Week Four

As I've touched on briefly before, my research at UIUC deals with the use of textured surfaces to reduce friction and leakage in fluid power systems. The hope is to design and test small dimples that, when added to metal machine parts, improve lubrication and mechanical efficiency. For my project, we are studying the impacts of three different metal plates: one is entirely flat, which we use for our control, one has "linear slope depth" dimples, and one has "symmetric depth" dimples (see my diagram to understand the difference in dimple shape). We use each of these plates in a rheometer, which is a machine that allows us to load samples of various fluids, apply a particular shear rate, and measure quantities such as the viscosity, shear stress, or axial force production.

At the moment, we are running tests with three different oils of varying viscosities and looking for a reduction in shear stress with the addition of the various textures. Since shear stress is given by the product of viscosity and shear rate (and we are controlling shear rate with the rheometer), a reduction in shear stress implies a proportionally reduced viscosity. Of course, all of our tests so far have been performed on Newtonian fluids at a constant temperature, so it would be impossible for the viscosity to actually have decreased, but what this means is that our textures are reducing friction in such a way that the rheometer believes it is dealing with a less viscous sample than in actuality; it is applying a smaller torque to spin the fluid the same amount.

That was a bit of a crash course in the project, but it is much more straightforward and easy to understand when you actually see the rheometer. The main idea, however, is that surface textures of various shapes can be used to induce slippage--and thereby reduce friction--between the oil and the metal plate. The impact of this in fluid power applications is that the lower friction would preserve the life of metal parts and the reduction in frictional energy loss would enable systems to run more efficiently. Thus, my project's overarching goal is to find a way to improve the machine parts that many of your projects then employ towards solving real-world problems.

Hope you all are enjoying your work, and I'm looking forward to reading more about each of your projects!

Nikita

P.S. Donny, I thought you should know that your flip phone has officially outlived mine; little guy's heart finally gave out last night when I tried to charge him. Cherish every moment with yours while you still can.