Author: Formule ETS - Ecole de Technologie Superieure
Team history
The ETS team was founded in 1988 and started to compete in 1989. All cars are mostly designed, fabricated and tested in-house by the students. Before 2004, all cars had the similar architecture: a steel tubular frame and a 4-cylinder engine. In 2004, the team introduced their first carbon fiber monocoque, formed with tooling and processes developed in-house. The car had a 4-cylinder engine and weighted around 220 kilograms. In 2005, the team focused on reducing the weight of the car, switching to a single cylinder engine, ten inch wheels and designing a lighter monocoque. Since 2007, the cars have a hybrid frame combining a front monocoque with a tubular steel engine compartment, ten-inch wheels, inboard dampers and a single cylinder Yamaha engine.
Design criteria
Before designing this year’s racecar, we first took a closer look to last year’s car to highlight its strengths and weaknesses. We partially based our design criteria on the improvements we wished to do for the next car. Last year’s car had poor fuel economy, an unreliable shifting mechanism, malfunctioning critical engine sensors (TPS & cam angle sensor), custom fabricated components failures and a lack of simulation in the design process.
Our four major design criteria are based on what the customer wants: easy maintenance & preparation, good drivability, confidence inspiring safety features and low cost.
The engine removal time was reduced to less than an hour by integrating quick-release connections on the engine wiring harness and the cooling system. The powertrain is attached to a simple subframe, the only chassis part removed in the process.
The engine and differential are linked together by articulated supports, reducing the load on the transmission output shaft, the subframe and the backplate.
Every part failure is investigated and documented in the failure analysis database to help avoiding repeated design flaws and mistakes.
A hydraulic clutch pedal system reduces friction and improves driver feel, thus making starts easier.
The seat is molded to each driver for perfect body support and comfort.
The driver position is based on SAE comfort standards.
There are no spherical bearings on the suspension arms, reducing the cost of the rebuilt after an accident.
All composite parts are built using the vacuum infusion process, which doesn’t require an autoclave.
The use of a single cylinder engine simplifies all the rebuilding process, the fabrication of the intake and the exhaust, the development process and the removal from the chassis. It is also cheaper and parts are easily findable in motocross shops.
Most impact sacrificial members are made of sheet metal and tubing.
Tires, wheels, spindles and dampers fit on all corners of the car.
The car fits in any standard pick-up truck bed to simplify transportation.
Simulation
We try to incorporate more and more simulation in our design. This year we developed the suspension kinematics using OptimumG’s OptimumK kinematics simulator. The chassis, the impact attenuation zones and the suspension arms were developed, simulated and analyzed on Ansys. Most components of the car have been analyzed using Ansys workbench to ensure acceptable durability. Fabrication Most of the parts of the 2009 car are fabricated in-house to better understand everything that fabricating a racecar implies. The machined parts are all student-made and inspected, using specific inspection procedures for each part. The composite tooling is mostly developed and built in-house. Through research and testing, the team’s infusion process is refined enough approach the limits of the compromise between impact attenuation, structural rigidity and weight that building a chassis implies. The precision of the rear tube frame and its mating with the tub are ensured by the design of a laser-cut steel chassis jig.
Validation & testing
The car’s reliability is validated by doing 40 kilometer endurances followed by a thorough inspection.
This routine lasts for two weeks. We then start to do some work on setups and to do some validation tests.
Here are some of the tests we do along the project.
Brake test bench
Material physical characterization.
Flow bench testing and validation on the intake system and the cylinder head.
Engine dynamometer testing for engine calibration and engine development validation.
Vehicle mass inertia measured on an inertia jig.
Damper characterization on a shock dyno.
Torsional rigidity test.
Suspension kinematics & compliance test: This year we will test compliance and kinematics on a K&C machine at the Goodyear test facilities in Akron, Ohio (reward prize for scoring first in endurance/fuel economy at FSAE-M 2009).
Wheel assembly compliance test: We test the compliance of the complete wheel assembly (wheel, bearings, spindle and upright) by installing the assembly on a electric powered jig and applying cornering load on the rim and measuring angular deflection.
Tips to a better design report
Define clear design criteria for team to follow through out design process
Set goals which will give direct gains with respect to points system
Show specific process used to attain goals
Don’t mention questionable concepts that are not facts
Don’t use the word ‘’optimize’’
Make sure the design report follow rules, ie. proper characters, page quantity, etc…!
Comments
With the win at the UofT Shootout, I hope Jude made his peace and can graduate now! :-)
All the best for 2010!
Thomas
jr08evo
joanneum racing graz