The rock and ice mechanics lab at Lamont-Doherty is led by PIs Heather Savage, Christine McCarthy and Ben Holtzman. We are in the process of growing our lab and building our experimental program. Along with a team of postdocs, undergrads, grads, and longtime staff engineer Ted, we are rehabilitating and revamping some of the old equipment and building new rigs for exciting new experiments on both rock and ice. You can follow along with our progress here.

Saturday, 22 November 2014

Reaction driven cracking with Sarah

There's a new experimental project occurring in the rock mechanics lab right now. Sarah Lambart, who is usually over in the petrology labs, is conducting some preliminary desktop studies of reaction-driven cracking that may ultimately be performed in the triax. Below, her sample material sits within a steel cylindrical die and she is using weightlifting equipment to determine if the reaction rate depends on stress (it does!)
 Another test determines the rate of the reaction with warm basic fluid (but without stress).
Strain gages attached to a copper jacket around the sample should capture volume expansion and cracking caused by a reaction of water and calcium oxide. 
 Transducers attached to the sample will monitor cracking. Sarah tests one out and observes the signal.

Saturday, 15 November 2014

Cryostat stage 1

Our newest member of the lab is Mike Nielson, who will be doing his senior thesis project working on ice. Specifically he will be troubleshooting and calibrating the cryostat and testing standard ice samples for grain growth or degradation after thermal pulses.  On his first day he already made a big contribution to the ice project. Rather than the duct taped styrofoam contraption that I was envisioning for insulation, he suggested we use expanding foam to get a perfect fit to the cryostat dimensions. 
At home he built a wooden box lined with wax paper. We placed the cryostat inside the box and released two full cans of Great Stuff expanding foam in the area around it. A wooden bar over the top covered the ball bearing sleeve that the piston goes into. The bar also held down the cryostat when the foam expanded.
And did it ever expand!  He taped the sides so that the foam would "grow" toward the center. We actually worried that it wouldn't fully cover the top of the cryostat. Clearly we didn't have to worry. It covered completely and pushed its way out. After it fully dried, he easily removed it from the box,  cut the top off, and cut the insulation into two halves. Eventually we will use duct tape or velcro to make a seam that will hold the two parts together.
He cut a hole in the side to allow for the peltier cooling device and heat sink that I will discuss in more detail later. Shown here is a fan sink. In the next blog installment I will show the circulating liquid sink that we are now using instead. Stay tuned!