Finite element simulation of the effect of different initial contact on nano-indentation

To effectively estimate the test deviation of nano-indentation due to surface roughness, a finite element simulation of nano-indentation is carried on pure aluminium. A two dimension model is adopted and the maximum height Ry of the model contour is regarded as the assessment of the sample surface roughness parameters. Parameter D represents the horizontal distance between the peaks and valleys of the contour. The angle θ between the valley's midperpendicular and the tangent of adjacent convex is introduced. Compared with the smooth surface, for different initial contact, simulation results show obvious diversity: for initial contact at the peak of the rough surface, the maximum load is smaller; for initial contact at the valley of the rough surface, the maximum load is bigger; for initial contact at the edge of indenter and the bulge of the contour, the result is relatively close to the smooth one.