE

    Fedorov, Vladimir; Dimitrov, Nikolay Krasimirov; Berggreen, Christian; Krenk, Steen; Branner, Kim; Berring, Peter

    2010-01-01

    One of the problematic issues concerning the design of future large composite wind turbine blades is the prediction of bend-twist couplings and torsion behaviour. The current work is a continuation of a previous work [1,2], and it examines different finite element modelling approaches for predicting the torsional response of the wind turbine blades with built-in bend-twist couplings. Additionally, a number of improved full-scale tests using an advanced bi-axial servo-hydraulic load control ha...

  5. Textile artificial magnetic conductor jacket for transmission enhancement between antennas under bending and wetness measurements

    Science.gov (United States)

    Kamardin, Kamilia; Rahim, Mohamad Kamal A.; Hall, Peter S.; Samsuri, Noor Asmawati; Latef, Tarik Abdul; Ullah, Mohammad Habib

    2016-04-01

    Textile artificial magnetic conductor (AMC) waveguide jacket for transmission enhancement between on-body antennas is proposed. Transmission characteristics between antennas with different orientations and placements are studied. Significant transmission enhancement is observed for all tested positions. Bending and wetness measurements are also conducted. Bending is found not to give significant effect to the antennas and AMC performance, while wetness yields severe performance distortion. However, the original performance is retrieved once the antennas and AMC dried. The proposed AMC jacket will act as a new approach for efficient wearable body-centric communications.

  6. On the Effect of Green Water on Deck on the Wave Bending Moment

    DEFF Research Database (Denmark)

    Wang, Zhaohui; Jensen, Jørgen Juncher; Xia, Jinzhu

    1998-01-01

    and a momentum term, using an effective relative motion calibrated with the model tests, model the green water load. The resulting loads are of the same magnitude as the slamming loads. The results show only a marginal influence of the green water load on the maximum wave bending moment, although the time signal...

  7. Fretting fatigue behavior of high-strength steel monostrands under bending load

    DEFF Research Database (Denmark)

    Winkler, Jan; Georgakis, Christos T.; Fischer, Gregor

    2015-01-01

    along the length of the monostrand. Information about the monostrand bending stiffness and the extent of relative displacement between core and outer wires of a monostrand undergoing flexural deformations is provided. From the series of dynamic fatigue tests, a fretting fatigue spectrum is derived...

  8. High speed bending of 2nd level interconnects on printed circuit boards for automotive electronics

    NARCIS (Netherlands)

    Kouters, M.H.M.; Ubachs, R.; Wiel, H.J. van de; Waal, A. van der; Veer, J. van der

    2011-01-01

    Standard drop tests for portable electronics are not representative for the qualification of automotive electronics. High-frequency vibrations are more dominant than abrupt shocks during normal operation. In this work a high speed board bending (HSB) method is developed to mimic the constant cyclic

  9. Span-Dependent Distributions of the Bending Strength of Spruce Timber

    DEFF Research Database (Denmark)

    Ditlevsen, Ove; Källsner, Bo

    2005-01-01

    Tests data of bending strengths of a large number of timber beams of different spans obtained at the Swedish Institute for Wood Technology Research reveal a statistical structure that can be represented in a simple probabilistic model of series system type. A particular feature of the data from one...

  10. Face/core interface fracture characterization of mixed mode bending sandwich specimens

    DEFF Research Database (Denmark)

    Quispitupa, Amilcar; Berggreen, Christian; Carlsson, L.A.

    2011-01-01

    and PVC H45, H100 and H250 foam core materials were evaluated. A methodology to perform precracking on fracture specimens in order to achieve a sharp and representative crack front is outlined. The mixed mode loading was controlled in the mixed mode bending (MMB) test rig by changing the loading...

  11. Secondary turbulent flow in an infinte bend

    DEFF Research Database (Denmark)

    Christensen, H. Bo; Gislason, Kjartan; Fredsøe, Jørgen

    1999-01-01

    The flow in an infinite circular bend is inverstigated in both the laminar and fully turbulent flow case, by use of laminar flow solver, a k-e turbulence model, and a fully Reynolds stress turbulence model. The topic of the analysis is to investigate whether a counter-rotating secondary flow cell...... model, the influence of the curvature ratio and cross section geometry on the vortex pattern is investigated. Furthermore, it is demonstrated that an-isotropy of turbulence plays an important role for the structure of flow pattern and existence of an extra flow cell....

  12. The bend stiffness of S-DNA

    CERN Document Server

    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.

  13. Wooden Model of Wide AA Bending Magnet

    CERN Multimedia

    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.

  14. Great Bend tornadoes of August 30, 1974

    Science.gov (United States)

    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.

  15. Bending of X65 Offshore Steel Pipes

    OpenAIRE

    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 ...

  16. 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.

  17. Bending in laminas of NFPR: type of reinforcement, fracture and properties

    Directory of Open Access Journals (Sweden)

    Mirtânia Antunes Leão

    2011-03-01

    Full Text Available Natural fiber reinforced plastics (NFRP have awakened considerable interest in the area of polymer composites, because of the need to develop new, environmentally friendly materials. One of the most complex ways of manufacturing this type of material is in the form of ultrathin laminar layers; however, this process hinders mechanical testing, mainly three and four-point bending. The present investigation faces this challenge and shows the influence of parameters, such as the grammage of reinforcing fabric and lamination process, on strength, stiffness and fracture characteristics for three-point bending in this type of structural element. The industrially manufactured laminas were composed of orthophthalic polyester resin reinforced with licuri fibers. Macromechanical and micromechanical analyses were conducted in the study of fracture characteristics for all the parameters. The mechanical behavior in the three-point bending of the laminar composite showed that the use of licuri fiber to obtain natural fiber-based plastic is completely viable.

  18. Dynamic investigation of twist-bend coupling in a wind turbine blade

    DEFF Research Database (Denmark)

    Luczak, M.; Manzato, S.; Peeters, B.;

    2011-01-01

    This paper presents some results and aspects of the multidisciplinary and interdisciplinary research oriented for the experimental and numerical study in static and dynamic domains on the bend-twist coupling in the full scale section of a wind turbine blade structure. The main goal of the conducted...... research is to confirm experimentally the numerical prediction of modification of the dynamic and static properties of a wind turbine blade. The bend-twist coupling was implemented by adding angled UD (UniDirectional) layers on the suction and pressure side of the blade. Static and dynamic tests were...... performed on a section of the full scale wind turbine blade provided by VestasWind Systems A/S. The results are presented and compared with the measurements of the original and modified blade. Comparison analysis confirmed that UD layers introduce measurable bend-twist couplings, which was not present...

  19. 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.

  20. Structural effects of three-dimensional angle-interlock woven composite undergoing bending cyclic loading

    Science.gov (United States)

    Jin, LiMin; Yao, Yao; Yu, YiMin; Rotich, Gideon; Sun, BaoZhong; Gu, BoHong

    2014-03-01

    This paper reports the structural effects of three-dimensional (3-D) angle-interlock woven composite (3DAWC) undergoing three-point bending cyclic loading from experimental and finite element analysis (FEA) approaches. In experiment, the fatigue tests were conducted to measure the bending deflection and to observe the damage morphologies. By the FEA approach, a micro-structural unit-cell model of the 3DAWC was established at the yarn level to simulate the fatigue damage. The stress degradation at the loading condition of constant deformation amplitude was calculated to show the degradation of mechanical properties. In addition, the stress distribution, fatigue damage evolution and critical damage regions were also obtained to qualitatively reveal the structural effects and damage mechanisms of the 3DAWC subjected to three-point bending cyclic loading.

  1. Critical current and strand stiffness of three types of Nb3Sn strand subjected to spatial periodic bending

    International Nuclear Information System (INIS)

    Knowledge of the influence of bending on the critical current (Ic) of Nb3Sn strands is essential for the understanding of the reduction in performance due to transverse electromagnetic load. In particular, for the large cable-in-conduit conductors (CICCs) meant for the international thermonuclear experimental reactor (ITER), we expect that bending is the dominant mechanism for this degradation. We have measured the Ic of a bronze, a powder-in-tube and an internal tin processed Nb3Sn strand when subjected to spatial periodic bending using bending wavelengths from 5 to 10 mm. Two of these strands were applied in model coils for the ITER. We found that the tested strands behave according to the so-called low interfilament resistivity limit, confirming full current transfer between the filaments. This is supported by AC coupling loss measurements giving an indication of the interfilament current transfer length. The reduction of Ic due to bending strain can then be simply derived from the bending amplitude and the Ic versus axial applied strain (ε) relation. This Ic(ε) sensitivity can vary for different strand types but since the electromagnetic force is the driving parameter for strand bending in a CICC, the stiffness of the strands definitively plays a key role, which is confirmed by the results presented

  2. Critical current and strand stiffness of three types of Nb3Sn strand subjected to spatial periodic bending

    Science.gov (United States)

    Nijhuis, A.; Ilyin, Y.; Wessel, W. A. J.; Abbas, W.

    2006-11-01

    Knowledge of the influence of bending on the critical current (Ic) of Nb3Sn strands is essential for the understanding of the reduction in performance due to transverse electromagnetic load. In particular, for the large cable-in-conduit conductors (CICCs) meant for the international thermonuclear experimental reactor (ITER), we expect that bending is the dominant mechanism for this degradation. We have measured the Ic of a bronze, a powder-in-tube and an internal tin processed Nb3Sn strand when subjected to spatial periodic bending using bending wavelengths from 5 to 10 mm. Two of these strands were applied in model coils for the ITER. We found that the tested strands behave according to the so-called low interfilament resistivity limit, confirming full current transfer between the filaments. This is supported by AC coupling loss measurements giving an indication of the interfilament current transfer length. The reduction of Ic due to bending strain can then be simply derived from the bending amplitude and the Ic versus axial applied strain (ɛ) relation. This Ic(ɛ) sensitivity can vary for different strand types but since the electromagnetic force is the driving parameter for strand bending in a CICC, the stiffness of the strands definitively plays a key role, which is confirmed by the results presented.

  3. Thick fibrous composite reinforcements behave as special second-gradient materials: three-point bending of 3D interlocks

    Science.gov (United States)

    Madeo, Angela; Ferretti, Manuel; dell'Isola, Francesco; Boisse, Philippe

    2015-08-01

    In this paper, we propose to use a second gradient, 3D orthotropic model for the characterization of the mechanical behavior of thick woven composite interlocks. Such second-gradient theory is seen to directly account for the out-of-plane bending rigidity of the yarns at the mesoscopic scale which is, in turn, related to the bending stiffness of the fibers composing the yarns themselves. The yarns' bending rigidity evidently affects the macroscopic bending of the material and this fact is revealed by presenting a three-point bending test on specimens of composite interlocks. These specimens differ one from the other for the different relative direction of the yarns with respect to the edges of the sample itself. Both types of specimens are independently seen to take advantage of a second-gradient modeling for the correct description of their macroscopic bending modes. The results presented in this paper are essential for the setting up of a correct continuum framework suitable for the mechanical characterization of composite interlocks. The few second-gradient parameters introduced by the present model are all seen to be associated with peculiar deformation modes of the mesostructure (bending of the yarns) and are determined by inverse approach. Although the presented results undoubtedly represent an important step toward the complete characterization of the mechanical behavior of fibrous composite reinforcements, more complex hyperelastic second-gradient constitutive laws must be conceived in order to account for the description of all possible mesostructure-induced deformation patterns.

  4. Effect of antimicrobial compounds on cut Gerbera flowers: Poor relation between stem bending and numbers of bacteria in the vase water

    NARCIS (Netherlands)

    Witte, van de Y.; Harkema, H.; Doorn, van W.G.

    2014-01-01

    Gerbera flowers (Gerbera jamesonii) often show stem bending. In four cultivars (Tamara, Liesbeth, Cora, and Mickey), we tested the effects on bending of antimicrobial compounds (chlorine bleach, a slow release chlorine compound, 8-hydroxyquinoline citrate [HQC], silver nitrate, carvacrol and thymol)

  5. Torsion and antero-posterior bending in the in vivo human tibia loading regimes during walking and running.

    Science.gov (United States)

    Yang, Peng-Fei; Sanno, Maximilian; Ganse, Bergita; Koy, Timmo; Brüggemann, Gert-Peter; Müller, Lars Peter; Rittweger, Jörn

    2014-01-01

    Bending, in addition to compression, is recognized to be a common loading pattern in long bones in animals. However, due to the technical difficulty of measuring bone deformation in humans, our current understanding of bone loading patterns in humans is very limited. In the present study, we hypothesized that bending and torsion are important loading regimes in the human tibia. In vivo tibia segment deformation in humans was assessed during walking and running utilizing a novel optical approach. Results suggest that the proximal tibia primarily bends to the posterior (bending angle: 0.15°-1.30°) and medial aspect (bending angle: 0.38°-0.90°) and that it twists externally (torsion angle: 0.67°-1.66°) in relation to the distal tibia during the stance phase of overground walking at a speed between 2.5 and 6.1 km/h. Peak posterior bending and peak torsion occurred during the first and second half of stance phase, respectively. The peak-to-peak antero-posterior (AP) bending angles increased linearly with vertical ground reaction force and speed. Similarly, peak-to-peak torsion angles increased with the vertical free moment in four of the five test subjects and with the speed in three of the test subjects. There was no correlation between peak-to-peak medio-lateral (ML) bending angles and ground reaction force or speed. On the treadmill, peak-to-peak AP bending angles increased with walking and running speed, but peak-to-peak torsion angles and peak-to-peak ML bending angles remained constant during walking. Peak-to-peak AP bending angle during treadmill running was speed-dependent and larger than that observed during walking. In contrast, peak-to-peak tibia torsion angle was smaller during treadmill running than during walking. To conclude, bending and torsion of substantial magnitude were observed in the human tibia during walking and running. A systematic distribution of peak amplitude was found during the first and second parts of the stance phase.

  6. 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.

  7. Numerical investigation on the effect of skin passing and roller leveling on the bending behaviour of mild steel

    Science.gov (United States)

    Marnette, Jascha; Rolfe, Bernard; Hodgson, Peter; Weiss, Matthias

    2013-12-01

    The common grades of steel used in roll forming are: hot rolled, high strength low alloy and recovery annealed cold rolled sheet. These steels are prone to ageing and are often skin passed and/or roller leveled to eliminate ageing as this can lead to problems in forming. Shape defects such as bow, twist and camber can be increased due to a change of the elastic-plastic transition point of the material. In consideration of this effect the knowledge of the material properties in the elastic plastic transition range is necessary if the processes are to be modelled accurately. Previous studies have indicated that residual stresses are not well identified in the standard tensile test, but were shown clearly in a bending test. The elastic plastic transition in bending and the moment curvature characteristic were changed significantly by a light cold rolling reduction. In this work the FEA package Abaqus is used to investigate the effect of residual stresses introduced through skin passing and/or roller leveling on the bending/yielding behaviour of mild steel. Therefore, a skin passing/ roller leveling process is simulated, followed by a subsequent bending test. Residual stress free sheet is compared in bending to just "skin passed", "roller leveled" and a combined "skin passed and roller leveled" strip. Skin passing significantly reduces the bending yield stress due to residual stresses. This has a softening effect on subsequent bending operations. A roller level process prior to roll forming can restore the bending yield stress by reducing the residual stress across the thickness. This has implications for forming aged material.

  8. Bending Strength and Fracture Investigations of Cu Based Composite Materials Strengthened with δ-Alumina Fibres

    Directory of Open Access Journals (Sweden)

    J.W. Kaczmar

    2013-04-01

    Full Text Available Bending strength, thermal and electric conductivity and microstructure examinations of Cu based composite materials reinforced with Saffil alumina fibres are presented. Materials were produced by squeeze casting method applying the designed device and specially elaborated production parameters. Applying infiltration pressure of 90MPa and suitable temperature parameters provided manufacturing of copper based composite materials strengthened with Saffil alumina fibres characterized by the low rest porosity and good fibre-matrix interface. Three point bending tests at temperatures of 25, 100 and 300ºC were performed on specimens reinforced with 10, 15 and 20% of Saffil fibres. Introduced reinforcement effected on the relatively high bending strengths at elevated temperatures. In relation to unreinforced Cu casting strength of composite material Cu - 15vol.% Saffil fibres increase by about 25%, whereas at the highest applied test temperature of 300oC the improvement was almost 100%. Fibres by strengthening of the copper matrix and by transferring loads from the matrix reduce its plastic deformation and hinder the micro-crack developed during bending tests. Decreasing of thermal and electrical conductivity of Cu after incorporating fibres in the matrix are relatively small and these properties can be acceptable for electric and thermal applications.

  9. Investigation of Structural Behavior due to Bend-Twist Couplings in Wind Turbine Blades

    DEFF Research Database (Denmark)

    Fedorov, Vladimir; Dimitrov, Nikolay Krasimirov; Berggreen, Christian;

    2010-01-01

    One of the problematic issues concerning the design of future large composite wind turbine blades is the prediction of bend-twist couplings and torsion behaviour. The current work is a continuation of a previous work [1,2], and it examines different finite element modelling approaches for predict......One of the problematic issues concerning the design of future large composite wind turbine blades is the prediction of bend-twist couplings and torsion behaviour. The current work is a continuation of a previous work [1,2], and it examines different finite element modelling approaches...... for predicting the torsional response of the wind turbine blades with built-in bend-twist couplings. Additionally, a number of improved full-scale tests using an advanced bi-axial servo-hydraulic load control have been performed on a wind turbine blade section provided by Vestas Wind Systems A/S. In the present...... of the blade cross section as the defining surface, off-setting the location of the shell elements according to the specified thickness. The experimental full-scale tests were carried out on an 8 m section of a 23 m wind turbine blade with specially implemented bend-twist coupling. The blade was tested under...

  10. Bending Under Tension Test with Direct Friction Measurement

    DEFF Research Database (Denmark)

    Andreasen, Jan Lasson; Olsson, David Dam; Chodnikiewicz, K.;

    2004-01-01

    enabling accurate measurement of friction and direct determination of lubricant film breakdown for varying normal pressure, sliding speed, tool radius and tool preheat temperature. The transducer is applied in an experimental investigation focusing on limits of lubrication in drawing of stainless steel......A special BUT-transducer has been developed in which friction around the tool radius can be directly measured when drawing a plane sheet strip around a cylindrical tool-pin under constant back tension. The front tension, back tension and torque on the tool-pin are all measured directly, thus...... showing the influence of varying process conditions and the performance of different lubricants....

  11. Acoustic emission monitoring of recycled aggregate concrete under bending

    Science.gov (United States)

    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.

  12. Study on Thickness Effect of Three-Point-Bend Specimen

    Science.gov (United States)

    Kikuchi, Masanori; Ishihara, Takehito

    The thickness effect of a three-point-bend (3PB) specimen on dimple fracture behavior is studied experimentally and numerically. At first, fracture toughness tests were conducted using 3PB specimens of different thicknesses. Fracture toughness values and R-curves are obtained, and the thickness effect is discussed. Using scanning electron microscopy (SEM), dimple fracture surfaces are observed precisely. It is found that the thickness effect appears clearly in the void growth process. Finite element (FEM) analyses are conducted based on these experimental data. Using Gurson’s constitutive equation, the nucleation and growth of voids during the dimple fracture process are simulated. The distribution patterns of stress triaxiality and the crack growth process are obtained. The results show a good agreement with experimental ones qualitatively. The effects of specimen thickness on R-curves are explained well on the basis of these numerical simulations.

  13. Flexible bending of aluminum profiles with polyurethane pad

    Institute of Scientific and Technical Information of China (English)

    HE Zhu-bin; LIU Gang; WANG Zhong-ren

    2006-01-01

    The high flexibility of profile bending with hyperelastic pad enables it to be a promising method for small lot or single part production, especially for space frame and roof-rail parts in automotive and aerospace industries. Bending of two aluminum profiles with different sections was carried out to investigate the effect of main process parameters on the bending process. Results show that the shape of the cross-section and its relative thickness and section modulus in bending are the main factors that determine the bending properties of the profiles. Roller stroke, properties of polyurethane pad and constraints on profiles are key factors that determine the bending radius and section deformation of bent profiles. Failures and quality problems met in experiments were also analyzed.

  14. 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%.

  15. Bending strain tolerance of MgB2 superconducting wires

    Science.gov (United States)

    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.

  16. Pitting and Bending Fatigue Evaluations of a New Case-Carburized Gear Steel

    Science.gov (United States)

    Krantz, Timothy; Tufts, Brian

    2007-01-01

    The power density of a gearbox is an important consideration for many applications and is especially important for gearboxes used on aircraft. One approach to improving power density of gearing is to improve the steel properties by design of the alloy. The alloy tested in this work was designed to be case-carburized with surface hardness of Rockwell C66 after hardening. Test gear performance was evaluated using surface fatigue tests and single-tooth bending fatigue tests. The performance of gears made from the new alloy was compared to the performance of gears made from two alloys currently used for aviation gearing. The new alloy exhibited significantly better performance in surface fatigue testing, demonstrating the value of the improved properties in the case layer. However, the alloy exhibited lesser performance in single-tooth bending fatigue testing. The fracture toughness of the tested gears was insufficient for use in aircraft applications as judged by the behavior exhibited during the single tooth bending tests. This study quantified the performance of the new alloy and has provided guidance for the design and development of next generation gear steels.

  17. 49 CFR 192.315 - Wrinkle bends in steel pipe.

    Science.gov (United States)

    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)...

  18. BEND3 mediates transcriptional repression and heterochromatin organization.

    Science.gov (United States)

    Khan, Abid; Prasanth, Supriya G

    2015-01-01

    Transcription repression plays a central role in gene regulation. Transcription repressors utilize diverse strategies to mediate transcriptional repression. We have recently demonstrated that BEND3 (BANP, E5R and Nac1 domain) protein represses rDNA transcription by stabilizing a NoRC component. We discuss the role of BEND3 as a global regulator of gene expression and propose a model whereby BEND3 associates with chromatin remodeling complexes to modulate gene expression and heterochromatin organization.

  19. Bending instability characteristics of double-walled carbon nanotubes

    OpenAIRE

    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...

  20. PERMEABILITY OF SALTSTONE MEASUREMENT BY BEAM BENDING

    Energy Technology Data Exchange (ETDEWEB)

    Harbour, J; Tommy Edwards, T; Vickie Williams, V

    2008-01-30

    One of the goals of the Saltstone variability study is to identify (and, quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone mixes. A performance property for Saltstone mixes that is important but not routinely measured is the liquid permeability or saturated hydraulic conductivity of the cured Saltstone mix. The value for the saturated hydraulic conductivity is an input into the Performance Assessment for the SRS Z-Area vaults. Therefore, it is important to have a method available that allows for an accurate and reproducible measurement of permeability quickly and inexpensively. One such method that could potentially meet these requirements for the measurement of saturated hydraulic conductivity is the technique of beam bending, developed by Professor George Scherer at Princeton University. In order to determine the feasibility of this technique for Saltstone mixes, a summer student, David Feliciano, was hired to work at Princeton under the direction of George Scherer. This report details the results of this study which demonstrated the feasibility and applicability of the beam bending method to measurement of permeability of Saltstone samples. This research effort used samples made at Princeton from a Modular Caustic side solvent extraction Unit based simulant (MCU) and premix at a water to premix ratio of 0.60. The saturated hydraulic conductivities for these mixes were measured by the beam bending technique and the values determined were of the order of 1.4 to 3.4 x 10{sup -9} cm/sec. These values of hydraulic conductivity are consistent with independently measured values of this property on similar MCU based mixes by Dixon and Phifer. These values are also consistent with the hydraulic conductivity of a generic Saltstone mix measured by Langton in 1985. The high water to premix ratio used for Saltstone along with the relatively low degree of hydration for

  1. 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

  2. Bend loss in surface plasmon polariton band-gap structures

    DEFF Research Database (Denmark)

    Bozhevolnyi, S.I.; Volkov, V.S.; Leosson, Kristjan;

    2001-01-01

    Using near-field optical microscopy, we investigate propagation of surface plasmon polaritons (SPPs) excited in the wavelength range of 720-830 nm at a corrugated gold-film surface with areas of 200-nm-wide and 45-nm-high scatterers arranged in a 410-nm-period triangular lattice containing line...... defects with double bends. We find that, for similar to2-mum-wide line defects and the wavelength of similar to 740 nm, the double bend losses for bend angles of 15 degrees and 30 degrees are below 2 and 10 dB, respectively. Our data indicate that the bend loss increases approximately quadratically...

  3. Bend sensors based on periodically-tapered soft glass fibers

    OpenAIRE

    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...

  4. 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

  5. Distributed force probe bending model of critical dimension atomic force microscopy bias

    Science.gov (United States)

    Ukraintsev, Vladimir A.; Orji, Ndubuisi G.; Vorburger, Theodore V.; Dixson, Ronald G.; Fu, Joseph; Silver, Rick M.

    2013-04-01

    Critical dimension atomic force microscopy (CD-AFM) is a widely used reference metrology technique. To characterize modern semiconductor devices, small and flexible probes, often 15 to 20 nm in diameter, are used. Recent studies have reported uncontrolled and significant probe-to-probe bias variation during linewidth and sidewall angle measurements. To understand the source of these variations, tip-sample interactions between high aspect ratio features and small flexible probes, and their influence on measurement bias, should be carefully studied. Using theoretical and experimental procedures, one-dimensional (1-D) and two-dimensional (2-D) models of cylindrical probe bending relevant to carbon nanotube (CNT) AFM probes were developed and tested. An earlier 1-D bending model was refined, and a new 2-D distributed force (DF) model was developed. Contributions from several factors were considered, including: probe misalignment, CNT tip apex diameter variation, probe bending before snapping, and distributed van der Waals-London force. A method for extracting Hamaker probe-surface interaction energy from experimental probe-bending data was developed. Comparison of the new 2-D model with 1-D single point force (SPF) model revealed a difference of about 28% in probe bending. A simple linear relation between biases predicted by the 1-D SPF and 2-D DF models was found. The results suggest that probe bending can be on the order of several nanometers and can partially explain the observed CD-AFM probe-to-probe variation. New 2-D and three-dimensional CD-AFM data analysis software is needed to take full advantage of the new bias correction modeling capabilities.

  6. Bending and torsional vibration control of composite beams through intelligent constrained-layer damping treatments

    Science.gov (United States)

    Shen, I. Y.

    1995-05-01

    This paper is to develop a mathematical model to predict bending, twisting, and axial vibration response of a composite beam with intelligent constrained layer (ICL) or active constrained layer (ACL) damping treatments. In addition, preliminary experiments are conducted on composite beams to evaluate this new technique. The ICL composite beam model is obtained by integrating the existing ICL composite plate model proposed by Shen. When the plate width (along the x-axis) is much smaller than the plate length (along the y-axis), integration of the ICL composite plate equations and linearization of displacement fields with respect to x leads to a set of equations that couples bending, tosional, and axial vibrations of a composite beam. The equations of motion and associated boundary conditions are normalized and rearranged in a state-space matrix form, and the vibration response is predicted through the distributed transfer function method developed by Yang and Tan. A numerical example is illustrated on a composite beam with bending-torsion coupling stiffness. Numerical results show that ICL damping treatments may or may not reduce coupled bending and torsional vibrations of a composite beam simultaneously. When the deflection is fed back to actuate the ICL damping treatment, a sensitivity analysis shows that only those vibration modes with significant bending response are suppressed simultaneously with their torsional components. In the preliminary experiments, two different ICL setups are tested on a composite beam without bending-torsion coupling. Damping performance of both ICL setups agrees qualitatively with existing mathematical models and experimental results obtained from other researchers. The damping performance, however, is not optimized due to the availability of materials and their dimensions in the laboratory. An optimization strategy needs to be developed to facilitate design of ACL damping treatments with maximized damping performance.

  7. Failure analysis of fusion clad alloy system AA3003/AA6xxx sheet under bending

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Y., E-mail: shiyh@mcmaster.ca [Department of Mechanical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Jin, H. [Novelis Global Technology Center, P.O. Box 8400, Kingston, Ontario, Canada K7L 5L9 (Canada); Wu, P.D. [Department of Mechanical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada); Lloyd, D.J. [Aluminum Materials Consultants, 106 Nicholsons Point Road, Bath, Ontario, Canada K0H 1G0 (Canada); Embury, D. [Department of Mechanical Engineering, McMaster University, 1280 Main Street West, Hamilton, Ontario, Canada L8S 4L7 (Canada)

    2014-07-29

    An ingot of AA6xxx Al–Si–Mg–Cu alloy clad with AA3003 Al–Mn alloy was co-cast by Fusion technology. Bending tests and numerical modeling were performed to investigate the potential for sub-surface cracking for this laminate system. To simulate particle-induced crack initiation and growth, both random and stringer particles have been selected to mimic the particle distribution in the tested samples. The morphology of cracking in the model was similar to that observed in clad sheet tested in the Cantilever bend test. The crack initiated in the core close to the clad-core interface where the strain in the core is highest, between particles or near particles and propagates along local shear bands in the core, while the clad layer experiences extreme thinning before failure.

  8. Bending the Cost Curve in Childhood Cancer.

    Science.gov (United States)

    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

  9. Design Study: ELENA Bending Magnet Prototype

    CERN Document Server

    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).

  10. Separation of blood in microchannel bends

    Science.gov (United States)

    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.

  11. Modular correction method of bending elastic modulus based on sliding behavior of contact point

    International Nuclear Information System (INIS)

    During the three-point bending test, the sliding behavior of the contact point between the specimen and supports was observed, the sliding behavior was verified to affect the measurements of both deflection and span length, which directly affect the calculation of the bending elastic modulus. Based on the Hertz formula to calculate the elastic contact deformation and the theoretical calculation of the sliding behavior of the contact point, a theoretical model to precisely describe the deflection and span length as a function of bending load was established. Moreover, a modular correction method of bending elastic modulus was proposed, via the comparison between the corrected elastic modulus of three materials (H63 copper–zinc alloy, AZ31B magnesium alloy and 2026 aluminum alloy) and the standard modulus obtained from standard uniaxial tensile tests, the universal feasibility of the proposed correction method was verified. Also, the ratio of corrected to raw elastic modulus presented a monotonically decreasing tendency as the raw elastic modulus of materials increased. (technical note)

  12. Characterization of the Bauschinger effect in sheet metal undergoing large strain reversals in bending

    Science.gov (United States)

    Hanzon, Drew Wyatt

    This work consists on the quantification of sheet metal uniaxial stress-strain reversals from pure bending tests. Bending strains to approximately 10% were measured by strain gages and interferometry. Bending-unbending moments and strains were modeled and compared closely to the experimental data. The reverse uniaxial stress-strains curves were determined from the optimal fit of the model. Bauschinger effects were described by the reverse uniaxial response at the elasto-plastic range, between the elastic and the large strain, power fit ranges. Arc and straight line fittings on the lnsigma-lnepsilon scale proved accurate to describe the elasto-plastic behavior. Reverse uniaxial data determined for DP590 and DP780 steels and two Aluminum alloys showed significant Bauschinger effects with distinct features. For the DP steels the magnitudes of the reverse compressive sigma-epsilon curves compared moderately higher, and merging to a power curve with parameters K, n previously defined by tension testing. Bauschinger effects at small reversed strains were less pronounced for the aluminum alloys. However, at higher strains the reverse elasto-plastic response softened considerably, and during the unbending span the magnitudes of the reverse compressive strains remained below the corresponding K, n tensile values. The results showed pure bending as an efficient, simple to use technique to generate sigma-epsilon data for sheet metal at large reverse strains without the complicating restraining hardware required by direct compression methods.

  13. Fracture Strength and Bending of Fiber-Reinforced Composites and Metal Frameworks in Fixed Partial Dentures

    Directory of Open Access Journals (Sweden)

    M. Sadeghi

    2008-09-01

    Full Text Available Objective: This in vitro study evaluated the fracture strength and bending amount of twotypes of fiber reinforced composite (FRC and cast metal frameworks used for fabrication of inlay fixed partial dentures (IFPDs.Materials and Methods: Seventy-two extracted first maxillary premolars and molars (36 each were embedded in acrylic resin to represent a missing of second maxillary premolar. FRC IFPDs were fabricated using Stick and Fiber-Braid fiber bundles and IFPDs using cast metal alloy (12 for each group. The specimens were stored for 2 weeks at 37°C(SD=1 in distilled water, thermocycled (5-55°C, x 2500 and statically loaded to fracture. The initial bending prior to fracture was evaluated. The data were analyzed using paired t-test and ANOVA test.Results: The fracture strength was significantly higher in the FRC groups (P<0.05; also, the fracture strength was significantly higher in Stick group than Fiber-Braid group (P<0.05. The amount of bending was significantly greater in the FRC groups (P<0.05. The amount of difference in bending between the two groups of FRC was not statistically significant.Conclusion: Within the limits of this in vitrostudy, the results suggest that the FRC IFPDs can be used as a conservative, esthetic alternative to the IFPDs with cast metal frameworks. The results of this study should be confirmed by long-term clinical investigations.

  14. Influence of basketball shoe mass, outsole traction, and forefoot bending stiffness on three athletic movements.

    Science.gov (United States)

    Worobets, Jay; Wannop, John William

    2015-09-01

    Prior research has shown that footwear can enhance athletic performance. However, public information is not available on what basketball shoe properties should be selected to maximise movement performance. Therefore, the purpose of the study was to investigate the influence of basketball shoe mass, outsole traction, and forefoot bending stiffness on sprinting, jumping, and cutting performance. Each of these three basketball shoe properties was systematically varied by ± 20% to produce three shoe conditions of varying mass, three conditions of varying traction, and three conditions of varying bending stiffness. Each shoe was tested by 20 recreational basketball players completing maximal effort sprints, vertical jumps, and a cutting drill. Outsole traction had the largest influence on performance, as the participants performed significantly worse in all tests when traction was decreased by 20% (p < 0.001), and performed significantly better in the cutting drill when traction was increased by 20% (p = 0.005). Forefoot bending stiffness had a moderate effect on sprint and cutting performance (p = 0.013 and p = 0.016 respectively) and shoe mass was found to have no effect on performance. Therefore, choosing a shoe with relatively high outsole traction and forefoot bending stiffness should be prioritised, and less concern should be focused on selecting the lightest shoe.

  15. Numerical analysis of singly curved shallow composite panels under three-point bend load

    OpenAIRE

    Guedes, RM; Alcides Sa

    2008-01-01

    The experimental methodology to test curved panels under three-point bend (3PB) load is assessed. The problem arises when mechanical and strength characterization of pipe material systems is required. Test specimens cut out from pipe samples oriented in the tangential direction were used to measure hoop modulus and strength. In this procedure singly curved beams with the same radius as the pipe are obtained. The present assessment was made using three different approaches: Finite Element Meth...

  16. 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)

  17. Turbulence characteristics in sharp open-channel bends

    NARCIS (Netherlands)

    Blanckaert, K.; De Vriend, H.J.

    2005-01-01

    In spite of its importance, little is known about the turbulence characteristics in open-channel bends. This paper reports on an experimental investigation of turbulence in one cross section of an open-channel bend. Typical flow features are a bicellular pattern of cross-stream circulation (secondar

  18. On the Bending Problem for Large Scale Mapping

    NARCIS (Netherlands)

    Esteban, I.; Booij, O.; Dijk, J.; Groen, F.

    2010-01-01

    During Simultaneous Localization And Mapping, geometrical constraints are established between map features. These constraints, introduced through measurements and motion prediction, produce a bending effect in the event of closing a large loop. In this paper we present a discussion of the bending pr

  19. On the bending problem for large scale mapping

    NARCIS (Netherlands)

    I. Esteban; O. Booij; J. Dijk; F. Groen

    2009-01-01

    During Simultaneous Localization And Mapping, geometrical constraints are established between map features. These constraints, introduced through measurements and motion prediction, produce a bending effect in the event of closing a large loop. In this paper we present a discussion of the bending pr

  20. 36 CFR 7.41 - Big Bend National Park.

    Science.gov (United States)

    2010-07-01

    ... 36 Parks, Forests, and Public Property 1 2010-07-01 2010-07-01 false Big Bend National Park. 7.41 Section 7.41 Parks, Forests, and Public Property NATIONAL PARK SERVICE, DEPARTMENT OF THE INTERIOR SPECIAL REGULATIONS, AREAS OF THE NATIONAL PARK SYSTEM § 7.41 Big Bend National Park. (a) Fishing; closed...

  1. System effects influencing the bending strength of timber beams

    DEFF Research Database (Denmark)

    Ditlevsen, Ove Dalager; Källsner, B.

    1998-01-01

    A stochastic model of hierarchical series system type for the bending strength of spruce beams isdefined from the anticipation that the bending failure takes place at a cross-section with a defect cluster formed by knots or grain irregularities. The parameters of the model are estimated from meas...

  2. Fatigue Assessment of High Strength Steel Welded Joints Under Bending Loading

    International Nuclear Information System (INIS)

    In this study, a fatigue assessment method for vehicle suspension systems having welded geometries was established under a bending loading condition. For the fatigue life estimation of the actual products welded joints made of different steels, bending fatigue tests were performed on welded specimens with a simplified shape for obtaining the moment-fatigue-life plot. Further, geometry modeling of the simplified welded specimens was conducted. Results of finite element analysis were used to obtain the stress-fatigue-life plot. The analysis results were also used to calculate the stress concentration factors for notch-factor-based fatigue life estimation. The test results were compared with results of the general notch-factor-based fatigue life estimation for improving fatigue assessment. As a result, it was concluded that both the welded fatigue tests and the notch-factor-based fatigue life estimation are necessary for accurate fatigue assessment

  3. 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.

  4. 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.

  5. Properties of NiTi wires with direct electric resistance heat treatment method in three-point bending tests%直流电热处理对镍钛合金丝三点弯曲性能的影响

    Institute of Scientific and Technical Information of China (English)

    王红梅; 王邦康; 任超超; 白玉兴

    2011-01-01

    Objective To investigate the mechanical properties of Ni-Ti wires with direct electric resistance heat treatment(DERHT) method in three-point bending tests. Methods Two superelastic Ni-Ti wires(wire A: Smart SE, wire B: SENTALLOY SE, 0.406 mm ×0.559 mm) and 2 heat-actived Ni-Ti wires(wire C: Smart SM, wire D: L&H TITAN, 0.406 mm ×0.559 mm) were selected. They were heattreated using the DERHT method by a controlled electric current(6. 36 A) applied for different period of time[0(control), 1.0, 1.5, 2. 0, 2. 5 seconds). Then, a three-point bending test was performed under controlled temperature (37 ℃ ) to examine the relationships between the deflection and the load in the bending of wires. Results After DERHT treatment, the plateau in the force-deflection curve of superelastic Ni-Ti wires and heat-actived Ni-Ti wires were increased. When the wires were heated for 2. 0 seconds and deflected to 1.5 mm, the loading force of A, B, C and D Ni-Ti wires increased from (3.85 ± 0. 11 ),(3.62±0.07), (3.28±0.09), (2.91 ±0.23) Nto (4.33 ±0.07), (4.07 ±0.05), (4.52±0.08),(3.27 ± 0. 15 ) N respectively. Conclusions DERHT method is very convenient for clinical use. It is possible to change the arch form and superelastic force of NiTi wires. The longer the heating time is, the more the superelastic characteristics of the wires are altered.%目的 探讨直流电热处理后镍钛合金丝三点弯曲性能的变化规律,以期更好地发挥镍钛合金丝在临床治疗中的作用.方法 选择两种超弹性镍钛合金丝(弓丝A:圣马特超弹性镍钛合金牙齿矫形丝;弓丝B:SENTALLOY(R)超弹性镍钛合金丝)和两种热激活镍钛合金丝(弓丝C:圣马特热激活镍钛合金牙齿矫形丝;弓丝D:L&H镍钛丝),用加热仪分别对弓丝进行0(对照)、1.0、1.5、2.0、2.5 s的直流电热处理(恒定电流强度6.36 A);在37℃下利用三点弯曲实验检测弓丝的性能变化.结果 热处理后镍钛合金丝的平台期

  6. TECHNOLOGICAL CHARACTERISTICS OF THE WOOD OF Luehea divaricata, Carya illinoinensis AND Platanus x acerifolia WHEN SUBMITTED TO BENDING

    Directory of Open Access Journals (Sweden)

    Darci Alberto Gatto

    2009-10-01

    Full Text Available This work was conducted with the purpose of investigating bending characteristics of the wood of Platanus x acerifolia (Ait. Willd., Luehea divaricata Mart. et Zucc and Carya illinoinensis (Wangenh K. Koch. Such species were collected from non-managed forests located in Depressão Central and Encosta Superior do Nordeste, Rio Grande do Sul, Brazil. Five representative adult trees from each species per studied area were cut down, corresponding to a total of thirty trees. From the trunk, a 2.5 m long log was taken and, afterwards, transported to a sawmill for processing. A central 8 cm thick plank was sawn, from which samples for bending were manufactured. The samples were conditioned in standard room to a moisture content of approximately 14%. Then, the samples were placed in boiling water during 35 minutes and bended in rays of 16 and 21cm. For the qualification of the bending defects, the methodology presented by Vorreiter (1958 was used. Results showed that the wood of Carya illinoinensis (Wangenh K. Koch had the best bending characteristics when compared to the other two species, independently of the ray bending tested. It seems that the ring porosity, characteristic of the Carya illinoinensis wood, contributed to the result. On the other hand, the wood of Platanus x acerifolia (Ait. Willd. and Luehea divaricata Mart. et Zucc, with diffuse porosity and larger parenchyma proportion, presented more defective pieces.

  7. Ultrasensitive vector bending sensor based on multicore optical fiber.

    Science.gov (United States)

    Villatoro, Joel; Van Newkirk, Amy; Antonio-Lopez, Enrique; Zubia, Joseba; Schülzgen, Axel; Amezcua-Correa, Rodrigo

    2016-02-15

    In this Letter, we demonstrate a compellingly simple directional bending sensor based on multicore optical fibers (MCF). The device operates in reflection mode and consists of a short segment of a three-core MCF that is fusion spliced at the distal end of a standard single mode optical fiber. The asymmetry of our MCF along with the high sensitivity of the supermodes of the MCF make the small bending on the MCF induce drastic changes in the supermodes, their excitation, and, consequently, on the reflected spectrum. Our MCF bending sensor was found to be highly sensitive (4094  pm/deg) to small bending angles. Moreover, it is capable of distinguishing multiple bending orientations. PMID:26872200

  8. Sorting of bending magnets for the SSRF booster

    Institute of Scientific and Technical Information of China (English)

    HOU Jie; LIU Gui-Min; LI Hao-Hu; ZHANG Man-Zhou

    2008-01-01

    The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.

  9. Sorting of bending magnets for the SSRF booster

    Science.gov (United States)

    Hou, Jie; Liu, Gui-Min; Li, Hao-Hu; Zhang, Man-Zhou

    2008-04-01

    The Shanghai Synchrotron Radiation Facility (SSRF)booster ring, a full energy injector for the storage ring, is deigned to accelerate the electron beam energy from 150 MeV to 3.5 GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping. Closed orbit distortion (COD) caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting. Considering the affections of random errors in measurement, both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5 is given as the final installation sequence of the booster bending magnets in this paper. Supported by SSRF Project

  10. Analysis and Simulation of Adiabatic Bend Transitions in Optical Fibers

    Institute of Scientific and Technical Information of China (English)

    YAO Lei; LOU Shu-Qin; JIAN Shui-Sheng

    2009-01-01

    A low-loss criterion for bend transitions in optical fibers is proposed. An optical fiber can be tightly bent with low loss to be adiabatic for the fundamental mode, provided that an approximate upper bound on the rate of change of bend curvature for a given bend curvature is satisfied. Two typical adiabatic bend transition paths, the optimum profile and linear profile, are analyzed and studied numerically. A realizable adiabatic transition with an Archimedean spiral profile is introduced for low bend loss in tightly bent optical fibers. Design of the transitions is based on modeling of the propagation and coupling characteristics of the core and cladding modes,which clearly illustrate the physical processes involved.

  11. Atmospheric Refractive Electromagnetic Wave Bending and Propagation Delay

    CERN Document Server

    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^...

  12. Bending Modulus Measurement of Single High Performance Fiber

    Institute of Scientific and Technical Information of China (English)

    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.

  13. Analysis of residual stress and hardness in regions of pre-manufactured and manual bends in fixation plates for maxillary advancement.

    Science.gov (United States)

    Araújo, Marcelo Marotta; Lauria, Andrezza; Mendes, Marcelo Breno Meneses; Claro, Ana Paula Rosifini Alves; Claro, Cristiane Aparecida de Assis; Moreira, Roger William Fernandes

    2015-12-01

    The aim of this study was to analyze, through Vickers hardness test and photoelasticity analysis, pre-bent areas, manually bent areas, and areas without bends of 10-mm advancement pre-bent titanium plates (Leibinger system). The work was divided into three groups: group I-region without bend, group II-region of 90° manual bend, and group III-region of 90° pre-fabricated bends. All the materials were evaluated through hardness analysis by the Vickers hardness test, stress analysis by residual images obtained in a polariscope, and photoelastic analysis by reflection during the manual bending. The data obtained from the hardness tests were statistically analyzed using ANOVA and Tukey's tests at a significance level of 5 %. The pre-bent plate (group III) showed hardness means statistically significantly higher (P < 0.05) than those of the other groups (I-region without bends, II-90° manually bent region). Through the study of photoelastic reflection, it was possible to identify that the stress gradually increased, reaching a pink color (1.81 δ / λ), as the bending was performed. A general analysis of the results showed that the bent plate region of pre-bent titanium presented the best results.

  14. The effect of skin passing on the material behavior of metal strip in pure bending and tension

    Science.gov (United States)

    Weiss, Matthias; Ryan, Will; Rolfe, Bernard; Yang, Chunhui

    2010-06-01

    The metal strip used in roll forming has often been preprocessed by (tension or roller) leveling or by skin-pass rolling, and as a consequence, may contain residual stresses. These stresses are not well observed by the tensile test, but could have a significant effect on the bending and springback behavior. With the advent of improved process design techniques for roll forming, including advanced finite element techniques, the need for precise material property data has become important. The major deformation mode of roll forming is that of bending combined with unloading and reverse bending, and hence property data derived from bend tests could be more relevant than that from tensile testing. This work presents a numerical study on the effect of skin passing on the material behavior of stainless steel strip in pure bending and tension. A two dimensional (2-D) numerical model was developed using Abaqus Explicit to analyze the affect of skin passing on the residual stress profile across a section for various working conditions. The deformed meshes and their final stress fields were then imported as pre-defined fields into Abaqus Standard, and the post-skin passing material behavior in pure bending was determined. The results show that a residual stress profile is introduced into the steel strip during skin passing, and that its shape and stress level depend on the overall thickness reduction as well as the number of rolling passes used in the skin passing process. The material behavior in bending and the amount of springback changed significantly depending on the skin pass condition.

  15. An Investigation on the causes of a rotor bending and its thermal straightening

    International Nuclear Information System (INIS)

    Distortion or bend in a turbine rotor (especially HIP rotors) may be caused by a number of factors, either singularly or in combination. In general, the causes of rotor bend can he classified invariably in two categories: Rapidly forming permanent rotor bends and/or Slower forming rotor bends. Which could trip the turbines' emergency stop. One of the major modifying solutions for rapid repairing of bent rotors is hot spotting. For this purpose, after the initial tests (visual inspection, chemical analysis, nondestructive hardness), the hot spotting was performed seven consecutive times. The results or experimental investigations and experiences with different temperatures and times showed that, the 690 ±20degC and 210 S. are as an optimum temperature and time respectively, for hot spotting which can provide a noticeable straightening in bent areas, in addition to having no affects on mechanical properties. Also, this result were simulated by F.E.M in view of heat distribution in different temperatures in three states (without insulation, with moisture and dry insulation), in order to find out the optimum restraint effects around hot spot area

  16. Fresh-wood bending: linking the mechanical and growth properties of a Norway spruce stem.

    Science.gov (United States)

    Lundström, Tor; Heiz, Urs; Stoffel, Markus; Stöckli, Veronika

    2007-09-01

    To provide data and methods for analyzing stem mechanics, we investigated bending, density and growth characteristics of 207 specimens of fresh wood from different heights and radial positions of the stem of one mature Norway spruce (Picea abies L. Karst.) tree. From the shape of each stress-strain curve, which was calculated from bending tests that accounted for shear deformation, we determined the modulus of elasticity (MOE), the modulus of rupture (MOR), the completeness of the material, an idealized stress-strain curve and the work involved in bending. In general, all mechanical properties increased with distance from the pith, with values in the ranges of 5.7-18 GPa for MOE, 23-90 MPa for MOR and 370-630 and 430-1100 kg m(-3) for dry and fresh wood densities, respectively. The first three properties generally decreased with stem height, whereas fresh wood density increased. Multiple regression equations were calculated, relating MOR, MOE and dry wood density to growth properties. We applied these equations to the growth of the entire stem and considered the annual rings as superimposed cylindrical shells, resulting in stem-section values of MOE, MOR and dry and fresh densities as a function of stem height and cambial age. The standing tree exhibits an inner stem structure that is well designed for bending, especially at a mature stage. PMID:17545123

  17. Coefficient of Superelevation for the Flow Using Movable Pillar in Channel Bend

    Directory of Open Access Journals (Sweden)

    M. Galib Ishak

    2015-02-01

    Full Text Available To construct a bridge as a crossing building on a very wide river it might not used one span only, therefor, in middle of the river it is needed pillar as support. The existing of the pillars will change velocity distribution, surface water and topography of sediment, especially when the pillar is located on the bend of the river where the very large hydraulic can be hepened. Therefore, this study will be focused on the effect of the coordinate pillar to the superelevation coefficient. The research has done by making a model of channel with and without sediment for the both testing conditions, the pillar was moved by every interval of 300 on bends of the channel. Results of the research showed that the greatest value of Cs for the flow without sediment at the position of pillar of 00 at the bend of 1200 is 3.413. On the otherhand, the greatest value of Cs for the flow with sediment was 3.509 wich was given by pillar at position 1500 at bend of 300.

  18. Fabrication and reliable implementation of an ionic polymer-metal composite (IPMC) biaxial bending actuator

    Science.gov (United States)

    Lee, Gil-Yong; Choi, Jung-Oh; Kim, Myeungseon; Ahn, Sung-Hoon

    2011-10-01

    Ionic polymer-metal composites (IPMCs) are one of the most popular types of electro-active polymer actuator, due to their low electric driving potential, large deformation range, and light weight. IPMCs have been used as actuators or sensors in many areas of biomedical and robotic engineering. In this research, IPMCs were studied as a biaxial bending actuator capable of smart and flexible motion. We designed and fabricated this bending actuator and implemented it to have a reliable actuating motion using a systematic approach. The resulting device was bar shaped with a square cross section and had four insulated electrodes on its surface. By applying different voltages to these four electrodes, a biaxial bending motion can be induced. To construct this actuator, several fabrication processes were considered. We modified the Nafion stacking method, and established a complete sequence of actuator fabrication processes. Using these processes, we were able to fabricate an IPMC biaxial bending actuator with both high actuating force and high flexibility. Several experiments were conducted to investigate and verify the performance of the actuator. The IPMC actuator system was modeled from experimentally measured data, and using this actuator model, a closed-loop proportional integral (PI) controller was designed. Reference position tracking performances of open-loop and closed-loop systems were compared. Finally, circular motion tracking performances of the actuator tip were tested under different rotation frequencies and radii of a reference trajectory circle.

  19. 75 FR 71666 - Bend/Ft. Rock Ranger District; Deschutes National Forest; Deschutes County, OR; West Bend...

    Science.gov (United States)

    2010-11-24

    ... decision-making process so interested and affected public may ] participate and contribute to the final... improve forest health and fuel conditions within the 25,700-acre West Bend planning area. The planning..., and on the west by the Bend Watershed Roadless Area. The planning area is entirely within public...

  20. Bending strain effects on the critical current in Cu-stabilized IBAD/EDDC processed SmBCO coated conductor tape

    International Nuclear Information System (INIS)

    Influences of bending strain on the critical current, Ic, in Cu-stabilized IBAD/EDDC processed SmBCO coated conductor (CC) tapes were investigated at 77 K and self-field using a small-scale Goldacker type bending test rig. Considering the location of the superconducting layer against the neutral axis, tensile and compressive bending strains were applied to the SmBCO coating layer and the strain effect on Ic degradation was discussed. Under tensile bending strain, the Ic decreased monotonically but recovered reversibly up to the irreversible strain limit. Under compressive bending strain, however, the Ic increased but in some cases it suddenly dropped after straightening due to the delamination of the copper stabilizer. Also, repeated bending strains were applied to Cu-stabilized SmBCO CC samples in order to observe the behavior of Ic under cyclic loading. Ic Initially decreased with the application of 0.7% bending strain, but when the tape was subjected to repeated bending up to 100 cycles, no more degradation occurred. And finally, the Ic almost recovered to Ic0 when the tape was straightened

  1. 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.

  2. 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.

  3. Occipital bending (Yakovlevian torque) in bipolar depression.

    Science.gov (United States)

    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

  4. Damage and fracture in fabric-reinforced composites under quasi-static and dynamic bending

    Science.gov (United States)

    Ullah, H.; Harland, A. R.; Silberschmidt, V. V.

    2013-07-01

    Fabric-reinforced polymer composites used in sports products can be exposed to different in-service conditions such as large deformations caused by quasi-static and dynamic loading. Composite materials subjected to such bending loads can demonstrate various damage modes - matrix cracking, delamination and, ultimately, fabric fracture. Damage evolution in composites affects both their in-service properties and performance that can deteriorate with time. Such behaviour needs adequate means of analysis and investigation, the main approaches being experimental characterisation and non-destructive examination of internal damage in composite laminates. This research deals with a deformation behaviour and damage in carbon fabric-reinforced polymer (CFRP) laminates caused by quasi-static and dynamic bending. Experimental tests were carried out to characterise the behaviour of a CFRP material under large-deflection bending, first in quasi-static and then in dynamic conditions. Izod-type impact bending tests were performed on un-notched specimens of CFRP using a Resil impactor to assess the transient response and energy absorbing capability of the material. X-ray micro computed tomography (micro-CT) was used to analyse various damage modes in the tested specimens. X-ray tomographs revealed that through-thickness matrix cracking, inter-ply and intra-ply delamination such as tow debonding, and fabric fracture were the prominent damage modes both in quasi-static and dynamic test specimens. However, the inter-ply damage was localised at impact location in dynamically tested specimens, whereas in the quasi-static specimens, it spread almost over the entire interface.

  5. Behaviour of cracked branch pipes subjected to out of plane bending

    International Nuclear Information System (INIS)

    This article presents the results of a test campaign on the behavior of cracked branch pipes subjected to increasing out of plane bending. The test series was conducted to investigate the influence of a weld or an internal pressure on the global comportment of the structure (maximum load or excessive strain load) or crack tear initiation loading. To supplement the test results, a numerical analysis was performed to simulate phenomena observed and to calculate the stresses around the junction. Experimental comparison between the tests and a numerical analysis on the comportment of the branch pipe without crack are presented. (orig.)

  6. 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.

  7. A wearable, highly stable, strain and bending sensor based on high aspect ratio graphite nanobelts

    Science.gov (United States)

    Alaferdov, A. V.; Savu, R.; Rackauskas, T. A.; Rackauskas, S.; Canesqui, M. A.; de Lara, D. S.; Setti, G. O.; Joanni, E.; de Trindade, G. M.; Lima, U. B.; de Souza, A. S.; Moshkalev, S. A.

    2016-09-01

    A simple and scalable method was developed for the fabrication of wearable strain and bending sensors, based on high aspect ratio (length/thickness ˜103) graphite nanobelt thin films deposited by a modified Langmuir-Blodgett technique onto flexible polymer substrates. The sensing mechanism is based on the changes in contact resistance between individual nanobelts upon substrate deformation. Very high sensor response stability for more than 5000 strain-release cycles and a device power consumption as low as 1 nW were achieved. The device maximum stretchability is limited by the metal electrodes and the polymer substrate; the maximum strain that could be applied to the polymer used in this work was 40%. Bending tests carried out for various radii of curvature demonstrated distinct sensor responses for positive and negative curvatures. The graphite nanobelt thin flexible films were successfully tested for acoustic vibration and heartbeat sensing.

  8. A wearable, highly stable, strain and bending sensor based on high aspect ratio graphite nanobelts

    Science.gov (United States)

    Alaferdov, A. V.; Savu, R.; Rackauskas, T. A.; Rackauskas, S.; Canesqui, M. A.; de Lara, D. S.; Setti, G. O.; Joanni, E.; de Trindade, G. M.; Lima, U. B.; de Souza, A. S.; Moshkalev, S. A.

    2016-09-01

    A simple and scalable method was developed for the fabrication of wearable strain and bending sensors, based on high aspect ratio (length/thickness ∼103) graphite nanobelt thin films deposited by a modified Langmuir–Blodgett technique onto flexible polymer substrates. The sensing mechanism is based on the changes in contact resistance between individual nanobelts upon substrate deformation. Very high sensor response stability for more than 5000 strain–release cycles and a device power consumption as low as 1 nW were achieved. The device maximum stretchability is limited by the metal electrodes and the polymer substrate; the maximum strain that could be applied to the polymer used in this work was 40%. Bending tests carried out for various radii of curvature demonstrated distinct sensor responses for positive and negative curvatures. The graphite nanobelt thin flexible films were successfully tested for acoustic vibration and heartbeat sensing.

  9. Response of Flexible Risers in Bend Stiffener Area

    OpenAIRE

    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...

  10. Response of Flexible Risers in Bend Stiffener Area

    OpenAIRE

    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...

  11. Buffers Affect the Bending Rigidity of Model Lipid Membranes

    DEFF Research Database (Denmark)

    Bouvrais, H.; Duelund, L.; Ipsen, J. H.

    2014-01-01

    In biophysical and biochemical studies of lipid bilayers the influence of the used buffer is often ignored or assumed to be negligible on membrane structure, elasticity, or physical properties. However, we here present experimental evidence, through bending rigidity measurements performed on giant...... vesicles, of a more complex behavior, where the buffering molecules may considerably affect the bending rigidity of phosphatidylcholine bilayers. Furthermore, a synergistic effect on the bending modulus is observed in the presence of both salt and buffer molecules, which serves as a warning...... to experimentalists in the data interpretation of their studies, since typical lipid bilayer studies contain buffer and ion molecules....

  12. 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)

  13. Bends in nanotubes allow electric spin control and coupling

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Marcus, Charles Masamed

    2010-01-01

    We investigate combined effects of spin-orbit coupling and magnetic field in carbon nanotubes containing one or more bends along their length. We show how bends can be used to provide electrical control of confined spins, while spins confined in straight segments remain insensitive to electric...... fields. Device geometries that allow general rotation of single spins are presented and analyzed. In addition, capacitive coupling along bends provides coherent spin-spin interaction, including between otherwise disconnected nanotubes, completing a universal set of one- and two-qubit gates....

  14. Hamiltonian system for orthotropic plate bending based on analogy theory

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Damage Analysis of Rectangular Section Composite Beam under Pure Bending

    Science.gov (United States)

    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.

  16. 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...

  17. Experimental analysis of the fatigue life of threaded pipe connections under cyclic bending

    OpenAIRE

    Van Wittenberghe, Jeroen; Galle, Timothy; De Waele, Wim; DE BAETS, Patrick

    2012-01-01

    When subjected to cyclic loads, fatigue cracks can cause failure of pipe systems joined by threaded pipe connections. In this study, the effect of contact conditions and coupling geometry is investigated experimentally. Fatigue tests under cyclic bending are carried out on three different threaded connection configurations. The resulting fatigue lives are compared and fracture surfaces are investigated. The fatigue cracks are found to initiate at the last engaged thread of the pin and fatigue...

  18. Bending performance of concrete beams strengthened with textile reinforced mortar TRM

    OpenAIRE

    Gil Espert, Lluís; Escrig Pérez, Christian; Bernat Masó, Ernest

    2013-01-01

    This work presents a method of strengthening concrete structures based on textiles of high strength and mortars. The combination of textiles and mortars produces a new composite material with cementitious matrix. This material can be used for the reinforcement of concrete beams under bending loads. We tested several combinations of fibers: glass, Poliparafenil Benzobisoxazol (PBO), steel and carbon fibers with mortar and we used them to reinforce precast concrete beams. All the specimens were...

  19. Compression and bending behavior of steel fiber reinforced self-compacting concrete

    OpenAIRE

    Pereira, E. N. B.; Barros, Joaquim A. O.; Cunha, Vitor M. C. F.; Santos, S. P. F.

    2005-01-01

    A method to design cost competitive steel fiber reinforced self-compacting concrete (SFRSCC) for precasting industrial applications is described in this paper. Since demolding the elements as soon as possible is an important requirement in this industry, the influence of the age on the resistance and toughness of the designed SFRSCC was assessed carrying out an experimental program. Based on the force-deflection relationship obtained in the three point bending notched beam tests performed acc...

  20. Comments on chevron bend specimen for determining fracture toughness of rock

    Institute of Scientific and Technical Information of China (English)

    孙宗颀; 陈枫; 徐纪成

    2001-01-01

    Based on a number of tests on different rocks, Suggested Methods for Determining the Fracture Toughness of Rock (SMs) was reviewed. The advantages of SMs are obvious, but some problems are also discovered. A serious one is that the nonlinear corrected fracture toughness of chevron bend specimens, KCCB, is less than the uncorrected one, KCB, for hard rock like granite, marble and others. The reason is discussed and the proposal is given.

  1. Applications of circularly polarized photons at the ALS with a bend magnet source

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    The purpose of this workshop is to focus attention on, and to stimulate the scientific exploitation of, the natural polarization properties of bend-magnet synchrotron radiation at the ALS -- for research in biology, materials science, physics, and chemistry. The topics include: The Advanced Light Source; Magnetic Circular Dichroism and Differential Scattering on Biomolecules; Tests of Fundamental Symmetries; High {Tc} Superconductivity; Photoemission from Magnetic and Non-magnetic Solids; Studies of Highly Correlated Systems; and Instrumentation for Photon Transport and Polarization Measurements.

  2. Applications of circularly polarized photons at the ALS with a bend magnet source

    International Nuclear Information System (INIS)

    The purpose of this workshop is to focus attention on, and to stimulate the scientific exploitation of, the natural polarization properties of bend-magnet synchrotron radiation at the ALS -- for research in biology, materials science, physics, and chemistry. The topics include: The Advanced Light Source; Magnetic Circular Dichroism and Differential Scattering on Biomolecules; Tests of Fundamental Symmetries; High Tc Superconductivity; Photoemission from Magnetic and Non-magnetic Solids; Studies of Highly Correlated Systems; and Instrumentation for Photon Transport and Polarization Measurements

  3. 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.

  4. An Experimental Study of a Stitched Composite with a Notch Subjected to Combined Bending and Tension Loading

    Science.gov (United States)

    Palmer, Susan O.; Nettles, Alan T.; Poe, C. C., Jr.

    1999-01-01

    A series of tests was conducted to measure the strength of stitched carbon/epoxy composites containing through-thickness damage in the form of a crack-like notch. The specimens were subjected to three types of loading: pure bending, pure tension, and combined bending and tension loads. Measurements of applied loads, strains near crack tips, and crack opening displacements (COD) were monitored in all tests. The transverse displacement at the center of the specimen was measured using a Linear Variable Differential Transformer (LVDT). The experimental data showed that the outer surface of the pure tension specimen failed at approximately 6,000 microstrain, while in combined bending and tension loads the measured tensile strains reached 10,000 microstrain.

  5. Research on Effective Electric-Mechanical Coupling Coefficient of Sandwich Type Piezoelectric Ultrasonic Transducer Using Bending Vibration Mode

    Directory of Open Access Journals (Sweden)

    Qiang Zhang

    2015-01-01

    Full Text Available An analytical model on electromechanical coupling coefficient and the length optimization of a bending piezoelectric ultrasonic transducer are proposed. The piezoelectric transducer consists of 8 PZT elements sandwiched between four thin electrodes, and the PZT elements are clamped by a screwed connection between fore beam and back beam. Firstly, bending vibration model of the piezoelectric transducer is built based on the Timoshenko beam theory. Secondly, the analytical model of effective electromechanical coupling coefficient is built based on the bending vibration model. Energy method and electromechanical equivalent circuit method are involved in the modelling process. To validate the analytical model, sandwich type piezoelectric transducer example in second order bending vibration mode is analysed. Effective electromechanical coupling coefficient of the transducer is optimized with simplex reflection technique, and the optimized ratio of length of the transducers is obtained. Finally, experimental prototypes of the sandwich type piezoelectric transducers are fabricated. Bending vibration mode and impedance of the experimental prototypes are tested, and electromechanical coupling coefficient is obtained according to the testing results. Results show that the analytical model is in good agreement with the experimental model.

  6. Study on the application of active balancing device to solve the vibration problem for the rotor with bending fault

    Institute of Scientific and Technical Information of China (English)

    He Lidong; Shen Wei; Gao Jinji; Zhou Weihua

    2006-01-01

    The rotor with bending faults that occurrs on the rotating machinery usually vibrates seriously. This paper investigates to apply the active balancing device on a flexible rotor with bending faults to solve the vibration problem. Two problems are studied by finite element method firstly: Where the balance actuator is fixed on the shaft and how much the balancing capacity of the active balancing device is needed. The experiment is then carried out on the test rig, which consists of a flexible rotor with bending faults. The test results indicate that the bending rotor peak vibration response can be decreased from 550μm to 40μm below by using the active balancing device. The peak vibration response decreases approximately by 93%. The synchronous vibration due to the rotor bending faults can be controlled effectively by using active balancing device. The active balancing device is especially adapted to solve the problem caused by thermal distortion with time-variation and randomness, which is varied with working conditions, thus it has good practical value in practice.

  7. EFFECT OF CORROSION ON BOND BEHAVIOR AND BENDING STRENGTH OF REINFORCED CONCRETE BEAMS

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    There is growing concern for corrosion damage in reinforced concrete structures with several decades' service. Pullout tests and beam tests were carried out to study the effect of reinforcement corrosion on the bond behavior and bending strength of reinforced concrete beams. The bond strength of plain bars and concrete initially increases with increasing corrosion, then declines. The turning point depends on the cracking of the concrete cover. The bond strength of deformed bars and concrete increases with corrosion up to a certain amount, but with progressive increase in corrosion, the bond strength decreases, and the cracking of the concrete cover seems to have no effect on the bond strength. On the basis of test data, the bond strength coefficient recommended here, which, together with the bond strength of uncorroded steel bars and concrete, can be used to easily calculate the bond strength of corroded steel bars and concrete. The bond strength coefficient proposed in this paper can be used to study the bond stress-slip relationship of corroded steel bars and concrete. The bending strength of corroded reinforced concrete beams declines with increasing reinforcement corrosion. Decreased bending strength of corroded RC beam is due to reduction in steel bar cross section, reduction of yield strength of steel bar, and reduction of bond capacity between steel bar and concrete.

  8. 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

  9. NUMERICAL INVESTIGATION ON FLOW CHARACTERISTICS IN RIBBED BEND

    Institute of Scientific and Technical Information of China (English)

    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.

  10. Computational Strategies for the Architectural Design of Bending Active Structures

    DEFF Research Database (Denmark)

    Tamke, Martin; Nicholas, Paul

    2013-01-01

    Active bending introduces a new level of integration into the design of architectural structures, and opens up new complexities for the architectural design process. In particular, the introduction of material variation reconfigures the design space. Through the precise specification...... of their stiffness, it is possible to control and pre-calibrate the bending behaviour of a composite element. This material capacity challenges architecture’s existing methods for design, specification and prediction. In this paper, we demonstrate how architects might connect the designed nature of composites...... with the design of bending-active structures, through computational strategies. We report three built structures that develop architecturally oriented design methods for bending-active systems using composite materials. These projects demonstrate the application and limits of the introduction of advanced...

  11. Holla Bend National Wildlife Refuge: Comprehensive Conservation Plan

    Data.gov (United States)

    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...

  12. Preliminary Project Investigation : Holla Bend National Wildlife Refuge

    Data.gov (United States)

    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...

  13. 1984 Deer Harvest Summary for Holla Bend National Wildlife Refuge

    Data.gov (United States)

    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.

  14. Fishery Manangement Plan : Holla Bend National Wildlife Refuge

    Data.gov (United States)

    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...

  15. 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

  16. 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

  17. 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.

  18. Effect of Solder Joint Length on Fracture Under Bending

    Science.gov (United States)

    Akbari, Saeed; Nourani, Amir; Spelt, Jan K.

    2016-01-01

    Fracture tests were conducted on copper-solder-copper joints of various lengths using double-cantilever-beam (DCB) specimens under mode I loading conditions. The thickness and length of the solder joints were large enough to neglect any anisotropy associated with the solder microstructure. It was found that the critical strain energy release rate at crack initiation, G ci, was insensitive to the length of the solder joint; however, for joints shorter than a characteristic length which was a function of the thickness and the mechanical properties of the solder layer and the substrates, the fracture load increased with increasing solder joint length. A sandwich model was developed for the analysis of the stress and strain in solder joints, taking into account the influence of both the bending deformation and the shear deformation of the substrates on the solder joint stresses. Consistent with the experimental results, it was found that solder joints longer than the characteristic length have a maximum peel stress that remains unchanged with joint length, causing the joint strength to become independent of the joint length. A closed-form analytical solution was developed for the characteristic length of DCB specimens under mode I loading. The experimental results were in good agreement with the analytical model and with finite element results. The generality of the G ci failure criterion was demonstrated by comparing the experimental results and the fracture load predictions of mode I DCB solder joints with different lengths.

  19. Optimal Orthogonal Graph Drawing with Convex Bend Costs

    CERN Document Server

    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...

  20. Tunable characteristics of bending resonance frequency in magnetoelectric laminated composites

    Science.gov (United States)

    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.

  1. 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.

  2. Bending Boundary Layers in Laminated-Composite Circular Cylindrical Shells

    Science.gov (United States)

    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.

  3. Variability in Flexion Extension Radiographs of the Lumbar Spine: A Comparison of Uncontrolled and Controlled Bending

    Science.gov (United States)

    Cheng, Boyle; Castellvi, Anthony E.; Davis, Reginald J.; Lee, David C.; Lorio, Morgan P.; Prostko, Richard E.

    2016-01-01

    Background While low back pain is one of the most prevalent, if not the most prevalent reasons for visits to physicians, a majority of patients with low back pain cannot be given a definitive diagnosis. While there have been substantial advances in imaging technologies over the past 30 years, relatively little has changed in the methodologies for evaluating functionality of the lumbar spine. The current standard of care for function assessment of the lumbar spine focuses on uncontrolled patient directed motion which results in increased inter-patient variability. Recent advancements in functional lumbar spine testing utilize controlled bending and computerized imaging evaluation. Purpose To compare the measurement variability of lumbar spine motion when diagnosed using measurements of intervertebral motion taken from standard bending flexion/extension radiographs (FE) between uncontrolled and controlled motion. Study Design One-hundred nine patients (57 asymptomatic, 52 symptomatic) were consented in the prospective investigation. The research was designed to compare studies involving FE to controlled motion bending radiographs using the Vertebral Motion Analysis (VMA), (Ortho Kinematics, Inc) within the same patient. Each patient agreed to undergo fluoroscopic still imaging to capture FE data and to undergo cine fluoroscopic imaging to capture VMA data. Outcome Measures Measurement variability was determined by the mean and standard deviation of intervertebral rotation when evaluated by 5 independent observers evaluating each of the 109 patients FE and VMA. The resulting standard deviation of the intervertebral rotation determinations was used as the measure of variability. Methods The VMA measurements for assessing intervertebral motion were characterized by the use of: (1) a handling device that assists patients through a standard arc of lumbar bending in both an upright and recumbent posture (70 degree flexion/extension arcs; 60 degree left/right bending arcs

  4. 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.

  5. Weibull statistical analysis of Krouse type bending fatigue of nuclear materials

    Science.gov (United States)

    Haidyrah, Ahmed S.; Newkirk, Joseph W.; Castaño, Carlos H.

    2016-03-01

    A bending fatigue mini-specimen (Krouse-type) was used to study the fatigue properties of nuclear materials. The objective of this paper is to study fatigue for Grade 91 ferritic-martensitic steel using a mini-specimen (Krouse-type) suitable for reactor irradiation studies. These mini-specimens are similar in design (but smaller) to those described in the ASTM B593 standard. The mini specimen was machined by waterjet and tested as-received. The bending fatigue machine was modified to test the mini-specimen with a specially designed adapter. The cycle bending fatigue behavior of Grade 91 was studied under constant deflection. The S-N curve was created and mean fatigue life was analyzed using mean fatigue life. In this study, the Weibull function was predicted probably for high stress to low stress at 563, 310 and 265 MPa. The commercial software Minitab 17 was used to calculate the distribution of fatigue life under different stress levels. We have used 2 and 3- parameters Weibull analysis to introduce the probability of failure. The plots indicated that the 3- parameter Weibull distribution fits the data well.

  6. Stress Intensity Factors of Semi-Circular Bend Specimens with Straight-Through and Chevron Notches

    Science.gov (United States)

    Ayatollahi, M. R.; Mahdavi, E.; Alborzi, M. J.; Obara, Y.

    2016-04-01

    Semi-circular bend specimen is one of the useful test specimens for determining fracture toughness of rock and geo-materials. Generally, in rock test specimens, initial cracks are produced in two shapes: straight-edge cracks and chevron notches. In this study, the minimum dimensionless stress intensity factors of semi-circular bend specimen (SCB) with straight-through and chevron notches are calculated. First, using finite element analysis, a suitable relation for the dimensionless stress intensity factor of SCB with straight-through crack is presented based on the normalized crack length and half-distance between supports. For evaluating the validity and accuracy of this relation, the obtained results are then compared with numerical and experimental results reported in the literature. Subsequently, by performing some experiments and also finite element analysis of the SCB specimen with chevron notch, the minimum dimensionless stress intensity factor of this specimen is obtained. Using the new equation for the dimensionless stress intensity factor of SCB with straight-through crack and an analytical method, i.e., Bluhm's slice synthesis method, the minimum (critical) dimensionless stress intensity factor of chevron notched semi-circular bend specimens is calculated. Good agreement is observed between the results of two mentioned methods.

  7. Damage Behaviors of Foam Sandwiched Composite Materials Under Quasi-Static Three-point Bending

    Science.gov (United States)

    Zhang, Fa; Mohmmed, Ramadan; Sun, Baozhong; Gu, Bohong

    2013-12-01

    This paper reports the quasi-static three-point bending damage behaviors of foam sandwiched composites in finite element analyses (FEA) and experimental. Finite element calculations were performed to characterize the static response of foam sandwich composites with different ply angle face sheets. Quasi-static three-point bending tests were conducted with a MTS materials testing system to obtain the load-displacement curves and energy absorption under quasi-static bending. A crushable foam model was used in order to explore the mechanical behaviors of core materials, while the Hashin criterion was employed to predict the failure of the face sheets. The load-displacement curves show a satisfactory agreement between the experimental and numerical results. The finite element calculations can also be used to obtain the failure mode included the core damage, face sheet damage and face-core interface damage. It can be observed that the damage at the core material can be classified as either core cracking or core crushing. The damage of the face sheet was through matrix cracking and delamination, with fiber breakage. The significant indentation occurs as a result of the fiber breakage. The face-core interface crack was typically induced by the cracks initiated from the tensile side and propagated to the compressive side.

  8. Textile Diamond Dipole and Artificial Magnetic Conductor Performance under Bending, Wetness and Specific Absorption Rate Measurements

    Directory of Open Access Journals (Sweden)

    K. Kamardin

    2015-09-01

    Full Text Available Textile diamond dipole and Artificial Magnetic Conductor (AMC have been proposed and tested under wearable and body centric measurements. The proposed antenna and AMC sheet are entirely made of textiles for both the substrate and conducting parts, thus making it suitable for wearable communications. Directive radiation patterns with high gain are obtained with the proposed AMC sheet, hence minimizing the radiation towards the human body. In this study, wearable and body centric measurements are investigated which include bending, wetness and Specific Absorption Rate (SAR. Bending is found not to give significant effect to the antenna and AMC performance, as opposed to wetness that yields severe performance distortion. However, the original performance is retrieved once the antenna and AMC dried. Moreover, notable SAR reduction is achieved with the introduction of the AMC sheet, which is appropriate to reduce the radiation that penetrates into human flesh.

  9. Investigation of hydrodynamics on local scour by shape of single spur dike in river bend

    International Nuclear Information System (INIS)

    A series of experiments were conducted in which the the scour hole associated with model spur dike was measured in a 180 degree laboratory flume bend under clear-water overtopping flows. In this study, the local scour were conducted for three different shapes of oblong, rectangulat chamfered of straight spur dikes at the bend with various Froude number. The main goals of the experiments were to evaluate the effect of the three different shapes of straight spur dikes on the volume of scour and potential aquatic habitat and on minimizing erosion adjacent to the streambanks. The experiments showed that of the three different shapes of straight spur dikes tested, the least erosion of the around in the near bank region was associated with the spur dikes with oblong shape, while the greatest volume of the scour hole was associated with the rectangular shape. So it was observed that, as Froude number increases, the scour increases.

  10. Plastic limit load of cylindrical shells with cutouts subject to pure bending moment

    International Nuclear Information System (INIS)

    In this paper, the results of limit analyses of thin-walled cylindrical shells with a circular hole under the action of a pure bending moment are presented in dimensionless form for a wide range of geometric parameters. Analytical estimation of lower bound limit load is carried out using the feasible sequential quadratic programming (FSQP) technique. The finite element calculations of limit load consist of elastic-plastic and lower and upper bound predictions by elastic compensation methods. A testing device was made to perform experiments to obtain limit bending moment of cylinders with circular openings. The analytical and finite element calculations are compared with experimental results and their correlation is discussed. The finite element calculation results were found to be in good agreement with lower bound estimations by the nonlinear mathematical programming (FSQP) method and the formula proposed by Shu

  11. Draw-Bending Analysis of a Cold Rolled DP980 Steel Sheet

    Science.gov (United States)

    Verma, Rahul K.; Noma, Nobuyasu; Chung, Kwansoo; Kuwabara, Toshihiko

    2011-05-01

    To assess the springback prediction accuracy of the recently proposed model (Verma et. al., 2011), simulations for tension-compression (TC) and draw-bending of a cold rolled DP980 steel sheet (Noma and Kuwabara, 2010b) were performed. Using a rotating die and a specimen specially designed to introduce the uniaxial state of stress during the draw bending test, friction could be neglected and the shape of the yield surface did not play any role in accurate simulations. The effects of incorporating permanent softening and the plastic strain dependent Young's modulus were studied in detail and it was found that the incorporation of permanent softening and the plastic strain dependent Young's modulus both was important for accurate springback prediction.

  12. Influence of Tension-Compression Asymmetry on the Mechanical Behavior of AZ31B Magnesium Alloy Sheets in Bending

    Science.gov (United States)

    Zhou, Ping; Beeh, Elmar; Friedrich, Horst E.

    2016-03-01

    Magnesium alloys are promising materials for lightweight design in the automotive industry due to their high strength-to-mass ratio. This study aims to study the influence of tension-compression asymmetry on the radius of curvature and energy absorption capacity of AZ31B-O magnesium alloy sheets in bending. The mechanical properties were characterized using tension, compression, and three-point bending tests. The material exhibits significant tension-compression asymmetry in terms of strength and strain hardening rate due to extension twinning in compression. The compressive yield strength is much lower than the tensile yield strength, while the strain hardening rate is much higher in compression. Furthermore, the tension-compression asymmetry in terms of r value (Lankford value) was also observed. The r value in tension is much higher than that in compression. The bending results indicate that the AZ31B-O sheet can outperform steel and aluminum sheets in terms of specific energy absorption in bending mainly due to its low density. In addition, the AZ31B-O sheet was deformed with a larger radius of curvature than the steel and aluminum sheets, which brings a benefit to energy absorption capacity. Finally, finite element simulation for three-point bending was performed using LS-DYNA and the results confirmed that the larger radius of curvature of a magnesium specimen is mainly attributed to the high strain hardening rate in compression.

  13. Motion Track Modeling and Analysis of Belt Spindle under Combined Effects of Bending Moment-Torque-Thermal Deformation

    Institute of Scientific and Technical Information of China (English)

    齐向阳; 高卫国; 刘腾; 张大卫

    2015-01-01

    The motion track of belt spindle is important for the radial error of belt spindle. An analytical modeling method for the motion track of belt spindle under the combined effects of bending moment-torque-thermal deforma-tion is proposed in this paper. Three running phases of belt spindle have been analyzed and modeled:the start-up phase with leaping change due to the change in force and bending moment, the accelerating phase with axis deflection, and the constant speed phase with axis regression because of the combined effects of bending moment-torque-thermal de-formation. The simulation and test were completed on the belt spindle of SKVM850 machine tool, which illustrates the variation law of the radial error of belt spindle during the whole running phases.

  14. Modeling of the Bending Stiffness of a Bimaterial Beam by the Approximation of One-Dimensional of Laminated Theory

    Directory of Open Access Journals (Sweden)

    M. Flores-Domínguez

    2014-03-01

    Full Text Available In this paper, a mathematical model representing the bending stiffness of a bimaterial beam is proposed. The classical laminated plate theory specialized to 1D is used for modeling the stiffness bending of a beam. Different material configurations (metal-polymer, metal-composite material and metal-metal with three different ratios of layer thickness were evaluated by the analytical model were proposed. Virtual experiments by finite element analysis were carried out to verify the accuracy of the proposed approach. Finite element models of each arrangement were built and the recommendations for the ASTM three-point bending test were followed in the numerical simulation. The average difference of the stiffness results calculated by the analytical model and by finite element simulation was less than 2.11%.

  15. Determination of the fatigue life of the AD33-V composite under conditions of low-cycle loading in pure bending

    Energy Technology Data Exchange (ETDEWEB)

    Utkin, V.S.; Salibekov, S.E.; Chubarov, V.M.

    1986-06-01

    Specimens of AD33-V, an aluminum/boron composite, were tested in cyclic bending to determine the dependence of accumulated damage and fatigue life on the stress amplitude under conditions of pure bending. It is shown that the fatigue life of the composite is proportional to its ultimate strength. Conditional endurance limits are determined as a function of the permissible amount of accumulated damage.

  16. 埋弧焊钢管导向弯曲不合格因素分析%Analysis on Guide Bending Unqualified Factor of SAW Pipe

    Institute of Scientific and Technical Information of China (English)

    甘正红; 苏继权; 余洋

    2011-01-01

    The guide bending test can inspect many properties of samples, including judging plasticity of weld and HAZ, inner defects of welded joints, weld compactness, coordinating deformation ability of welded joints in different areas. The guide bending test is conducted in the routine tests of SAW pipe, welding procedure qualification test and repair welding qualification test. It briefly introduced the relevant regulations to guide bending tests in commonly applied standards for transporting oil and gas, analyzed various factors of occurring face bend and foot bend unqualified samples during guide bending test, and gave various measures to prevent generating unqualified guide bending.%导向弯曲试验可以检测试样的多项性能,包括判定焊缝和热影响区的塑性、焊接接头的内部缺陷、焊缝的致密性以及焊接接头不同区域协调变形的能力等.埋弧焊管的常规试验和焊接工艺评定及补焊工艺评定都要进行导向弯曲试验.简要介绍了常用油气输送用管标准对导向弯曲试验的相关规定,分析了埋弧焊管导向弯曲试验过程中出现的正弯和反弯不合格试样的各种因素,给出了防止导向弯曲不合格的各种措施.

  17. 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.

  18. 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.

  19. A micrographic study of bending failure in five thermoplastic-carbon fibre composite laminates

    Science.gov (United States)

    Yurgartis, S. W.; Sternstein, S. S.

    1988-01-01

    The local deformation and failure sequences of five thermoplastic matrix composites were microscopically observed while bending the samples in a small fixture attached to a microscope stage. The thermoplastics are polycarbonate, polysulfane, polyphenylsulfide, polyethersulfane, and polyetheretherketone. Comparison was made to an epoxy matrix composite, 5208/T-300. Laminates tested are (0/90) sub 2S, with outer ply fibers parallel to the beam axis. Four point bending was used at a typical span-to-thickness ratio of 39:1. It was found that all of the thermoplastic composites failed by abrupt longitudinal compression buckling of the outer ply. Very little precursory damage was observed. Micrographs reveal typical fiber kinking associated with longitudinal compression failure. Curved fracture surfaces on the fibers suggest they failed in bending rather than direct compression. Delamination was suppressed in the thermoplastic composites, and the delamination that did occur was found to be the result of compression buckling, rather than vice-versa. Microbuckling also caused other subsequent damage such as ply splitting, transverse ply shear failure, fiber tensile failure, and transverse ply cracking.

  20. Damage states in laminated composite three-point bend specimens: An experimental-analytical correlation study

    Science.gov (United States)

    Starbuck, J. Michael; Guerdal, Zafer; Pindera, Marek-Jerzy; Poe, Clarence C.

    1990-01-01

    Damage states in laminated composites were studied by considering the model problem of a laminated beam subjected to three-point bending. A combination of experimental and theoretical research techniques was used to correlate the experimental results with the analytical stress distributions. The analytical solution procedure was based on the stress formulation approach of the mathematical theory of elasticity. The solution procedure is capable of calculating the ply-level stresses and beam displacements for any laminated beam of finite length using the generalized plane deformation or plane stress state assumption. Prior to conducting the experimental phase, the results from preliminary analyses were examined. Significant effects in the ply-level stress distributions were seen depending on the fiber orientation, aspect ratio, and whether or not a grouped or interspersed stacking sequence was used. The experimental investigation was conducted to determine the different damage modes in laminated three-point bend specimens. The test matrix consisted of three-point bend specimens of 0 deg unidirectional, cross-ply, and quasi-isotropic stacking sequences. The dependence of the damage initiation loads and ultimate failure loads were studied, and their relation to damage susceptibility and damage tolerance of the mean configuration was discussed. Damage modes were identified by visual inspection of the damaged specimens using an optical microscope. The four fundamental damage mechanisms identified were delaminations, matrix cracking, fiber breakage, and crushing. The correlation study between the experimental results and the analytical results were performed for the midspan deflection, indentation, damage modes, and damage susceptibility.

  1. Bending actuation in a single-layer carbon-nanofiber/polypyrrole composite film and its fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Shuai; Kim, Cheol [Kyungpook National University, Daegu (Korea, Republic of)

    2011-07-15

    Thin CNF/PPy composite single-layer films were produced by the electrophoretic deposition and polymerization process which was developed for this study. It was demonstrated that the films could generate a bending motion subjected to an actuating electric voltage even though they consisted of only single-layer. Carbon nanofiber and polypyrrole composite films were obtained from only one side of a working electrode. Several different CNF/PPy films were synthesized, as varying the CNF weight ratios from 3%, 5%, and 7% to 10%. Conductivity of pure PPy and CNF/PPy composite films were measured. Conductivity of the films is improved linearly from 77.9S/cm (pure PPy film) to 124.3 S/cm (10% CNF/PPy) as the CNF weight ratio increases. Adding CNF was effective for improving the conductivity of PPy. As results of electromechanical actuation tests with the films, it was noticed that the strain of the films was reduced a little as the CNF weight ratio increased. Bending motions were observed for both PPy and CNF/PPy films subjected to a voltage. The tip bending deflections was in the range of 0.5 mm to 2 mm. CNF/PPy films showed a great potential to be a good candidate for small light actuators.

  2. Temperature Induced Instabilities in Macro-bend Fiber Based Wavelength Measurement Systems

    OpenAIRE

    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...

  3. Dynamic statistical optimization of GNSS radio occultation bending angles: an advanced algorithm and its performance analysis

    Directory of Open Access Journals (Sweden)

    Y. Li

    2015-01-01

    Full Text Available We introduce a new dynamic statistical optimization algorithm to initialize ionosphere-corrected bending angles of Global Navigation Satellite System (GNSS based radio occultation (RO measurements. The new algorithm estimates background and observation error covariance matrices with geographically-varying uncertainty profiles and realistic global-mean correlation matrices. The error covariance matrices estimated by the new approach are more accurate and realistic than in simplified existing approaches and can therefore be used in statistical optimization to provide optimal bending angle profiles for high-altitude initialization of the subsequent Abel transform retrieval of refractivity. The new algorithm is evaluated against the existing Wegener Center Occultation Processing System version 5.6 (OPSv5.6 algorithm, using simulated data on two test days from January and July 2008 and real observed CHAMP and COSMIC measurements from the complete months of January and July 2008. The following is achieved for the new method's performance compared to OPSv5.6: (1 significant reduction in random errors (standard deviations of optimized bending angles down to about two-thirds of their size or more; (2 reduction of the systematic differences in optimized bending angles for simulated MetOp data; (3 improved retrieval of refractivity and temperature profiles; (4 produces realistically estimated global-mean correlation matrices and realistic uncertainty fields for the background and observations. Overall the results indicate high suitability for employing the new dynamic approach in the processing of long-term RO data into a reference climate record, leading to well characterized and high-quality atmospheric profiles over the entire stratosphere.

  4. Flow resistance of ice slurry in bends and elbow pipes

    Science.gov (United States)

    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

  5. Platonic scattering cancellation for bending waves in a thin plate

    KAUST Repository

    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.

  6. The viscoelastic effect in bending bucky-gel actuators

    Science.gov (United States)

    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

  7. Bending of light in modified gravity at large distances

    Science.gov (United States)

    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.

  8. 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

  9. On the global ship hull bending energy in ship collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Li, Yujie

    2009-01-01

    of the struck ship hull during ship–ship collisions. The striking ship is still considered as a rigid body. The local interaction between the two ships is modeled by a linear load–deflection relation. The analysis results for a simplified model of a struck coaster and of a large tanker show that the elastic...... is confined to the impact location and where local and global bending vibration modes are neglected. That is, the structural deformation problem is considered quasi-static. In this paper a simple uniform free–free beam model is presented for estimating the energy transported into the global bending vibrations...

  10. On the Global Ship Hull Bending Energy in Ship Collisions

    DEFF Research Database (Denmark)

    Pedersen, Preben Terndrup; Li, Y.

    2004-01-01

    ship hull during ship-ship collisions. The striking ship is still considered as a rigid body. The local interaction between the two ships is modeled by a linear load-deflection relation. The analysis results for a simplified model of a struck coaster and of a large tanker show that the elastic energy...... to the impact location and where local and global bending vibration modes are neglected. That is, the structural deformation problem is considered quasi-static. In this paper a simple uniform free-free beam model is presented for estimating the energy transported into the global bending vibrations of the struck...

  11. 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

  12. 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...

  13. Quasimolecular Dynamic Simulation for Bending Fracture of Laminar Composite Materials

    Institute of Scientific and Technical Information of China (English)

    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

  14. Solution structure of an A-tract DNA bend.

    Science.gov (United States)

    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

  15. Proteomic Analysis of Fruit Bending in Cucumber (Cucumis sativus L.)

    Institute of Scientific and Technical Information of China (English)

    WANG Li-li; ZHANG Peng; QIN Zhi-wei; ZHOU Xiu-yan

    2014-01-01

    In cucumber, fruit shape is an important quality criterion, and fruit bending is known to limit growth, yield, and taste. To investigate the post-transcriptional changes that regulate fruit bending and to better understand the underlying molecular mechanisms, we generated a proteomic proifle of the abdomen and back of cucumber bending fruit. Two-dimensional gel electrophoresis (2-DE) allowed the detection of approximately 900 distinct protein spots in each gel, 32 of which were differentially expressed in the abdomen and back of bending cucumber fruit. Ten of the differentially expressed proteins were analyzed using matrix-assisted laser ionization time of lfight mass spectrometry (MALDI-TOF/MS). A search of primary databases showed that the identiifed proteins are involved in various metabolic processes and cellular responses, including photosynthesis metabolism, energy metabolism, defense and stress response, and regulation. The identiifed proteins included large subunits of ribulose-1,5-bisphosphate carboxylase/oxygenase, which are involved in photosynthesis and photorespiratory metabolism, and isocitrate dehydrogenase, which is involved in the tricarboxylic acid cycle. It is possible that imbalances in catabolic and anabolic processes directly affect the bending of cucumber fruit. The predicted function of the cobalamin-independent methionine synthase isozyme is closely related to ethylene biosynthesis; fruit bending may be regulated by ethylene, or by ethylene signaling crosstalk during fruit development. The 14-3-3 protein is usually considered to be a regulation-related protein, which plays a role in regulating cell hyperplasia, cell differentiation during growth, and apoptosis during senescence. Involvement of guanosine triphosphate (GTP)-binding proteins in signal transmission is known to regulate the development of cells in cucumber fruits and to play a role in fruit shape variation. Patterns of protein expression showed high repeatability. We hypothesize

  16. 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.

  17. Elastostatic bending of a bimaterial plate with a circular interface

    Science.gov (United States)

    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.

  18. 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.

  19. Ductile fracture behavior of 3-inch diameter carbon steel piping with a circumferential through-wall crack under bending load

    International Nuclear Information System (INIS)

    In order to introduce Leak-Before-Break (LBB) concept into the piping design criteria of the LWR pressure boundary pipings, it is necessary to investigate the pipe fracture behaviors, such as fracture condition and crack opening area, etc. At JAERI, pipe fracture tests of stainless steel and STS42 carbon steel pipes under bending load have been conducted as a part of the LBB research program. This report summarizes the four-point bending test results of 3-inch diameter STS42 carbon steel pipe with a circumferential through-wall crack. Tests were carried out at room temperature. In the tests, the fracture behavior of pipes was investigated to evolute the validity of Net-section collapse criterion, J-R curve and crack opening area. It is shown that the Net-section collapse criterion gives a conservative evaluation for the fracture load of 3-inch diameter carbon steel pipes. (author)

  20. Test

    DEFF Research Database (Denmark)

    Bendixen, Carsten

    2014-01-01

    Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers.......Bidrag med en kortfattet, introducerende, perspektiverende og begrebsafklarende fremstilling af begrebet test i det pædagogiske univers....

  1. J-integral in the description of fatigue crack growth rate induced by different ratios of torsion to bending Loading in AlCu4Mg1

    Energy Technology Data Exchange (ETDEWEB)

    Rozumek, D.; Macha, E. [Opole University of Technology, Department of Mechanics and Machine Design, Opole (Poland)

    2009-10-15

    The paper presents the results of tests on fatigue crack growth under proportional torsion with bending in AlCu4Mg1 aluminium alloy. Specimens with rectangular cross-sections and stress concentrator in the form of external one-sided sharp notch were used. The tests were performed under the different ratios of torsion to bending moments. The results of the experimental tests have been described by a nonlinear formula based on {delta}J-integral range. The tests have shown that the change of ratio of torsion to bending moments from 0.58 to 1.73 caused an increase in crack growth rate. It has been shown that at the constant loading and the change of stress ratio (R) from - 1 to 0, the fatigue crack growth rate also increases. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  2. Crack growth rate under cyclic bending in the explosively welded steel/titanium bimetals

    International Nuclear Information System (INIS)

    Highlights: ► The results of the tests on fatigue crack growth in a steel/titanium composite under oscillatory bending. ► Hardness of both joined materials in all their section is higher than hardness of the materials before cladding. ► The main crack propagated in the direction parallel to the loading action and they did not include secondary cracks. ► When the crack growth was being passed along the interface line, decrease of the crack growth rate took place. -- Abstract: The paper presents the results of the tests on fatigue crack growth in a steel/titanium composite under oscillatory bending. Two kinds of specimens of rectangular cross sections were tested. In the tested specimens, the ratio of heights of basic and overlaid materials was h1:h2 = 2.5:1 and 1:1. In the specimens, the fatigue crack growth was parallel to the applied loading and its direction changed at the interface line. Next, the crack growth along the interface line or the crack growth passing through the interface line were observed. When the crack growth passed along the interface line, decrease of the crack growth rate took place. The specimens have the uniform crack growth at both sides of lateral surfaces. At the composite fractures in the steel and titanium, transcrystalline cracks are dominating.

  3. Bending strength model for internal spur gear teeth

    Science.gov (United States)

    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.

  4. Optimization of bandwidth in 60^o photonic crystal waveguide bends

    DEFF Research Database (Denmark)

    Xing, P. F.; Borel, Peter Ingo; Frandsen, Lars Hagedorn;

    2005-01-01

    A systematic scheme utilizing 2D and 3D finite-difference time-domain calculations to design 60^o photonic crystal waveguide bends is presented. The method results in an improved transmission bandwidth from 70 to 160 nm in 2D simulations, and from 50 to 100 nm in 3D simulations. The design...

  5. Secondary flow in sharp open-channel bends

    NARCIS (Netherlands)

    Blanckaert, K.; De Vriend, H.J.

    2004-01-01

    Secondary currents are a characteristic feature of flow in open-channel bends. Besides the classical helical motion (centre-region cell), a weaker and smaller counter-rotating circulation cell (outer-bank cell) is often observed near the outer bank, which is believed to play an important role in ban

  6. 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

  7. Band bending and electrical transport at chemically modified silicon surfaces

    Science.gov (United States)

    Lopinski, Greg; Ward, Tim; Hul'Ko, Oleksa; Boukherroub, Rabah

    2002-03-01

    High resolution electron energy loss spectroscopy (HREELS) and electrical transport measurements have been used to investigate how various chemical modifications give rise to band bending and alter the conductivity of Si(111) surfaces. HREELS is a sensitive probe of band bending through observations of the low frequency free carrier plasmon mode. For hydrogen terminated surfaces, prepared by the standard etch in ammonium flouride, HREELS measurements on both n and n+ substrates are consistent with nearly flat bands. Chlorination of these surfaces results in substantial upward band bending due to the strong electron withdrawing nature of the chlorine, driving the surface into inversion. The presence of this inversion layer on high resistivity n-type samples is observed through a substantial enhancement of the surface conductivity (relative to the H-terminated surface), as well as through broadening of the quasi-elastic peak in the HREELS measurements. We have also begun to examine organically modified silicon surfaces, prepared by various wet chemical reactions with the H-terminated surface. Decyl modified Si(111) surfaces are seen to exhibit a small degree of band bending, attributed to extrinsic defect states cause by a small degree of oxidation accompanying the modification reaction. The prospects of using conductivity as an in-situ monitor of the rate of these reactions will be discussed.

  8. A theoretical model for suspended sediment transport in river bends

    NARCIS (Netherlands)

    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

  9. 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...

  10. Finite element analysis of damage in pipeline bends

    NARCIS (Netherlands)

    Swart, A.E.; Karamanos, S.A.; Scarpas, A.; Blaauwendraad, J.

    2010-01-01

    The present paper describes a numerical formulation for the analysis of damage in steel pipeline bends. In particular, the numerical implementation of Gurson plasticity model is described in the framework of a special element, referred to as “tube element”. This is a three-node element, which simula

  11. Enhanced resolution of long-period grating bend sensor

    DEFF Research Database (Denmark)

    Glavind, Lars; Gao, S; Cook, K;

    2013-01-01

    We present an optical fiber bend sensor with enhanced resolution based on the principle of a Mach-Zehnder interferometer in transmission. The sensor is based on two identical Long-Period Gratings separated by approximately 100 mm in a D-shaped single-mode optical fiber. The sensor provides a narrow...

  12. Multiphase fluid structure interaction in bends and T-joints

    NARCIS (Netherlands)

    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

  13. Size Effects on the Bending Behaviour of Reinforced Concrete Beams

    DEFF Research Database (Denmark)

    Brincker, Rune; Henriksen, M. S.; Christensen, F. A.;

    1999-01-01

    Load-deformation curves for reinforced concrete beams subjected to bending show size effects due to tensile failure of the concrete at early stages in the failure process and due to compression failure of the concrete when the final failure takes place. In this paper these effects are modelled...

  14. The Clinch Bend Regional Industrial Site and economic development opportunities

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-12-31

    This effort focuses initially on the Clinch Bend site. Other sites and developable tracts of land are identified with the assistance of communities in proximity to Oak Ridge, the State of Tennessee, and others, and compared with the projected site requirements for large industrial facilities.

  15. A Second Look at Brian Simon's "Bending the Rules"

    Science.gov (United States)

    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…

  16. Photoacoustic elastic bending in thin film—Substrate system

    Energy Technology Data Exchange (ETDEWEB)

    Todorović, D. M., E-mail: dmtodor@imsi.bg.ac.rs [Institute for Multidisciplinary Research, University of Belgrade, P.O. Box 33, 11030 Belgrade (Serbia); Rabasović, M. D.; Markushev, D. D. [Institute of Physics, University of Belgrade, Pregrevica 118, 11080 Belgrade-Zemun (Serbia)

    2013-12-07

    Theoretical model for optically excited two-layer elastic plate, which includes plasmaelastic, thermoelastic, and thermodiffusion mechanisms, is given in order to study the dependence of the photoacoustic (PA) elastic bending signal on the optical, thermal, and elastic properties of thin film—substrate system. Thin film-semiconductor sample (in our case Silicon) is modeled by simultaneous analysis of the plasma, thermal, and elastic wave equations. Multireflection effects in thin film are included in theoretical model and analyzed. Relations for the amplitude and phase of electronic and thermal elastic bending in the optically excited two-layer mechanically-supported circular plate are derived. Theoretical analysis of the thermodiffusion, plasmaelastic, and thermoelastic effects in a sample-gas-microphone photoacoustic detection configuration is given. Two normalization procedures of the photoacoustic elastic bending signal in function of the modulation frequency of the optical excitation are established. Given theoretical model can be used for various photoacoustic detection configurations, for example, in the study of optical, thermal, and elastic properties of the dielectric-semiconductor or metal-semiconductor structure, etc., Theoretical analysis shows that it is possible to develop new noncontact and nondestructive experimental method—PA elastic bending method for thin film study, with possibility to obtain the optical, thermal, and elastic parameters of the film thinner than 1 μm.

  17. Ultrathin 90-degree sharp bends for spoof surface plasmon polaritons

    DEFF Research Database (Denmark)

    Yang, Yihao; Chen, Hongsheng; Xiao, Sanshui;

    2015-01-01

    surface plasmons around 90-degree sharp bends on ultrathin metallic films in the microwave regime. We demonstrate that by judiciously engineering the structure, the dispersion relation can be designed to reduce the scattering. Furthermore, the reflection can be suppressed by proper structural decoration...

  18. Determination of piezo-optic coefficients of crystals by means of four-point bending.

    Science.gov (United States)

    Krupych, Oleg; Savaryn, Viktoriya; Krupych, Andriy; Klymiv, Ivan; Vlokh, Rostyslav

    2013-06-10

    A technique developed recently for determining piezo-optic coefficients (POCs) of isotropic optical media, which represents a combination of digital imaging laser interferometry and a classical four-point bending method, is generalized and applied to a single-crystalline anisotropic material. The peculiarities of measuring procedures and data processing for the case of optically uniaxial crystals are described in detail. The capabilities of the technique are tested on the example of canonical nonlinear optical crystal LiNbO3. The high precision achieved in determination of the POCs for isotropic and anisotropic materials testifies that the technique should be both versatile and reliable.

  19. Simulation analysis of minimum bending radius for lead frame copper alloys

    OpenAIRE

    Su, Juanhua; Shuguo, Jia; Fengzhang, Ren

    2013-01-01

    Copper alloy has a lot of excellent properties, so it becomes an important alloy for lead frame materials for the integrated circuit. The minimum bending radius of three different copper alloys (Cu-Fe-P, Cu-Ni-Si, Cu-Cr-Sn-Zn) for lead frame materials was analyzed by using finite element. Tensile tests for the three kinds of materials were done to obtain yield stress, ultimate strength and other parameters. The strain-hardening exponent n and normal anisotropy index r of the materials were ob...

  20. Finite element analysis of elasto-plastic plate bending problems using transition rectangular plate elements

    Institute of Scientific and Technical Information of China (English)

    Bahattin Kanber; O.Yavuz Bozkurt

    2006-01-01

    In this work,the finite element analysis of the elasto-plastic plate bending problems is carried out using transition rectangular plate elements.The shape functions of the transition plate elements are derived based on a practical rule.The transition plate elements are all quadrilateral and can be used to obtain efficient finite element models using minimum number of elements.The mesh convergence rates of the models including the transition elements are compared with the regular element models.To verify the developed elements,simple tests are demonstrated and various elasto-plastic problems are solved.Their results are compared with ANSYS results.

  1. A weighted extended B-spline solver for bending and buckling of stiffened plates

    CERN Document Server

    Verschaeve, Joris C G

    2015-01-01

    The weighted extended B-spline method [Hoellig (2003)] is applied to bending and buckling problems of plates with different shapes and stiffener arrangements. The discrete equations are obtained from the energy contributions of the different components constituting the system by means of the Rayleigh-Ritz approach. The pre-buckling or plane stress is computed by means of Airy's stress function. A boundary data extension algorithm for the weighted extended B-spline method is derived in order to solve for inhomogeneous Dirichlet boundary conditions. A series of benchmark tests is performed touching various aspects influencing the accuracy of the method.

  2. A Study On Critical Thinning In Thin-walled Tube Bending Of Al-Alloy 5052O Via Coupled Ductile Fracture Criteria

    Science.gov (United States)

    Li, Heng; Yang, He; Zhan, Mei

    2010-06-01

    Thin-walled tube bending(TWTB) method of Al-alloy tube has attracted wide applications in aerospace, aviation and automobile,etc. While, under in-plane double tensile stress states at the extrados of bending tube, the over-thinning induced ductile fracture is one dominant defect in Al-alloy tube bending. The main objective of this study is to predict the critical wall-thinning of Al-alloy tube bending by coupling two ductile fracture criteria(DFCs) into FE simulation. The DFCs include Continuum Damage Mechanics(CDM)-based model and GTN porous model. Through the uniaxial tensile test of the curved specimen, the basic material properties of the Al-alloy 5052O tube is obtained; via the inverse problem solution, the damage parameters of both the two fracture criteria are interatively determined. Thus the application study of the above DFCs in the TWTB is performed, and the more reasonable one is selected to obtain the critical thinning of Al-alloy tube in bending. The virtual damage initiation and evolution (when and where the ductile fracture occurs) in TWTB are investigated, and the fracture mechanisms of the voided Al-alloy tube in tube bending are consequently discussed.

  3. Ocean acidification bends the mermaid's wineglass.

    Science.gov (United States)

    Newcomb, Laura A; Milazzo, Marco; Hall-Spencer, Jason M; Carrington, Emily

    2015-09-01

    Ocean acidification lowers the saturation state of calcium carbonate, decreasing net calcification and compromising the skeletons of organisms such as corals, molluscs and algae. These calcified structures can protect organisms from predation and improve access to light, nutrients and dispersive currents. While some species (such as urchins, corals and mussels) survive with decreased calcification, they can suffer from inferior mechanical performance. Here, we used cantilever beam theory to test the hypothesis that decreased calcification would impair the mechanical performance of the green alga Acetabularia acetabulum along a CO₂ gradient created by volcanic seeps off Vulcano, Italy. Calcification and mechanical properties declined as calcium carbonate saturation fell; algae at 2283 µatm CO₂ were 32% less calcified, 40% less stiff and 40% droopier. Moreover, calcification was not a linear proxy for mechanical performance; stem stiffness decreased exponentially with reduced calcification. Although calcifying organisms can tolerate high CO₂ conditions, even subtle changes in calcification can cause dramatic changes in skeletal performance, which may in turn affect key biotic and abiotic interactions. PMID:26562936

  4. Experimental and Numerical Analysis of Damage in Woven GFRP Composites Under Large-deflection Bending

    Science.gov (United States)

    Ullah, Himayat; Harland, Andy R.; Silberschmidt, Vadim V.

    2012-10-01

    Textile-reinforced composites such as glass fibre-reinforced polymer (GFRP) used in sports products can be exposed to different in-service conditions such as large bending deformation and multiple impacts. Such loading conditions cause high local stresses and strains, which result in multiple modes of damage and fracture in composite laminates due to their inherent heterogeneity and non-trivial microstructure. In this paper, various damage modes in GFRP laminates are studied using experimental material characterisation, non-destructive micro-structural damage evaluation and numerical simulations. Experimental tests are carried out to characterise the behaviour of these materials under large-deflection bending. To obtain in-plane shear properties of laminates, tensile tests are performed using a full-field strain-measurement digital image correlation technique. X-ray micro computed tomography (Micro CT) is used to investigate internal material damage modes - delamination and cracking. Two-dimensional finite element (FE) models are implemented in the commercial code Abaqus to study the deformation behaviour and damage in GFRP. In these models, multiple layers of bilinear cohesive-zone elements are employed to study the onset and progression of inter-ply delamination and intra-ply fabric fracture of composite laminate, based on the X-ray Micro CT study. The developed numerical models are capable to simulate these features with their mechanisms as well as subsequent mode coupling observed in tests and Micro CT scanning. The obtained results of simulations are in agreement with experimental data.

  5. Bending of Light Near a Star and Gravitational Red/Blue Shift Alternative Explanation Based on Refraction of Light

    CERN Document Server

    Gupta, D R C

    2004-01-01

    Many of the general-relativity-tests such as bending of light near a star and gravitational red/blue shift are explained without general-relativity and without Newtonian-approach. The author first casts doubts on both, the Newtonian and the relativistic approach; and proposes a novel alternative-explanation. The new alternative-explanation is based on refraction-phenomenon of optics. It predicts that as the ray passes through/near the stars atmospheric-medium, it bends due to refraction-phenomenon towards star-core, like a ray bends while passing through a prism or water-drop. A semi-empirical estimation of the atmospheric-height and its refractive-index are made to find the refraction-results. The refraction-based theory also suggests new explanation for gravitational red/blue shift; it tells that frequency remains constant (as it is so in refraction-phenomenon) and the red/blue shift is due to change in wavelength due to change in velocity of light in the medium . Estimated results for bending of light and ...

  6. Membrane-bending constitutive law and perforation criterion for the analysis of reinforced concrete plate structures under soft impact

    International Nuclear Information System (INIS)

    In order to study the protection offered by reinforced concrete shell structures against soft projectiles impacts, we need first to characterize that kind of impact. In this document, we propose a new unified classification of shocks, allowing to distinguish soft and hard impacts. We show that aircraft crash, like every soft impact, produces bending and shear waves, which generate global and local damage: concrete cracking and reinforcement yielding in the whole structure, and possible perforation with a yield cone in the impact area. To model these phenomena we propose two computational tools. The first one is a membrane-bending non linear constitutive law for reinforced concrete slabs. This global model, using resultant variables, can simulate concrete cracking through damage theory and inelastic strains through plasticity theory. The Johansen bending yield criterion is improved to account for membrane effects. This material law has been implemented in Europlexus, an industrial finite element software for fast dynamics, and validated by comparison with experimental tests and other computational models. The second simulation tool is a perforation criterion for reinforced concrete slabs. It is a static criterion depending on bending moment, normal force, and shear force, and derived using limit analysis. We prove that it is possible to predict perforation in case of soft impact, applying this criterion on stress resultant variables coming from a dynamic computation. (author)

  7. T-Cap Pull-Off and Bending Behavior for Stitched Structure

    Science.gov (United States)

    Lovejoy, Andrew E.; Leone, Frank A., Jr.

    2016-01-01

    The Pultruded Rod Stitched Efficient Unitized Structure (PRSEUS) is a structural concept that was developed by The Boeing Company to address the complex structural design aspects associated with a pressurized hybrid wing body aircraft configuration. An important design feature required for assembly is the integrally stitched T-cap, which provides connectivity of the corner (orthogonal) joint between adjacent panels. A series of tests were conducted on T-cap test articles, with and without a rod stiffener penetrating the T-cap web, under tension (pull-off) and bending loads. Three designs were tested, including the baseline design used in largescale test articles. The baseline had only the manufacturing stitch row adjacent to the fillet at the base of the T-cap web. Two new designs added stitching rows to the T-cap web at either 0.5- or 1.0-inch spacing along the height of the web. Testing was conducted at NASA Langley Research Center to determine the behavior of the T-cap region resulting from the applied loading. Results show that stitching arrests the initial delamination failures so that the maximum strength capability exceeds the load at which the initial delaminations develop. However, it was seen that the added web stitching had very little effect on the initial delamination failure load, but actually decreased the initial delamination failure load for tension loading of test articles without a stiffener passing through the web. Additionally, the added web stitching only increased the maximum load capability by between 1% and 12.5%. The presence of the stiffener, however, did increase the initial and maximum loads for both tension and bending loading as compared to the stringerless baseline design. Based on the results of the few samples tested, the additional stitching in the T-cap web showed little advantage over the baseline design in terms of structural failure at the T-cap web/skin junction for the current test articles.

  8. Influence of Additional Tensile Force on Springback of Tube Under Rotary Draw Bending

    Science.gov (United States)

    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.

  9. Torsion testing of bed joints

    DEFF Research Database (Denmark)

    Hansen, Klavs Feilberg; Pedersen, Carsten Mørk

    2008-01-01

    This paper describes a simple test method for determining the torsion strength of a single bed joint between two bricks and presents results from testing using this test method. The setup for the torsion test is well defined, require minimal preparation of the test specimen and the test can...... be carried out directly in a normal testing machine. The torsion strength is believed to be the most important parameter in out-of-plane resistance of masonry walls subjected to bending about an axis perpendicular to the bed joints. The paper also contains a few test results from bending of small walls about...... an axis perpendicular to the bed joints, which indicate the close connection between these results and results from torsion tests. These characteristics make the torsion strength well suited to act as substitute parameter for the bending strength of masonry about an axis perpendicular to the bed joints....

  10. Optimization of Bending Process Parameters for Seamless Tubes Using Taguchi Method and Finite Element Method

    OpenAIRE

    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...

  11. An All-fiber Temperature Sensor Based on a Macro-bend Singlemode Fiber Loop

    OpenAIRE

    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...

  12. Flow behavior and pressure drop of two-phase flow through C-shaped bend in vertical plane, (1)

    International Nuclear Information System (INIS)

    Experimental results are presented on the flow behavior, average void fraction and pressure drop in air-water two-phase flow mixture flowing upward through a C-shaped bend curved in vertical plane. The curved test section of transparent acrylic resin tubing was varied in four versions of (a) 90 mm, (b) 132.5 mm and (c) 180 mm radii of curvature with 16 mm inside diameter tube, and (d) 135 radius with 24 mm diameter tube. The combined action of gravity and centrifugal force acting on the two-phase flow is expressed in terms of a modified Froude number representing the balance of radial forces between those acting on the liquid and the gaseous phases of the flow passing through the reclined vertical U-bend. The average void fraction in the curved test section was determined, and empirically correlated to the pressure drop, by means of a series of nondimensional numbers. (author)

  13. Bending characteristic of a cantilevered magnetostrictive film-substrate system

    Institute of Scientific and Technical Information of China (English)

    B.; Narsu

    2007-01-01

    The bending problem of a film-substrate cantilever with arbitrary film-to-substrate thickness ratio is solved exactly by employing the force equilibrium equation, and then the optimization and application of the bending characteristic of the magne-tostrictive cantilever is discussed. Furthermore, the influence of geometrical and physical parameters of the two cantilever components on the maximum free-end deflection of the cantilever is addressed. The results indicate that as the substrate thickness is kept constant, the greater film-to-substrate stiffness ratio will induce a larger deflection, while for the case of fixed total cantilever thickness, the optimal cantilever deflection is independent of the physical parameters of the materials such as Young’s modulus and Poisson’s ratio.

  14. Bending characteristic of a cantilevered magnetostrictive film-substrate system

    Institute of Scientific and Technical Information of China (English)

    B. Narsu; YUN GuoHong

    2007-01-01

    The bending problem of a film-substrate cantilever with arbitrary film-to-substrate thickness ratio is solved exactly by employing the force equilibrium equation, and then the optimization and application of the bending characteristic of the magnetostrictive cantilever is discussed. Furthermore, the influence of geometrical and physical parameters of the two cantilever components on the maximum free-end deflection of the cantilever is addressed. The results indicate that as the substrate thickness is kept constant, the greater film-to-substrate stiffness ratio will induce a larger deflection, while for the case of fixed total cantilever thickness, the optimal cantilever deflection is independent of the physical parameters of the materials such as Young's modulus and Poisson's ratio.

  15. 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.

  16. 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

  17. 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

  18. Plastic Optical Fiber Displacement Sensor Based on Dual Cycling Bending

    Directory of Open Access Journals (Sweden)

    Yung-Chuan Chen

    2010-11-01

    Full Text Available In this study, a high sensitivity and easy fabricated plastic optical fiber (POF displacement sensor is proposed. A POF specimen subjected to dual cyclic bending is used to improve the sensitivity of the POF displacement sensor. The effects of interval between rollers, relative displacement and number of rollers on the sensitivity of the displacement sensor are analyzed both experimentally and numerically. A good agreement between the experimental measurements and numerical calculations is obtained. The results show that the interval between rollers affects sensitivity most significantly than the other design parameters. Based on the experimental data, a linear equation is derived to estimate the relationship between the power loss and the relative displacement. The difference between the estimated results and the experimental results is found to be less than 8%. The results also show that the proposed POF displacement sensor based on dual cyclic bending can be used to detect displacement accurately.

  19. 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.

  20. 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.

  1. Elastoswellability: Will it bend or will it buckle?

    Science.gov (United States)

    Holmes, Douglas; Pandey, Anupam

    2013-03-01

    Soft mechanical structures such as biological tissues and gels exhibit motion, instabilities, and large morphological changes when subjected to external stimuli. Swelling is a robust approach for inducing structural change as it occurs naturally in humid environments and can be easily adapted for industrial design. Small volumes of fluid that interact favorably with a material can cause large, dramatic, and geometrically nonlinear deformations including beam bending, plate buckling, and surface wrinkling. In this talk we address an overarching question regarding swelling-induced deformations: will the structural change occur globally, or will it be confined to the material's surface? We introduce a materials and geometry defined transition point that describes a fluid-structure's characteristic ``elastoswellability'' lengthscale. By locally swelling unconstrained slender beams and plates with solvents of varying solubility, we identify a transition between local surface wrinkling and global structural bending.

  2. Effect of Accelerated Global Expansion on Bending of Light

    CERN Document Server

    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 $H(t)$.

  3. Transfer matrices of dipoles with bending radius variation

    Institute of Scientific and Technical Information of China (English)

    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.

  4. 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.

  5. 14 CFR 33.43 - Vibration test.

    Science.gov (United States)

    2010-01-01

    ... Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION AIRCRAFT AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES Block Tests; Reciprocating Aircraft Engines § 33.43 Vibration test. (a) Each engine must undergo a vibration survey to establish the torsional and bending vibration...

  6. Effect of bending on anodized Ti6Al4V alloy: I. Surface layers characteristics

    Directory of Open Access Journals (Sweden)

    A. Kierzkowska

    2006-08-01

    Full Text Available Purpose: The plastic deformation behaviour of the anodized binary titanium alloy Ti6Al4V was characterizedin mechanical and electrochemical tests.Design/methodology/approach: The effect of tensile and compressive stresses on properties of differentclinically relevant surfaces of the deformed by bending implant rods was investigated. The deformationbehaviour was characterized by FEM analysis. Relevant surfaces in tensile and compressive zones werecharacteristics by microhardness and roughness measurements, and electrochemical testing (Ecor, anodicpolarization, EIS in oxygen-saturated Ringer’s solution.Findings: It was concluded that bending influenced mostly the properties of material in the tensile zone of thespecimen, whereas the properties of surface layer in the compressive zone and the properties of surface layer intensile zone after rebending are comparable and not so severe.Research limitations/implications: Studies were performed in static conditions, fatique studies are planned inthe future.Practical implications: Results are of great importance in for surgical practice in the in the evaluation of theinfluence of shaping process applied during pre-operative procedures on the performance of spinal implantsystems.Originality/value: In the paper a typical pre-operative procedure of shaping was applied to anodized titaniumimplants in order to evaluate its influence on the characteristics of the surface layer. Studies were focused onthe safety their application in vivo.

  7. Fatigue Crack Propagation in Steel A131 Under Ice Loading of Crushing, Bending and Buckling

    Institute of Scientific and Technical Information of China (English)

    DUAN Menglan(段梦兰); SONG Lisong(宋立崧); FAN Xiaodong(樊晓东); James C.M.LId; FANG Huacan(方华灿)

    2001-01-01

    Three types of ice loading, which are most commonly present when ice acts on structures,are chosen and simulated for use of fatigue crack propagation tests on offshore structural steel Al31. The three types of ice categorized in accordance with the failure modes when acting on structures called crushing ice, bending ice, and buckling ice,respectively. This paper presents an experimental investigation on the fatigue crack propagation behavior of widely used high strength steel A 131 for offshore jackets in the loading environment of ice crushing, bending, and buckling. The test results of fatigue crack propagation in steel A 13 l under these simulated ice loading at temperature 292K are presented and analyzed in detail in this paper. The amplitude root mean square stress intensity factor is optimized to be the fundamental parameter of fatigue crack propagation for all types of ice loading histories. The results are also compared with constant amplitude fatigue crack propagation conclusions as in wave load mode, and a joint investigation on the results from ice forces, ice-induced vibrations, and ice-induced fatigue crack propagation is conducted, Conclusions are drawn for reference in structural design and material selection for offshore structures in ice environments.

  8. Rotary-bending fatigue characteristics of medical-grade Nitinol wire.

    Science.gov (United States)

    Pelton, A R; Fino-Decker, J; Vien, L; Bonsignore, C; Saffari, P; Launey, M; Mitchell, M R

    2013-11-01

    The rotary bending fatigue properties of medical-grade Nitinol wires were investigated under conditions of 0.5-10% strain amplitudes to a maximum of 10(7) cycles. The results from this study provide insight into the behavior of Nitinol under fully reversed (εmin/εmax=-1) fatigue conditions for three compositions, two surface conditions and three test temperatures. For pseudoelastic conditions there are four distinct regions of the strain-cycle curves that are related to phases (austenite, stress-induced martensite, and R-Phase) and their respective strain accommodation mechanisms. In contrast, there are only two regions for the strain-cycle curves for thermal martensite. It was further observed that the strain amplitude to achieve 10(7)-cycles increases with both decreasing test temperature and increasing transformation temperature. Fatigue behavior was not, however, strongly influenced by wire surface condition. SEM of the fracture surfaces showed that the fatigue fracture area increased with decreasing strain amplitude. Finite element analysis was used to illustrate strain distributions across the wire as well as to calculate the tension-compression contributions to the rotary bending curves. The results from this investigation are discussed with respect to mechanisms of strain accommodation under cyclic tensile and compressive conditions.

  9. Residual stress evaluation in brittle coatings using indentation technique combined with in-situ bending

    International Nuclear Information System (INIS)

    The indentation crack length approach was adopted and further elaborated to evaluate residual stress and toughness of the brittle coatings: two kinds of glass coatings on steel. The influence of the residual stress on indentation cracking was examined in as-received coating condition and by in-situ superimposing a counteracting tensile stress. For purpose of providing reference toughness values stress-free pieces of separated coating material have also been examined. Thus results of the two complementary sets of experiments were assumed to prove self-consistently toughness and residual stress data of the coating. In particular, the in-situ bending of specimen in combination with the indentation test allowed us to vary deliberately the residual stress situation in glass coating. Thus experiments which utilized the combination of bending test and micro-indentation were introduced as a method to provide unambiguous information about residual compressive stress. Toughness and residual compressive stress of glass coatings used in this study were 0.46-0.50 MPa·m1/2 and 94-111 MPa, respectively. Furthermore, a thermoelastic calculation of the residual compressive stress was performed and it is found that the value of residual compressive stress at coating surface of specimen was 90-102 MPa. (author)

  10. A new set of bending Td symmetry coordinates for MX4 molecules.

    Science.gov (United States)

    Schmidling, David

    2013-12-15

    The conventional set of Td symmetry coordinates for the bending modes of MX4 molecules can lead to ambiguous geometries when displacements from equilibrium are large. It is proposed here to use internal coordinates that are haversines of the bending angles divided by their sum. The A1 representation becomes a constant, enabling recovery of the bending angles unambiguously, analytically, and without approximation.

  11. Requirements for Bend Insensitive Fiber in Millimeter-Wave Fronthaul Systems

    DEFF Research Database (Denmark)

    Rommel, Simon; Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José;

    2015-01-01

    The impact of fiber bending on mm-wave radioover-fiber transmission is investigated and the need for bend insensitive fiber for front-haul installation confirmed. A 70m Wband hybrid photonic-wireless link including bend insensitive fiber is demonstrated with BER

  12. Bending fatigue and its evaluation of ropes used in equipment for recovery of rare metals from seawater

    Energy Technology Data Exchange (ETDEWEB)

    Tamada, Masao; Kasai, Noboru; Seko, Noriaki; Hasegawa, Shin; Takeda, Hayato; Katakai, Akio; Sugo, Takanobu [Takasaki Radiation Chemistry Research Establishment, Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan)

    2000-12-01

    Recovery experiment of rare metals such as vanadium and uranium in seawater was carried out in the offing of Mutsu-works to evaluate the performance of the adsorbent which was synthesized by radiation induced graft-polymerization. In September 1999, we set equipment for dipping 100 kg adsorbents into seawater and instruments for selective elution of adsorbed metal. The present report clarified the primary factor which cuts a cushion-buoy-mounting-rope (CBMR) of the equipment for the recovery of the significant metals from seawater after 7 months' experiment, and then described its countermeasure. The CBMR plays the role installing the cushion buoy onto the horizontal rope in the sea. There are two CBMRs for each buoy and totally 16. Four cases of the cutting occurred in the cushion buoys placed outside. These cushion buoys have been installed in September, 1999, and it already passed through 7 months until the rope-cutting accident. Horizontal swings and rotation motions with a short period were observed especially in the cushion buoy placed outside. Therefore, the CBMR was cut by the unexpected bending fatigue which was caused by these bending and twist with the small angle. Fatigue estimation was equivalent for the cutting level when strength was calculated by considering bending fatigue in addition to the tension fatigue of the CBMR. The present polyethylene CBMRs were replaced by the nylon ones having excellent characteristic against bending fatigue. lt was calculated that tension and bending fatigue strength of the nylon CBMR were enough to maintain its strength during the test period for 2 years. (author)

  13. Wooden models of an AA quadrupole between bending magnets

    CERN Multimedia

    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.

  14. Bending rigid molecular rods: formation of oligoproline macrocycles.

    Science.gov (United States)

    Scully, Conor C G; Rai, Vishal; Poda, Gennadiy; Zaretsky, Serge; Burns, Darcy C; Houliston, R Scott; Lou, Tiantong; Yudin, Andrei K

    2012-12-01

    Bent but not broken: cyclic oligoprolines are accessed in a reaction that effectively bends rigid oligoproline peptides (see scheme; TBDMS=tert-butyldimethylsilyl). The stitching is accomplished during macrocyclization enabled by aziridine aldehydes and isocyanides. Molecular modeling studies suggest that electrostatic attraction between the termini of the linear peptide is pivotal for macrocyclization. The macrocycles were studied by circular dichroism with a polyproline II structure being observed in larger macrocycles.

  15. Influence of Whipping on Long term Vertical Bending Moment

    DEFF Research Database (Denmark)

    Baarholm, G. S.; Jensen, Jørgen Juncher

    2004-01-01

    This paper is concerned with estimating the response value corresponding to a long return period, say a twenty years. Time domain simulation is required to obtain the nonlinear response, and long time series are required to limit the statistical uncertainty in the simulations. It is crucial to in......). Results are presented for the S-175 container ship, (15th & 16th ITTC Seakeeping Committee 1983). The analysis shoes that whipping increases the vertical bending moment and that the correlation is significant...

  16. Bending and Deformation of Sandwich Panels Due to Localized Pressure

    OpenAIRE

    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...

  17. Predicting the static bending behavior of pallets with panel decks

    OpenAIRE

    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...

  18. Bending and compressive behaviours of a new cement composite

    OpenAIRE

    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...

  19. Bending resistance of composite steel truss and concrete beam

    OpenAIRE

    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...

  20. BENDING ANALYSIS OF COMPOSITE PLATES USING HIGHER ORDER THEORY

    OpenAIRE

    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...

  1. How two-dimensional bending can extraordinarily stiffen thin sheets

    Science.gov (United States)

    Pini, V.; Ruz, J. J.; Kosaka, P. M.; Malvar, O.; Calleja, M.; Tamayo, J.

    2016-07-01

    Curved thin sheets are ubiquitously found in nature and manmade structures from macro- to nanoscale. Within the framework of classical thin plate theory, the stiffness of thin sheets is independent of its bending state for small deflections. This assumption, however, goes against intuition. Simple experiments with a cantilever sheet made of paper show that the cantilever stiffness largely increases with small amounts of transversal curvature. We here demonstrate by using simple geometric arguments that thin sheets subject to two-dimensional bending necessarily develop internal stresses. The coupling between the internal stresses and the bending moments can increase the stiffness of the plate by several times. We develop a theory that describes the stiffness of curved thin sheets with simple equations in terms of the longitudinal and transversal curvatures. The theory predicts experimental results with a macroscopic cantilever sheet as well as numerical simulations by the finite element method. The results shed new light on plant and insect wing biomechanics and provide an easy route to engineer micro- and nanomechanical structures based on thin materials with extraordinary stiffness tunability.

  2. 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.

  3. 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.)

  4. Optimal Recursive Digital Filters for Active Bending Stabilization

    Science.gov (United States)

    Orr, Jeb S.

    2013-01-01

    In the design of flight control systems for large flexible boosters, it is common practice to utilize active feedback control of the first lateral structural bending mode so as to suppress transients and reduce gust loading. Typically, active stabilization or phase stabilization is achieved by carefully shaping the loop transfer function in the frequency domain via the use of compensating filters combined with the frequency response characteristics of the nozzle/actuator system. In this paper we present a new approach for parameterizing and determining optimal low-order recursive linear digital filters so as to satisfy phase shaping constraints for bending and sloshing dynamics while simultaneously maximizing attenuation in other frequency bands of interest, e.g. near higher frequency parasitic structural modes. By parameterizing the filter directly in the z-plane with certain restrictions, the search space of candidate filter designs that satisfy the constraints is restricted to stable, minimum phase recursive low-pass filters with well-conditioned coefficients. Combined with optimal output feedback blending from multiple rate gyros, the present approach enables rapid and robust parametrization of autopilot bending filters to attain flight control performance objectives. Numerical results are presented that illustrate the application of the present technique to the development of rate gyro filters for an exploration-class multi-engined space launch vehicle.

  5. Bending instability in galactic discs. Advocacy of the linear theory

    CERN Document Server

    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.

  6. 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.

  7. 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.

  8. Bending light on demand by holographic sculpturing its wavefront

    CERN Document Server

    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 ...

  9. Bending-induced symmetry breaking of lithiation in germanium nanowires.

    Science.gov (United States)

    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

  10. Electro-active material (EAM) based bend sensors

    Science.gov (United States)

    LaComb, Ronald; LaComb, Julie

    2010-04-01

    The capability to accurately estimate strain and orientation of cables in an undersea environment is important for a multitude of applications. One way to estimate the positional location of a submersed cable is to utilize a network of distributed bend sensors providing inputs to a curve fitting algorithm. In this work commercially available bend sensors are characterized for small deflections. In addition proto-type devices are presented which can potentially improve device sensitivity. Commercially available bend sensors are based upon electro-active materials and variable resistance materials. Electro-active materials (EAM) are known for their actuator functionality but certain EAMs are capable of sensing as well. New advances in materials such as Ionic Polymer Metal Composites (IPMC) are proving suitable for quasi-static sensor applications. These sensors are low power, conformal and produce directionally dependent output voltages which are linearly proportional to deflection, with voltage polarity representative of the deflection direction. IPMCs are capable of being morphed for increased sensitivity. Variable resistivity sensors are based on smart epoxy polymer and carbon loaded inks. These sensors are inexpensive and conformal and unlike EAMs provide static measurements.

  11. Bending and fracture toughness of woven self-reinforced composite poly(methyl methacrylate).

    Science.gov (United States)

    Wright, D D; Lautenschlager, E P; Gilbert, J L

    1997-09-15

    Loosening remains an impediment to the long-term success of total hip replacements despite numerous improvements in the materials used. In cemented prostheses, fatigue and fracture of bone cement have been implicated in the failure of these devices. A new material, self-reinforced composite poly(methyl methacrylate). (SRC-PMMA), has been developed. SRC-PMMA is formed by a novel processing method that will be described. The composite consists of high strength, highly oriented PMMA fibers embedded in a matrix of PMMA. Using a woven form of SRC-PMMA, an in vitro physical and mechanical evaluation was performed to assess the feasibility of its use in an orthopedic prosthesis. Three different weaves of SRC-PMMA were evaluated in bending and fracture toughness in air, after immersion for 30 days in 37 degrees C saline, and after gamma irradiation followed by immersion. Bending modulus and strength were decreased by gamma irradiation followed by saline immersion. The effect of saline immersion alone on bending strength and modulus was negligible. Saline immersion and gamma irradiation followed by saline immersion was shown to have little or no effect on the fracture toughness of woven SRC-PMMA. Differences in the fracture processes of the different weaves were found and can be related to the differing orientation of fibers to the fracture toughness pre-crack. Optimally incorporated SRC-PMMA absorbs the same amount of water as bone cement. Comparison to previous and current work with bone cement controls shows that SRC-PMMA is a material equal to or better than bone cement in all tests performed. It deserves further consideration as a candidate biomaterial. PMID:9294760

  12. Bending elasticity of charged surfactant layers: the effect of mixing.

    Science.gov (United States)

    Bergström, L Magnus

    2006-08-01

    Expressions have been derived from which the spontaneous curvature (H(0)), bending rigidity (k(c)), and saddle-splay constant (k(c)) of mixed monolayers and bilayers may be calculated from molecular and solution properties as well as experimentally available quantities such as the macroscopic hydrophobic-hydrophilic interfacial tension. Three different cases of binary surfactant mixtures have been treated in detail: (i) mixtures of an ionic and a nonionic surfactant, (ii) mixtures of two oppositely charged surfactants, and (iii) mixtures of two ionic surfactants with identical headgroups but different tail volumes. It is demonstrated that k(c)H(0), k(c), and k(c) for mixtures of surfactants with flexible tails may be subdivided into one contribution that is due to bending properties of an infinitely thin surface as calculated from the Poisson-Boltzmann mean field theory and one contribution appearing as a result of the surfactant film having a finite thickness with the surface of charge located somewhat outside the hydrophobic-hydrophilic interface. As a matter of fact, the picture becomes completely different as finite layer thickness effects are taken into account, and as a result, the spontaneous curvature is extensively lowered whereas the bending rigidity is raised. Furthermore, an additional contribution to k(c) is present for surfactant mixtures but is absent for k(c)H(0) and k(c). This contribution appears as a consequence of the minimization of the free energy with respect to the composition of a surfactant layer that is open in the thermodynamic sense and must always be negative (i.e., k(c) is generally found to be brought down by the process of mixing two or more surfactants). The magnitude of the reduction of k(c) increases with increasing asymmetry between two surfactants with respect to headgroup charge number and tail volume. As a consequence, the bending rigidity assumes the lowest values for layers formed in mixtures of two oppositely charged

  13. Effect of Bend Curvature Ratio on Flow Pattern at a Mixing Tee after a 90 Degree Bend

    Directory of Open Access Journals (Sweden)

    Hidetoshi Hashizumeh

    2009-11-01

    Full Text Available Many nuclear power plants report high cycle thermal fatigue in their cooling system, caused by temperature fluctuation in a non-isothermal mixing area. One of these areas is the T-junction, in which fluids of various temperatures and velocities blend. The objective of this research is to classify turbulent jet mechanics in order to examine the flow-field structure under various operating conditions. Furthermore, this research discovers the optimum operating conditions of the mixing tee in this piping system. An experimental model, including the T-junction with a 90 degree bend upstream, is operated to analyze this mixing phenomenon based on the real operation design of the Phenix Reactor. The temperature and velocity data show that a 90 degree bend has a strong effect on the fluid mixing mechanism and the momentum ratio between the main velocity and the branch velocity of the T-junction, which could be an important parameter for the classification of the fluid mixing mechanism. By comparing their mean velocity distributions, velocity fluctuations and time-series data, the behavior of the branch jet is categorized into four types of turbulent jets; sorted from the highest to the lowest momentum ratios, the jets are categorized as follows: the wall jet, the re-attached jet, the turn jet, and the impinging jet. Ultimately, the momentum ration of the turn jet was selected as the optimum operating condition as it has the lowest velocity and the lowest temperature fluctuations near the wall of the mixing tee. By changing the bending ratio from 1.41 to 1.0 the results show that most of data are in the turn jet region. Therefore, with the sharpened bend, the re-attached region is compressed.

  14. 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.

  15. In situ transmission electron microscopy of individual carbon nanotetrahedron/ribbon structures in bending

    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.

  16. 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.

  17. Fatigue Debond Growth in Sandwich Structures Loaded in Mixed Mode Bending (MMB)

    DEFF Research Database (Denmark)

    Quispitupa, Amilcar; Berggreen, Christian; Carlsson, Leif A.

    2008-01-01

    Static and cyclic debond growth in sandwich specimens loaded in mixed mode bending (MMB) is examined. The MMB sandwich specimens were manufactured using H100 PVC foam core and E-glass/polyester non-crimp quadro-axial [0/45/90/-45]s DBLT-850 face sheets. Static test were performed to determine...... tests were performed at 90% of the static fracture toughness at a loading ratio of R=0.1. Fatigue results revealed higher debond crack growth rates when the lever arm distance was increased. For some specimens, the crack propagated just below the face/core interface in the foam core and for others...... the crack kinked into the face sheet....

  18. SPRINGBACK SIMULATION AND ANALYSIS OF STRONG ANISOTROPIC SHEET METALS IN U-CHANNEL BENDING PROCESS

    Institute of Scientific and Technical Information of China (English)

    柳玉起; 胡平; 王锦程

    2002-01-01

    The springback phenomenon of strong anisotropic sheet metals with U-channel bending as well as deep-drawing is numerically studied in detail by using Updating Lagrange FEM based on virtual work-rate principle, Kirchhoff shell element models and the Barlat-Lian planar anisotropic yield function. Simulation results are compared with a benchmark test. Very good agreement is obtained between numerical and test results. The focus of the present study is on the numerical simulation of the springback characteristics of the strong anisotropic sheet metals after unloading.The effects of the planar anisotropy coefficients and yield function exponent in the B-L yield function on the springback characteristics are discussed in detail. Some conclusions are given.

  19. The effect of kinesio taping in forward bending of the lumbar spine.

    Science.gov (United States)

    Lemos, Thiago Vilela; Albino, Anna Carolina Gonçalves; Matheus, Joao Paulo C; Barbosa, Aurélio de Melo

    2014-09-01

    [Purpose] The aim of this study was to evaluate the influence of a lumbar fascia Kinesio Taping(®) technique forward bending range of motion. [Subjects and Methods] This was a longitudinal study with a randomized clinical trial composed of 39 subjects divided into three groups (control, Kinesio Without Tension-KWT, and Kinesio Fascia Correction-KFC). The subjects were assessed by Schober and fingertip-to-floor tests and left the tape in place for 48 hours before being reassessed 24 hours, 48 hours and 30 days after its removal. [Results] In all three experimental groups no significant differences were observed with the Schober test, but it was possible to observe an increase in lumbar flexion after 30 days. With the fingertip-to-floor distance assessment, the KFC and KWT groups showed significantly improved flexibility 24 hours and 48 hours after tape removal. [Conclusion] The Kinesio Taping(®) influenced fascia mobility, allowing for slight improvement of lumbar flexibility.

  20. Effect of Heat Treatment upon Dimensional Stability and Static Bending Strength of Sessile Oak Wood

    Directory of Open Access Journals (Sweden)

    Alin OLARESCU

    2011-06-01

    Full Text Available The paper presents the results of an experimentalstudy performed with sessile oak wood (Quercuspetrea L.. After drying and conditioning at 12%MC,the test pieces were heat-treated at three differenthigh temperatures (120, 130 and 140°C for 1h, 2hand 3h. After the treatment and cooling, standardsamples for physical and mechanical tests were cut,in order to determine comparatively the density, thedimensional stability, the static bending strength andMOE of the differently treated samples.Based on the obtained results, the optimumtreatment schedule was established, namely the onewhich enables improved dimensional stability withoutaffecting significantly the wood strength. Theseresults can be applied at the manufacturing of solidwood panels with improved dimensional stabilityusing heat-treated wood lamellas.