双粗糙表面接触模型中微观摩擦系数的确定

通过考察双粗糙表面接触模型中微观摩擦系数的取值对接触表面的法向变形与法向载荷关系的影响,研究了磨削表面接触模型中微观摩擦系数的取值问题。采用表面轮廓仪测量磨削表面的轮廓数据,然后建立二维弹塑性有限元模型,计算不同微观摩擦系数时试样的法向变形与法向载荷关系。计算结果表明,接触表面间的微观摩擦系数对低面压下的接触变形影响比较大,载荷比较高的时候,摩擦系数的取值并不显著影响接触变形。在微观摩擦系数不为零时,法向变形与法向载荷关系曲线存在一个下陷区,摩擦系数越小,下陷区越小。与实验结果对比,发现忽略摩擦系数的计算结果与通过实验获得的法向变形与法向载荷关系最为接近,双粗糙表面接触模型中忽略微观摩擦系数比较合适。此外还根据计算结果研究了微观摩擦系数的取值对最高接触应力和真实接触面积的影响,发现忽略微观摩擦时,接触应力水平降低,真实接触面积有减小的趋势。

Determination of Microcosmic Friction Coefficient in Contact Model of Double Rough Surfaces

The problem of value determination of microcosmic friction coefficient in contact model of ground surface is studied by means of analysis of influence upon microcosmic friction coefficient on relation between normal deformation and normal load in the contact model of double rough surfaces.Data of surface profile obtained by surface profiler are adopted and then two dimension model based on finite element method is built to calculate relation between normal deformation and normal load in samples of different microcosmic coefficients.Computation results show that microcosmic friction coefficient between two contact surfaces markedly influences contact deformation under low pressure but microcosmic friction coefficient hardly influences contact deformation under high pressure.When microcosmic friction coefficient is not equal to zero,there exists a subsidence range in curve of relation between normal deformation and normal load,and the subsidence range is small when friction coefficient is lower.By comparison with trial result of relation between normal deformation and normal load,computation results ignoring friction coefficient is closest to trial result.Therefore,in contact model of double rough surfaces,microcosmic friction coefficient should be ignored.Moreover,by means of analysis of numerical computation,influence of microcosmic friction coefficient is studied on the highest contact stress and real contact area.Level of contact stress and real contact area are decreased in tendency when microcosmic friction is ignored.