Friday, December 6, 2019

A striking materials science lab demonstration

On November 26, 2019 I blogged about Avoid falling on your face during a new product demonstration. That post got me thinking about a great metallurgy lab demonstration I had seen almost five decades ago at Carnegie Mellon University. We were shown a Charpy impact test machine and how much the energy to break a V-notched steel specimen varied with temperature. As shown above, the machine has a weighted pendulum which can be released to hit the 1 cm (0.394”) square specimen opposite the notch and measure absorbed energy via rebound height.

At a low temperature there just was a quiet click, the sample broke in two in a brittle fashion, and pieces flew across the room. The pendulum rose to almost the same height as it had started at (less than 10 J). At a high temperature the sample instead bent in a ductile manner. It did not even break completely and it absorbed lots of energy (over 100 J). Examples of intact and broken specimens are shown above.   

Let’s look at an example set of data for a conventional pressure vessel steel plate in the (L-T) orientation (from the ASM Metals Handbook Volume 8, Mechanical Testing, Ninth Edition, 1985 - Figure 3 on page 262). At – 78 C (-108 F), using dry ice and ethanol for cooling, it took just 5 J to break. At ice water temperature, 0 C (32 F), it took 97 J. At room temperature, 20 C (68 F), it took 143 J. At boiling water temperature 100 C (212  F) it took 200 Joules (J). The S-shaped curve has a transition from ductile behavior and high absorbed energy at high temperatures to brittle behavior and low absorbed energy at low temperatures. It is typical for steels.  

Back during World War II this transition was not well understood, and some spectacular brittle failures occurred in welded structures. As shown above, The T2 tanker SS Schenectady broke almost in two on a cold January 1943 day while it just was sitting at a dock in Portland, Oregon. Then in October 1944 a cylindrical tank in Cleveland, Ohio used for storing liquified natural gas broke and the resulting explosion killed 130 people and destroyed a square mile area.  

You can read more about the test in a web page from TWI (The Welding Institute) titled What is Charpy testing? You also can watch a five-minute YouTube video from Materials Science 2000.

Images of the Charpy test (from Laurens vanLieshout), test specimens (from Dumontierc), and the SS Schenectady all came from Wikimedia Commons.

Tuesday, December 3, 2019

Please don’t mystify us about fear of public speaking

Yesterday at the Forbes Communication Council there was an article by marketer Ahmad Daher titled Public Speaking Tips You Need to Know. Most of it is useful and more than decent, except for this overblown opening paragraph:

“Every year, numerous lists of peoples’s biggest fears are published, and without fail, public speaking consistently sits near the top. In order to thrive, and stand out in today’s content-heavy and video-saturated world, we need to demystify and alleviate the fears around public speaking.”

The claim that fear of public speaking consistently sits near the top is belied by results from the last four annual Chapman Surveys of American Fears, as stated in their blog posts. For 2015 it ranked #26 of 88, for 2016 it ranked #33 of 79, for 2017 it ranked #52 of 80, and for 2018 it ranked #59 of 94. Another way to express these ranks is in terms of the percentage measured going up from the bottom of the list, as shown above in a graph. That percentage wasn’t in the top 25%, and for 2017 and 2018 it wasn’t even in the top 50%. When you make an overblown claim ‘without fail’, just one example can shoot you down – but I have four.   

On September 29, 2019 I blogged about those results in a post titled Stop playing – do serious digging before you come up with an opening statement. And back on October 19, 2018 I also blogged about how You probably won’t hear public speaking coaches discuss the 2018 Chapman Survey of American Fears. Usually the Chapman survey comes out before Halloween, but the 2019 one has not appeared yet.

The mystifying image was adapted from an October 6, 1897 Puck magazine at the Library of Congress.

Monday, December 2, 2019

How we know things, and can talk about what we know - climbing from concrete to abstract

Back on September 17, 2013 I blogged about The Ladder-of-Abstraction and the Data-Information-Knowledge-Wisdom Pyramid. The Ladder of Abstraction shown above describes six levels, but as Patty Mulder described in an article at Toolshero, S. I Hayakawa originally used eight. You can find an eight-page white paper by Richard Freishtat and Adam Leipzig titled INFORMATION ACROBAT: Climbing the Ladder of Abstraction about picking the right levels when organizing a speech.

Another way for going from concrete to abstract is the Data-Information-Knowledge-Wisdom or DIKW Pyramid shown above. Last year, in the Online Journal of Public Health Information, there was an article by Olaf Dammann titled Data, information, evidence and knowledge: a proposal for health informatics and data science.

He suggested another hierarchy as shown above both as a stepstool and via a table (which I have condensed from Table 1 in his article).   

Images of a stepladder and a stool both came from Wikimedia Commons.