Central film thickness in EHL point contacts under pure impact revisited

Squeeze effects in elastohydrodynamic lubrication are extremely general, however, their contribution to film formation is difficult to quantify. Full numerical solutions allow one to assess the importance of the transient terms, but simple equations to predict the transient film thickness do not exist. The current paper analyses the film thickness generated by an impacting ball. The problem is first studied assuming isoviscous elastic lubrication. It is shown that the film thickness evolution depends on a single parameter. Similarly, the central film thickness in a piezoviscous elastic impact problem is shown to depend on two parameters. These results are presented in the form of a single graph and two curve fitted solutions are supplied.