This week I was able to solve the problem with the assembly. The reason I was getting an over-defined error was due to the fact that the end arch pieces had some geometric issues. Two of the faces were something like 0.067 degrees to each other instead of being parallel. This means that when I was mating the faces of those pieces to the rest of the bridge I would have contradictory statements resulting in the error. I fixed this by adding a geometric constraint (parallel) to the parent sketch for the extrusion and this fixed the problem. Aside from this I’ve been slowly but surely piecing the bridge together. I’ll post the completed bridge once it’s finished after spring break. From there, I’ll try and have it 3D printed at Wilbur for a small scale model the fabrication crew can use as an aid to help them build it in real life. More updates to come.
This past week we have really made progress with the Solidworks model. All of the members are made but we’ll need to make just a few changes like adding holes for the bolts.The last big thing we need to figure out is the connection designs for the chord and leg pieces (pictured above). We have a general idea of how they should look but we are working out the fine details and dimensions of what we will finally decide on. Hopefully this Wednesday we can finish those and start the final assembly. More updates to come.
Over the break, a lot of progress was made on the bridge design. It is pretty much finalized by now with only a few things left. These last two things are very important however. We are currently undecided about how to handle the bridge chords, they are the horizontal pieces the weight will be applied to. Originally our main designer Jamie had a somewhat complicated truss design for the chords. But while playing with her computer model she replaced them with a simple rectangular tube and noticed a strange occurrence. Apparently when she changed the chords to simple hollow tubes the bridge deformed only slightly more but reduced the overall weight of the bridge drastically. She will do some more tests but hopefully this was no fluke. Using hollow tubes makes modeling the bridge on Solidworks easier, it makes fabrication easier, and it’ll make assembly during the competition faster and easier as well. The other bit of unfinished business is also extremely important, the connections. Connections are arguably the most important part of the bridge design. Not only do they need to be strong and hold the bridge together under large amounts of stress, but they also need to be easily accessible making assembly easy. Last year Lafayette had a very simple but effective connection design that allowed them to rotate their connections into place which facilitated their assembly and helped them achieve the fastest build time at the competition last year. We are currently abiding by the K.I.S. rule (keep it simple) and will hopefully decide on the design soon. By the end of the week hopefully we will be done with design and can focus solely on Solidworks modeling. More updates to come.
3D printing has become much more popular in the engineering world in recent years. Some reasons for this are that it is much cheaper than it used to be and it can make very complicated shapes that would be impossible to make using normal manufacturing methods. Lehigh understands this trend and they have, in Wilbur Powerhouse, many 3D printers available so that students can get experience using this technology. However, because of the large volume of people wanting to print stuff they have a rule that the printing must be done for an academic reason.
For a while now I have been wanting to use these 3D printers but yet I have not had a class or any reason to use them. However, just a few days ago, the graduate student I work for asked if I could use them to print models of the air vehicle we are working on. He needed them to conduct wind tunnel tests of the design. After I said yes, he showed me some of the basics for how to use the machines. After some trial and error, mostly error, I finally got the 3D printed parts he wanted. Below are some pictures of the parts and of the machine I used to print them. Once I got the hang of the machines I enjoyed making them and I look forward to using the machines again.
Two nights ago in Lower Court there was a Chef Challenge competition between four schools. The way it works is schools send a few of their chefs to a school where they each prepare a few offerings with a specific cultural theme. Students sample food from each of the four and vote for their favorite at the end. The four schools were Lehigh, Moravian, Muhlenberg, and DeSales.
Lehigh’s cultural theme was Italy and they made quite a few offerings. They made some garlic bread, spinach salad with olives, chicken parmigiana sandwich, pasta with vodka sauce, and tiramisu for dessert.
If I’m not mistaken Moravian’s theme was Mexico and they made chicken and cheese quesadillas, guacamole with some chips, and these chocolate covered cookies for dessert.
Then Muhlenberg’s theme was India where they had naan with chicken curry, a lamb biryani, some curried vegetables, and some kind of rice dessert with dried fruits and nuts.
Finally DeSales theme was America where they made a cheese steak sandwich with potato chips and also a vanilla shake.
I was only able to eat from Lehigh, Moravian, and Muhlenberg but friends of mine got some of what DeSales made too. Everything the schools made was great. It was much better than a normal night of dinner and it was a lot of fun to try each of what the schools made. It was also very crowded so the lines were quite long. In the end though Lehigh won by a landslide. I think we had over 300 votes compared to the other schools where none of them surpassed even 60 votes. It was a great night and now I can’t wait for next years competition.
For those of you who have not been following what I have been doing, here is a quick recap. When I came back from Pacing Break I found out that some people tried to fly the practice airplane. However, it was a windy day and consequently they crashed it and broke the motor mount. Since I could not get just the motor mount without having to buy a whole new plane, I had to create a new one. So, I went into Solidworks (a 3D drawing program) and created a model of it. This is where I left off on my last post.
Before Thanksgiving break, I sent the material with which to make the mount (top left picture) and the computer drawings for the parts to the laser cutting staff. They cut them out and on Monday I went in and got them (top right).
I spent a few hours putting it all together and gluing it. This is the result.
Finally the plane is fixed and ready to fly again.
A few weeks ago I wrote about being filmed for the commercial Lehigh would air during the 150th meeting for LeLaf over CBS. I finally got to see the finished product at the game and see myself on the Jumbotron. I’ve never been on TV before so this was really cool for me to be a part of it. You can see the commercial here or watch below. I’m the guy welding on the second floor in the closing scene.