Extraction of superelasticity parameter values from instrumented indentation via iterative FEM modelling

• Published in: Mechanics of materials Vol. 134; pp. 143 - 152
• Main Authors: Roberto-Pereira, FF, Campbell, JE, Dean, J, Clyne, TW
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2019
• Subjects: Finite element analysis; Indentation; Superelasticity; Superelasticity; Indentation; Finite element analysis
• ISSN: 0167-6636; 1872-7743
• DOI: 10.1016/j.mechmat.2019.04.007

•An iterative FEM procedure is described for extraction of SE parameters from instrumented indentation data.•The key issues that determine the reliability of the procedure are examined in detail.•Good agreement is obtained regarding the loading part of the stress-strain curve, but there are problems for unloading. This is caused by limitations to the constitutive law formulations currently available in commercial FEM packages. This paper concerns the use of (load-displacement) data obtained during spherical indentation of a superelastic (NiTi) alloy, so as to obtain a stress-strain curve. The methodology, which is already starting to become established for conventional plasticity, involves iterative FEM simulation of the indentation process, aiming to optimize agreement between modeled and measured outcomes (load-displacement plots in this case), by systematically varying the values of the parameters in a constitutive law. This worked well for the loading part of the stress-strain curve, but much more poorly for the unloading part. This inaccuracy is attributed to limitations in the standard representation (as implemented via the UMAT routine in ABAQUS) of the unloading part of the loop. A simple analytical formulation is proposed that might be suitable for future use in FEM software for simulation of superelastic deformation. [Display omitted]