Exploitation of static and dynamic methods for the analysis of themechanical nanoproperties of polymethylmetacrylate by indentation

摘要

Elaborating an instrumented nanoindentation is to exercise nondestructive tests to be applied to volumes of polymethylmetacrylate (PMMA)materials in miniature. This work focuses on factors that explain the trendsvariation of mechanical properties like Young's modulus (E), contact hardness(H) and indentation force (P). The evolution of E and H with depth (h) and Pshows a 2.77 nm inflection point at low penetrations, separating two zones:the first increasing and the second decreasing. This is respectively explainedby the surface hardening induced by preparing the material surface, and theexistence of a surface hardness gradient denoted by an indentation size effect(ISE) observed at very low depths. Moreover, In addition, a criticalpenetration depth of 9.71 nm below which the surface effect dominates thevariation of the penetrating load is detected. E and H results differencesbetween dynamic and static modes are 8.46% and 6.44% inducing anoverestimation of 35 MPa in E value, and an underestimation of 1.23 MPa inH value. This tends to affect the expected nanoscale precision of theindentation to determine the nanomechanical properties of PMMA. .