Title page for ETD etd-06032013-114013

Type of Document Master's Thesis
Author Malladi, Vijaya Venkata Narasimha Sriram
Author's Email Address sriram@vt.edu
URN etd-06032013-114013
Title Development and Design of Self-Sensing SMAs using Thermoelectric Effect
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Pablo A. Tarazaga Committee Chair
Andrew J. Kurdila Committee Member
Daniel J. Inman Committee Member
  • ANN
  • Postion Control
  • Seebeck Coefficient
  • Thermoelectric Effects
  • Sensorless Control
  • Shape Memory Alloys
Date of Defense 2013-05-20
Availability unrestricted
Active research of SMAs has shown that its Seebeck coefficient is sensitive to its martensitic phase transformation and has the potential to determine the SMAs state of transformation. The combination of Shape Memory Alloys, which have a positive Seebeck coefficient, and Constantan which has a negative Seebeck coefficient (-35 mV/K) results in a thermocouple capable of measuring temperature. The work presented in this thesis is based on the development and design of this sensor.

This sensor is used to study the hysteretic behaviour of SMAs. Although Shape Memory Alloys (SMAs) exhibit a myriad of nonlinearities, SMAs show two major types of nonlinear hysteresis. During cyclic loading of the SMAs, it is observed that one type of hysteretic behavior depends on the rate of heating the SMAs, whilst the variation of maximum temperature of an SMA in each cycle results in the other hysteretic behavior. This later hysteretic behavior gives rise to major and minor nonlinear loops of SMAs. The present work analyzes the nonlinearities of hysteretic envelopes which gives the different maximum temperatures reached for each hysteretic cycle with respect to stress and strain of the SMA. This work then models this behavior using Adaptive Neuro Fuzzy Inference System (ANFIS) and compares it to experimental results. The nonlinear learning and adaptation of ANFIS architecture makes it suitable to model the temperature path hysteresis of SMAs.

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