LUNAR WHEEL TEAM TEAM: ADAM ANDERSON DAN BARRET RICHARD FREDRICKSON KRISTINA LYNN RAMOS ERIC SOLIS ADVISORS: Dr. COLIN BRITCHER Dr. SEBASTIAN BAWAB
OBJECTIVE design a wheel that would be resistant to the harsh terrain and environment of the lunar surface. The Wheel must be able to hold an applied load of 5,000 pounds anticipated rules for the new competition are different from those of the previous one
OVERVIEW PROGRESS SO FAR DESIGN MATERIAL SELECTION CHARACTERISTICS & COSTS WHEEL BREAKDOWN OF IDEAS TREADS DIAMOND TREADS VERTICAL CHEVRONS HORIZONTAL CHEVRONS
INTRODUCTION Space is one of the only remaining frontiers It holds countless new discoveries Our closest celestial neighbors are the Moon, Mars, and Venus. The Moon http://www.space.com/55-earthsmoon-formation-composition-andorbit.html Mars http://teacher.scholastic.com/scholastic news/indepth/space/mars/index.asp?ar ticle=lifeonmars Venus http://www.earthtimes.org/scite ch/venus-ozone-layer/1486/
FACTS ABOUT THE MOON 384,000 km away from Earth No protective atmosphere Radiation Meteors Lunar Day: between 27.3 to 29.5 days Large temperature swings from 253 F to -387 F The coldest recorded temperature in our solar system was taken on the moon which was 4K Complete Vacuum View of earth from the moon http://www.planetsforkids.org/m oon-moon.html
FACTS ABOUT THE MOON CONT. Composed of igneous rocks Basalt Anorthosite. Covered by regolith extreme terrain variance Craters of varied grades and depths Anorthosite rock http://oedg.niu.edu/summer09/and erson/anorthosite.html Basalt rock http://en.wikipedia.or g/wiki/basalt Lunar Regolith http://www.psrd.hawaii.edu/jul y04/newmineral.html Lunar craters http://www.pbs.org/newshour/extra/features/science /jan-june09/moon_06-23.html
THE REVOLUTIONARY AEROSPACE SYSTEMS CONCEPTS ACADEMIC LINKAGE (RASC-AL) LUNAR WHEEL DESIGN CHALLENGE Held by NASA at Johnson Space Center Seeks ideas for technology to improve exploration on the moon and Mars Rules not currently released
MATERIAL SELECTION LIGHT WEIGHT INEXPENSIVE DESIGN CALLS FOR ELASTIC DEFORMATION ALUMINUM!!!
RANKED BY CHARACTERISTICS
RANKED BY COST * 24"x12"x1/4" SHEET ** 24"x12"x2" FLAT BAR *** 12"X12"X0.1" SHEET **** PER LB @ 12"X12"X0.09" SHEET + 12"X4"X3/4" FLAT BAR
DESIGN OPTIONS
INNOVATIVE BICYCLE WHEEL http://www.bikerumor.com/2013/04/14/loopwheels-curl-carbon-fiber-loops-into-suspensioninside-the-wheels/
CONSIDERATIONS PROS CONS Unique elliptical pattern Utilized series of ellipses to allow for equal deflection around circumference of wheel Offset connection Frequency of ellipses not suitable for rumored load of 5000 lbs Overly simplistic for competitive purposes
WIRED PATTERN http://www.googlelunarxprize.org/teams /frednet/blog/scaled-wrv1-wheeldesign-for-the-jaluro-lunar-rover http://lh3.ggpht.com/- tnjxyjkuu0w/tvtb284poqi/aaaaaaaaaaa/ilij_ky0ubc/ s400/wrv1_wheel_evolution-1.jpg
CONSIDERATIONS PROS Aesthetically unique for competitive purposes Outer hinged plates allow for single point deflection Isolated failure Wire design promotes deflection even deflection around circumference CONS Individual components subjected to large stress values Unlikely for thin, flexible wire with circular cross section to support rumored load of 5000 lbs Large multitude of independent components presents higher risk of failure
MICHELIN TWEEL http://www.frc.ri.cmu.edu/project/lri/scarab/fieldn otes_mk.html
CONSIDERATIONS PROS Introduced an alternative spring design Inspired use of leaf springs and increased frequency of springs CONS Relatively new technology Extremely complex design Expensive and unknown material
DOWN SELECT
PRELIMINARY DESIGN
WEIGHING THE OPTION CHARACTERISTICS Large inner hub Large quantity of holes to decrease waste material and cost Series of ellipses on outer layer to allow for deflection Flat sheet of aluminum on outermost layer for stability WEAKNESSES TO MODIFY Immense size of hub Absence of bolt pattern Single layer of springs to support deflection
SECOND DESIGN
WEIGHING THE OPTION CHARACTERISTICS WEAKNESSES TO MODIFY Smaller hub with realistic design and bolt pattern Second deflective layer added utilizing leaf springs A) Diamond-shaped treads placed on outermost layer of aluminum B) Chevron based tread pattern Tread designs and patterns allows vehicle to traverse radially and laterally 10 ellipses and leaf springs total Single row of ellipses and leaf springs could compromise entire structure if single component fails Bolt Pattern may not be correctly designed A) Diamond treads could result in excessive build up of soil Increase number of springs within structure
FINAL DESIGN
CHARACTERISTICS Bolt Pattern based upon actual pictures of LRV Three series of springs for each layer Rows of springs offset to decrease torsional stresses Offset springs also reduces risk of compromising entire structure if single component fails 16 ellipses and leaf springs in each series and 3 within each row
FABRICATION
HUB CNC MACHINING 6 EVENLY SPACED BOLT HOLES CAST ALUMINUM
LEAF SPRINGS 48 leaf springs Allow the outer rim to deform Welded to center hub Bolted to middle rim
ELLIPSE 48 Ellipses Connects outer rim to middle rim Overlapped and bolted to inner rim
TREADS VERTICAL CHEVRONS DIAMOND VERTICAL CHEVRONS
GOALS FINITE ELEMENT METHOD ANALYSIS BUDGET PROPOSAL PROTOTYPE 3D PRINT OF TREADS TO TEST MINIATURE PROTOTYPE A WHOLE WHEEL--TENTATIVE
QUESTIONS, COMMENTS, AND CONCERNS