Thermomechanical cyclic loading and fatigue life characterization of nickel rich NiTi shape-memory alloy actuators Conference Paper uri icon

abstract

  • Within the last decade, the development of compact SMA actuators has led to the design of smart structures such as the Variable Geometry Chevron (VGC), designed by Boeing engineers. The chevrons are aerodynamic devices actuated by SMA beam actuators and placed along the trailing edge of a jet engine to provide noise reduction. The SMA actuators are clamped on an elastic substrate that provides a biasing force allowing repeated one-way shape memory effect under cyclic thermal actuation. In this work, a comprehensive characterization of thermally induced fatigue behavior of nickel-rich NiTi SMA actuators subject to different constant applied stresses is presented. The influence of various parameters is studied in order to assess the fatigue behavior of nickel-rich NiTi, namely: two heat treatments, two heat treatment environments, three fatigue test specimen thicknesses and four stress levels. The purpose of this thermomechanical fatigue study is to evaluate the shape recovery stability, the influence of large applied stresses, the amount of permanent deformation and the resulting failure mechanisms. Fatigue limits of 5,000 to 60,000 cycles were found for applied stress levels ranging from 250 MPa to 100 MPa.

name of conference

  • The 15th International Symposium on: Smart Structures and Materials & Nondestructive Evaluation and Health Monitoring

published proceedings

  • Behavior and Mechanics of Multifunctional and Composite Materials 2008

author list (cited authors)

  • Bertacchini, O. W., Lagoudas, D. C., Calkins, F. T., & Mabe, J. H.

editor list (cited editors)

  • Dapino, M. J., & Ounaies, Z.

publication date

  • January 1, 2008 11:11 AM

publisher