In 2006 the University of Maine Team started to work on a sled based on a Yamaha snowmobile. This project focuses on the improvements to this sled in the noise vibration and harshness area. In 2008 the snowmobile competed in the clean snowmobile competition. As a result of some problems encountered with the fuel system the team had the worst finish in the history of the UMaine CSC team. In order to perform better in the 2009 competition, it will be necessary to optimize the effort. One key aspect of the project is the noise and comfort events at the competition. For these events additional exhaust modifications may be necessary, but the drive train, mechanical noise, induction and other noise sources are also important sources of significant gains in noise reduction.
Currently the snowmobile also uses foam added to the internal panels of the cooling. It is expected that fresh cowlings will be built using novel designs such as using the sound deadening material as a core material in the cowling. This overall part of the snowmobile is one of the most important part of the Clean Snowmobile effort. In the past a test method other than the SAE J192 has been used. This test was poorly designed and not repeatable. Two years ago the test was modified to be done in a way that we can prepare properly for the competition. We have consistently had a good showing on this event. However.... the Yamaha snowmobile is not an easy snowmobile to design for low noise. The 2008 team did a good job of building a good looking snowmobile, but integration of the NVH was not good.
A basic computer model of several of the key noise paths based on literature in the area and previous year's efforts will be used to design sound attenuation strategies. Evaluation of the exhaust noise to determine if that is a significant factor in the overall noise from the snowmobile and determining a method for reducing track noise in particular the use of low noise components on the idlers and slides. An engineering evaluation of the effect of the induction system on the overall sound level produced by the snowmobile should also be included.
1. Summary report of sources of noise including baseline data on noise from snowmobile including octave or 1/3 octave data
2. Design with justification of a quiet cowling design as well as key elements of other noise sources (bogey wheels etc.)
2. New cowlings, esthetically pleasing, with measured transmissibility and reflectivity data
3. Demonstration of new cowlings at a public event in Maine
4. Performance at competition
5. Documentation of the efforts in the form of a design report and presentation for competition and for class.
# Project Team Selection Complete: September 4, 2008
# First Revised Milestones Submitted: September 11, 2007
# Design Notebook Initial sign-off: September 16, 2007
# Obtain J192 noise standard: September 25, 2007
# Design and conduct a repeatable noise level test on the dyno (RPM vs. Time): October 2nd
# Have noise testing equipment running for SAE J192 standard: October 11th
# Have completed cowl on the sled, and know cooling issues: October 16th
# First web page goes live with introductory page and menu on left. Page must include resumes, individual photos and milestones: October 14, 2008, 2 pm.
# Milestone review: November 4th , 2008
# Determine mechanical noise issues: November 6th
# Test J192 noise on snow: December 4th (snow permitting)
# Draft Midterm Report: December 9th , 2008
# Midterm Report due as a PDF posted as a completed web page: December 18th, 11:30 am
# Isolate vibrations on handlebars and foot-rail: January
#Attend and present snowmobile at least two events: February 26, 2009
#Attend Clean Snowmobile Competition: March 10 - 15, 2009
# Lab Cleanup & Infrastructure Project Completed: Maine Day, April 29, 2009
# Open House -- Review of Projects, April 30, 2009, Afternoon
# Final Web Page submitted, for review during final exam period: Monday May 6th, 2009 Noon,
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