Thermodynamics and Fluids

Thermodynamics (ME 104) and Fluids (ME 231) are quite similar. While they cover different areas, the ideas and laws used in the two classes overlap quite frequently. Things learned in ME 104, such as the first and second laws of Thermodynamics, as well as basic pressure/stress systems share many similarities.

Which sucks because I trashed a lot of my old Thermodynamics stuff. I still have my old notebook, which helps, because we kind of gloss over those basics in ME 231 as we’re expected to know those things already, but I do wish I had old class handouts and quizzes to refer to.

So here’s a tip to any freshmen mechanical engineers or prospective students: don’t trash your notes from mechanical engineering courses. You’re going to need them later. Chemistry, Economics, and that other gen ed stuff though? Forget it, you don’t need it anymore. Unless you want to minor in those subjects, then by all means, go ahead and keep your stuff.

So while renting textbooks is easier on the wallet, sometimes it’s better to buy a book if you can. It turns out the textbooks are quite helpful if you read them. I know the textbooks are expensive, but if you dig deep enough, you could probably find them for a reasonable price (cough adfafreeaddsfasf cough cough).

 

Advertisements

Research Project – A Power Plant Tour

So part of the research project that I’m working on involves creating a more visual learning process when it comes to learning about the Rankine Cycle. Frankly, the Rankine cycle was one of the few parts of Thermodynamics that interested me, but trying to decipher what was really happening through some crazy looking T-S diagram didn’t come naturally. In fact, if it did, you’re probably the next Einstein in the making. Look at this graph and tell me you know how a power plant operates because the graph is just that clandestine.

rankine cycle regen

Yeah don’t lie, you’d probably need some time to study before you even knew what was going on in that graph. And even if you did, it’s still not easy to see how this fits into a power plant.

So one thing that I’ve been trying to do is find a virtual tour of a power plant and point out each phase of the Rankine Cycle in that power plant. However, much to my despair, nothing has come up. One company does have a power plant online, but it’s so fundamental and basic tat it wouldn’t help at all with something more complex, such as a Rankine Cycle with Regen.

Perhaps I should make my own power plant “tour” using PowerPoint, but honestly, I’m not being paid enough for that. It’s my passion for the subject that pushes me to go this far for the research project. Before I do anything that drastic, however, I’ll probably meet with the professor again to discuss things.

Time Flies When You’re Having Fun

Wow, Spring Break is already over. I hope everyone had a good time, whether you went home, hung out with friends, or stayed on campus relaxing, but I’m kind of sad. It’s the last long break I’ll be having in a while, seeing how the only other break I’ll be getting is another week long break between my last final and the start of the summer session. Once my Co-Op starts, however, I’ll be able to come home from a 9-5 and have no responsibilities afterwards.

But before that, I have nearly half a year of classes that I still need to get through. While it was nice living a life of no work and all play, it’s time to switch it around to all work and no play. Or so I say but I know I’ll lose my will to study and be back to gaming within the week.

However, it’s also amazing to think that I’m nearly done with my sophomore year. I’m almost halfway done with my college career, and it still feels like there is so much that I don’t know. I suppose that feeling is a good thing, knowing that there’s still so much for you to learn. But before that, there is still an hour and twenty minutes left before my break is over, and I have a few more episodes of Marco Polo that I can watch in the meantime.

Good luck with the rest of the semester everyone! We’re almost at the finish line (not really there’s still more than 1.5 months left).

Why NX?

One class that all mechanical engineers are required to take is ME-10, Engineering Graphics and Communication or something along those lines. Whatever it is, we learn how to use NX 8.5 to create models of specific solids. But why NX 8.5? When you talk to someone about CAD modeling, the first question they usually ask is “Oh you mean like Solidworks?” When you mention NX, they just give you a blank stare, and my usual response is “Oh it’s like Solidworks but with more bells and whistles.”

The problem with NX is that hardly anyone uses it. Sure, it has more functions and gadgets at it’s disposal, but nine times out of ten, the company you interview for will use Solidworks instead. It’s much cheaper and it gets the job done. So when I was interviewing with Sanofi for a possible position, when I mentioned that I had experience with CAD modeling, they questioned me, saying, “But I don’t see Solidworks anywhere on your resume.”

I then went on to explain as I did earlier. Situations like this are why I’m probably going to be taking that advanced CAD course as an elective later on in my senior year. I don’t remember the exact name but I think it was ME 3xx. Hopefully I’ll be able to get some Solidworks experience in before I graduate.

Co Op Position

The past few weeks before spring break have been quite taxing. Not only did I have some rigorous exams, but I also had to balance out my study time with prepping for interviews. And while I may have bombed a few exams here and there, something good did come out of this whole fiasco. I got a Co-Op Position with Sanofi Pasteur, a French multinational pharmaceutical company.

Wait a minute, what is a mechanical engineering student doing at a pharmaceutical company? Well that’s the thing with us mechanical engineers, we’re needed everywhere. The description of my position stated that I would be working as a member of the Manufacturing Technology VDL2 Platform, which is responsible for improving bioprocessing, fermentation, and purification platforms.

It sounds like a lot right now, and it probably is, but hopefully, after a few days there, the day to day responsibilities that I’ll have will become clearer and I’ll know what I’m doing. I’m excited, despite the fact that I won’t have a summer vacation. I’m excited because accepting this position marks my first steps into a larger world. Before I accepted this position, I never really did anything outside of the academic world. I was, and still am, a full time student. But hopefully my time at Sanofi will give me the needed experience to feel comfortable post-graduation.

ME 310: Fatigue Precracking

Hey everyone. Here’s the latest update with everything thus far:

This past month consisted of fatigue precracking of our compact tension (CT) specimens and getting the software of the hydraulic Instron to work. Might not seem so much, but when you have other students wanting to use the Instron…. Well your in line to face delays. But anyways, things are at least much smoother than they were last semester and we finally got the hang of this fatigue precracking.

So what exactly is fatigue precracking? Well it is essentially placing a specimen under a cyclic load for certain amount of time and propagating a small crack at the end of a notch. In our case, we usually fatigue precrack our specimens until the crack grows a certain length and then we place them under the microscope to make sure that the crack on each side of the specimen is of equal length.

So how is this all done?  Well check out this photo:

img_5044

The above picture shows one of the CT specimens attached to the 8801 hydraulic Instron. The specimen is connected at the holes by Grade 8 dowel pins that are also attached to the clevises made in house. The ends of each clevis have 1/2-20 holes for the same size bolts, which are then attached to the hydraulic grips. And last but not least: the clip gauge extensometer. This devices measures the crack growth of the specimen and sends it to the da/dN software that calculates the crack growth rate per increasing amount of cycles (a= crack length and N=number of cycles) along with other various parameters. While fatigue precracking a specimen, the following screen is shown:

img_5133

This screen displays various parameters and plots that are changing with each ongoing cycle. One of the important things to know when fatiuge precracking is the way you go about doing this procedure. That is, are you letting the Instron run until you click Finish Test or are you setting a limit to the number of cycles or crack length that you want it to stop at? What types of loads will the specimen see during the fatiguing: increasing, decreasing or maybe even constant? Without getting into too much detail, we basically ran our test at a constant delta K, which basically means that our loads were decreasing as the fatigue precracking went on.

And thus so far, we’ve been able to fatigue precrack about 12 specimens. Some of the problems we encountered through the past month is that we initially had no idea how to work the da/dN software when we had finished machining the specimens. I had to contact Instron and other places to get answers to some of the questions we had. We luckily got some help from Professor Vinci in the Material Science department and he helped us a ton on how to work the Instron itself. Another problem we faced was that we broke 3 specimens during the fatigue precracking. We figured out that the software can sometimes go haywire with the some of the calculations it performs and that it can then go at full load and break the specimen as shown in the picture below.

img_5046

If you examine closely, the specimen is broken at its centerline where the notch is formed. This isn’t too critical of a problem since we have 36 in total, but I was honestly amazed on how much of a load the Instron can output. We never got to see at what load this specimen broke, but it was definitely higher than 15kN for sure. In order to debug this problem, we just defaulted the coefficients of the calculations then we never had the problem again.

But anyways, that is where we are so far. Next, we will start da/dN testing where we would like to obtain a value for Kmin threshold, which is basically the minimum stress intensity factor needed to begin propagating crack. Stay tuned for more updates!

Co-Op Interviews

I know I haven’t been posting as much, and a lot of that has to do with busy weeks crammed with Co-Op interviews and exams. One great thing about majoring in Mechanical Engineering is that it opens up a ton of opportunities for you.

Just take Co-Op positions as an example. Nearly every job listing under the Co-Op program was available for Mechanical Engineers, not so much for Civil, CS, or the other fields. As a result, I ended up applying to 11 different Co-Op positions, and I’ve had 8 interviews so far. Yes, 8 in a week. A good chunk of them were with Sanofi, however.

The companies that I interviewed for include GE, Exxon, Sanofi, Materion, Consigli, and Air Products & Chemicals. After a while, you start to realize that many of the interviewers ask the same questions, so you get used to them after a while. You just have to start tailoring your responses according to the company you’re applying for.