プラスチックスの摩擦と変形

第1報:静的接触におけるプラスチックスの変形

抄録

Diameter of contact circle and deformation of plastic surface neighbouring the contact region between a glass hemisphere and a flat plate of plastic are measured by observing Newton's rings. The cube of diameter of contact circle is proportional to the load and radius of curvature. It is, therefore, verified that Hertz's equation for elastic contact is applicable to plastics. However, in a wide range of time of loading, it is indicated that Young's modulus in Hertz's equation is also dependent upon the load as well as the time of loading.
It is found that a wave-like deformation takes place on the surface of plastics neighbouring contact region. The surface deformation extends to a considerable large distance from contact region as compared with the radius of contact circle. It seems that the size of surface deformation increases with load W in proportional to W^2/3. An application of tangential force increases the size of surface deformation on one side of contact region and decreases on the other side. When the applied tangential force is 80_??_90 percent of the maximum static friction, the height from the position of contact circle to the deformed surface of plastic reaches one-half of or over the amount of contact depth.
In applying the tangential force smaller than the maximum static friction, it is observed that the abrupt slip does not occur, but a very slow slip occurs.