A mechanical contact model for superelastic shape memory alloys

2020 ◽  
pp. 1045389X2095361
Author(s):  
Mohammad Sattari ◽  
Hossein Ashtari Esfahani ◽  
Mahmoud Kadkhodaei ◽  
Saleh Akbarzadeh
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Constitutive Equations ◽  
Contact Model ◽  
Stress And Strain ◽  
Resistant Material ◽  
Niti Wire ◽  
Contact Models ◽  
Acceptable Agreement ◽  
Pseudoelastic Behavior

Shape memory alloys (SMA) are nowadays widely used in different industries. The two extraordinary behaviors of superelasticity and shape memory effect make these alloys a super wear-resistant material. In a range of SMA applications, contact between adjacent surfaces occurs. In this research, a formerly-developed contact model, which individually considers each asperity, is extended to cases where superelastic shape memory alloys are used. Since constitutive equations of SMAs are based on stress and strain, to establish a relationship between classical contact models and the main arguments of these constitutive equations, a representative strain based on the pseudoelastic behavior of SMAs was defined. Experiments were conducted to verify the model’s predictions. In these experiments, a NiTi wire was pressed against a Steel plate; then, the measured penetration in the test and the values predicted by the contact model were compared. The reported results show an acceptable agreement between theory and experiment.

A New and Consistent Approach for Deriving Brinson’s 1-D Constitutive Equation for Shape Memory Alloys

2008 ◽  
Author(s):  
Rasoul Khandan ◽  
Mojtaba Mahzoon ◽  
Seyed Ahmad Fazelzadeh ◽  
Ali Hemmasizadeh
Keyword(s):  
Constitutive Equation ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Compatibility Condition ◽  
Constitutive Equations ◽  
Modified Model ◽  
Clear Cut ◽  
Straightforward Approach ◽  
Consistent Approach

One of the first 1-D constitutive equations for shape memory alloys was presented by Brinson L.C in 1993 that became the base of later works typically. In Brinson’s equation, several proposed functions are considered in order to simplify the model and obtain the constitutive equation for SMA. In a recent paper V. R. Buravalla and A. Khandelwal (2007) have shown certain anomalies in Brinson’s model and have tried to present a modified model which unlike Brinson’s model satisfies the compatibility condition. However, their formulation, besides being lengthy, lacks clarity and in particular does not address proper expressions for transformation tensors Ωs and ΩT. In the present work, Brinson’s constitutive equation is derived from fundamental relations using a simple, clear-cut and straightforward approach. Without any extra and unnecessary assumption the consistency of the model is confirmed.

Response of Grip Force as Effect of Electrics Power Input at Gripper Actuator of NiTi SM495 Wire

2014 ◽  
Vol 493 ◽  
pp. 564-569
Author(s):  
Tjuk Oerbandono ◽  
Hari Budiarto
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Grip Force ◽  
Electrical Power ◽  
Power Input ◽  
Nickel Titanium ◽  
Robot Arm ◽  
Niti Wire ◽  
Electric Voltage ◽  
Power Grip

Gripper is mechanism that mounted on the end of the robot arm and used to hold an object and move it to a certain position. Generally, classical gripper is equipped with the driving motor (electric, pneumatic, fluid power) to move the gripper mechanism. In this research, the function of driving motor replaced with gripper motor actuators made of Shape Memory Alloys (SMA) of Nickel Titanium (NiTi) wire type SM495. Problem studied is response of grip force of gripper to varied electrics power input that given to the actuator of gripper made of NiTi SM495 wire. This is a real experimental research using parameters electrical power input which is obtained by varying the applied electric voltage 3, 6, 9, 12 Volt and constant electric current 5 A. Linear springs with various springs constants of 0.14 N/mm; 0.49 N/mm; 0.981 N/mm; 1.308 N /mm were used for measuring grip force of gripper. The obtained data then analyzed using statistics (analysis of variance). The results showed that the electrical power which given to the NiTi based actuator significantly influenced the grip force of gripper.Keywords: actuators, electric power, grip force, gripper, Nickel Titanium,Shape Memory Alloys, SM495 wire

A Thermodynamically Based Model of the Superelastic Behavior of Shape Memory Alloys Using a Discrete Preisach Model

2009 ◽  
Author(s):  
Srikrishna Doraiswamy ◽  
Mrinal Iyer ◽  
Arun R. Srinivasa ◽  
Srinivasan M. Sivakumar
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Vibration Control ◽  
Stress And Strain ◽  
Preisach Model ◽  
Thermomechanical Response ◽  
Superelastic Behavior ◽  
Seismic Applications

Shape Memory Alloys are increasingly being used in aeronautic [1], vibration control and seismic applications [2–6]. These applications require models that faithfully represent the full thermomechanical response of SMA wires but which at the same time are simple and fast to implement. In this paper we present a model for the superelastic behavior of Shape Memory Alloys that combines a thermodynamical framework with a Preisach model. This approach allows us to easily account for both stress and strain controlled responses as well as changes in termperature in a simple and straightforward way.

Thermomechanical Models for NiTi Shape Memory Alloys and Their Applications

2010 ◽  
Author(s):  
Petr Sedla´k ◽  
Miroslav Frost ◽  
Tarak Ben Zineb ◽  
Petr Sˇittner
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Material Model ◽  
Computational Time ◽  
Niti Wire ◽  
Macroscopic Models ◽  
Material Element ◽  
Niti Wires ◽  
Constitutive Material ◽  
Niti Shape Memory Alloys

Optimal design of SMA structures must be based on a deep knowledge of the material properties. As the SMA structures increase in complexity (stents, textiles, microdevices), modeling becomes increasingly involved. Macroscopic models of shape memory alloys are being developed with the ultimate aim to effectively simulate thermomechanical response of a constitutive material element. Computational robustness, stability, adaptability and reasonable computational time with respect to the modeling goal becomes however an issue which seems to play an ever increasing role. For instance, the non-proportional mechanical loading seems to be one of the most challenging issues for models of shape set wire structures as stents or textiles made of wires. Based on systematic experimental research of behavior of NiTi wires in uniaxial tension and tension-torsion tests, we discuss several weak aspects of the existing phenomenological models and describe here a SMA material model optimized for simulation of NiTi wire structures where combination of tension, torsion and bending strains dominate.

Constitutive equations for polycrystalline thermoelastic shape memory alloys.

1999 ◽  
Vol 36 (28) ◽  
pp. 4289-4315 ◽  
Author(s):  
N. Siredey ◽  
E. Patoor ◽  
M. Berveiller ◽  
A. Eberhardt
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Constitutive Equations
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