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

Berg, Brian T.

doi:10.1115/1.2895953

Cited by 13 publications

(8 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Despite the myriad of applications that employ superelastic SMA in bending, and despite the number of SMA bending models (we found 13) (Atanacković and Achenbach, 1989;Thier et al, 1991;Pelton et al, 1994;Plietsch et al, 1994;Berg, 1995b;Auricchio and Sacco, 1997;Raniecki et al, 2001;Rejzner et al, 2002;Purohit and Bhattacharya, 2002;Liew et al, 2004;Rajagopal and Srinivasa, 2005;Buratti, 2005;De la Flor et al, 2010), few careful pure-bending experiments exist in the literature. Traditional 4-point bending fixtures operate under the assumptions of small beam displacements and rotations, which are easily violated when used with slender SMA specimens.…”

Section: Introductionmentioning

confidence: 82%

“…In fact, Kyriakides et al (2008) measured a flat moment-curvature response at the onset of plasticity in steel tubes with Lüders bands, and observed propagating regions of high curvature. In addition, several researchers (Berg, 1995b;Purohit and Bhattacharya, 2002;Buratti, 2005) have postulated this sort of behavior for bending of SMAs, and have built models to simulate curvature propagation. In our case, the moment-curvature response is always at least slightly positive during loading, suggesting a structurally stable response, and curvature does not appear to propagate here.…”

Section: Single-cycle Bending Experiments (B1)mentioning

confidence: 99%

See 1 more Smart Citation

Tension, compression, and bending of superelastic shape memory alloy tubes

Reedlunn

Churchill

Nelson

et al. 2014

Journal of the Mechanics and Physics of Solids

176

View full text Add to dashboard Cite

While many uniaxial tension experiments of shape memory alloys (SMAs) have been published in the literature, relatively few experimental studies address their behavior in compression or bending, despite the prevalence of this latter deformation mode in applications. In this study, superelastic NiTi tubes from a single lot of material were characterized in tension, compression, and pure bending, which allowed us to make direct comparisons between the deformation modes for the first time. Custom built fixtures were used to overcome some long-standing experimental difficulties with performing well-controlled loading and accurate measurements during uniaxial compression (avoiding buckling) and large-rotation bending. In all experiments, the isothermal, global, mechanical responses were measured, and stereo digital image correlation (DIC) was used to measure the evolution of the strain fields on the tube's outer surface.As is characteristic of textured NiTi, our tubes exhibited significant tension-compression asymmetry in their uniaxial responses. Stress-induced transformations in tension exhibited flat force plateaus accompanied by strain localization and propagation. No such localization, however, was observed in compression, and the stress "plateaus" during compression always maintained a positive tangent modulus. While our uniaxial results are similar to the observations of previous researchers, the DIC strain measurements provided details of localized strain behavior with more clarity and allowed more quantitative measurements to be made. Consistent with the tension-compression asymmetry, our bending experiments showed a significant shift of the neutral axis towards the compression side. Furthermore, the tube exhibited strain localization on the tension side, but no localization on the compression side during bending. This is a new observation that has not been explored before. Detailed analysis of the strain distribution across the tube diameter revealed that the traditional assumption of elementary beam theory, that plane sections remain plane, does not hold. Yet when the strain was averaged over a few diameters of axial length, the tensile and compressive responses input into elementary beam theory predicted the global bending response with reasonable accuracy. While it is encouraging that a simple model could predict the moment-curvature response, we recommend that beam theory be used with caution. The averaged strain field can under/over predict local strains by as much as two-fold due to the localized deformation morphology.

show abstract

Section: Introductionmentioning

confidence: 82%

Section: Single-cycle Bending Experiments (B1)mentioning

confidence: 99%

Tension, compression, and bending of superelastic shape memory alloy tubes

Reedlunn

Churchill

Nelson

et al. 2014

Journal of the Mechanics and Physics of Solids

176

View full text Add to dashboard Cite

show abstract

“…To consider a three-point-bending test with a constant distance between the end supports 2' and an applied force in the central support of 2F , in which the elastica can slide on the end supports upon deformation (see Berg, 1995b for an experimental setup), it is sufficient to complete the above solution by the symmetry yðÀxÞ ¼ yðxÞ.…”

Section: Cantilever Beam and Three-point-bending Solutionsmentioning

confidence: 99%

Rippling and a phase-transforming mesoscopic model for multiwalled carbon nanotubes

Arroyo

Arias

2008

Journal of the Mechanics and Physics of Solids

View full text Add to dashboard Cite

We propose to model thick multiwalled carbon nanotubes as beams with non-convex curvature energy. Such models develop stressed phase mixtures composed of smoothly bent sections and rippled sections. This model is motivated by experimental observations and large-scale atomistic-based simulations. The model is analyzed, validated against large-scale simulations, and exercised in examples of interest. It is shown that modelling MWCNTs as linear elastic beams can result in poor approximations that overestimate the elastic restoring force considerably, particularly for thick tubes. In contrast, the proposed model produces very accurate predictions both of the restoring force and of the phase pattern. The size effect in the bending response of MWCNTs is also discussed.Peer ReviewedPostprint (author’s final draft

show abstract

“…In the experimental field, the most important analysis of SMA bending behaviour has been done by Wick et al. [12] and Berg [13, 14] who studied 3‐point and 4‐point bending and pure bending in superelastic NiTi, and Matsui [15] and Wagner et al. [16, 17] who focused their study on the rotating‐bending fatigue properties of superelastic SMA.…”

Section: Introductionmentioning

confidence: 99%

Asymmetrical Bending Model for NiTi Shape Memory Wires: Numerical Simulations and Experimental Analysis

Flor

Urbina

Ferrando

2011

Strain

View full text Add to dashboard Cite

A detailed numerical and experimental study of a NiTi Shape Memory Alloy (SMA) wire subjected to bending is presented in order to provide a complete characterisation of the material under this load case. The beam model presented is based on the classic Euler-Bernoulli theory and uses De la Flor one-dimensional constitutive equations modified to take into account different material responses to tension and compression as well as the different elastic properties of austenite and martensite. All the necessary experimental techniques were designed to determine the bending behaviour of NiTi SMA wire over the entire range of transformation temperatures. These experimental bending results were then compared with the numerical results. The numerical model proposed agrees quantitatively and qualitatively with the experimental bending results obtained for NiTi wire, representing an effective tool for the analysis of one-dimensional structural devices. A comparison of the numerical results that assume symmetrical behaviour between tension and compression with the results that assume asymmetrical behaviour has shown that the tension/compression asymmetry is more pronounced in the martensitic range and has little influence on the response of the SMA wire subjected to bending at temperatures above A f . These results are analyzed and discussed.KEY WORDS: bending behaviour, nitinol, numerical modelling, shape memory alloys Ó

show abstract

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

Cited by 13 publications

References 1 publication

Tension, compression, and bending of superelastic shape memory alloy tubes

Tension, compression, and bending of superelastic shape memory alloy tubes

Rippling and a phase-transforming mesoscopic model for multiwalled carbon nanotubes

Asymmetrical Bending Model for NiTi Shape Memory Wires: Numerical Simulations and Experimental Analysis

Contact Info

Product

Resources

About