Presentation Poster The University of Maine by mikesanye

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									                                                                                                            Material Choice
                                                                                                A number of material options exist for hood reinforcement.
                                                                                                Fiberglass was previously used as it is cheap and relatively light
                                                                                                weight. Carbon fiber and Kevlar are other options available, too.
                     Motivation                                                                 Due to the stiffness driven design for the part, carbon ended up being
                                                                                                the logical choice as it has a higher modulus in comparison to other
                                                                                                available materials.

The stock cowling cannot be used on the modified snowmobile due                                 Once we had determined carbon fiber was the material of choice, we
to the under hood clearance issues brought on by the addition of                                still needed to determine how many layers and of what orientation
emission control hardware. Two replacement hoods have been built                                fabric to use. A simple test was devised that enabled us to test the
previously and yielded mixed results. Neither of the hoods looked                               endurance of the carbon fiber in bending. A lever arm was attached
particularly appealing, and both had fitment and performance issues.                            to one end of a sheet of carbon fiber, with the other end attached to
                                                                                                the stock style hinge mechanism on the sled. With a weight to
                                                                                                simulate the hood attached to the end of the lever arm, it was cycled
                                                                                                100 times and checked for any signs of cracking. This test proved
                            Goals                                                               that two layers of carbon are the optimal number of layers for this
                                                                                                application.


 •Improve quality of hood                                                  Group Members            This Years Achievements
                                                                                                It can be seen in the pictures that this years cowling is a drastic
 •Decrease overall weight of hood
                                                                                                improvement over previous years and even over the original stock
 •Improve rigidity and optimize fiber orientation                           Matthew Bodwell     cowling. This years hood was designed to better clear the muffler
                                                                             Christopher Hill   under the hood, while simultaneously improving looks and helping
 •Increase hood clearance over previous years
                                                                                                the fitment. The new cowling has a far more impressive appearance,
                                                                              Evan Merritt      boasting the carbon fiber look with custom air brushed graphics. As
                                                                                                expected, overall rigidity is up due to the material strength gained by
                         Processes                                             Jesse Morin
                                                                                                choosing carbon fiber over glass fiber, and the increase in the total
                                                                                                amount of material that makes up the cowling. This years hood did
                                                                                                not show a significant weight decrease because most of the time had
This years hood was made using a three stage process. The first
                                                                                                to be spent on creating the mold and learning the proper fabrication
stage was to create a plug in the desired shape of the hood. This was
                                                                                                procedures. Learning the proper procedures helped ensure
made from a rough shape of plywood and foam, which was then
                                                                                                professional quality.
covered with a layer of Bondo to smooth and create the final shape.
The next stage of the build was to create a female mold of the hood
out of fiberglass. We took the male plug we had made, applied paint
and a release agent to it and carefully laid many small layers of
fiberglass over the plug. This gave the mold the shape of the plug
while enabling the fiberglass to take the shape of the plug with
minimal deviations.
                                                                                                                    Future Work
Once the hand lay-up of the mold was completed, a practice hood                                 The new mold will allow future teams to concentrate on more in-
was made. We used the SCRIMP resin infusion process for this.                                   depth stress analysis and lay-up optimization. A more highly
This is a vacuum process that pulls the resin over the surface of the                           optimized design will better utilize core and reinforcement
material, eventually fully infusing the fabric evenly. It gives a closer                        materials that will allow the overall strength and rigidity to
to optimal fiber-volume ratio while reducing void spaces. Once we                               remain at current levels while weight is reduced. Weight
had established a working process, we made the final hood out of                                reduction using modern materials will remain a focus of the
carbon fiber and had it gel-coated and painted by a local bike shop.                            Maine Clean Snow Mobile Team.

								
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