Indentation of a plastically deforming metal crystal with a self-affine rigid surface: A dislocation dynamics study
Indentation of a plastically deforming metal crystal with a self-affine rigid surface: A dislocation dynamics study
复制标题
具有自仿射刚性表面的塑性变形金属晶体的压痕：位错动力学研究
DOI：
10.1016/j.actamat.2018.10.020
复制
发表时间：
2019
期刊：
影响因子：
9.4
通讯作者：
L. Nicola
中科院分区：
文献类型：
--
作者：
S. P. Venugopalan;L. Nicola
虽然自仿射粗压头对弹性体的压痕已经进行了广泛的研究，但迄今为止对塑性的研究还很少。这主要是因为建模可塑性以及与自仿射粗糙表面的接触在计算上相当具有挑战性。在这里，我们通过使用格林函数位错动力学成功地实现了这一目标，该动力学允许使用波长从5 nm到100 μ m描述自仿射粗糙表面，这项工作的目的是了解塑性变形如何影响接触面积，接触压力和硬度，间隙轮廓和亚表面应力，同时压头粗糙度发生变化。对于具有较大均方根高度和/或赫斯特指数的压头，发现塑性变形更为明显，并且与尺寸有关。后者意味着不可能像在弹性接触问题中通常所做的那样对可观测值进行缩放。此外，在给定的压痕深度（干涉）下，接触面积比相应的弹性接触问题小，但间隙闭合更明显。发现接触硬度比经典塑性研究报告的大得多。这主要是由于位错可用性有限造成的，因此变形晶体的刚度介于线弹性和完全弹塑性材料之间。在计算硬度和标称接触压力时，没有必要在表面描述中包括非常小的波长，因为在给定波长以下，次表面应力对实际接触面积的进一步减小是不变的。对于弹性材料和塑性材料都是如此。考虑小波长反而需要准确捕获粗化和接触应力分布。
Although indentation of elastic bodies by self-affine rough indenters has been studied extensively, little attention has so far been devoted to plasticity. This is mostly because modeling plasticity as well as contact with a self-affine rough surface is computationally quite challenging. Here, we succeed in achieving this goal by using Green's function dislocation dynamics, which allows to describe the self-affine rough surface using wavelengths spanning from 5 nm to 100 μ m. The aim of this work is to gain understanding in how plastic deformation affects the contact area, contact pressure and hardness, gap profile and subsurface stresses, while the roughness of the indenter is changed. Plastic deformation is found to be more pronounced for indenters with larger root-mean-square height and/or Hurst exponent, and to be size dependent. The latter means that it is not possible to scale observables, as typically done in elastic contact problems. Also, at a given indentation depth (interference) the contact area is smaller than for the corresponding elastic contact problem, but gap closure is more pronounced. Contact hardness is found to be much larger than what reported by classical plasticity studies. Primarily, this is caused by limited dislocation availability, for which the stiffness of the deforming crystal is in between that of a linear elastic and an elastic-perfectly plastic material. When calculating hardness and nominal contact pressure, including very small wavelength in the description of the surface is not necessary, because below a given wavelength the subsurface stresses become invariant to a further decrease in true contact area. This is true for both elastic and plastic materials. Considering small wavelengths is instead required to capture accurately roughening and contact stress distribution.
影响因子：
3.2
作者：
Mueser, Martin H.;Dapp, Wolf B.;Greenwood, James A.
通讯作者：
Greenwood, James A.