Transformation characteristics of shape memory alloy composites
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Shape memory alloy (SMA) composites are being used in an ever-expanding set of applications. For new applications, SMA composites are being developed incorporating a wide variety of matrices. The effect of these new compositions on the transformation behavior of the SMA inhomogeneities and on the effective composite behavior is explored here. An analytic methodology combining micromechanical methods with an SMA constitutive model is developed to determine the overall transformation properties of the composite. Specifically, the effective phase diagram, the effective transformation strains and the composite stress state before and after transformation are determined. The results obtained from the analyses of an SMA-ceramic composite show that after transformation the stress distribution between the two phases is modified such that the stress in the direction of applied loading in the SMA phase is reduced while the stress in the same direction in the ceramic phase increases. This stress redistribution decreases the local transformation strain in the direction of loading and results in an increase of the applied stress necessary to initiate and complete the forward and reverse transformation at a specific temperature. The effects of the elastic modulus of the matrix and volume fraction of the SMA inhomogeneities on the transformation behavior are explored through a parametric study to understand their influence on SMA composite design. 2011 IOP Publishing Ltd.
Smart Materials and Structures
author list (cited authors)
Lester, B. T., Chemisky, Y., & Lagoudas, D. C.