Micromechanical Modeling and Analysis of Shape Memory Alloy Composite Materials at Different Scales
Dimitris Lagoudas (Texas A&M - Aerospace Eng.), Brian Lester (Texas A&M - Aerospace Eng.), Austin Cox (Texas A&M - Aerospace Eng.), Theocharis Baxevanis (Texas A&M - Aerospace Eng.)
Prager Medal Symposium in honor of George Weng: Micromechanics, Composites and Multifunctional Materials
Mon 9:00 - 10:30
MacMillan 117
The micromechanics of non-linear materials, especially multifunctional materials like shape memory alloys (SMAs), has been an area of active research in recent decades. SMAs exhibit a hysteretic response associated with a thermomechanically coupled reversible martensitic transformation. This coupling gives rise to the multifunctional aspect as transformation may be induced through thermal or mechanical loadings - the shape memory effect and pseudoelasticity, respectively. These behaviors result in large, reversible deformations and a change in elastic properties. In composites, these characteristics yield a variety of interesting applications at both the macro and microstructural scales. Micromechanical methods provide an attractive basis for analyzing both of these scales as they provide a way to optimize the associated responses. In this work, these approaches are used to investigate SMA composites at two scales. First, the role of precipitates in NiTi on the bulk behavior is considered. Specifically, a computational model of the precipitate and surrounding SMA matrix is developed. In addition to differences in the constitutive responses, coherency and compositional effects are considered. The role of single and multiple precipitates is studied and the influence on the response of the bulk SMA response determined. At the larger scale, a SMA-MAX phase ceramic composite is considered. These two inelastic constituents are considered to take advantage of the interaction of the SMA martensitic transformation with the irrecoverable deformations of the MAX phases associated with kink band formation. Through this combination, it is intended that a compressive residual stress may be developed in the ceramic phase to take advantage of superior mechanical responses. The micromechanics of these residual stresses are explored through a computational model of the system and their development demonstrated.