Engineering – Page 5 – CA Work Experience Program

Day 4 – Wind Tunnels

Today was an exciting day. I continued to work on my airplane models, attended a meeting, explored another aerodynamics experimental lab, and saw a wind tunnel. The meeting was conducted to update a project’s members on each individuals status. The experimental group found some patterns in oscillations and experimented with utilizing different formulas to create a more accurate and representational model of the theorized. The computational group made changes to the code to allow for a 50% decrease in computational time.

In the aerodynamics experimental lab that I visited, there was a mini wind tunnel, artificial muscles, and more. I thought that the artificial muscle was pretty cool. It contracted by having air pushed through the surgical tubing. This artificial muscle was combined with a skeleton to give it the ability to throw an object.

Lastly, I got a small tour of the large wind tunnel at NC State. The wind tunnel and giant pressurized air tanks were adjacent to EB3. This circular wind tunnel sped up the air by releasing pressurized air into the tunnel and turning on a fan to continuously blow the air to sustain its speed. Because of the circular design of this wind tunnel, the air stays at the relative speed it was sped up too, decreasing the amount of energy needed to sustain it. It is easier to keep air moving than to speed up air from normal room conditions. Inside the tunnel, there are numerous screens streamline the air in the same direction. While each individual part of this equipment seems confusing, it is easy to understand when put together. A picture of the NCSU wind tunnel years ago is below.

Day 3: Surveying the Land

My third day at SEPI Engineering and Construction was spent with the Site/Civil Land Planning and Survey team. A surveyor is the first person on a construction site and the last person to leave one. Their job is to map out the land that is being scouted as a construction site and note very specific, detailed aspects of it. Examples include the dimensions of the site, the types of plants and animals in the area, the height/type of trees in the area, if there are any large objects or obstacles (such as large boulders, bodies of water, etc.), the type of soil in the area, and more. They also note and map any permanent structures on an in-progress construction site, such as sidewalks, storm drains, etc., and make sure that the construction is in line with city/town code. Today, we traveled to a middle school being constructed beside Apex Friendship Highschool. We set up a stationary tripod with a camera on top that shot a high-powered laser at a rod with a reflective mirror-prism. You stand at different locations around the construction site, carrying the prism rod mirror thing with you as you go. The laser from the camera reflects off of the prism and shoots back towards the camera, capturing a rough image of where you were standing with the rod. The camera has software which allows it to compile all of the pictures taken to form a digital map of the construction site. I also got to mess around with a $210,000 3d scanner that basically does the exact same thing that the laser-camera does, but in a much more efficient way. It has a laser pointer inside of it which spins at hundreds of rotations per minute, shooting lasers in every direction which bounce off of surfaces and come back to the camera. This process captures many pictures per second, and the scanner compiles the gigabytes of pictures into an almost exact 3d replica of the area around you. It basically does the same thing a 3d printer does, but in reverse. I got to mess around with several multi-thousand-dollar pieces of equipment today, and I didn’t break any of them, so that means that today was a success!

The 3d scanner

Day 4 – Projects Galore!

Back at Chesterfield today! Even though it’s Friday, everyone in the lab was working as hard as ever. Will and I started off the morning with a jam-packed session of activity as he explained to me the three main projects he is working on this summer. His first and most prominent project is working with PVA (Polyvinyl alcohol) a soft but sturdy material that has a widespread array of applications. He is currently developing a PVA material to be used in patients with arthritis, specifically with repairs in the joint between the toe and the foot. Overtime, the cartilage in these joints deteriorates, so Will is trying to develop a self-healing material that can act as cartilage for patients. The self-healing properties are extremely important because patients shouldn’t have to obtain replacement fixes again and again. The material is made of PVA, water, and melamine, a nitrogen-rich material used to strengthen the PVA through hydrogen bonding. The PVA samples are made by mixing solid PVA powder and water in a flask that’s placed in a hot oil bath. Overtime, the PVA will dissolve and turn the liquid into an amorphous structure.

The second project we dove into was the use of hydrogels. Will is helping Shelley Huang, a famous breast cancer surgeon and author, develop an injectable biomaterial for breast cancer tumor resection. The goal is to create a colored material that can be injected into the patient’s tissue while retaining its shape around the tumor so surgeons can more easily locate the tumor before surgical operations. In the lab, we tested this theory by injecting an arbitrary facial cream into a matrix of polyethylene glycol and seeing if it would hold its shape. (Refer to the photos for more detail). The polyethylene glycol (yellow jello-like substance) mimics a patients tissue and the facial cream acts as the injectable biomaterial. Ultimately, if it can be proven that something as generic as the facial cream can be injected while retaining its shape, commonly produced creams or gels can be dyed and up for consideration to use to enhance this medical procedure.

It was brought to my attention today that Dr. Ken Gall, the head professor of this lab, owns a startup company known for developing a new material called polycarbonate urethane (PCU). The plastic-like material is slightly malleable yet substantial, so it retains its shape well. Most importantly, it can be 3D printed easily. The astonishing thing is that few materials with the malleability and durability of PCU can be 3D printed on a mass scale. Dr. Gall is using this creation to develop tracheal support structures for patients that may need implants in their throats to breathe properly. The intrinsic qualities of PCU makes it a good material for this application because it will work effectively, last long, and its dimensions can be tailored for each respective patient. Furthermore, the use of such support structures is far more efficacious than simply cutting a hole in a patient’s trachea so they can breathe – it is a viable and cost-effective solution. In the lab, Will is currently testing the PCU using a laser cutters to determine its true durability, but there are already several cases at Duke Hospital in which the PCU tracheal support structures are up for consideration to be used!

In the afternoon, we carried out tests for each of the three projects. For project one, we poured the batch of PVA that will had prepared into dog bone molds so they could be frozen later for testing. For project two, we checked on the test tube we had injected with facial cream earlier to see how it retained its shape; it did fairly well. Finally, for project three, we spent a few hours at the laser cutter making dog bone samples of the PCU. This was hands down the most enjoyable part of the day since I single-handedly cut two dog bones with the laser cutter by myself! I have never worked with a machine so powerful and was happy that Will gave me the opportunity to do so. The dog bones I cut are going to be used for future strength testing to see just how viable PCU will be as a tracheal support material.

Today was a short, but fun day. Looking back at this week, I have come a long way. I have learned about countless test procedures and several unparalleled projects that immediately captivated my interest. Lab work is definitely where a part of my passion lies, yet I am thankful for the weekend to come so I can take a quick break before going back to Chesterfield on Monday.

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Day 2: Subservice Utility Engineering

My second day at SEPI kicked off with meeting Wally Little, the Subservice Utility Engineering Manager. He explained to me that the responsibilities of his department consist of locating, mapping out, and planning the installation and management of any underground system or utility. This includes sewers, gas lines, water lines and pipes, electrical lines, phone lines, TV lines, and more. Do you ever see those spray-painted colored markings, lines, and words on streets, grass, and sidewalks and wonder what they’re for? Well I did too until today. The markings are used to show the location of the underground utilities listed above. Often times, the pipes and/or lines are at different levels of depth, but they are always (or at least they should be) directly underneath their designated marking. Blue spray paint represents a water line or system, green represents a waste/sewer system, red represents electric power lines, orange represents communication lines (cable, phone, TV lines, etc.), and yellow represents gas lines. We traveled to a project that Mr. Little was working on where he and his team were hired to locate and mark the underground utilities in a neighborhood. I received a detailed explanation about how they are able to exactly locate an underground system without being able to see it, or without the aid of previously drawn maps of the different utilities in an area. I’ll give you guys the short version. So basically, they hook up a complicated device similar to a metal detector that makes a loud noise whenever it is swung over any electrical or metal object. Based on the type of sound the device makes and some other information that appears on a screen on the device, you can tell what type of utility you’ve located. Once you’ve decided which type of line, pipe, or system you’ve located, you then use the appropriate spray paint color to paint a dot, line, or short description (usually abbreviations or initials – i.e. TV, Tele., etc.) of the system after every 15 or so steps of following the utility’s trail. I was allowed to spray-paint an entire quarter-mile long electric line! The reason for marking these utilities’ locations is usually to ensure the safety of those near them, and to show where and where not to dig into the ground so that you will not damage or strike one of these systems. For example, you wouldn’t want to stick a metal fence post into the ground and hit a 300,000-volt electric line, because you would instantaneously explode and die. We would like to avoid that if possible. It felt like I was potentially saving lives when they let me mark the electric lines, so that was quite a nice feeling to end my day with.

Mr. Little showing me how to use the scanning device while I hold the spray paint gun

Day 3 – Some Hardcore Testing!

This morning was especially exciting; I got to visit several different labs on Duke’s West Campus. Cambre, a graduate student from Atlanta currently studying at Duke, explained to me in detail each of the steps we took today towards a bigger picture. In the morning, we focused mainly on tensile testing, a process by which samples are pulled apart with a significant amount of force until they break. Of course, very detailed data was collected throughout the process. As you can see in the images, the hydraulic press we used for the tensile testing was rather substantial. Each of the silver clamps depicted weighs 50 pounds, and the grip holding each end of the sample exerts 10,000 Newtons of force onto the sample to prevent it from slipping. That’s right, 10,000 Newtons of force! The test is done by moving the upper grip up ever so slightly over time (fractions of a millimeter per second). As the distance between the clamps increases, the force exerted on the sample increases. That way, when it breaks the machine won’t shoot straight up since the top grip is only set to move up at an infinitesimal rate per second that nonetheless makes all the difference. The whole procedure was recorded by a professional camera called an extensometer, which has the ability to measure precision to the ten-thousandth of a millimeter. This helped to document the total displacement of the sample when tensile tested (how much it “stretched”). Unfortunately, I was not able to operate the extremely dangerous machine, but I did get to tape some broken samples back up together for later use!

Cambre also explained the specific shape choice of the samples. As you can see, the titanium alloy samples are made in a dog bone shape, and this is done for multiple reasons. First, the two ends are paddle shaped in order to be easily gripped by testing machines. Second, the middle, or the “gauge” is thinner so that when the samples are tested, all the force is concentrated into that area, forcing it break in that area and not anywhere else on the bone. The connection between the gauge and the paddle is also tapered to prevent any right-angled corners from being a stress absorption point during testing. In the lab today, we tested samples with solid gauges and those with a funky design in the middle called a gyro. The gyros provided a slightly porous gauge section and varied in wall thickness, from 0.25 mm, 0.5 mm and 1.0 mm. We found that the solid filled gauge dog bones required over 10,000 Newtons of pull to break, while those with 0.25 mm thick gyros only required a little over 2000 Newtons to break.

The whole reason for testing all of these seemingly plain dog bones is because we wanted to determine the quality of the laser titanium printer used to create the dog bones. That’s right, Duke has a 3D printer that literally prints titanium! I was lucky enough to take a peek at it after it was just cleaned, so I didn’t have to wear all the extensive safety equipment required to operate the machine. The 3D printing of the titanium is done through powderbed fusion, whereby an extremely thin layer of titanium powder is placed on a building plate in an inert atmosphere (filled with argon), and a laser melts the powder so it can solidify and reform into the desired shape. A sample can take up to 5 days to print depending on its complexity. Today, we were testing the reproducibility, or in simpler terms, the precision of the laser at different portions of the build plate. The laser in the printer is stationary, so when it shoots to a corner of the build plate, some of the energy may be lost when compared to shooting directly done because the distance the laser has to travel is increased. The tensile testing will determine whether or not samples printed at the corner of the build plate and at the center have any quality difference in terms of their strengths.

After Cambre analyzes the data we collected yesterday and determines how the laser’s distance affects the quality of the print, she will move on the printing more useful applications that can be used in medical procedures! She explained how the gyro shape used in some of the dog bones is actually crucial in the medical field because of its design and can be used in potentially many new applications.

In addition to our time spent in the compression lab, we also visited the Pratt Student Shop, a machinery-filled space for engineering students to complete their projects. Cambre happened to be mentoring an undergraduate student and dropped by in the shop to see how things were going. She showed me an extremely powerful machine called a EDM (Electrical Discharge Machine). This $200,000 gargantuan machine took up over half the room, all for the purpose of cutting materials with a thin wire using electrical discharge. Of course, it can cut metals of various strengths, and this is all done while submerged underwater. The student shop also had other massive tools, including several table saws, laser cutters, and rotary cutters.

Overall, today was a bit repetitive, but nonetheless, I learned much more about the mechanical side of engineering. I appreciated the amount of detail Cambre went into explaining the project and learned just how intricate testing can be. I am looking forward to another day at Chesterfield tomorrow, as I will be working with a new graduate student, Will!

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Day 1: Construction Engineering and Inspection

To start off my first day at SEPI Engineering and Construction, I met with Ms. Karen Crawford, my initial contact at the engineering firm. She took me on a tour of the two main buildings that the firm operates in and explained the responsibilities and purpose of each department in them. I then met with Mr. John Wolf, who is the CEI (Construction Engineering and Inspection) Construction Services Manager at SEPI. We initially planned to go walk around and review some construction projects that were underway in the field, but with the weather not cooperating and calling for rain all day, we sadly were unable to do so. Luckily, Mr. Wolf had an exciting meeting to go in Morrisville. We were meeting with the town manager of Morrisville and several other contractors and business partners of SEPI to discuss the progress of a project that they were working on. It was really interesting to experience the side of engineering that you might not think about too often, which is the business and political aspect, and how much money, risk, paperwork, planning, etc. is involved with construction projects. I was warned ahead of time that the meeting might get a little confrontational and aggressive, as its purpose was to meet with a representative from a construction company that was hired by the town to construct a railroad and to widen the roads in specific areas, and they weren’t doing a very good job. The construction crew was severely behind schedule, costing the town and business partners a lot of money in liquidated damages, and unreliable in terms of following plans and sticking to their word. The meeting did get a little intense at times, but that just reinforced the importance and gravity of the “construction” that takes place behind the scenes, not just out in the field. I’m excited to see what’s in store for me in the upcoming days at SEPI Engineering and Construction!

Part of the construction site that was discussed in the meeting

Day 3 at Pentair – I forgot to hit save ://

Today I arrived at Pentair at 9:00am, a little later then yesterday. I felt like a true employee, using my keycard to enter the building. Today was an especially interesting day at the office, as it was “closing day”. “Closing Day” is at the end of every month, where every employee has a lot of work due. The office was quieter in the morning and as people began to finish up their month’s work, the office was filled with chatter. I got to meet a few interesting people, most of whom worked in finance. We talked about a wide variety of things and I even got some advice on what classes I should take in college.

When I wasn’t chatting with the recently freed employees, I had some other tasks given to me by Dr. Rai. First I read over a bunch of documents, to help me understand the project Dr. Rai was working on. I read the manuals of the fish pump, both the 6 inch and 8 inch models. Dr. Rai pointed out an interesting line in one of the manuals that was put in as a little companywide joke, I can’t remember exactly what it said, but basically it explained the company warranty does not protect against any “acts of god”. Ha ha, I can’t believe that made it in there.

After the reading, I went back to work on my Geneva mechanism project. The project was broken into three main steps. The first, which I did the majority of yesterday, was designing and creating each individual piece. The second step was to bring all the pieces together in assembly, which I did today. I learned more about the software, solid works, and how helpful it is. It was not easy, but I think I can getting better and better as the days have gone on. The final step, which I hope to complete tomorrow it to actually run the mechanism, with an add in called “simulation”. Unfortunately, I forgot to save the new assembly file before lunch, and lost my progress for step 2. I was a little bummed at first, but then I realized it would be good practice for me to put it back together. And sure enough I was able to put the pieces back together in record time! (for me) After I finished step 2, I had some time left over and I was able to mess around with the colors of my creation and decide to go with the classic gold and blue. Right about now would be great time for me to add in a picture of that, but I forgot to take one. Oh well, tomorrow maybe.

Day 3 – OpenVSP and GitHub

For the full duration of work experience, I was given a task to make two aircraft using a 3D modeling program, Open VSP. I will be making a Cessna 210 and another of my choosing. The picture below shows the beginning stages of by Cessna 210 model. After completing the 3D models, I will be able to run a variety of tests to show the aerodynamics of each. The main challenges that I have found with this program are figuring out how to utilize the different operations, to be able to imagine parts of the 3D object in relation to other parts and to understand some terms. Terms include ellipsoid, tessellation, and CFD mesh.

In the afternoon, I attended a meeting with other Ph.D. students to understand how to use GitHub, which allows for a more reliable and more organized way of storing commits of code. We made several repertoires and experimented with branching, forking, cloning, merging, pulling. We soon discovered that GitHub, similar to other online collaboration programs, still has trouble merging different versions. We will be problem-solving tomorrow to decrease the likelihood of lost work due to this issue.

Day 3

Today, I was with the Mechanical Engineers. While I wish I could tell you everything I did today, I can’t there isn’t enough space. Daniel explained many aspects of mechanical engineering. We spoke a lot about injection molding and how plastics act during the process. I have included a picture below of a model that he showed me of the machine that actually does the injection molding. The machine is made up of several components the cavity, the mold, the ejector pins, and the gate. The gate releases the liquid plastic into the cavity which the mold is compressed into. During this process the plastic is under a lot of pressure from the cavity and the mold and is at a very high temperature. The ejector pins are used to remove the plastic part once it has been made. You can often times identify parts that have been made by injection molding because they have small circles that are different in texture from where they have been pushed out of the mold. Additionally, we talked about living hinges which are hinges that are made during ejection molding and they will never break due to the material in which they are made out of. The neat thing about the picture below of the living hinges is that the interior triangles shows the different finishes that injection molded pieces come in because they show machining marks when made. I did know that injection molding was very expensive due to the molds; however, I didn’t know how few times the molds could be used only a few hundred times. He also showed my their all the different machines they have from cutting solid metal, taping, sheet metal, wood, and paint or sanding. They really have endless possibilities. After discussing my project with him, I decided on a design for my project. My project is an automatic plant watering system. I decided on a design that would sit below the potted plant. I spent the rest of my day doing drawings and math to make sure that it would work out. Then I CADed my design. I also added my pictures from yesterday below. Enjoy!

Day 2 – New and Old Creations

Today, I woke up excited to pay another visit to Suite 420 at the Chesterfield Lab in Durham, working on refining yesterday’s project and exploring a new realm of creation. In the morning, Dr. Kirillova and I worked with 3D printing expert Rex; he explained the fundamentals of using a rather sophisticated software to 3D print a model that Dr. Kirillova had in mind. Rex clarified that there are many careful considerations when choosing settings to 3D print a model! These include factors like the material used (PLA, polylactic acid, or PVA, polyvinyl alcohol), the nozzle and Printcore used, the temperature of the Printcore, and the speed at which the object is filled.

At first, the settings we had used to print the object did not make the printer happy and it wouldn’t complete the job at all. After spending a good hour troubleshooting the machine, we finally got our first model. However, it wasn’t our best model because it lacked an outer perimeter, so the volume percent of the filler was not entirely accurate since the model was not a perfect cube. We tried a second time, adding a perimeter layer so that the object would be more substantial and accurate. Surprisingly, it worked well! After Olivia’s return later in the afternoon, we all printed several more models. Dr. Kirillova also brought to my attention that there are several other types of 3D printing used for different applications. Today, we used one called fuse deposition, whereby solid material is melted to print the new models. Other techniques include carbon printing, titanium printing, printing that uses liquid resin, and even bioprinting, whereby living cells are printed in hydrogels!

The purpose of the print today was to combine it with the bone adhesive to test its structural durability. In other words, the PGLA fiber filler that I mentioned yesterday is similar to the PLA (Polylactic Acid) material used today to print the models. We printed porous cubes of different designs, all 28% PLA and 72% open space by volume, so that tetranite could later be applied inside the open spaces within the cube and solidify to create a strong structure. The PLA housing acts almost like a scaffold for the tetranite. These filled cubes can later be strength tested to see how much the PLA structure will help reinforce the brittle tetranite. In theory, these PLA cubes (or those of other shapes) can be used alongside the tetranite to create the most durable, efficient, and biodegradable solution to help mend broken bones together inside bodies! More complex bone repairs will of course require more durability relative to the size of the combination used. Lucky for us, PLA is a biodegradable material despite its plastic-like appearance.

In the afternoon, Olivia and I polished the bone adhesive samples we made yesterday (her titanium and my salt sample). The process consists of placing the cylindrical sample in a mold that will hold it in place while it is sanded against fine sandpaper with water. This helps to smoothen the top and bottom surfaces of the cylinder, so when it undergoes compression testing later, the data collected will be more accurate. In addition, we measured the lengths and widths of the polished samples with a caliper, something I had actually never used before this day! Olivia’s titanium samples were quite easy to polish, and they even gave off a nice shine after they were completed. My salt samples, however, proved to be more brittle, so I was only able to successfully polish two of my four original samples. Nevertheless, I am thankful that I was granted permission to collect my samples and one of the 3D printed models today to bring home; they will serve as a lasting souvenir of an incredibly captivating project!

Tomorrow, I am assigned to work in a compression lab to witness some of the actual strength tests that are performed on the polished bone adhesive samples. This lab will be on Duke’s campus, so I am eager to take the next step of this invigorating journey in a fresh environment!

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