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Results for “BENDING”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
DOE OSTI2021

A 90 ° bend curved light-guide for TOF scintillating detectors

We report here a bench study of TOF resolution using a 90° bend curved solid light-guide (LG) used to transport the light from a plastic scintillator counter to a photomultiplier (PMT). The 90° LG allows the rotation of the PMT axis to be vertical to the detector axis, in an environment featured by a strong magnetic field along the detector surface, or other geometrical constrains. We show that with a TOF counter of 2000 x 100 x 60 mm 3 and light read-out by PMTs at its two 100 × 60 mm 2 sides, when 90° LG benders are used between the scintillating bar and the PMTs on both sides, the TOF resolution is worsen, by 5–10%.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2024

Effect of layer bending on montmorillonite hydration and structure from molecular simulation

Conceptual models of smectite hydration include planar (flat) clay layers that undergo stepwise expansion as successive monolayers of water molecules fill the interlayer regions. However, X-ray diffraction (XRD) studies indicate the presence of interstratified hydration states, suggesting non-uniform interlayer hydration in smectites. Additionally, recent theoretical studies have shown that clay layers can adopt bent configurations over nanometer-scale lateral dimensions with minimal effect on mechanical properties. Therefore, in this study we used molecular simulations to evaluate structural properties and water adsorption isotherms for montmorillonite models composed of bent clay layers in mixed hydration states. Results are compared with models consisting of planar clay layers with interstratified hydration states (e.g. 1W–2W). The small degree of bending in these models (up to 1.5 Å of vertical displacement over a 1.3 nm lateral dimension) had little or no effect on bond lengths and angle distributions within the clay layers. Except for models that included dry states, porosities and simulated water adsorption isotherms were nearly identical for bent or flat clay layers with the same averaged layer spacing. Similar agreement was seen with Na- and Ca-exchanged clays. In conclusion, while the small bent models did not retain their configurations during unconstrained molecular dynamics simulation with flexible clay layers, we show that bent structures are stable at much larger length scales by simulating a 41.6×7.1 nm 2 system that included dehydrated and hydrated regions in the same interlayer.

58 GEOSCIENCES↗
DOE OSTI2014

Dielectrophoretic bending of directly printed free-standing ultra-soft nanowires

Electrohydrodynamic printing has shown superior resolution compared to conventional ink-jet printing, but the use of electrically charged liquid commonly leads to unwanted repulsion effects posing a threshold to resolution capabilities. However, a recently demonstrated controlled dripping process of nanoscale, particle-laden droplets, could circumvent such resolution obstacles even on insulating substrates. Here, we show that so-printed free-standing nanostructures can be autonomously deformed, and mechanically characterized due to the presence of the electrified nozzle, or, after voltage termination, due to transient charge residuals on the structures themselves. Dielectrophoretic forces, arising between two subsequently printed nanopillars lead to their contactless bending and to the formation of out-of-plane arc structures arising from the connection of the pillar apexes. Once connected, the ultra-soft nanopillars are found to be tightly merged and could, for example, serve in electronics as out of plane nanobonds.

77 NANOSCIENCE AND NANOTECHNOLOGY↗
DOE OSTI2014

Experimental and numerical analysis of pre-compressed masonry walls in two-way-bending with second order effects

The buckling behavior of slender unreinforced masonry (URM) walls subjected to axial compression and out-of-plane lateral loads is investigated through a combined experimental and numerical homogenizedapproach. After a preliminary analysis performed on a unit cell meshed by means of elastic FEs and non-linear interfaces, macroscopic moment-curvature diagrams so obtained are implemented at a structural level, discretizing masonry by means of rigid triangular elements and non-linear interfaces. The non-linear incremental response of the structure is accounted for a specific quadratic programming routine. In parallel, a wide experimental campaign is conducted on walls in two way bending, with the double aim of both validating the numerical model and investigating the behavior of walls that may not be reduced to simple cantilevers or simply supported beams. Panels investigated are dry-joint in scale square walls simply supported at the base and on a vertical edge, exhibiting the classical Rondelet’s mechanism. The results obtained are compared with those provided by the numerical model.

42 ENGINEERING↗
DOE OSTI2015

Dynamic hysteretic sensing model of bending-mode Galfenol transducer

A dynamic hysteretic sensing model has been developed to predict the dynamic responses of the magnetic induction, the stress, and the output voltage for a bending-mode Galfenol unimorph transducer subjected simultaneously to acceleration and bias magnetic field. This model is obtained by coupling the hysteretic Armstrong model and the structural dynamic model of the Galfenol unimorph beam. The structural dynamic model of the beam is founded based on the Euler-Bernouli beam theory, the nonlinear constitutive equations, and the Faraday law of electromagnetic induction. Comparisons between the calculated and measured results show the model can describe dynamic nonlinear voltage characteristics of the device, and can predict hysteretic behaviors between the magnetic induction and the stress. Moreover, the model can effectively analyze the effects of the bias magnetic field, the acceleration amplitude, and frequency on the root mean square voltage of the device.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Fuzzy analysis of serviceability limit state of slender steel beam under bending

In the present paper, deformations of a beam under equal end moments solved with influence of lateral buckling are studied. It has been found by numerical studies that the lateral deflection of slender beam under major axis bending can be relatively high.The acceptability of high values of lateral deflections within the framework of serviceability limit state is discussed. In the next part of the paper, the limit value of maximum deflection was introduced as a fuzzy number. The fuzzy analysis of the maximum moment which causes the maximum deflection was carried out. The slendernesses of beams for which the serviceability limit state is the limiting state for design were identified.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

Electron microscopic investigation of crystal lattice bending-torsion and internal stresses in deformed polycrystalline alloys

Generalization of the results of electron microscopy investigations of the crystal lattice bending-torsion (χ) and the internal stresses (IS) was conducted. The deformed polycrystalline alloys and steels were investigated. The sources of χ and IS origin were established. The regularities of their change with the distance from the sources and the evolution with deformation were revealed. The contribution of IS into the deformation resistance was determined. The nature of formation of two sequences of dislocation substructure transformations during deformation of alloys was established.

36 MATERIALS SCIENCE↗
DOE OSTI2016

Sensitivity analysis of static resistance of slender beam under bending

The paper deals with statical and sensitivity analyses of resistance of simply supported I-beams under bending. The resistance was solved by geometrically nonlinear finite element method in the programme Ansys. The beams are modelled with initial geometrical imperfections following the first eigenmode of buckling. Imperfections were, together with geometrical characteristics of cross section, and material characteristics of steel, considered as random quantities. The method Latin Hypercube Sampling was applied to evaluate statistical and sensitivity resistance analyses.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2016

Bending of I-beam with the transvers shear effect included – FEM calculated

The paper is devoted to three-point bending of an I-beam with include of transvers shear effect. Numerical calculations were conducted independently with the use of the SolidWorks system and the multi-purpose software package ANSYS The results of FEM study conducted with the use of two systems were compared and presented in tables and figures.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2020

High precision magnetic field measurement and mapping of the LEReC 180 degree bending magnet using very low field NMR with hall combined probe (140 - 350 gauss)

The Relativistic Heavy Ion Collider (RHIC) at BNL are using the Low Energy RHIC Electron Cooling (LEReC) to conduct experiments that search for the quantum chromodynamic (QCD) critical point. The first ever electron cooling based on the RF acceleration of electron beams was experimentally demonstrated on April 5, 2019 at LEReC at BNL. The first critical step in obtaining successful 3D non-magnetized cooling of the Au ion bunches in the RHIC cooling section was matching the electron beam energy with a relative error less than 5*10 -4 to the ion beam energy. Part of the LEReC beamline is a dipole magnet that bends the electron beam 180 degree. One of the most outstanding measurement challenges is that the dipole field is so low (≈200 G). Most of the existing NMR probes can only measure fields >400 G. Lower signal-to-noise ratio at low fields is requires the use of larger sample volumes. Working with CAYLAR, a NMR probe has been redesigned and optimized for these low field measurements with high resolution. We report the methods, challenges, and results for extensive magnetic field mappings of the 180 dipole magnet. A combination of NMR and Hall sensors has been successfully implemented to measure uniform field regimes inside the magnet center area and non-uniform field regimes at the magnet ends. Detailed measurement and mapping have been performed at five radii and five heights along the beam trajectory. Meanwhile a finite element magnetic modeling simulation of the magnet using Opera software has been performed. The calculated and measured data are compared, and the calculated data is good reference for measured data over long length mapping from magnet edge to center. The measured magnetic measurement data is directly useful for beam instrumentation, diagnostics and operation.

Magnetic Field Measurement↗
DOE OSTI2021

Small-sized specimen design with the provision for high-frequency bending-fatigue testing

The testing and study of emerging materials—such as additively manufactured materials—demands for specimen designs that are cost effective and time saving. Here the design of a small-sized bending-fatigue test specimen for an ultrasonic fatigue testing system is reported in this paper. The design is optimized based on the finite element analysis and analytical-solution results to achieve the proper vibration shape and stress distribution. The proposed design is evaluated in the high- and very-high-cycle fatigue regimes under 20-kHz frequency. Both simulation and testing results confirm that the desirable vibration mode occurs and the specimen fails at the designated test (gauge) section, where the maximum stress exists. The stress–life (S–N) curve is obtained for Inconel alloy 718 and indicates an expected trend.

36 MATERIALS SCIENCE↗