Development of a Novel Evaluation Method for the Extension of the Oliver-Pharr Instrumented Indentation Test to the Macro-Scale Range
Year: 2026
Type: conference-paper
Abstract: Instrumented Indentation Testing (IIT) and the Oliver-Pharr evaluation method are widely employed in the nano-and micro-scale domains. However, their extension to the macro-scale measurement range encounters substantial challenges. Under high loads, the elastic deformation of the testing machine frame (machine stiffness) significantly distorts the measured indentation depth, leading to an artificial underestimation of hardness. This paper presents a novel, automated, Python-based evaluation algorithm that isolates frame deformation from actual indentation in the specimen during cyclic loading-unloading sequences. Creep effects occurring at maximum load are eliminated by fitting a linear regression to the upper 92%-76% segment of the unloading curve, after which contact depth and contact stiffness are corrected by applying an exponential machine stiffness function. The results demonstrate that the proposed algorithm successfully compensates for frame elongation and provides stable Vickers hardness (HV) values that are in practical agreement with the reference hardness block throughout the entire investigated load range (20 N-960 N).
Institution: Obuda University
Language: English
Subfield: Mechanics of Materials
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
OpenAlex ID: W7204194158