Team HPV: A Quick Review

Transcription

1 : A Quick Review Prepared By: Tyler Jandreau, Taylor Brown, Jamie Huffman, Joey Stine, Kevin Villa, Matt Strand, Kyle Chapman, Jimmy Woodard, Adam Cooper and is only reproducible with permission of 1

2 Overall Goal To Design and Build one of These: and is only reproducible with permission of 2

3 Objectives will design and build an aerodynamically and mechanically efficient vehicle that uses pure human power to achieve a top speed of at least 61.5 mph. Presents a Unique Challenge: Rider Watt Feasibility Calculations Aerodynamic Considerations Frame Analysis and Design Shell Analysis and Design Drivetrain Analysis and Design Fabrication of all necessary not off the shelf parts and is only reproducible with permission of 3

4 Evolution of Requirements To determine the validity of the requirements, we must first understand needs of product: Crash Preparedness? Fabrication Process? Correct Velocity? Testing? Time constraint? and is only reproducible with permission of 4

5 Functional Requirements To determine the success or failure of the HPV project, it is necessary to determine what the HPV has to actually do: HPV has to be completed before Senior Showcase, 2009 HPV has to be rideable HPV has to have basic rider safety features HPV must be light enough for one rider to propel HPV shell must be puncture resistant and resist a specific point load HPV drive train must not have a mechanical loss of more than 5% of total input to reduce frictional losses and is only reproducible with permission of 5

6 Team Goals The HPV team s goals include: will assemble and build a vehicle to compete in land speed challenge will perform all necessary calculations for success by hand Computer tools will be used to verify previously completed hand calculations Success will be met by meeting 100% of functional requirements and ~80% of nonfunctional requirements and is only reproducible with permission of 6

7 Basic Systems Engineering Introduction of Basic Flow Chart Literature Review helps team create revolutionary ideas Literature Review also eliminates exploring dead ends Design and Analysis obviously lends itself to Prototyping and is only reproducible with permission of 7

8 Calculations The equations to the left were used to perform basic feasibility of the HPV to determine if the human body can break the 61.5 mph barrier wright.nasa.gov/airplane/drageq.html The equation to the right was used for analysis on the frame. It is the equation for deflection of a beam with two free ends and a force in the middle. Also, standard deflection was used with one ridged end. δ = Fa 2 (3L -4a)/6EI δ = FL 3 /3EI and is only reproducible with permission of 8

9 Power Feasibility Impulse from the high watts has little effect on overall change in velocity while long, slow burns have a significant change in velocity. This also shows that if vehicle is lighter, it will have greater change in velocity. and is only reproducable with permission of 9

10 Rider/Watt Feasibility Obtaining the Human Power Curve Trained Humans only 25% Efficient Watt Output Decreases Rapidly Ergonomic Position Greatly Effects Watt Output Cycling Envelope can be Calculated from these Parameters and is only reproducible with permission of 10

11 Rider/Watt Feasibility Graphical Power Envelope: Velocity in MPH OUR GOAL Plotted with a CdA of 0.2. Ours can afford to be higher than this. It is substantially more difficult to accelerate at already high velocities Distance in Miles and is only reproducible with permission of 11

12 Rider/Watt Feasibility Creating a Cycling Envelope. It is clear that a small aerodynamic increase will yield the speeds we need MPH Watts MPH Watts CdA = 0.25 (our vehicle) and is only reproducible with permission of CdA = 2.4 (road cyclist) 12

13 Drivetrain Calculations Feasibility calculations for drivetrain system were also preformed, showing HPV team that a minimum loss of power can be achieved with proper engineering: Drivetrain must be able to meet or exceed 8.4:1 Ratio. Most ideally, 9:1 Calculations and analysis of CVT transmission showed that 8:1 is nearly impossible for standard CVT transmissions (~4:1). We needed to double this. To obtain 9:1, manual production of a CVT must be facilitated, which exceeds groups ability in machine shop. Hybrid drive train system developed, using half belt, half chain mechanisms for power transfer and is only reproducible with permission of 13

14 Drivetrain Calculations Speed calculations using mid drive and possible cassette option. 700x23mm Series Wheels Dia (in) Md Drv Ratio Crank Pulley Unit Conversion Mid Drive Pulley INPUT 3" Pulley w/ Cranks 2" Mid Drive Pulley Belt 53 Tooth Chain Ring Bike Chain 700x23 Race Wheel # of Teeth Ratio Overall Ratio Speed (mph) Chain Ring Cassette < Min Start speed < Optimal Overlap Cassette T < 88 rpm at same above speed Wheel Dia (in) Wheel Rad (in) Circumference (in) and is only reproducable with permission of 14

15 Drivetrain Calculations Validity testing using standard road bike to ensure accuracy of calculations. Calculation Validity TESTING 700x23mm Series Wheels NO MID DRIVE Unit Conversion Theoretical Experimental # of Chain Ring Teeth # of Cassette TeethRatio Cadence (Rpm) Speed (Mph) Speed (Mph) % Diff. (%) Wheel Dia (in) Wheel Rad (in) and is only reproducible with permission of Circumference (in) Tests performed on Jimmy s road bike. 15

16 First Mock Up Mock up with 53 tooth chain ring and standard bike cassette/derailleur Test runs indicate > 61 mph This confirms initial drivetrain calculations. Picture taken on 9/1/2008 in Jimmy s Garage. and is only reproducible with permission of 16

17 First Mock Up Hybrid belt and chain drive system to minimize losses. 700x23c series wheels at 100 cadence requires a total gear ratio of 8.4:1. Picture taken on 9/1/2008 in Jimmy s Garage. and is only reproducible with permission of 17

18 Drivetrain The incredible torque from the belt made our wood model unstable. Further testing required an aluminum/steel frame MAX STRESS Picture taken on 9/1/2008 in Jimmy s Garage. and is only reproducible with permission of 18

19 Video of First Mock Up This video details the base level prototype testing. and is only reproducable with permission of 19

20 Frame Team Human Power will be designing and building two frames: 1. Aluminum Frame Easy to Build Use as Testing Mule Practice Operating 2. Composite Frame Lighter Stronger Integral Piece of Shell More Torsional Rigidity and is only reproducible with permission of 20

21 Frame Aluminum test frame to be used for practice and calculation purposes. Not a Wine Bottle and is only reproducible with permission of 21

22 Frame Frame Considerations Stability Rider Ergonomics Strength Torsion Rigidity Weight Basic Force Directions Max Tension 1.88 kip Max Compression.56 kip Max Shear 1.88 kip Max Moment 28.4 ft*kip and is only reproducible with permission of 22

23 Frame Moment, ft*lb Normal Shear Force, lb lb Internal Normal Moments Forces Internal Shear Forces F = 0, F = 0, F = 0 x y n M = 0 x F = 0 v and is only reproducible with permission of 23

24 Frame Both ANSYS and Hand Calculations were done on the Aluminum Frame This technique ensures accuracy through redundancy and is only reproducible with permission of 24

25 Frame 100 Weight of Beam at Given Core Thickness to Resist Internal Forces (Carbon-epoxy T300/N5208) σ = M bht Beam Weight, lb HRH-10 Al 1/ Al ACG-1 HRH-49-1/ τ c = V Core Thickness, in bh and is only reproducible with permission of 25

26 Frame Findings Greatest internal forces between seat mount and front fork Greatest moment between front fork and pedals Sandwich core greatly reduces weight required Future Tasks More research in material selection Optimize local ply thickness Finalize design to use shell structurally and is only reproducible with permission of 26

27 Shell Considerations Power Loss for HPV by Percentage. Loss System % Total Power Loss Aerodynamic Drag 85 90% Rolling Resistance 5 10% Drivetrain Friction Loss ~1 2% Wheel Rotation Power ~1% Miscellaneous Loss Power to Overcome Gravity (Hill Application) Varies Greatly Depending on % Grade of Hill and is only reproducable with permission of 27

28 Shell Feasability This shows relation between frontal area, Cd, and power required to travel 61.5mph. Power Available: 1200 W A = 0.45 or 0.3 Cd = 0.2 or 0.3 and is only reproducable with permission of 28

29 Shell Designs CdAof 2.4 Bad Good CdAof 0.25 CdAof and is only reproducable with permission of 29

30 Shell Foam Donation Used to make multiple shell models Will be tested in wind tunnel Model with lowest CdA value will be modeled in Pro E and is only reproducible with permission of 30

31 Shell Reverse Engineering Why Reinvent the Wheel? Testing and improving on previous designs increase efficiency. Much easier to determine what worked and what didn t. YES NO and is only reproducible with permission of 31

32 Shell What Will it Look Like? Fast NO and is only reproducible with permission of 32

33 Auxiliary Systems What are Auxiliary Systems? Secondary systems that fulfill necessary functional requirements: Braking Cooling Turning Saftey NO and is only reproducible with permission of 33

34 Braking Feasability Shows Kinetic energy associated with different weights and speeds Will be used for braking distance calculations and is only reproducable with permission of 34

35 Current Budget Total Budget = $62 and is only reproducable with permission of 35

36 Current Sponsors At this time, our sponsors are as follow: and is only reproducable with permission of 36

37 Timeline Jimmy Conditioning Fundraising Frame Assemble Sponsorship Package Brainstorm Potential Businesses Design Re-Design Pro Engineer March April May June July Aug Sept Oct Nov Dec Jan Feb March April May Shell Drivetrain Determine Materials Ansys Manufacture Design Pro Engineer Determine Materials CFD Manufacture Design Manufacture Build Final HPV Test Present Final Results and is only reproducable with permission of 37

38 References and is only reproducible with permission of 38

39 Questions? and is only reproducable with permission of 39