scholarly journals Effect of Phase Changes on the Axial Modulus of an FeMnSi-Shape Memory Alloy

Materials ◽  
2021 ◽  
Vol 14 (17) ◽  
pp. 4815
Author(s):  
Yajiao Yang ◽  
Matteo Breveglieri ◽  
Moslem Shahverdi
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Shape Memory ◽  
Early Stage ◽  
Phase Changes ◽  
Stress And Strain ◽  
Interaction Forces ◽  
Strain Behavior ◽  
Different Temperatures ◽  
The Relationship

The axial modulus ESMA(κ) of FeMnSi-based shape memory alloys (FeMnSi-SMAs) is a parameter introduced in this study to characterize the relationship between stress and strain behavior at the early stage of tensile loading. ESMA(κ) can be used to correctly estimate and model the interaction forces between FeMnSi-SMAs and other materials. Unlike the conventional Young’s modulus, which is usually given at room temperature, the ESMA(κ) is evaluated at different temperatures and strongly depends on phase transformation and plastic deformation. This study investigated the evolution of ESMA(κ) during and after pre-straining as well as in the course of the activation processes. The effect of different factors (e.g., phase transformation and plastic deformation) on the magnitude of ESMA(κ) is discussed. The result shows that the ESMA(κ) can differ significantly during activation and thus needs to be modified when interaction forces between FeMnSi-SMAs and other substrates materials (e.g., concrete) must be modeled and evaluated.

Study on Nitridation of Silicon Added With Amorphous Silicon Nitride

2011 ◽  
Author(s):  
Yanhui Li ◽  
Li Wang ◽  
Shaowu Yin ◽  
Fuming Yang ◽  
Chuanping Liu ◽  
...  
Keyword(s):  
Silicon Nitride ◽  
Amorphous Silicon ◽  
Early Stage ◽  
Conversion Ratio ◽  
Amorphous Silicon Nitride ◽  
Nitridation Process ◽  
Silicon Nitride Powder ◽  
Different Temperatures ◽  
Direct Nitridation ◽  
The Relationship

The direct nitridation process of silicon added with amorphous silicon nitride powder at atmospheric pressure was investigated and the product was analyzed by XRD and SEM. Based on the relationship between the conversion ratio of silicon and the reaction time at different temperatures, a physical and mathematical model was derived to describe the nitridation process of silicon particles. The results showed that the conversion ratio of silicon increased rapidly at the early stage of reaction. And the reaction would be accelerated by reducing the size of silicon particle and increasing the pressure of N2. At the range of experimental temperature, the conversion ratio of silicon increases with improving temperature.

In situ Transmission Electron Microscopy and Nanoindentation Studies of Phase Transformation and Pseudoelasticity of Shape-memory Titanium-nickel Films

2005 ◽  
Vol 20 (7) ◽  
pp. 1808-1813 ◽  
Author(s):  
X.-G. Ma ◽  
K. Komvopoulos
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Phase Transformation ◽  
Shape Memory ◽  
Heating And Cooling ◽  
Transmission Electron ◽  
Different Temperatures ◽  
Titanium Nickel ◽  
In Situ Heating

Transmission electron microscopy (TEM) and nanoindentation, both with in situ heating capability, and electrical resistivity measurements were used to investigate phase transformation phenomena and thermomechanical behavior of shape-memory titanium-nickel (TiNi) films. The mechanisms responsible for phase transformation in the nearly equiatomic TiNi films were revealed by heating and cooling the samples inside the TEM vacuum chamber. Insight into the deformation behavior of the TiNi films was obtained from the nanoindentation response at different temperatures. A transition from elastic-plastic to pseudoelastic deformation of the martensitic TiNi films was encountered during indentation and heating. In contrast to the traditional belief, the martensitic TiNi films exhibited a pseudoelastic behavior during nanoindentation within a specific temperature range. This unexpected behavior is interpreted in terms of the evolution of martensitic variants and changes in the mobility of the twinned structures in the martensitic TiNi films, observed with the TEM during in situ heating.

NiTi Shape Memory Alloy Wire’s Constitutive Describe at Different Temperatures

2017 ◽  
Vol 729 ◽  
pp. 13-17
Author(s):  
Guang Yong Yang ◽  
Yang Zhong ◽  
Zhi Fei Qiu ◽  
Jun Wang ◽  
Wei Na Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Niti Shape Memory Alloy ◽  
Thermal And Mechanical Properties ◽  
Restoring Force ◽  
Intelligent Material ◽  
Different Temperatures ◽  
Relationship Of ◽  
The Relationship

NiTi shape memory alloy is an intelligent drive and awareness materials which develop very rapidly and is used in many fields in recent years, whose mechanical properties are not only related to chemical composition, but also closely related to the temperature. This article aims to study the NiTi shape memory alloy wire’s constitutive behavior coupled thermal and mechanical properties at different temperatures. By analyzing the results, the relationship of NiTi shape memory alloy between deformation and the restoring force at elevated temperature is obtained, thus providing a basis for the engineering design and simulation process of NiTi intelligent material.

scholarly journals Finite Element Simulation of NiTiNb Shape Memory Alloy Pipe-Joint Subjected to Coupled Transformation and Plastic Deformation

2020 ◽  
Vol 2020 ◽  
pp. 1-14
Author(s):  
Xiang Chen ◽  
Bin Chen ◽  
Xianghe Peng ◽  
Xiaoqing Jin ◽  
Ying Ma ◽  
...  
Keyword(s):  
Plastic Deformation ◽  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
High Performance ◽  
Coupling Effect ◽  
Longitudinal Direction ◽  
Design Parameters ◽  
Pull Out ◽  
Pipe Joint

The assembling process of Ni47Ti44Nb9 alloy pipe joints considering the phase transformation and plasticity was numerically simulated for the first time with a developed constitutive model. The simulated process was based on the experimental material parameters, which were determined with the experimental tensile results of Ni47Ti44Nb9 shape memory alloy (SMA) and steel bars. The results showed that, after assembly, the Mises stress distributed uniformly along the longitudinal direction of the NiTiNb joint, but nonuniformly along the radial direction. The maximum σeq does not appear at the inner wall of the joints due to the coupling effect of the plastic deformation and the recoverable transformation. The contact pressure distributed uniformly along the circumferential direction, but nonuniformly along the longitudinal direction. The sizes of the SMA joint and the pipe should be properly matched to ensure contact during the stage of the rapid reverse phase transformation to obtain stable connection performance. The pull-out force was also computed, and the results were in good agreement with the experimental results. The results obtained can provide available information for the optimization of the design parameters of the high-performance SMA pipe-joint, such as inner diameter and assembly clearance.

Investigation on Mechanical Behaviors of Shape Memory Alloy Torsion Rod

2011 ◽  
Vol 179-180 ◽  
pp. 455-458
Author(s):  
Bo Zhou ◽  
Zhen Qing Wang ◽  
Yan Ju Liu ◽  
Jin Song Leng
Keyword(s):  
Phase Transformation ◽  
Constitutive Equation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Martensitic Phase Transformation ◽  
Mechanical Behaviors ◽  
Transformation Temperatures ◽  
Mechanics Of Materials ◽  
Niti Sma ◽  
The Relationship

DSC test is carried out to determine the phase transformation temperatures of a NiTi SMA, which include martensitic starting temperature, martensitic finishing temperature, austenitic starting temperature and austenitic finishing temperature. The mechanical behaviors of shape memory alloy (SMA) torsion rod are investigated by using Zhou’s shear constitutive equation of SMA and the theorem of circular shaft in mechanics of materials. A critical torque equation is developed to describe the relationship between the martensitic phase transformation critical torque of SMA torsion rod and temperature.

The Selected Shape-Memory Characteristics of the Ni-Ti Alloy in Thermo-Mechanical Loading Conditions

2007 ◽  
Vol 22 (1) ◽  
pp. 245-256
Author(s):  
Krzysztof KUŚ
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Mechanical Loading ◽  
Ti Alloy ◽  
Loading Conditions ◽  
Thermomechanical Cycling ◽  
Different Temperatures ◽  
Annealing Heat Treatment ◽  
Set Up ◽  
Memory Characteristics

The Selected Shape-Memory Characteristics of the Ni-Ti Alloy in Thermo-Mechanical Loading ConditionsThis paper deals with the testing work to examine some selected shape-memory characteristics (mainly recovery and permanent strains) in the Ni-Ti alloy during the thermomechanical cycling. The variations of shape memory effect (SME) were assessed using a special bending set-up, and discussed with respect to different thermo-mechanical loading profiles. The required phase-transformation temperatures of the alloy under examination were achieved by applying the annealing process at different temperatures for different times. The phase transformation behavior was observed using a differential scanning calorimeter (DSC). The X-ray diffractometry (XRD) was employed to identify phases present after the annealing heat treatment. It was found that the nature of a transformation cycle during two applied thermo-mechanical loading profiles (especially, the stress during reverse phase transformation), and also changes developed in the microstructure of a cycled material can affect behavior of strains.

Determination of Transformation Temperatures of SMAs by Varying the Force Using Dead Weight Method

2015 ◽  
Vol 813-814 ◽  
pp. 166-171
Author(s):  
Kiran D. Jadhav ◽  
U.S. Mallikarjun ◽  
S.H. Adarsh ◽  
S. Prashantha
Keyword(s):  
Phase Transformation ◽  
Shape Memory ◽  
Transformation Temperature ◽  
Phase Transformation Temperature ◽  
Scanning Calorimetry ◽  
Dead Weight ◽  
Strain Behavior ◽  
Weight Method ◽  
Nitinol Alloy ◽  
Dsc Method

Shape-memory material is an alloy that “Remembers” its original shape and that when deformed to its Pre-deformed shape when heated. Phase transformation temperature is one of the most important parameters for the shape memory alloys. In this present work phase transformation temperature is measured by the dead weight method and compared with standard Differential scanning calorimetry (DSC) method. The objective of this paper is to study the microstructure of the Shape memory alloy (SMA) wire, determining the Phase Transformation temperature of NiTinol alloy i.e. Marteniste start (Ms), Martensite finish (Mf), Austenite Start (As), Austenite finish (Af) by a Dead Weight method and also studying the stress-strain behavior with variation of Temperatures to show the Shape memory effect in the NiTinol SMA wire.

Study on Measurement of Group Velocity of Lamb Waves in Shape Memory Alloy Sheets

2014 ◽  
Vol 1065-1069 ◽  
pp. 2021-2024
Author(s):  
Kai Sheng Wang ◽  
Wei Chun Zhang
Keyword(s):  
Phase Transformation ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Group Velocity ◽  
Lamb Waves ◽  
Niti Alloy ◽  
Effective Means ◽  
Niti Shape Memory Alloy ◽  
Time Frequency ◽  
Different Temperatures

This paper describes the nondestructive evaluation of microstructure using laser-excited Lamb waves to detect the phase transformation in NiTi shape memory alloy sheets. Lamb waves were applied in the NiTi sheet using a pulse laser beam. Piezoelectricity transducers were used to receive the Lamb waves, the group velocities of which were measured using a time-frequency analysis method at different temperatures. Results show that a marked variation in the group velocity occurs during the phase transformation in the NiTi alloy. The dependence of group velocity on temperature provides a effective means of inspecting microstructure transformation in NiTi alloys.

Numerical simulation of the behavior of steel T-stubs connected by Fe-based shape memory alloy bolts

2018 ◽  
Vol 29 (16) ◽  
pp. 3284-3292 ◽  
Author(s):  
Cheikh Cissé ◽  
Wael Zaki ◽  
Tarak Ben Zineb
Keyword(s):  
Numerical Simulation ◽  
Plastic Deformation ◽  
Phase Transformation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Implicit Time ◽  
Integration Scheme ◽  
Iron Based

The article focuses on the numerical simulation of the thermomechanical behavior of steel T-stubs connected by iron-based shape memory alloys bolts. The three-dimensional macroscopic model used in this work was previously developed by the authors considering different thermomechanical properties between austenite and martensite, and coupling between phase transformation and plasticity. The model is implemented in a UMAT code using an implicit time-discrete integration scheme that follows a “multisurface plasticity”-like approach. The numerical results show that the shape memory effect can be used to preload the bolt if the initial length of its shank is less than the total thickness of the flanges. For an initial shank length of 21.38 mm and a total flange thickness of 21.4 mm, the shape memory effect produced average contact forces of 101 N between the bolt head and the flange, and 37 N between the two flanges. The resulting average contact pressures were 210 and 25 MPa, respectively. The average bolt force after preload was approximately 22.6 kN. Subsequent application of 2 mm normal displacements at the top and bottom faces of the upper and lower webs induced local plastic deformation around the flange holes and phase transformation in the bolt. The reversibility of martensitic transformation and the confinement of the plastic deformation in a limited zone around the holes allowed nearly complete shape recovery by heating. The obtained results highlight the advantage of using low-cost iron-based shape memory alloys as alternatives to steel bolts for connecting T-stubs.

Sign in / Sign up

Export Citation Format

Share Document