Friday, August 26, 2011

You Already Have a Seismometer In Your Lab

This past Tuesday, a 5.8 magnitude earthquake hit the east coast of the United States.  The last major quake to hit the Virginia area was in December 2003, which had a magnitude of 4.5.  I was living in Virginia in 2003 and remember the quake vividly.  I was running some rheometer tests during the seismic event; unfortunately, the experiment was in the middle of a thermal equilibration step, and so the data were not affected.  If anyone out there was running a test this week that was trashed by the recent quake, drop me an email at rheolworldblog -at- gmail dot com. 

Friday, August 12, 2011

Quotation of the Moment

"Ask the material how it deforms, because the only the material knows."

Joachim Meissner, as noted in the latest Rheology Bulletin.

Wednesday, August 10, 2011

The Equations Left Behind

The latest Rheology Bulletin (link not available yet) announced the death of Professor Dr. Joachim Meissner this year.  During graduate school, I often spoke Meissner's name, because of his work in constitutive equations.  In 1972, Arthur Lodge and Meissner used phenomenological arguments to show that the first normal stress difference and shear stress are proportional to each other when a single strain is applied at time zero [1].

This relationship is supported by many experiments and constitutive equations.  During graduate school, I used the above equation to infer the sample thickness in my optical rheometer [2].
In addition to single-step strains, I and others did work on reversing double-step strains, where a second strain is in the opposite direction to the first.  Osaki and co-workers [3] proposed a relationship similar to the equation shown above:

When Venerus and Kahvand published their study of mechanical double-step strain rheology [4], Lodge somehow heard of the work and proved and generalized the second equation for multiple reversing step strains where the absolute value of the strain is constant.  Following this chain of events, I started referring to the second equation as the Osaki-Lodge relationship.  (I always thought this chain of events showed scientific collaboration at its best.)

[1] Lodge, A.S.; Meissner, J. Rheol. Acta 1972, 11, 351-352.
[2] Brown, E.F. et al., Rheol. Acta 1995, 34, 221-234.
[3] Osaki, K. et al. J. Polym. Sci., Part B: Polym Phys. 1981, 19, 517-527.
[4] Venerus, D.C.; Kahvand, H. J. Rheol. 1994, 38, 1297-1315 (with an appendix by Lodge).

Surely You're Joking (#11): Knock Knock

Knock, knock
Who's there?
The fluid mechanics
The fluid mechanics who?
The fluid mechanics, so they're out today.

Knock, knock
Who's there?
Rheology who?
Real?  Gee!  I thought they were fake!

Tuesday, August 9, 2011

I Acknowledge I Have a Problem with This

We just wrapped up our summer intern cycle at ConAgra Foods [1], and I noticed a pattern in the final presentations.  All the presentations I observed used the words "Acknowledgements."  According to the dictionary, this is the British spelling of the word.  If you're going to add that extra e, then you might as well put a discussion of the latest rumours on your "shed-yule".
I suspect that this British spelling slips by because the base word is spelled acknowlege acknowledge, and the extra e doesn't look out of place the way that extra u in rumours does to American eyes.

[1]     Information on internships at ConAgra can be found here.  The main opportunities are in food science, but other interested parties are welcome to apply.

Sunday, August 7, 2011

Jobs Report (August '11)

Keyword searches (rheolog*) conducted on August 7 found 31 jobs on Monster and 20 jobs on Careerbuilder.