PSI - Issue 28

Konstantinos Tserpes et al. / Procedia Structural Integrity 28 (2020) 1644–1649 Tserpes, Bazios, Pantelakis, Michailidis / Structural Integrity Procedia 00 (2019) 000–000

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Fig. 1. The nanoindentation testing apparatus

3. Numerical model FE simulation of the nanoindentation test was performed using the Abaqus CAE (Computer Aided Engineering) modeling software. The model consists of two objects, a representative pyramidal indenter with the real dimensions of the Berkovich indenter and an orthogonal solid representing the specimen. The dimensions of the solid are 5 μm × 5 μm × 3 μm. The dimensions of the indenter are shown in Fig. 2. The indenter was modeled as a rigid solid. The definition of elastic-plastic response of the solid was realized by using an innovative nanoscale numerical model (Bazios, Tserpes and Pantelakis, 2019; Bazios, Tserpes and Pantelakis, 2020). Appropriate surface-to-surface frictional contact interactions with a coefficient of friction of 0.1 were applied to the indent model. The indented material was meshed with 62.000 hexahedral elements of type C3D8R (eight node) with a similar heavy bias towards the region of the sample directly beneath the indenter tip. A typical FE mesh of the solid specimen and the indenter are illustrated in Fig. 3.

Fig. 2. The dimensions of the indenter modeled.

Fig. 3. A typical FE mesh of the solid specimen and the indenter. In the loading phase, the indenter penetrates the specimen with a constant velocity of 5.5 nm/s until it reaches the pre-determined depth of 250 nm. In the unloading stage, the indenter is pulled out from the specimen with a constant