NASA Ames Research Center
January 13 – May 1, 2020
Describe what you did during the internship.
During my internship, I created two main designs for the locking and actuating mechanism. The first uses a previous intern’s actuation design where a current is sent through a wire to melt the thin plastic restraint and releases the arms. The permanent locking design I created uses two compression springs which would sit on the sides of the arm compressed while stowed, once released they will expand into the holes in the base locking the arms in place. The second design uses a permanent electromagnet which restrains the arms then releases when a current is run through it, this would use the same locking mechanism as the previous design. I was able to prototype and test the first design before I began to work remotely. While working remotely, I improved this design based on the tests I ran to increase its rigidity preventing the arm from oscillating which interferes with the controls of the vehicle. For my second project, I conducted an experiment to measure the deflection of a carbon fiber tube under different loads in order to compare the FEA’s deflection results. This experiment was conducted to gather physical data to test the FEA’s accuracy. In SolidWorks, there are two ways to model a carbon fiber tube: it can be modeled as a solid, homogeneous material with the material’s properties such as elastic modulus. Or it can be modeled with layering which is how composites usually are made. I hypothesized that the layering model would be the most accurate. I modeled the tube from the experiment both ways in SolidWorks and compared. For the third project, I conducted a trade study SolidWorks to compare how much space different folding configurations of the landing gear take up. The goal is for the vehicle to take up the least amount of space so other supplies and equipment can fit in the aeroshell as well. Each folding configuration was evaluated by calculating the space that the legs take up and the gaps that cannot be used to store other objects. Then they were evaluated using a previous interns’ trade study on different types of landing gears and their performances.
Did you achieve your goals? What were the results and conclusions?
I achieved most of my projects’ goals but was unable to completely finish my first two projects because they required lab work, which was not possible after the transition to remote work. The next step for my first project would be to add the improvements to the first prototype, then to install the permanent electromagnet on the prototype. Then run tests to compare the power draw that the two actuation mechanisms require in order to choose one design. The results of my second project were calculated using the difference between the experiments’ data and the results from SolidWorks. Contrary to my original hypothesis the homogeneous displacement has a 10% error and the layering has a 50% error. So I concluded that the homogenous SolidWorks modeling is more accurate for the displacement of carbon fiber, but I was not able to make a conclusion about the stress and strain results because strain gauges are required in the physical experiment in order to get these values. Adding strain gauges to conduct this experiment was going to be my next step in the project, but I was unable to do that remotely. For my third project, I concluded that a configuration of the legs folded around and on top of the payload box uses the least amount of space, but it is a double-jointed leg system that adds a high amount of risk due to its complexity. Because of this, some of the single jointed configurations may be better to use. Future work will need to be done to evaluate the trade-offs of having a more complex design and the loss of space in the lander to decide which landing gear should be used.
Describe positive lessons learned from this experience:
This internship has taught me many valuable lessons in time management, conducting experiments, and using SolidWorks. The main take away from these is that before any data is taken in an experiment or from software, hand calculations should be performed so you can fact check the software. I learned not to blindly trust SolidWorks for anything, for example, its volume calculations included only on the part’s surface and it did not include the internal volume, which was crucial for the spatial calculations performed. Finite Element Analysis is only reliable if you fully understand how to set it up or you will not get the correct answers.
Describe negative lessons learned from this experience:
This unique experience during a pandemic has taught me resilience in how to adapt to new changes. Even though I was not able to achieve all of the goals of my projects I was able to draw meaningful conclusions from each project and recommend future steps that should be taken in order to finish each project. The switch to remote work also provided me with a chance to work on extra projects, such as the spatial trade study which was not initially assigned to me. This allowed me to learn about different aspects of the MSH project and gain a well-rounded experience.