Conference Dates
October 4-9, 2015
Abstract
Indentation is one of the most widely used techniques for determination of mechanical properties of materials. Many various methods for extraction of mechanical properties had been introduced for elasto-plastic materials. Later, the use of microindentation were extended to composite, porous, anisotropic and multi-phase materials. Use of microindentation for determination of such materials properties is impeded due to its complex behavior and larger number of material properties’ constants.
This work is focused on indentation of superelastic materials with austenite - martensite phase transformation and extraction of material properties. Finite element (FE) modeling was used to model indentation of superelastic alloys with Berkovich indenter. Several series of simulations were calculated with different elastic modulus of austenite and martensitic phases, stresses of phase transition in both directions. It is possible to create a method for determining mechanical characteristics of superelastic alloys using results of various materials’ simulations. Elasto-plastic material usually can be described with three constants: Young modulus, yield stress, strain-hardening exponent. Unlike elasto-plastic materials, superelastic materials have a larger number of properties due to their complex behavior. It includes stress of austenite transformation start and finish, stress of martensitic transformation start and finish, elastic modulus of austenite and martensitic phases, maximum transformation strain. Presence of many additional materials’ constant make the problem of determination of its determination much harder.
Several works exist that are proposing method for determination of phase transformation stresses [1] or elastic modulus of two phases (similar to Olive-Pharr method) [2] using spherical indenter. Yet, elastic modulus and transformation stress are found to make similar effect on indentation results. That being the case, the united method requires processing and determination of mechanical properties of superelastic by indentation.
Recommended Citation
[1] Yan, Wenyi, et al. "Determination of transformation stresses of shape memory alloy thin films: a method based on spherical indentation." Applied physics letters 88.24 (2006): 241912. [2] Kan, Qianhua, et al. "Oliver–Pharr indentation method in determining elastic moduli of shape memory alloys—A phase transformable material." Journal of the Mechanics and Physics of Solids 61.10 (2013): 2015-2033.