Tension-Compression Asymmetry of Solid, Shape Recovered “Bulk” Nitinol

2009 ◽  
Author(s):  
Matthew Fonte ◽  
Anil Saigal
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Experimental Studies ◽  
Small Diameter ◽  
Thin Wall ◽  
Solid Bulk ◽  
Novel Devices ◽  
Deformation Modes ◽  
Tension Compression Asymmetry

As the shape memory material Nitinol (55% Nickel – 45% Titanium alloy) emerges to find more and more applications in engineered products, understanding the effects of material processing becomes increasingly important. Its mechanical behavior is highly non-linear and is strongly dependent on alloy composition, heat treatment history and mechanical work. Published Nitinol literature is almost exclusively related to processing and testing of thin wall, very small diameter tubing and wire devices, usually exhibiting superelastic characteristics. In strain-controlled tension-compression testing of pseudoelastic Nitinol shape memory wires, compression recovery forces were found to be markedly higher than tension forces. However, most experimental studies of the thermomechanical behavior of Nitinol (NiTi) to date have been conducted in uniaxial tension on wire devices. There is a dearth of information in the literature regarding the compression recovery of solid blocks of Nitinol. Questions exist on whether or not solid, “bulk” Nitinol products when deformed in compression will exhibit shape recovery characteristics? The potential for shape recovery of compressed solid blocks of Nitinol products, which could have large stress-strain outputs, can enable the design of novel devices in many industries. The motivation for this research is to provide the first characterization of the shape recovery effects of “bulk” Nitinol material under compressive deformation modes versus the often practiced and well understood tensile loading of wire and thin wall tubing.

Characterization of Creeping and Shape Memory Effect in Laser Sintered Thermoplastic Polyurethane

2016 ◽  
Vol 16 (4) ◽  
Author(s):  
Shangqin Yuan ◽  
Jiaming Bai ◽  
Chee Kai Chua ◽  
Kun Zhou ◽  
Jun Wei
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Thermoplastic Polyurethane ◽  
Selective Laser Sintering ◽  
Thermal Transitions ◽  
Temperature Dependent ◽  
Shape Memory Effects ◽  
Viscoelastic Behaviors ◽  
High Flexibility

Thermoplastic polyurethane (TPU) powders were successfully processed in a selective laser sintering (SLS) system. The laser-sintered polyurethane products with viscoelastic behaviors exhibit high flexibility and elongation at break at room temperature. Moreover, the creeping and the thermoresponsive shape-memory effects (SME) were also characterized. The influences of the time-temperature relevant parameters on the shape-fixity and shape-recovery ratios were investigated quantitatively. The creeping and SME were time–temperature dependent phenomena, and the shape recovery mechanism is associated to the microsegments thermal transitions within the polymer matrix.

Shape Recovery and ε - γ Transformation in Fe29Mn7Si5Cr SMA

2008 ◽  
Vol 59 ◽  
pp. 86-91 ◽  
Author(s):  
Nele Van Caenegem ◽  
Kim Verbeken ◽  
Roumen H. Petrov ◽  
N.M. van der Pers ◽  
Yvan Houbaert
Keyword(s):  
Martensitic Transformation ◽  
Shape Memory ◽  
Shape Recovery ◽  
Electron Backscatter Diffraction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Electron Backscatter ◽  
Shape Memory Behaviour ◽  
Backscatter Diffraction

The shape memory behaviour of a Fe29Mn7Si5Cr based alloy has been investigated. Characterization of the martensitic transformation and the different structural constituents was performed using optical microscopy, X-ray diffraction (XRD) methods and electron backscatter diffraction (EBSD). The transformation temperatures and the shape recovery were determined by dilatometry on prestrained samples.

Classification and Characterization of the Shape Memory Binary Alloys

2006 ◽  
Vol 980 ◽  
Author(s):  
Mitsuo Notomi ◽  
Krystyn J Van Vliet ◽  
Sidney Yip
Keyword(s):  
Crystal Structure ◽  
Shape Memory ◽  
Shape Recovery ◽  
Major Element ◽  
Binary Alloys ◽  
Major Elements ◽  
The Other ◽  
Atomic Composition ◽  
Group 5

AbstractAll shape memory binary alloys (SMBA) that exhibit not only perfect shape recovery but also partial shape recovery were reviewed and classified into three groups, B2, A2 and A1 type, according to the parent phases. There are the thirteen, six and eleven alloys belonging to B2, A2 and A1 type, respectively. In the group of B2 type SMBA the alloys are divided into two categories due to the combination of the elements. Over A1 and A2 type SMBA the atomic composition of one element is larger than the other so the larger one is called a major element. The major elements, Ti, U, Fe, and Cu, of A2 type SMBA do not belong to the group 5 and 6 in which the elements have a typical BCC (A2) crystal structure. In the A1 type SMBA there are four major elements, Mn, Fe, Co, and In and the SMBA except for In-based SMBA have ferromagnetic or antiferromagnetic natures. The shape memory effect (SME) for A1 (FCC) type SMBA might need the magnetic properties.

Shape Recovery Characteristics of Shape Memory Polymers Subjected to Bending

2013 ◽  
Vol 834-836 ◽  
pp. 160-164 ◽  
Author(s):  
Tao Zhou ◽  
Hui Feng Tan ◽  
Yu Yan Liu
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymers ◽  
Recovery Ratio ◽  
Thin Sample ◽  
Ratio Measurement ◽  
Series Of Experiments ◽  
Finite Bending ◽  
Important Basis

Shape recovery is a critical characterization of the Shape Memory Polymers (SMP); so far, there has not been a set of uniform specifications, however, on the deformation recovery characterization of SMP, more exactly, on the shape recovery ratio measurement. A simple and effective experimental method is designed to obtain the shape recovery ratio of SMP; and a series of experiments are carried out to measure the shape recovery ratio of a thermoset shape-memory epoxy resin within the finite bending deformation at various test temperatures. And the results show that the shape recovery ratio and rate of the thin sample are larger than that of the thick one; the deformation curvature has little effect on the shape recovery ratio with the test temperatures over, or below, the glass-transition temperature,Tg, but has significant effect nearTg. The conclusions provide an important basis for the structural design of SMP.

scholarly journals 4D Printing and Characterization of Shape Memory Polymer (SMP) Based Smart Gripper

2020 ◽  
Vol 5 (10) ◽  
pp. 1204-1211
Author(s):  
Francis Irungu Maina ◽  
Nahashon Osinde ◽  
Japheth Ka’pesha Odira ◽  
Patrick Kariuki Wanjiru ◽  
Margaret Wanjiku Mwangi
Keyword(s):  
Shape Memory ◽  
Recovery Rate ◽  
Shape Recovery ◽  
Shape Memory Polymer ◽  
Print Quality ◽  
Stimuli Responsive ◽  
4D Printing ◽  
Printing Parameters ◽  
Made In

Shape Memory Polymer (SMP) is stimuli-responsive material with the ability to recover the original shape from a deformation upon triggering by an appropriate stimulus like heat, light, and electricity. The shape recovery properties can be harnessed through 4D printing of self-recoverable functional structures and made usable in fields like medicine and robotics. To investigate the recovery properties, best printing parameters and optimal sizes, 4D reconfigurable gripper designed in CAD was printed in Ultimaker 2 Printer. Different stencils were made in varying printing parameters of temperature, infill, speed and time. Analysis for the stencils proved best print quality at a temperature of 195 °C and nozzle retract speed of 40mm/s. Shape recovery characterization was done on MATLAB. A printing temperature of 203 °C, infill density of 38% and printing speed of 40 mm/s gave the gripper with the best print quality. Characterization of the varying performances of the four grippers was attributed to the different infill percentages. The lower the infill, the higher the recovery rate due to the low stiffness of the gripper. The best recovery rate of 96.93% was associated with an optimal printing temperature of 203 °C.

Synthesis and characterization of sisal fibre polyurethane network cross-linked with triple-shape memory properties

2018 ◽  
Vol 42 (9) ◽  
pp. 7130-7137 ◽  
Author(s):  
Lulu Pan ◽  
Zhongqiang Xiong ◽  
Laifu Song ◽  
Jianfeng Ban ◽  
Shaorong Lu
Keyword(s):  
Shape Memory ◽  
Shape Recovery ◽  
Shape Memory Polymer ◽  
Synthesis And Characterization ◽  
Sisal Fibre ◽  
High Elasticity ◽  
Shape Memory Properties ◽  
Triple Shape Memory

In this paper, a thermo-responsive network shape-memory polymer (SMP) which has high elasticity, triple shape-memory properties and rapid shape recovery effects was reported.

Applications of SIMS to electronic materials and devices

1992 ◽  
Vol 50 (2) ◽  
pp. 1682-1683
Author(s):  
S.F. Corcoran
Keyword(s):  
Depth Distribution ◽  
Secondary Ion Mass Spectrometry ◽  
Semiconductor Device ◽  
Electronic Materials ◽  
Profile Analysis ◽  
Semiconductor Industry ◽  
Small Diameter ◽  
Depth Resolution ◽  
Detection Sensitivity

Over the past decade secondary ion mass spectrometry (SIMS) has played an increasingly important role in the characterization of electronic materials and devices. The ability of SIMS to provide part per million detection sensitivity for most elements while maintaining excellent depth resolution has made this technique indispensable in the semiconductor industry. Today SIMS is used extensively in the characterization of dopant profiles, thin film analysis, and trace analysis in bulk materials. The SIMS technique also lends itself to 2-D and 3-D imaging via either the use of stigmatic ion optics or small diameter primary beams.By far the most common application of SIMS is the determination of the depth distribution of dopants (B, As, P) intentionally introduced into semiconductor materials via ion implantation or epitaxial growth. Such measurements are critical since the dopant concentration and depth distribution can seriously affect the performance of a semiconductor device. In a typical depth profile analysis, keV ion sputtering is used to remove successive layers the sample.

Highly Fluorescent Au25-xAgx Nanoclusters Protected with Poly(ethylene glycol) - and Zwitterion-Modified Thiolate Ligands

2018 ◽  
Author(s):  
Dinesh Mishra ◽  
Sisi Wang ◽  
Zhicheng Jin ◽  
Eric Lochner ◽  
Hedi Mattoussi
Keyword(s):  
Quantum Yield ◽  
Near Infrared ◽  
Small Diameter ◽  
Binding Energies ◽  
Thiolate Ligands ◽  
Nir Emission ◽  
Thiolate Complexes ◽  
Long Lifetime ◽  
Poly Ethylene

<p>We describe the growth and characterization of highly fluorescing, near-infrared-emitting nanoclusters made of bimetallic Au<sub>25-x</sub>Ag<sub>x</sub> cores, prepared using various monothiol-appended hydrophobic and hydrophilic ligands. The reaction uses well-defined triphenylphosphine-protected Au<sub>11</sub> clusters (as precursors), which are reacted with Ag(I)-thiolate complexes. The prepared nanoclusters are small (diameter < 2nm, as characterized by TEM) with emission peak at 760 nm and long lifetime (~12 µs). The quantum yield measured for these materials was 0.3 - 0.4 depending on the ligand. XPS measurements show the presence of both metal atoms in the core, with measured binding energies that agree with reported values for nanocluster materials. The NIR emission combined with high quantum yield, small size and ease of surface functionalization afforded by the coating, make these materials suitable to implement investigations that address fundamental questions and potentially useful for biological sensing and imaging applications.<br></p>

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