Why Lithium Is Dangerous But PERFECT For Batteries

Our chemistry book has a diagram of a battery in the electrochemistry chapter, and I discuss that battery for a bit before explaining to my students that the basics of ACME (anode, cathode, metallic path, electrolyte) hold for every battery but that the engineering of modern lithium-ion batteries is far different from the diagram in the book.

This video - again leaning into the algorithm-rewarded longer and longer format - explains some battery basics involving the activity series, the history of the development of the lithium-ion battery, and the methods of fiery failure when the battery overheats.

This is, as Dr Derek says, a technology that has allowed our modern, battery-dependent world.

Fast-Tracked Failure: The Hyatt Regency Walkway Collapse

I've been watching videos from Brick Immortar of late and will have another one from the same channel next week, but I could pick probably any of these videos and post them here. They all seem to analyze famous engineering failures, quickly recap the incident, then summarize the causes of the failure.

This one is one I'd heard about and that I've seen discussed as a famous case of plans being adjusted without proper checking to see if that seemingly minor change would be problematic. This is, however, the first video on the incident that I've seen discuss that the original design would have been problematic over time as well.

Understanding Material Strength, Ductility, and Toughness

Strength vs toughness is such a subtle concept for my students to understand.

That isn't really a tough (sorry) thing to reason out. The two words are used somewhat interchangeably in the non-material science world. 

This video does a great job animating and showing the differences between those words and using the stress strain curve to do so. 

The Disaster That Changed Engineering: The Hyatt Regency Collapse

The initial design was good.

The engineer signed off on the design change.

He shouldn't have.

I'm always appreciative of someone who can explain complex ideas in such a simple fashion, and Grady from Practical Engineering is such a someone, using a simple model to show the differences in forces in the original and revised design for the walkways.

Why Bridges Move... (and more thermal expansion demos)

I wouldn't want to get my hands caught between those jaws on a hot day.

I don't know that I would actually show this video in class. The demonstrations of thermal expansion aren't all that impressive. The explanation and theory is solid, but the demos could be a little more impressive.

Like these, for example...

The ingeneous design of the aluminum beverage can

Holy crap is the aluminum can complicated.

Maybe I should stop throwing them into the back of m'pick up truck and just letting them blow away into the coutryside.

Seriously, though, the aluminum can is - as are so many of our modern technologies - an absolute marvel of engineering. The number of steps involved in turning a 0.3"-thick aluminum disk into the finished can is stunning. Also stunning, by the way, are the examples that The Engineering Guy has along every step of the process. I'm desperately curious - and more than a little envious - as to how he got his hands on all of those.

After the jump I'll include all the videos he references at the end of the above video.

Scary! Massive waves on huge road bridge send Volgograd drivers ashpalt surfing

It's not the Tacoma Narrows Bridge or anything.

Actually, it's the Volgograd Bridge in a video taken in May 2010. Seems that it has - so far at least - had a much more successful fate than did good ol' Galloping Gertie. Seems that they've installed 'semi-active tuned mass dampers' to take care of the oscillations.

That must make for far less entertaining driving across the bridge.

Bridge to Classroom

My bridge didn't survive the magnitude 9.0 earthquake on the San Andreas fault. I'm not surprised about that, though, since Warren Zevon has been telling me to for years that California is going to slide into the ocean. I apparently helped a digital version to speed up that slide a bit thanks to Bridge to Classroom, an engineering simulation in which you (or your students) can test various bridge designs (beam girder, steel arch, cantilever-truss, suspension, and cable-stay) with a mixture of safety features (bearings, ductile materials, shock absorbers, and shear links) against earthquakes of eight different magnitudes after learning a little bit about the challenges presented in the San Francisco Bay.

Here's to hoping they built the real one better than my beam-girder/suspension/bean-girder model did.

How a lead-acid battery works

Batteries are just so freakin' cool.

I had no idea the specific chemistry inside a lead-acid battery. Lead plus lead oxide making lead sulfate in each case...brilliant.

The comment at 3:00 - "with most engineered objects, there are going to be trade-offs, giving away the characteristics you want to gain others you must have" - is a marvelous summary of much of our design challenges.

Light bulb filament

This video, made to accompany an article on Wired magazine's website, absolutely blows me away. First off, the ease with which The Engineer Guy takes off the glass envelope of the light bulb at 0:45 is stunning. Can anybody recreate that with a pipe cutter? I've been trying for a couple of weeks with absolutely no luck.

At 0:58 then, the video does a great zoom in on the supercoiled tungsten filament and shows the original 20-inch filament coiled then coiled again.

The next part of the video - from 1:30 through 2:30 - explores the ductility of tungsten and the processes necessary to make it ductile. The six steps - at 2:00 - absolutely blow my mind. That anybody could ever figure those steps out is amazing.

And the video closes with explaining the need for the glass envelope and the gas within.

Great, great video!

Point Pleasant Silver Bridge Part 2

Today is the 72nd anniversary of the failure of the Tacoma Narrows Bridge - a more famous bridge collapse here in the US than the one shown in the video here. I'll post that video in a bit, but this one caught my eye for MatSciWit because of the discussion of the failure detection methods used here to find out why the Point Pleasant Silver Bridge over the Ohio River collapsed in 1967. They video uses computer recreation and eye-witness testimony to explore the pitting corrosion, tension/compression in manufacturing, and material failure on the suspension bridge.

This is merely the middle of three parts to the video. Check out the other two after the jump...