Fuel Cell Project Composites Team Report - Plug

The composites team started working on the body of the fuel cell car in September 2002. The team leaders were Martin Indrajana and Ming Lai. Joon Kim designed the original shape of the car. It was modeled after a teardrop because it is the most aerodynamic shape in nature.

The beginning of the work started with the making of the plug, a full sized model of the car from which a mold would be made from. The plug was made from foam, and templates of the cross sections at 2-inch intervals were made to start the building of the plug. These templates were glued to foam blocks and cut out with the hot wire machine. These intervals were all strung together with two long metal bars to produce a very rough model of the car. This rough model was further cut and sanded down to refine the shape of the body to resemble the model that Joon designed. A major problem that arose was the realization that the front wheels were too big to fit in the body. A drastic change to the design of the car had to be made, and two blisters were added to the front of the body to accommodate the wheels. Two foam blisters had to be added to the existing plug. When the shape was roughly sanded out, Bondo auto body filler was used to cover the entire foam plug. This material was sanded down to get more definition to the car. This endless task lasted the rest of the 2002-2003 school year.

As the 2003-2004 school year started, the task of sanding the body to perfection continued with a new composites team led by Daniel Moran and Daniel Lee. Work on the plug continued for a few months into the new school year. Around this time, we hired Bob Santoro to be an advisor. He showed us that our plug was flawed from the beginning, because measurements for the basic structure of the car never existed. The shape of the car looked right, but when we took solid measurements of the plug, we found out that the shape was really messed up. Most of the surfaces were distorted; surfaces that should have been convex were concave, and vice versa. The distance from the top of the front blisters weren’t at the same height. More measurements showed that most of the parts of the body weren’t where they were supposed to be. The entire team became very disappointed at the news, and we found out that most of the work done on the plug was a waste of time because the entire plug was inaccurate. This meant for us a lot more work than we planned on doing, and the completion of the body within the year became questionable. We tried to fix these inaccuracies by using welding wire to get straight curves and applying more Bondo to shape the plug.

Then, we ran into an even bigger problem. Bob found out that the foam we used to build the plug was too soft, and that the Bondo we used to build upon it would heat up the foam to its melting point. The structural foam became so soft from the heat that the entire plug was very soft. This meant that we were getting nowhere fast by using Bondo to fix the problems because the shape wasn’t solid. The surfaces tended to dip and cave in. We had to have a hard plug to work on to continue, so we encased the entire structure in several layers of fiberglass.

Mr. Santoro showed us how to fix the plug by devising a way to get solid measurements on the body of the plug. We did this by figuring out where the wheels of the car are going to be. These points became the solid anchors from which the rest of the body would be judged. These points were drilled out and attached to a giant rectangle frame. This frame was aligned with the floor tiles to create a graph from which measurements can be drawn onto the plug. We created a system of lasers mounted on towers to check for inequalities on the surface. From these lasers we were able to graph longitude and latitude lines at 3 and 6-inch intervals all over the plug. With a graph of measurements on the surface of the plug, we were able to compare the two sides of the plug to real measurements, and finally make some fixes to the symmetry of the car. This was when work with Bondo actually paid off because we finally had a hard constant surface with the fiberglass, and we knew where the fixes had to be made thanks to the graph. Within a few weeks we were able to produce an accurate shape for the car. The plug was finally done. We added several layers of primer to cover up the hodgepodge of Bondo patches and give a definite color to the plug in late January.

With the plug finished, we started on the bottom mold of the car, which was made in two sections to allow for easy release from the plug and future parts. We first applied high temperature wax, then Coverall film onto the bottom of the plug. To create the surface of the mold, we applied several layers of gel coat. Now the plug was ready to be made. We finished each half of the bottom mold by applying several layers of fiber mat with polyester resin.

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