Semester Wrap-Up

Onward to 2017





Team Goals

Although it's been a bit too long since the last update, rest assured the team's been harder at work than ever before. We're constantly pushing ourselves to the limit to show just how excellent of engineers we are. And what better a way to do so than to debut our talent on the largest stage in the solar car world - World Solar Challenge 2017. We are determined to work at a pace that will allow us to race in Australia next October. But we can't do it alone. We're setting up a crowdfunding page through Indiegogo to raise money to help cover the cost of transporting our car and team to Australia to race against the best of the best.
Help us out at: https://www.indiegogo.com/projects/fighting-illini-vs-world-solar-challenge-car-competition#/


Business

We are currently updating our team sponsor packet. There have been considerable improvements within the team since our last update, and we are excited to elaborate that in our new packet. We also had the wonderful opportunity to meet with representatives from Molex, a sponsor helping us with our electrical connections. We were able to see some of the innovative technologies the company creates and how some of these could be implemented into our car.
A good chunk of the team showed up to learn how beneficial our partnership with Molex could be.
Some sample connectors provided to us by Molex.

Mechanical

Our slightly off-campus work space known as Linview has become a second home for the entire composite subteam, and for good reason. Fixing, sanding, and priming the molds in order to do fiberglass and carbon fiber layups is a manually intensive process that's had half the subteam occupied for months. The other half has been working on building a simple and safe oven to cure the layups. With the oven successfully working, all efforts are now on the creation of fiberglass molds for the wheel fairings.

An encompassing view of the progress at Linview.





The progression of priming the fairing (3 images above) to finally laying up carbon fiber.
Some of the team trying to stay warm inside the futuristic looking oven as we prepare it for initial testing.
The dynamics subteam has been working equally as important duties. Performing force analysis on the suspension system through CAD in order to optimize it in the future, the team is finding out how the car will react to turns, breaks, and bumps at various g-forces. We've also created a thorough analysis of the various nuts and bolts we've decided to use as a standard system, and what kind of loads they can take in what directions. These two combine to determine the very important aspect of our car's safety. For example, once a specific location has been analyzed, resulting in us knowing the forces and applied loads at that point, we can reference the nut and bolt analysis to determine whether there is a factor of safety of at least 2 at that location. If there isn't, then we'll have to find a way to make it safer. Those more interested in the nut and bolt analysis can read a brief description below.


Screenshot of g-force testing.

On any point of connection with bolt and nut are used to sustain the required normal and shear stresses, we are interested in finding the relationships between these two forces and make a selection of a proper grade and size bolt and nut. Also, considering the preload stress when we fasten the nut, we want to know how much torque we want to apply to make sure it’s within the safety standard. The king equation to make sure the bolts and nuts are going to be reliable and safe is the following:

(N+Ni)/Nd)^2+(V/Vd)^2≤1

First, Nd and Vd are the designed ultimate stresses for the bolts, the N and V will the normal and shear stresses the bolt need to withstand at that joint, and Ni is the initial load caused by fastening the bolt. The initial load depends on the coefficient of friction, the bolt geometry, and so on. With the calculation, we come up with plots for the four specific bolt size that will be used in our car. With all these information given, when building a car, people will be able to look at the loads at the certain point, telling which bolt size will be used and how much preload will be put to fasten the bolt.

Electrical

The precharge board, which works in conjunction with the power distribution system, and the test bench boards were sent out for manufacturing before Thanksgiving break and are now in our possession. This is integral as the test bench system will provide a platform for testing nearly every board in the electrical system with relative ease. Meanwhile, using LPCXpresso as an interface to debug our boards has been harder than we expected, but there are a number of people on the team who had past experience with the tool and they taught the rest of the members how to set it up. The battery system has been the least cooperative of our systems so far, since we have had mysteriously dead batteries for a period a few weeks ago. Rather excitingly however, we were recently able to put the whole system together to operate and control the speed of one of the motors.


Aerodynamics

New members are still in the process of learning CFD.  They have been very successful in matching the results of the Ahmed Body case. More experienced members are making great progress developing abstract model files to enable more efficient meshing and case setup. We’ve experienced some hiccups automating the post processing with PyFoam, but we hope to be back on track in the coming weeks!

Solar

Over the 2016 fall semester, the solar group has been working on teaching new group members about solar cells and training them on the complete process of making a module for the car. Most of our encapsulation modules are test modules and have yet transitioned to producing car modules. We have also decided to conduct all further encapsulation processes using our own oven (encapsulator) after an update with larger silicon heating pads during the winter break. The solar group has also tested previous modules out in the sun and are working on creating a database of module performances under different weather conditions for future output prediction. Two of our group members are working on making an IV curve tracer that will make cell testing easier and more efficient. We also used silicon adhesive to attach modules onto a wooden platform but further practice is needed in order to attach precisely. Below are various images of solar array testing on a beautiful day.








Closing Remarks

As always, if you've made it this far, then thanks for reading! Let us know how we can improve communication to you (more frequent, funnier writing, etc.). As a team, we know we wouldn't be here without your support, big or small. We're hoping to post more frequent updates as we near the completion of the car this upcoming semester. Happy holidays and don't forget to support us!