پياده سازي رفتار الكتروترموديناميكي سيم هاي آلياژ حافظه دار در نرم افزار ABAQUS

چكيده انگليسي :

Implementation of Electro thermo mechanical Behavior of Shape Memory Alloy Wires in ABAQUS Software Amin Alipour amin alipour@me iut ac ir July 24 2013 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor M Kadkhodaei Assist Prof kadkhodaei@cc iut ac irAbstractShape memory alloys SMAs are a subset of broad class of smart materials which exhibit unique properties ofshape memory effect and pseudoelasticity superelasticity Shape memory effect is the capability to recoverapparently permanent strains upon heating while superelasticity is the ability to recover very large strains up to8 during a mechanical loading unloading cycle The unique properties of shape memory and superelasticity aredue to a solid state martensitic transformation from a high symmetry high temperature phase known as austenite toa low temperature low symmetry martensite phase These recently revealed materials also benefit from otherproperties such as high force to weight ratio biocompatibility silent response smooth and lifelike operations whichcause them to gain an immense attention in many real life engineering applications from biomedical to aerospacefields Although they can be manufactured in different shapes SMAs are mainly used in the form of wire or ribbon Therefore 1 D simulation of SMAs is usually required in the investigation of real life problems Many constitutivemodels have been presented for SMAs by researchers since the last three decades and different numericalapproaches for the implementation of these models have been so far proposed Most of the existing solutions areonly applicable for SMA wires lonely or for particular simple types of structures consisting SMA wires Since smartstructures consisting SMA wires are various and complicated these special case studies are no longer effective insuch cases Beside these case studies there are also a few general works showing several drawbacks In the present study in order to provide a general solution a common 1 D constitutive model for SMAs capturingboth pseudoelasticity and shape memory effect was implemented into ABAQUS commercial finite element packagevia a user material subroutine UMAT One of the main benefits of this 1 D thermomechanical UMAT is itscapability to investigate any complex mechanical as well as thermal loading path Hence it can be utilized in finiteelement simulation of any complicated smart structure consisting of SMA wires Moreover this proposed UMATcan be employed in studying the static coupled thermomechanical dynamic and coupled electrothermomechanicalbehavior of SMAs In order to validate the proposed numerical approach its predictions were shown to be in a goodagreement with those obtained from analytical experimental and other approved numerical solutions under differentthermomechanical loading and boundary conditions The effect of heating rate conductive and convectivecoefficients on the actuation response of SMA actuators in static condition was investigated Also it was shown thatwhen mechanical loadings are applied relatively fast the isothermal assumption would be no longer valid and asloading rate increases thermal effects can lead to very different transformation characteristics In this case thetemperature variation is dependent on factors such as strain rate convective coefficient and wire diameter Moreover the influence of the latent heat of transformation on the performance of SMA actuators was numericallyexplored and it was demonstrated that the latent heat will decrease the resultant actuation due to reduced martensitictransformation Finally the electrothermomechanical behavior and the effective parameters in this case were studied It was shown that if the electrical resistivity assumed to be constant and equal to its martensitic value the resultingtemperature rise will be slower KeywordsSMA wire electrothermomechacial behavior Finite Element simulation ABAQUS subroutine

علي پور، امين

پياده سازي رفتار الكتروترموديناميكي سيم هاي آلياژ حافظه دار در نرم افزار ABAQUS

رفتار الكتروترموديناميكي , شبيه سازي اجزاي محدود , آباكوس , زير برنامه