1. Oregon State University Solar Vehicle Team

2. Solar Car Mechanical Design
“How do you start the design of a new solar car?”

3. Mechanical Design Maximize Power Input Maximize efficiency
(tractive force)
Minimize drag
Slide 7 of 62

4. A variety of vehicle designs
Michigan
Bochum
MIT
Honda
Principia
Minnesota
Taiwan
OSU, First Car
Queens
OSU, Odyssey

5. Design Tools Solidworks 2012 Solidworks Simulation 2012
Computer Aided Drafting
Solidworks Simulation 2012
Finite Element Analysis
Solidworks Flow Simulation 2012
Computational Fluid Dynamics

6. Initial Design Maximum power with minimum drag: Design process:
Lowest drag with maximum solar cell surface area
Design process:
Start with 6ft driver with helmet
Fit driver with body with max. surface area for cells (6 m2)
Good rule of thumb is to go to maximum width and length allowed
Wrap wheels, frame and suspension around driver inside body
Optimize body

7. Initial Design Process
Insert driver model
Design solar car body, draw in “dummy wheels”
Fit body to driver model, dummy wheels. Maximum low curvature array area
Run wind tunnel testing (Computational Fluid Dynamics, Flow Simulation 2012)
Evaluate drag force, power
Evaluate cross sectional area vs. coefficient of drag
Alter body shape
Can be “arbitrary” change
Repeat steps 3 and 4

8. Design to Rule (Initial Design)
6.5.B Forward Vision:
From the normal driving position, the driver must be able to see at all times, without artificial assistance, points at the following locations:
(1) A point on the ground 8 m in front of the solar car
(2) A minimum of 17° above the horizon on level ground
(3) A full 100° to either side of center
(4) The driver will be required to identify 40 mm high letters at a distance of 3 m through any of the required viewing angles.
6.1 Solar Car Dimensions
The solar car (including solar array) may not exceed the following maximum dimensions when moving under its own power:
(1) Length = 5.0 m
(2) Height = 1.8 m
(3) Width = 1.8 m
6.4.B Seating Position:
The driver must be seated at less than or at a 27° angle, as measured in Appendix B. The driver’s head must be above and behind the driver’s feet. The seat must be appropriately constructed with a solid base and back rest.

9. Chassis/Body Reconciliation
Best “body” initially designed with only driver, dummy wheels
Must “reconcile” body with chassis, due to chassis, suspension members taking up space
Remember:
Aerodynamics most important
Handling performance secondary
Mass considerations secondary

10. Chassis Design
Build smallest chassis necessary to hold driver, wheels and withstand structural requirements
5G frontal, side, rear impact
4G roll over impact
Verify chassis, suspension design with Finite Element Analysis (Solidworks Simulation 2012)

11. Body Re-work Chassis/suspension will “poke out” of body
Remake the body for least drag that will fit chassis tightly

12. Things to Remember Tips for a “smoother” design process:
All designs valid unless proven otherwise
Burden of good design proof is upon designer
Must meet all rules, or design is invalid
Absolutely avoid qualitative assertions: quantitative discussions much more useful
Offer constructive help, avoid criticism in general.
“You could perhaps enhance your design by X,Y,Z” and not “Your design is failing in X, Y, Z!”
Avoid stating absolutes, unless you can absolutely prove it!
Go offline to compute numbers. Don’t argue with qualitative arguments: doing so will often result in circular discussions.
Don’t be married to your own design if someone else’s design is better – we’re all in it together to make the best car possible!
No place in solar car team for ego contests.
Remember – you’re working with friends. Be friendly!!!