The Effect of Non-Constant Young's Modulus in Modelling of Tension and Compression of Superelastic NI-TI Shape Memory Alloys

2010 ◽  
Vol 26 (4) ◽  
pp. 553-561
Author(s):  
Andrej Puksic ◽  
Janez Kunavar ◽  
Miha Brojan ◽  
Franc Kosel
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Transformation Strain ◽  
Material Model ◽  
Stress Plateau ◽  
Micromechanical Approach ◽  
Tension And Compression ◽  
Tension Compression Asymmetry

ABSTRACTMany unresolved issues remain in the field of modelling of shape memory alloys. In this paper the problem of unequal elastic properties of austenite and martensite is addressed. We propose a modification of the micromechanical material model that enables the application of different Young's modulus for austenite and martensite. The corresponding computational model for the application of the micromechanical approach to modeling of superelasticity in shape memory alloys is demonstrated. Material properties for Ni-Ti alloy (50.8 at.% Ni) obtained from literature and from our own experiments were applied to the model and a sample calculation of a 3D model subjected to uniaxial loading was performed. The results were compared to experimental results obtained from tensile and compressive tests. In general the presented model predicts well the level of the superelastic stress plateau and maximum transformation strain in tension. The agreement in compression is worse but the overall characteristics of the tension-compression asymmetry are predicted correctly.

Design of Shape Memory Alloy Springs With Applications in Vibration Control

1993 ◽  
Vol 115 (1) ◽  
pp. 129-135 ◽  
Author(s):  
C. Liang ◽  
C. A. Rogers
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Vibration Control ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Design Method ◽  
Control Area ◽  
Spring Constant ◽  
Damping Capacity

Shape memory alloys (SMAs) have several unique characteristics, including their Young’s modulus-temperature relations, shape memory effects, and damping characteristics. The Young’s modulus of the high-temperature austenite of SMAs is about three to four times as large as that of low-temperature martensite. Therefore, a spring made of shape memory alloy can change its spring constant by a factor of three to four. Since a shape memory alloy spring can vary its spring constant, provide recovery stress (shape memory effect), or be designed with a high damping capacity, it may be useful in adaptive vibration control. Some vibration control concepts utilizing the unique characteristics of SMAs will be presented in this paper. Shape memory alloy springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some design approaches based upon linear theory have been proposed for shape memory alloy springs. A more accurate design method for SMA springs based on a new nonlinear thermomechanical constitutive relation of SMA is also presented in this paper.

scholarly journals Effect of Nanopores on Mechanical Properties of the Shape Memory Alloy

Micromachines ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 529
Author(s):  
Chunzhi Du ◽  
Zhifan Li ◽  
Bingfei Liu
Keyword(s):  
Mechanical Properties ◽  
Constitutive Model ◽  
Shape Memory ◽  
Young’S Modulus ◽  
Residual Strain ◽  
Surface Effect ◽  
Young's Modulus ◽  
Strain Curve ◽  
Stress Strain ◽  
Strength Limit

Nanoporous Shape Memory Alloys (SMA) are widely used in aerospace, military industry, medical and health and other fields. More and more attention has been paid to its mechanical properties. In particular, when the size of the pores is reduced to the nanometer level, the effect of the surface effect of the nanoporous material on the mechanical properties of the SMA will increase sharply, and the residual strain of the SMA material will change with the nanoporosity. In this work, the expression of Young’s modulus of nanopore SMA considering surface effects is first derived, which is a function of nanoporosity and nanopore size. Based on the obtained Young’s modulus, a constitutive model of nanoporous SMA considering residual strain is established. Then, the stress–strain curve of dense SMA based on the new constitutive model is drawn by numerical method. The results are in good agreement with the simulation results in the published literature. Finally, the stress-strain curves of SMA with different nanoporosities are drawn, and it is concluded that the Young’s modulus and strength limit decrease with the increase of nanoporosity.

Multiscale Modeling of Light Activated Shape Memory Polymer

2008 ◽  
Author(s):  
Richard Beblo ◽  
Lisa Mauck Weiland
Keyword(s):  
Shape Memory ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Shape Memory Polymer ◽  
Scale Model ◽  
Cross Link ◽  
Material Response ◽  
Rotational Isomeric State ◽  
Stress Strain Relation ◽  
Cross Links

Presented is the development of a multi-scale model predicting the material response of a light activated shape memory polymer. Rotational Isomeric State (RIS) theory is used to build a molecular scale model of the polymer chain backbone, tracking the distances between cross-links. Cross-link to cross-link distances are then used with Boltzmann statistical mechanics to predict material response, generating Young’s modulus and stress-strain relation predictions. Young’s modulus is predicted by the model to be 0.049 and 3.2 MPa for the soft and hard states of the polymer respectively. Experimentally determined properties are also presented with reported moduli of 2.0 and 11.4 MPa in the soft and hard states respectively.

Nucleation of martensite and thermal hysteresis of the young’s modulus in a Ni50.8Ti49.2 shape memory alloy

1999 ◽  
Vol 41 (11) ◽  
pp. 1211-1216 ◽  
Author(s):  
R. Campanella ◽  
B. Coluzzi ◽  
A. Biscarini ◽  
L. Trotta ◽  
G. Mazzolai ◽  
...  
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Young’S Modulus ◽  
Thermal Hysteresis ◽  
Young's Modulus
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