Thinking about crossheads, it seems to me that we’d like to have an oil that gets a little bit more viscous when it experiences less shear: when it is supporting a bearing that is changing from hydrodynamic behavior to hydrostatic behavior (midstroke at the con-rod top end or TDC and BDC on the guide shoes); and transition back when the behavior goes the other way. Newtonian fluids wont do that, and dilatant fluids make it much worse. So I’m wondering about pseudoplastic fluids. I got a book on tribology from the library, but it doesn’t go into any detail except to show the following graph.
Since the speed of the bearing surfaces relative to each other is also changing, I don’t know how useful this representation is. Based on what I’ve gleaned from the Internet, pseudoplastic fluids are often those which contain polymers, and polymers are an additive to some lube oils… but I haven’t been able to find anyone who says, “Polymers are added to lube oils in order to give them pseudoplastic fluid characteristics to cope with the change from hydrodynamic bearing support to hydrostatic bearing support.”
I’m wondering if you all could let me pick your brains on the topic, or direct me to better resources than I have thusfar been able to find.