ME 310 Research Update: Good News!

Hey guys! Now that it’s back to school, it’s time to rock and roll, but before we talk about the future of our Fracture Toughness Testing, let me give you a little update of what went down during winter break.

So while I was back home, Dick Towne, who is one of the staff members of the ME Department, finished making our clevises for our Compact Tension (CT) specimens. The clevises took some time to make considering they were made out of 17-4 Stainless Steel where the material was heat treated to an HRC value of 40, which basically meant it was really hard stuff! Nonetheless, the fact that we now have them helped us get closer to begin testing…. But wait! I have another update!

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Clevises are attached at both ends with 1/2-20 bolts that connect to the grips of the hydraulic Instron machine. We are using the 8801 Instron located in Whitaker Laboratory.

While the clevises were being fabricated, the 36 CT specimens that we sent out a while back finally returned with their wire EDM notches. 3 of the specimens were also fatigue pre-cracked, which basically means that we can conduct a Fracture Toughness test straight away. We still have to fatigue pre-crack the rest of the specimens, but this is something we don’t mind doing because we want to learn different ways to fatigue pre-crack. Fracture Toughness testing hasn’t been performed at Lehigh for several years now, but relearning how it all works including the preparation, setup, and testing procedures are the things we as a university want to how to do.

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Here are 8 out of the 36 specimens that have returned. The clip gauge attaches to the mouth of the specimen and the wire EDM notch has a thickness of .012″.

The next steps towards this research project will be to fatigue pre-crack our first specimen. A few days ago, we went to the Instron machine and examined the software that both measures K1C (fracture toughness) values and conducts fatigue pre-cracking. After a few hours of playing around with the software, we think we have it down. Tomorrow will be the moment of truth and hopefully, we get some good results.

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