The pressure-viscosity coefficient for Newtonian EHL film thiickness with general piezoviscous response

There has been a long-standing need for a piezoviscous parameter, α _film, that together with the ambient viscosity, μ ₀, will completely quantify the Newtonian rheology so that the film thickness for liquids that do not shear-thin in the inlet may be calculated as h = h (μ ₀, α _film,...) regardless of the details of the pressure-viscosity response. It seems that Blok's reciprocal asymptotic isoviscous pressure, α*, has certain advantages over the conventional pressure-viscosity coefficient that is poorly suited for this purpose. The first detailed review of piezoviscous models for low pressures is provided. A simulation code that is apparently stable for all realistic pressure-viscosity response was utilized with diverse piezoviscous models and model liquids to develop a satisfactory definition of α _film that reads α _film = [1-exp(-3)]/[∫ ₀ ^3/α* μ(0) dp/μ(p)]; 1/α*= ∫ ₀ ^∞ μ(0)dp/μ(p). In the case of μ = μ ₀ exp(αp), α _film = α and formulas are provided for other models.