Numerical analysis of crack tip fields in interface fracture of SMA/elastic bi-materials

The problem of an interface crack between a shape memory alloy and an elastic layer is numerically addressed. The shape memory alloy behavior is modeled with a continuum thermodynamics based constitutive model embedded within the finite element method. With the help of the boundary layer approach, and the assumption of small scale transformation zone, the K-dominated region in the tip of the interface crack is loaded under general mixed-mode condition. Both slow and fast loading rates are considered to study the effects of thermo-mechanical coupling on the interface crack tip fields, especially the crack tip energy release rate within a history-dependent J-integral framework, the stress/strain curve during the loading process, and the shape and size of the transformation zone and the heated zone. A special effort is made to investigate how changing the rate of applied loading, the mode-mixity, and the material properties of SMA and elastic layer modify the crack tip fields.