Use this URL to cite or link to this record in EThOS: https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.767896
Title: Extraction of superelastic parameter values from instrumented indentation data
Author: Roberto-Pereira, Francisco Fernando
ISNI:       0000 0004 7651 4868
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2019
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Abstract:
Interest in superelastic (and shape memory) materials continues to rise, and there is a strong incentive to develop techniques for monitoring of their superelastic characteristics. This is conventionally done via uniaxial testing, but there are many advantages to having a capability for obtaining these characteristics (in the form of parameter values in a constitutive law) via indentation testing. Specimens can then be small, require minimal preparation and be obtainable from components in service. Interrogation of small volumes also allows mapping of properties over a surface. On the other hand, the tested volume must be large enough for its response to be representative of behaviour. Precisely the same arguments apply to more "mainstream" mechanical properties, such as yielding and work hardening characteristics. Indeed, there has been considerable progress in that area recently, using FEM simulation to predict indentation outcomes, evaluating the "goodness of fit" for particular sets of parameter values and converging on a best-fit combination. A similar approach can be used to obtain superelastic parameters, but little work has been done hitherto on sensitivities, uniqueness characteristics or optimal methodologies and the procedures are complicated by limitations to the constitutive laws in current use. The current work presents a comprehensive examination of the issues involved, using experimental (uniaxial and indentation) data for a NiTi Shape Memory Alloy. It was found that it is possible to obtain the superelastic parameter values using a single indenter shape (spherical). Information is also presented on sensitivities and the probable reliability of such parameters obtained in this way for an unknown material.
Supervisor: Clyne, Trevor William Sponsor: National Council for Scientific and Technological Development (CNPq) - Brazil
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.767896  DOI:
Keywords: NiTi ; FEM Simulation ; Superelastic Parameter Values ; Indentation
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