Noise Vibration and Harshness
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. Initial benchmarking of the performance of our sled will be required, along with testing of the effect of a range of standard and new modifications. Exhaust modifications will be necessary, but the drive train, mechanical noise, induction and other noise sources are also important sources of significant gains in noise reduction.
This is perhaps 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. If this team does not do a good job we cannot win this year.
Design build and test, as a team, a quieter 4-stroke sled. 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.
Clean Snowmobile Challenge – Noise, Vibration and Harshness Team
# First Revised Milestones Submitted: September 18, 2007
# Design Notebook Initial sign-off: September 20, 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 11, 2007, 2 pm.
# Have exhaust re-routing completed with a new muffler? Installed: October 30th
# Determine mechanical noise issues: November 6th
# Milestone review: November 6th , 2007
# Test J192 noise on snow: December 4th (snow permitting)
# Draft Midterm Report: December 6th , 2007
# Midterm Report due as a PDF posted as a completed web page: December 19th, 11:30 am
# Isolate vibrations on handlebars and foot-rail: January
#Attend and present snowmobile at least two events: February 26, 2008
#Attend Clean Snowmobile Competition: March 10 - 15, 2008
# Lab Cleanup & Infrastructure Project Completed: Maine Day, April 30th, 2008
# Open House -- Review of Projects, May 1st, 2008, Afternoon
# Final Web Page submitted, for review during final exam period: Monday May 5th, 2008 Noon,
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