Bending of Superelastic Wires, Part I: Experimental Aspects

1995 ◽  
Vol 62 (2) ◽  
pp. 459-465 ◽  
Author(s):  
B. T. Berg
Keyword(s):  
Phase Region ◽  
Constitutive Relationship ◽  
Tension Stress ◽  
Bending Moments ◽  
Pure Bending ◽  
Three Point Bending ◽  
Strain Relationship ◽  
Niti Wires ◽  
Mixed Phase Region ◽  
Constant Moment

A pure-bending apparatus is used to measure the constitutive relationship between applied pure bending moments and the resulting curvatures of a few superelastic alloy wires. The sample nickel-titanium alloy (NiTi) wires change phase when ample bending moments are imposed. Like the material’s uniaxial tension stress-strain relationship, the measured moment-curvature relationship shows plateaus of constant moment and hysteresis. The bent shape is circular, except in the mixed phase region where it is composed of a phase mixture of circles. An example of the applications of the measured moment-curvature relations is presented in Part II of this paper where the three-point bending problem is considered.

Bending of Superelastic Wires, Part II: Application to Three-Point Bending

1995 ◽  
Vol 62 (2) ◽  
pp. 466-470 ◽  
Author(s):  
B. T. Berg
Keyword(s):  
Numerical Procedure ◽  
Bending Moment ◽  
Numerical Results ◽  
Constitutive Relationship ◽  
Pure Bending ◽  
Three Point Bending ◽  
Rod Theory ◽  
Soft Loading ◽  
Loading And Unloading ◽  
The Relationship

The constitutive relationship between applied pure bending moment and the resulting curvature of a few superelastic alloy wires is applied to the three-point bending problem. Three-point bending experiments on hard and soft loading machines are described. The relationship between the applied deflection and the resulting force in three-point bending is calculated from a nonlinear Euler-Bernoulli rod theory. A numerical procedure used to solve the three-point bending problem for both loading and unloading is briefly described and numerical results are compared with experiment.

Pure Moment Testing for Spinal Biomechanics Applications: Fixed Versus 3D Floating Ring Cable-Driven Test Designs

2012 ◽  
Author(s):  
Jessica A. Tang ◽  
Justin K. Scheer ◽  
Christopher P. Ames ◽  
Jenni M. Buckley
Keyword(s):  
Spinal Column ◽  
Bending Moments ◽  
Pure Bending ◽  
Uniform Loading ◽  
Flexion Extension ◽  
Driven System ◽  
Accepted Standard ◽  
Pure Moment ◽  
Bending Modes ◽  
Biomechanical Tests

For spine biomechanical tests, the cable-driven system in particular has been widely used to apply pure bending moments. The advantages to pure moment testing lie in its consistency as an accepted standard protocol across previous literature and its ability to ensure uniform loading across all levels of the spinal column. Of the methods used for pure moment testing, cable-driven set-ups are popular due to their low requirements and simple design. Crawford et al [1] were the first to employ this method, but prior work by our group indicated a discrepancy between applied and intended moment for this system in flexion-extension only [2]. We hypothesize that this discrepancy can be observed in other bending modes and minimized with a second-generation floating ring design to eliminate off-axis loads.

scholarly journals Simulating the Stress-Strain Relationship of Geomaterials by Support Vector Machine

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Hongbo Zhao ◽  
Zenghui Huang ◽  
Zhengsheng Zou
Keyword(s):  
Support Vector Machine ◽  
Constitutive Relationship ◽  
Support Vector ◽  
Nonlinear Relationship ◽  
Ann Model ◽  
Stress Strain ◽  
Svm Model ◽  
Strain Relationship ◽  
Artificial Neural Network Ann ◽  
Relationship Of

Stress-strain relationship of geomaterials is important to numerical analysis in geotechnical engineering. It is difficult to be represented by conventional constitutive model accurately. Artificial neural network (ANN) has been proposed as a more effective approach to represent this complex and nonlinear relationship, but ANN itself still has some limitations that restrict the applicability of the method. In this paper, an alternative method, support vector machine (SVM), is proposed to simulate this type of complex constitutive relationship. The SVM model can overcome the limitations of ANN model while still processing the advantages over the traditional model. The application examples show that it is an effective and accurate modeling approach for stress-strain relationship representation for geomaterials.

Technical Basis for Application of Collapse Moments for Locally Thinned Pipes Subjected to Torsion and Bending Proposed for ASME Section XI

2014 ◽  
Author(s):  
Kunio Hasegawa ◽  
Yinsheng Li ◽  
Bostjan Bezensek ◽  
Phuong H. Hoang ◽  
Howard J. Rathbun
Keyword(s):  
Power Plants ◽  
Bending Moments ◽  
Finite Element Analyses ◽  
Pure Bending ◽  
Plastic Bending ◽  
Evaluation Procedures ◽  
Wall Thinning ◽  
Applicable Range ◽  
Technical Basis ◽  
Local Wall Thinning

Piping components in power plants may experience combined bending and torsion moments during operation. There is a lack of guidance for pipe evaluation for pipes with local wall thinning flaws under the combined bending and torsion moments. ASME B&PV Code Section XI Working Group is currently developing fully plastic bending pipe evaluation procedures for pressurized piping components containing local wall thinning subjected to combined torsion and bending moments. Using elastic fully plastic finite element analyses, plastic collapse bending moments under torsions were obtained for 4 (114.3) to 24 (609.6) inch (mm) diameter pipes with various local wall thinning flaw sizes. The objective of this paper is to introduce an equivalent moment, which combines torsion and bending moments by a vector summation, and to establish the applicable range of wall thinning lengths, angles and depths, where the equivalent moments are equal to pure bending moments.

scholarly journals Spin excitations in [La[sub 1−x]Ca[sub x]MnO[sub 3]] in the mixed-phase region

2002 ◽  
Vol 91 (10) ◽  
pp. 7511 ◽  
Author(s):  
L. Stumpe ◽  
B. Kirby ◽  
H. Kaiser ◽  
J. J. Rhyne ◽  
J. F. Mitchell
Keyword(s):  
Phase Region ◽  
Mixed Phase ◽  
Spin Excitations ◽  
Mixed Phase Region

Phase diagrams for impurity-doped VO2

1976 ◽  
Vol 54 (1) ◽  
pp. 1-8 ◽  
Author(s):  
J. M. Reyes ◽  
S. L. Segel ◽  
M. Sayer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Phase Diagrams ◽  
Phase Region ◽  
Mixed Phase ◽  
Phase Boundaries ◽  
Temperature Changes ◽  
Impurity Doped ◽  
T Phase ◽  
Mixed Phase Region

The general form of the phase diagrams for impurity-doped VO2 is considered and shown to include mixed phase boundary regions. Phase diagrams for Cr and Al-doped VO2 are established on the basis of the temperature dependence of the 51V nuclear magnetic resonance (NMR) signal. In Cr-doped VO2, the (M2) phase is shown to exist over a smaller temperature–concentration range than reported previously and in Al-doped VO2, two intermediate single phases (M2) and (M3) are found. The (T) phase which has been previously suggested to be a definite phase having triclinic symmetry is shown to be a mixed phase region in which the contributions from the components change with temperature. Changes in NMR signal intensity at the phase boundaries show that half the V sites have paired spins in both the(M2) and (M3) phases.

Application of Pure Bending Moments to Crystals

1956 ◽  
Vol 27 (7) ◽  
pp. 546-547 ◽  
Author(s):  
John J. Gilman
Keyword(s):  
Bending Moments ◽  
Pure Bending

Nucleation Processes in Deep Convection Simulated by a Cloud-System-Resolving Model with Double-Moment Bulk Microphysics

2007 ◽  
Vol 64 (3) ◽  
pp. 738-761 ◽  
Author(s):  
Vaughan T. J. Phillips ◽  
Leo J. Donner ◽  
Stephen T. Garner
Keyword(s):  
Deep Convection ◽  
Phase Region ◽  
Mixed Phase ◽  
Cloud Droplets ◽  
Ice Concentration ◽  
Double Moment ◽  
Preferential Evaporation ◽  
Cloud Ice ◽  
Homogeneous Freezing ◽  
Mixed Phase Region

Abstract A novel type of limited double-moment scheme for bulk microphysics is presented here for cloud-system-resolving models (CSRMs). It predicts the average size of cloud droplets and crystals, which is important for representing the radiative impact of clouds on the climate system. In this new scheme, there are interactive components for ice nuclei (IN) and cloud condensation nuclei (CCN). For cloud ice, the processes of primary ice nucleation, Hallett–Mossop (HM) multiplication of ice particles (secondary ice production), and homogeneous freezing of aerosols and droplets provide the source of ice number. The preferential evaporation of smaller droplets during homogeneous freezing of cloud liquid is represented for the first time. Primary and secondary (i.e., in cloud) droplet nucleation are also represented, by predicting the supersaturation as a function of the vertical velocity and local properties of cloud liquid. A linearized scheme predicts the supersaturation, explicitly predicting rates of condensation and vapor deposition onto liquid (cloud liquid, rain) and ice (cloud ice, snow, graupel) species. The predicted supersaturation becomes the input for most nucleation processes, including homogeneous aerosol freezing and secondary droplet activation. Comparison of the scheme with available aircraft and satellite data is performed for two cases of deep convection over the tropical western Pacific Ocean. Sensitivity tests are performed with respect to a range of nucleation processes. The HM process of ice particle multiplication has an important impact on the domain-wide ice concentration in the lower half of the mixed-phase region, especially when a lack of upper-level cirrus suppresses homogeneous freezing. Homogeneous freezing of droplets and, especially, aerosols is found to be the key control on number and sizes of cloud particles in the simulated cloud ensemble. Preferential evaporation of smaller droplets during homogeneous freezing produces a major impact on ice concentrations aloft. Aerosols originating from the remote free troposphere become activated in deep convective updrafts and produce most of the supercooled cloud droplets that freeze homogeneously aloft. Homogeneous aerosol freezing is found to occur only in widespread regions of weak ascent while homogeneous droplet freezing is restricted to deep convective updrafts. This means that homogeneous aerosol freezing can produce many more crystals than homogeneous droplet freezing, if conditions in the upper troposphere are favorable. These competing mechanisms of homogeneous freezing determine the overall response of the ice concentration to environmental CCN concentrations in the simulated cloud ensemble. The corresponding sensitivity with respect to environmental IN concentrations is much lower. Nevertheless, when extremely high concentrations of IN are applied, that are typical for plumes of desert dust, the supercooled cloud liquid is completely eliminated in the upper half of the mixed phase region. This shuts down the process of homogeneous droplet freezing.

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