不同接触零点对纳米压痕测试影响的有限元解析

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

为了有效估计由于粗糙度因素造成纳米压痕测试结果的偏差,对纯铝的纳米压痕进行了有限元仿真研究。利用二维轮廓模型,采用模型轮廓最大高度Ry作为评定样品表面粗糙度的参数,并引入轮廓的波峰与波谷之间的水平距离D和波谷的中垂线与相邻凸面切线之间的夹角θ。仿真发现:相比光滑表面,在不同的接触零点,测试结果存在差异:接触零点为粗糙表面波峰时,最大载荷测试结果偏小;接触零点为粗糙表面波谷时,最大载荷测试结果偏大;压头压向波谷,压头棱边与凸起接触为接触零点时,测试结果引起的偏差相对较小。

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.