与冲蚀有关的粘着与犁沟摩擦系数

提出一种与冲击磨损有关的有效摩擦系数，它被定义为冲击过程中，每一瞬间的切向有效摩擦力与法向载荷之比．有效摩擦力被表示为剪切项与犁沟项之组合．剪切项依赖于剪切金屑接合点的状态——滑移或滚动．犁沟项依赖于冲击物在冲击途中使靶材料发生移动的状态．此有效摩擦系数被应用于研究刚性球自由斜冲击延性靶问题．在忽略剪切项仅计及犁沟项的情况下，研究表明，Hutchings实验中的有效冲击摩擦系数是冲击过程与初始冲击角的函数，就时间平均而言，大于Hutchins为拟合计算与实验结果所取的摩擦系数常值0.05．有迹象表明，对于与固粒延性冲蚀有关的刚性球自由斜冲击延性靶问题，在一定条件下，有效摩擦系数主要由犁沟效应确定．

FRICTION COEFFICIENT CAUSED BY ADHESION AND PLOUGHING RELEVANT TO IMPACT WEAR

An effective friction coefficient relevant to impact wear is defined as the ratio of the effective friction force in the tangential direction to the load in normal direction at each instant. The effective friction force is expressed as a combination of shearing term and ploughing term. The shearing term is dependent on the state of shearing the metallic junction by sliding or rolling and the ploughing term on the state of dragging the material ahead of the particle. In the case of continuous sliding with negligible ploughing term, the effective friction coefficient is estimated at 0.17-0.30 if Tresca's yielding criteria and Tabor law are applied. When the adhesion of sliding metals is negligible, the effective friction coefficient is (1.04-1.8) A'/A if Tabor law is also applied, where A' and A are the cross-section of the torn track and the real area of contact, respectively. The effective friction coefficient is applied to the study of the oblique impact of a rigid sphere against a ductile solid. By neglecting the shearing term, we have indicated that for Hutchings' experiments, a merely ploughing causes the effective friction coefficient to be a function of the impact process' and the initial impact angle and on an average greater than 0.05 which was used in all of the calculations by Hutchings for consistency with both experiments and calculations. In certain cases, it is suggested that the effective friction coefficient for the oblique impact of a free sphere against a ductile solid relevant to impact wear is determined, primarily, by ploughing.