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Tag: Engineering
Hello World
Day 8: Last Day at SEPI!
On my last day at SEPI Engineering and Construction, I met with Mike Harris, a construction project manager at SEPI. He is currently working on multiple road repair and widening projects around the state. We drove to some of the sites where the road was being widened and he explained to me what they were doing and the procedure used for widening a road. Afterwards, we went to Taco Bell for lunch and I got one of those Doritos tacos that they have. It was pretty good, if I do say so myself!
Day 7: Road trip!
Today at SEPI, I met with a construction project manager, and we drove about 2 hours to a meeting with multiple contractors where they discussed the progress of a community center that was being built. The project was basically completed, but they were just talking about finishing touches on the building. We spent the rest of our day driving back. Fun times!
Day 6: Roadway Design and Construction
Today, I worked with the Department of Roadway Design and Construction. They deal with anything involving roads, from widening them and extending the shoulders, to making sure that any underground utilities under the roads were in the correct location. They also deal with many of the environmental aspects of roadway design, such as runoff water and the impacts of road and street material. Today, I worked with a member of the department who was working on fixing traffic buildup in certain areas. He was using a program that analyzed different aspects of traffic, such as car speed, road size, and other things.
Day 8 – The End of the Journey
Today marks the final day of my brief yet incomparable time at Chesterfield. I started the day continuing to use the Lulzbots with Natalia. We printed another cylinder out of PCU for dog bone testing and finally got the other printer to work properly! For that one, we used a slightly different polymer that was more rigid at room temperature. Instead of printing a cylinder that would be cut into dog bones later, we directly printed dog bones onto the second Lulzbot, even though they did not turn out great (many of the samples ended up breaking). Natalia also fixed the other material extrusion printer that can go up to 600*C at the nozzle for printing special polymers, and we started some dog bone prints on that as well.
As we waited for the prints to finish, she explained to me some of the science behind the data analysis. There are two main things of importance when analyzing the data from mechanical testing of these dog bones: the stress vs. the strain. The strain is how much distance the sample moves while the stress is the amount of force used by/exerted on the object. As depicted in the graph below, the stress is the y-axis variable and the strain is the x-axis variable. Stress is measured in Megapascals (a standardized measurement of force) and strain is measured in millimeters. The x-mark on each curve represents the stress and strain at which the material breaks. The linear representation of glass in the graph reveals its brittleness: low strain yields high stress because it will break under a lot of force without stretching much. A material like rubber, evidently, will stretch more even when experiencing less stress. The unique corner on the aluminum curve represents the yield strength: the point at which the material will no longer return to its original shape after being stretched since the strain has exceeded the material’s ability to repair. Another interesting note is that the “stiffness” of each material is represented by the slope of the curve before the yield strength.
That’s basically all we did today! It was concise but fun at the same time. What strikes me is that my experience in the past eight days has been so much more beneficial than I had anticipated. I did not expect to understand so much of the information I was given, and it inspires me that there are such dynamic lab groups working on extraordinary projects that are truly aimed towards helping humankind. I think the bigger picture is what got me; the people I met here at Chesterfield are not motivated by publishing papers or pursuing degrees. Rather, they cherish the excitement that comes from developing devices that they know will go to help those in need. I sure will remember all the phenomenal educational learning opportunities I have had, and I definitely will not forget the benevolence and dedication of all the people I have worked with throughout this journey.
Day 8
I can’t believe it is over. Today, I spent most of my day preparing for my presentation. I was able to fix my program that program and make some improvements. It took a very long time to figure out the problem and then the solution. I figured out that my program was getting stuck trying to read from the serial. I was able to fix this be sending and receiving another data type an int. This seemed to speed the process up. Otherwise, my code from yesterday was just fine. The improvements that I made the code quicker and only update the variables when the user changes them. In the afternoon, I presented those who hosted me this week. I presented both the business and technical aspects of the device. After presenting the market, the ideation and the pros and cons of each design, I demoed the user interface and LED’s. I couldn’t demo the motor because it needed 12V. I loved the experience of being at Plexus and I learned so much from everyone that I worked with. I would just like to thank everyone who took time to talk to me while I was Plexus and thank them for hosting me these past two weeks. The lessons that I have learned are invaluable.
Last Day :(((
Today was my final day at Pentair. The first half of the day was dedicated to meetings and the other half was dedicated to working on a side project on solid works. The first meeting was cancelled because the other person didn’t show up, so we had some unplanned free time. In this time, Mrs. Rai gave me some Pentair “online classes”. These “classes” were short videos that helped Pentair employees with certain skills. After watching the specific video for the class, you could take a test to demonstrate your understanding. The first class I took was about marketing and it was pretty interesting and I passed the short test! Next, I took a lesson on sensing people’s emotions in the workplace, which was neat. The mini lessons showed that Pentair really wanted their employees on the same page, even though Mrs. Rai told me she hadn’t taken a single lesson.
After this and the next meeting, Mrs. Rai assigned me my final task or side project: to create a batarang in solid works. This task kept me busy for the remainder of the day. It was quite challenging, but I was happy with what I had learned about the software. Halfway through, I stopped for lunch. Because it was my last day, Mrs. Rai took me out to Ruckus, along with a few other employees. After a yummy and chatty lunch, it was back to my side project. I felt quite accomplished once I had finally finished the project.
Day 7 – Successful Troubleshooting
My visit to Chesterfield was an exciting one today. I worked with Natalia, a PHD student who explained to me various forms of 3D Printing and their pros and cons. See the photo below for a detailed chart of the main different types. For reference, I have worked with Material Extrusion (ultimaker), powder bed fusion (titanium printer), and vat photopolymerization (the carbon printer). Natalia explained how different printers have different tendencies to create structural defects and she is researching how to address and minimize these inconsistencies. For example, material extrusion printers result in printing by layer, so the x and y axis of the structure are relatively strong, but the z-axis may be weaker since the space between layers allows structural weakness. Natalia is testing what settings would be most optimal for printers to minimize this decrease in “weld strength.”
Natalia is currently working with three different materials: PCU (Polycarbonate urethane), the flexible but fairly strong polymer I worked with Friday, PEEK (Poly ether ether ketone) an crysalline polymer, and PEKK (poly ether ketone ketone), an amorphuous polymer. The latter two materials are unique in that they require much higher temperatures than the average 200*C to melt. Normal material extrusion printers can’t attain a temperature that high on their nozzles, so a special material extrusion printer with an enclosure and extra heated build plate is required to print PEEK and PEKK, going up to 450*C. Unfortunately, this printer had some teflon stuck in the spool feeder, so we had to put the whole tube in the oven at 190*C to melt it out. Luckily, we succeeded and reinstalled the tube into the printer after a an hour or two of heating!
After explaining the different material types, Natalia gave me a more detailed tour of the lab. One interesting contraption is the extruder that creates printable materials. Normally, a spool of material of a specified diameter (1.95 or 2.85 mm) is used for material extrusion printing (see the provided image for reference). However, manufactures may not produce materials that come in spools; rather, they come in pellet form. This extruder machine converts these pellets into a usable spool of printing material by melting the material and reforming it into a thread. It’s a shame, however, that the machine is currently broken since the extrusion tip is clogged. The lab members are working on fixing it, but they have no idea what is wrong after multiple attempts to follow standard protocol. In theory, the machine is highly useful for producing spools of important materials that you can’t buy of the shelf in spool form.
Throughout the lab, there are also other components that need fixing. We looked at the Lulzbot, a material extrusion printer with a twist; it has a flexistrude tip that allows for more accurate extrusion since the motor that moves the spool is closer to the tip. On this contraption, Natalia and I worked on fixing one of the resistors that heats up the nozzle, as well as the temperature indicator on the device. Meanwhile, we printed a cylinder of PCU on a second Lulzbot; this cylinder will later be cut with the laser cutter into a dog bone for mechanical testing, similar to what I did on Friday with Will. After a failed attempt and some more troubleshooting, the print was on its way to be done! One fun fact about material extrusion printing that we took into account while printing the cylinders is: a skirt (small ring around object) is required to help with inconsistencies in the extrusion and may also provide support for the structure.
Overall, today was a fun and educational day! Natalia was very friendly and explained the project well – I hope I can learn even more from her tomorrow. Hopefully the last day will be the best one yet!
Day 7
Today, I spent most of my time preparing for my presentation and finishing my project. I began my editing my CAD files this morning with the help of Daniel to make them easier to print. After this, I spent most of my time try to fix code. I was trying to send another value of serial communication. I also spent a lot of time testing the program to ensure it worked properly and the correct values were being received. I also created some algorithms to interpret what the user is inputting to change values in the program. After some help from Zack I was able to get the program working. I saved the working version as final and then it stopped working. Zack and I have not been able to figure out why it had mysteriously started to not function properly. I had been able to get serial communication in both directions and the screen to update properly and then serial communication broke down after no code changes. This will be my first priority tomorrow. Hopefully, I will be able to figure this out. The code below creates sliders on the user interface that allows them to adjust values within the code.
