Every Thursday afternoon, I make the trek over to Kaprielian Hall – home to the Sonny Astani Civil and Environmental Engineering Department – and head down to the basement classroom to take a seat in my favorite class of the semester: Mechanical Behavior of Materials, CE 334L lab. The lecture itself is earlier on in the week with Professor Masri, leaving our three hours on Thursdays to be dedicated solely to the lab portion of the class.
Testing for the max strength and fracture point of aluminum and steel samples in lab!
The main reason this part of the class has a special place in my academic heart is because the concepts and theories explained and discussed in the lectures turn into real life examples in the lab. As this is my first real engineering lab in my time here at USC, this is the first time I have had the chance to see the application of the things we learn. So far this semester our experiments have included stress and strain, Young’s Modulus and strength of materials (including fracture points), just to name a few.
some of the calculations required for the experiment
In the most recent lab, we used the UTS (Ultimate Tensile Strength Machine) to apply a force of 2” deflection to a 30”x1”x2” steel bar. Watching the bar bend while the force increased was pretty awesome to say the least. In so many of my past civil engineering classes, I have learned about deflection, sheer force and moment diagrams. But this was the first time I saw the real world example of what a deflection graph would look like. We also did an inverse beam bending experiment where we took the bent beam and applied the same force to the other side of the bar, hoping that it would straighten the bar back to its original state. Surprisingly, the bar was very flat after both experiments!
bending the beam with 2″ deflection
inverse bending of the beam with the same force
The other cool part of CE 334L class, which involves the lab, is the final project. Each student group, made up of 2-3 people, choose any topic that they’re interested in (within reason) and submit it to a committee made up of TAs and Professor Masri for approval. Topics can range anywhere from earthquake testing, concrete production, composite material testing even the use of smart phones to take and collect motion data. We get to choose our own materials, come up with a unique thesis and then test our thesis using any of the labs resources. We also have an analytical/design side of the project. I think that it is a great change from the way final projects usually work, where the students are given a topic they may or may not find particularly riveting. Here, I can choose something that truly interests me and something that I care about, which will only make me work harder. For my project, my partner and I will be testing to see if strain gauges, sensors that convert mechanical quantities into electrical quantities, are able to detect deformities weaknesses in a steel bar by drilling holes into the bar and applying force. Strain gauges are commonly used on aircrafts or spaceships to measure the stress and are relatively inexpensive and small.
While I’m sure this project will be a lot of work and will take time, I have no doubts that I will love the process and the final product. I can’t say the same for my lab partner though, who will have to put up with me through it all. I can only hope that the rest of my classes in the next year and a half will have lab sections and be as fun, useful and rewarding as this one.
before and after beam
– Maisie
