Measuring Microscale In-Plane Indentation Displacement Field for Material Characterization

초록

A method measuring microscale in-plane indentation displacement field uion the indented specimen surface is proposed by utilizing an optical flow (OF) algorithm. With images taken before and after indentation test, the calculated displacement field containing noise (uo) is computed using the OF algorithm. Due to the microvibration and the repositioningerror after indentation test, the originally calculated uocontainsthe displacement error ue. Thus, ueis corrected using the origin-symmetric condition of indentation displacement field formed by the axisymmetric indenter. The effect of the grain size and the surface roughness of specimen on the uifield are alsoinvestigated. The corrected uifields from the indentation tests for various materials (steel, copper, and aluminum) are verified by comparing to the indentation finite element analysis (FEA).After correcting the error ue, the average correlation coefficientR2between the displacement curve uifrom the OF and the indentation FEA is 99% for all materials. Finally, it is concluded that the proposed method can measure the accurate in-plane in dentation displacement field uion a microscale.

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