Sep 11 - "Why the Towers Fell" - Nova PBS

It is human nature to look back with one eye to the future. If we can just figure out why that happened, we can make sure it doesn't happen again. That is, at its core, what failure analysis is all about.

NOVA, the PBS series, produced the documentary "Why the Towers Fell" looking at the conclusions of the engineers and scientists on the government's exploration panel attempting to answer the titular question. In their findings there are a number of material science connections...

• tradoffs among cost, weight, and strength - particularly at 11:30
• design constraints - 12:45 (designed for impact of a Boeing 707, the largest at the time of design)
• mechanical testing methods (sheer, tension, vertical load) - 33:30
• heat softening of the steel - 37:45, 44:35 (and throughout in small mentions typically as "the heat would have softened the steel")
• failure analysis - all throughout, particularly at 45:00

NOVA also posted a website of information related to this episode, much of which is still online. Some links are starting to fail, however. The best of these are a very readable summary of the findings, the engineering history of the Towers, and a java interactive showing what metal atoms do as heat is applied.

This one's tough for me to post and was even tough for me to watch. I didn't have a direct connection to the tragedy of the Twin Towers, but I had at least one student who did, who knew someone on one of the planes. If it isn't already obvious, be aware that some of our students - or coworkers - may have closer connections and may still struggle with memories of the incident, of loved ones who were closer to the Towers, or even - like me - have memories of being in the Towers and being two or three relationship steps away from the tragedy.