A Homogenized Free Energy Model for Hysteresis in Thin-film Shape Memory Alloys

Abstract

Thin-film shape memory alloys (SMAs) have become excellent candidates for microactuator fabrication in MEMS due to their capability to achieve very high work densities, produce large deformations, and generate high stresses. In general, the material behavior of SMAs is nonlinear and hysteretic. To achieve the full potential of SMA actuators, it is necessary to develop models that characterize the nonlinearities and hysteresis inherent to the constituent materials. We develop a model that quantifies the nonlinearities and hysteresis inherent to SMAs. The model is based on free energy principles combined with stochastic homogenization techniques. The fully thermomechanical model predicts rate-dependent, polycrystalline SMA behavior, and it accommodates heat transfer issues pertinent to thin-film SMAs. We illustrate aspects of the model through comparison with thin-film SMA superelastic and shape memory effect hysteresis data.

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Document Details

Document Type
Technical Report
Publication Date
Jan 01, 2004
Accession Number
ADA453157

Entities

People

  • Jordan E. Massad
  • Ralph C. Smith

Organizations

  • North Carolina State University

Tags

Communities of Interest

  • Advanced Electronics
  • Energy and Power Technologies

DTIC Thesaurus Topics

  • Climate Change
  • Crystal Lattices
  • Crystal Structure
  • Crystals
  • Energy
  • Films
  • Free Energy
  • Heat Capacity
  • Heat Energy
  • Heat Transfer
  • Materials
  • Microelectromechanical Systems
  • Phase Transformations
  • Specific Heat
  • Stress Strain Relations
  • Thermodynamics
  • Thin Films

Readers

  • Computational Modeling and Simulation
  • Integrated Circuit Design and Technology.
  • Marine Propulsion Engineering and Naval Architecture