We usually think of hydrogels as slippery and wet — that’s their definition! But if a probe pushes on them to a higher pressure before applying lateral slip, that high pressure causes unstable friction, or stick-slip (just like the elastomer in our prior post!). So even inherently low-friction materials relieve interfacial strain in extreme ways. […]
Last year I had the privilege of hosting the now Dr. Chao Wang in my lab to use our optical in situ microtribometer to study the stick-slip behavior of seal elastomers. He obtained a supporting fellowship from the Austrian Marshall Plan Foundation, and used this work toward his PhD in Polymer Tribology from Montanuniversität Leoben. […]
We’ve had a bit of a hiatus in publicizing our work, but we’re back! The first big congratulations goes to Jiho, who defended his dissertation in the middle of a raging worldwide pandemic. He successfully presented from his residence, his dissertation entitled “SOFT HYDRATED SLIDING INTERFACES AS COMPLEX FLUIDS.” Jiho moved very quickly to a […]
The more you learn about hydrogels, the weirder they become. They take their shape from water, but act as a brittle solid when you try to break them in your hands. However, they are also quite stretchy. These contradictions are sorted out a bit in Shab’s new paper “Brittle or Ductile? Abrasive Wear of Polyacrylamide […]
Microindentation is a useful technique for assessing the local properties of soft materials. But applying an appropriate contact model and extracting those properties is a more complex matter, especially for anisotropic biological tissues like tendon. Do not despair! Jiho worked with the Wagoner Johnson Lab to demonstrate the elliptical contact areas between a spherical probe […]
Insects did it first! Inspired by beetle iridescence and a scientist who has studied them (Ainsley Seago), the ABC Lab, the INHS Insect Collection, and the Materials Tribology Lab teamed up to study the multifunctionality of insect cuticle. Back down the evolutionary tree of beetles, some species developed iridescent cuticle, and others did not. This […]
Shab gave a nice presentation yesterday on “Wear mechanisms of chemically and physically crosslinked hydrogels under mild abrasions.” Congrats to entering the final phase!
As soft robots are the new normal, polydimethylsiloxane, or PDMS, is becoming ubiquitious in labs. You know it as the material that makes “sticky hands” you throw against the wall, and it can be a clear, or slightly cloudy (turbid) soft solid. It can be molded into any shape conceivable, especially shapes with more than […]
Shab’s been busy lately, and it shows. Congrats for winning a travel award for IMECE 2019 in Salt Lake City to present her work “Abrasive wear behavior of polyacrylamide hydrogels under a range of loads and sliding speeds.”
Lihua worked hard with the Wissa group and Alleyne group to identify part of the mechanism of the click beetle hinge, and friction effects of diffraction grating features on insect cuticle. Congratulations Lihua!