Simulation of the response and evolution of localization in pseudoelastic NiTi tubes under biaxial stress states

• Published in: International journal of plasticity 2022-04, Vol.151, p.103179, Article 103179
• Main Authors: Kazinakis, Karlos, Kyriakides, Stelios, Landis, Chad M.
• Format: Article
• Language: English
• Subjects: Anisotropy; Axial forces; Axial stress; Biaxial stress; Combined internal pressure-axial load; Constitutive models; Energy dissipation; Evolution; Finite element method; Hardening; Inhomogeneity; Inhomogeneous deformation; Intermetallic compounds; Internal pressure; Localization; Mathematical models; Modeling; Nickel titanides; NiTi tubes; Phase transitions; Pseudoelasticity; Simulation; Strain; Stress ratio; Tubes
• ISSN: 0749-6419; 1879-2154
• DOI: 10.1016/j.ijplas.2021.103179

•Shape memory alloy tubes under combined axial load and internal pressure.•Constitutive modeling of phase transformation for pseudoelastic behavior.•Modeling incorporates tension/compression asymmetry and anisotropy.•Simulation of helical localization patterns for a range of biaxial stress ratios. The well-known tension/compression asymmetry exhibited by nearly equiatomic NiTi has been previously modeled using a hardening potential for compression and a partially softening one for tension to represent pseudoelastic phase transformations (Jiang et al., 2016b). The present study first extends this constitutive model to include anisotropy revealed in the combined axial force-internal pressure experiments on NiTi tubes of Bechle and Kyriakides (2016a). The model is then calibrated anew, implemented in a finite element analysis of tubes and used to simulate the entire range of biaxial experiments performed. Overall, the simulations reproduce well the stress-average strain hystereses and the transformation stress loci, while for hoop dominant stress paths the extents of the transformation strains are somewhat over-predicted. The evolution of localization in the form of high or low strain helical bands, the variation of helix angles with respect to the stress ratio, and the dissipated energy compare favorably. The hardening response and essentially homogeneous deformation exhibited in the neighborhood of the equibiaxial stress state is reproduced, but with reduced hardening and mild inhomogeneity. Despite some minor differences, the results demonstrate the overall success of the analysis in reproducing the phenomena-rich behavior exhibited by tubular NiTi structures under biaxial loadings.