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A Free Energy Model for the Inner Loop Behavior of Pseudoelastic Shape Memory Alloys

Published online by Cambridge University Press:  01 February 2011

Olaf Heintze
Affiliation:
Dept. Mech. & Aero. Eng. Campus Box 7910, 3211 Broughton Hall, North Carolina State Univ., Raleigh, NC 27695-7910
Stefan Seelecke
Affiliation:
Dept. Mech. & Aero. Eng. Campus Box 7910, 3211 Broughton Hall, North Carolina State Univ., Raleigh, NC 27695-7910
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Abstract

The paper presents a free energy model for the pseudoelastic behavior of shape memory alloys. It is based on a stochastic homogenization process, which uses distributions in energy barriers and internal stresses to represent effects typically encountered in polycrystalline materials. This concept leads to a realistic desription of the rate-dependent inner loop behavior, but is characterized by rather long computation times. This is prohibitive in regard to a potential implementation into other numerical codes, such as finite element or optimal control programs or a Matlab/Simulink environment. For this purpose a parameterization method is introduced, which is derived from the concept of a representative single crystal. The approach preserves the desirable properties of the original formulation, at the same time reducing the numerical effort significantly. Finally, we show that the method can reproduce the experimentally observed behavior accurately over a large range of strain rates including the minor loop behavior.

Type
Research Article
Copyright
Copyright © Materials Research Society 2005

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