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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.

Monday, 13 August 2018

COMPRES

Last week I was fortunate enough to be invited as a keynote speaker to the COMPRES annual meeting, which was held in Albuquerque, NM. COMPRES is an organization of high pressure experimentalists thinking about what's happening in the deep interiors of Earth and other planets. 
I just have to say, it was one of the best meetings ever. Not only was everyone there extremely friendly and encouraging, had great questions, was just a little bit quirky...

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But the venue was gorgeous, with an amazing view of the Sandia Mountains and the Rio Grande...

with multiple pools and walking trails, and there was even an onsite spa (I may or may not have enjoyed a spa treatment or two)...

I came to dinner Tuesday night already thinking that it was a pretty awesome meeting. And then the karaoke and dancing started, and I knew it to be true. Fabulous meeting! Thanks so much, COMPRES!
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Regelation or Viscous Deformation?

This summer, in addition to five other interns, we also had four students through the Climate and Life program: Camille, Jeremy, Naomi, and Jennifer. They were looking at the difference between regelation (pressure melting and recrystallization) and viscous deformation, which could be mechanisms of flow at the base of glaciers under the right conditions. Mike built a frame to go with Rob's dead weight apparatus that the students assembled. They calculated the stress for each increment of weight to be added. 
They did a great job drawing the below schematic of the set up. The frame was used to apply a dead weight to the top of the ice, which was resting on top of spheres of various size and composition. The  hypothesis was that under some conditions regelation would dominate over viscous deformation and other conditions it would not. Since any melt formed would drop down below the balls due to gravity, we would be able to tell the difference. Also, in theory, regelation should be faster with spheres of higher thermal conductivity so we thought me might be able to tell the difference that way.


They printed up their motivations, methods, and results into a nice poster. Title was all their idea, and I love it!
And they did a great describing their project to the other interns and my colleagues at an informal poster session held on the last day.
With about a half hour left before the bus, they enjoyed some competitive stress concentration and particle interaction.

Thursday, 2 August 2018

Also joining us in the lab this summer was Will, a local high school student. He worked on a pressure sensitive film project to quantify real area of contact changes of samples in the rig. After getting the method down on roughened teflon and PMMA, it was time to start working on ice.  Since he was looking at contact area change with time and normal stress (but zero velocity), we didn't need to use both pistons for his experiment. Working with Mike, they designed and built a special purpose cryostat with a wood frame and this green styrofoam for insulation.
The cryostat fit nicely into the apparatus, allowing it to be pre-chilled with circulating fluid and loaded with the prepared ice sample and forcing blocks. A small slot at the top allowed him to change the chilled pressure films in and out. 
With the horizontal hydraulic pistons, we applied 450 kPa normal stress at -2 degrees C and he measured the pressure on the films at 10 s, 100 s and 1000 s holds. The films were digitized and analyzed in ImageJ for %area. After lots of trouble shooting and trial and error to develop the protocol for this brand new method (for us anyway), his summer culminated in getting the below data set (Fig. b). It looks great! Well done, Will!


Tuesday, 31 July 2018

Summer 2018: cheese!

It's been a long while since we've posted. But with such a fun, busy summer, we had to share all our updates. Although we said goodbye to Tess and wished her success in her future adventures, we said hello to many new faces. Nine (9!!!!) summer interns joined the lab: 2 undergrads visiting us from Brown, and 7 high school interns. A lot of ice-related fun was had by all!

But before we can start working with ice, we have to learn about cheese. Rheology lab got the students learning about stress, strain, and how to run a creep experiment. The three teams were assembled.


 All cheese was measured and stresses calculated.
And the experiments started. They make sure to capture the immediate elastic response by measuring the height of the cheese as soon as they apply the weight. And then they continue taking a measurement every three minutes or so to capture the transient and steady state. One student holds the timer, one measures with the calipers and calls out the height, and one records it in excel.
This year we tried to support the weights to prevent tipping. It worked well in most cases...but not all. 



Monday, 11 September 2017

Possibly the cutest lab ever

"This is possibly the cutest lab ever" exclaimed one of our visitors last winter. And well, I might have to agree, what with all the babies and puppies.  Seb, our newest lab kid, made his appearance on the scene last summer and quite a few visits to the lab this winter (thanks to all those daycare germs giving him baby illnesses). Here he is color-coordinated with the best babysitter ever!

And sweet fluffy Charlie became the lab's new mascot/ferocious guard dog.
We even get cute visitors. Mike is still angry that we wouldn't let him keep the fawn.
Heck, even our snakes are freaking adorable.

So come on out to visit the lab, but just prepare yourself for the cuteness overload. You've been warned!



Wednesday, 23 August 2017

The Eclipse

Even though I was not prepared at all for the eclipse, my coworkers did not let me down. Lamont was a flurry of activity on the day of the big eclipse. All gathered conveniently right outside the lab.
All manner of viewing devices were fabricated by my creative co-workers.
The rock mechanics kids even joined in on the fun (though mine grew weary of all the "fun" after about 20 minutes..."mom, this eclipse is BORING").




Wednesday, 9 August 2017

First Q experiments

This little picture may not seem like much. But it's huge! This was our first ever attempt at imposing a sinusoidal load on top of a background load, at various frequencies (white curve). A new set up was used such that a stationary base was beneath sample (so that it can't slide). The resulting purple curve was the displacement of the sample. In this case we just used teflon, but it shows that all the components for controlling and measuring low amplitude cyclic loads are there. I'm very very excited about this.