I recently experienced a bit more excitement than I felt like I really needed, and it’s due to excessive amounts of stored strain energy being converted into cracks!
It all started a few weeks ago when a client asked me to cut a ring-shaped part so that we could examine the crack surfaces. In order to accomplish this, I had to cut through the ring in two places. Then the two sides of the crack would fall apart, and we’d be able to view them. The problem was that the material was a hardened tool steel. As I got close to cutting all the way through, the material on either side of the abrasive saw blade kept grabbing onto the blade due to residual stresses in the ring.
Eventually, with just about 2-3 square millimeters of cut left, I unclamped the part, flipped it over and started clamping it down in the new orientation. But just as I started to spin the wrench, the little tiny remaining ligament and surrounding material (maybe 0.1 grams worth) ejected itself backward and sent the rest of the several-pound ring forward, smashing my finger between it and the clamp.
It felt like I was going to lose my fingernail, but I was wrong. An hour later, the pain subsided. This was really weird. I’ve been doing quite a bit of my own lab work to support my failure-analysis practice for 30 years, and this had never happened before.
But there are strange synchronicities at times, as the great psychologist Carl Jung wrote about. Within a few days of this event, western Michigan suffered an extreme ice storm. As I drove home that night, I saw trees bent over with the load of ice. I was amazed that they were, at that time, apparently patiently waiting for the sun to melt the ice and relieve the load.
The next morning, after the freezing rain kept adding to the load all night, I was awakened 10 minutes before the alarm with a loud crack. Ten minutes later, the alarm did not go off because the power suddenly went out. I dragged myself out of bed to get a view out the window in the direction from which the sound had come and saw flames on the corner of my property.
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