FSAE, shortfor Formula SAE is a worldwide collegiate competition hosted by theSociety of Automotive Engineers (SAE). Teamscomposed of undergraduate and graduate students design,build and competea formula styleracecar in theFSAE series. In competitions, teams score pointsby delivering in four mainevents: design, cost,marketing, and performance events. FormulaSAE is an annual racing competition where student organizations from differentuniversities participate with a small scale Formula style race car.
“Designing, building, and racing” – these three words are probablythe cornerstones of FSAE competition. From ideation to design board, from CADmodeling to fabrication, from machining to lubrication, from testing totweaking, and last but not the least, racing and winning – all are blendedtogether in the PG Racing dream. A cliché definition of FSAE cars wouldprobably go something like this – “single-seat, open-wheeled, open-cockpitperformance race car”.
PG Racing is the official representative of Gdansk Universityof technology in the FSAE competitions held around the Europe. Teams are gradedin the competitions based on their performance in different areas such aspresentation, design, cost effectiveness, acceleration, skid-pad, autocross,fuel economy and endurance of the car.In orderfor teams to be successful in thesecompetitions, their cars must be built to very strictspecifications or else they willbe disqualified from thecompetition. These specifications can be foundin the official most up?to?date FSAE rules on the web. 2.
0 Suspensionsystem of PGR Beforediving into the world of carbon fiber, it is worth getting a good grasp of thesuspension system: a suspension system of a car is a system of springs, shockabsorbers and linkages that connects a vehicle to its wheels and allowsrelative motion between the two. Various geometries have been taken intoaccount while designing the suspension system for the FSAE cars. There arevarious geometries thatsuspension systems cantake in formula one car. The mostwidely?used suspension geometry, even in professional?sized formula carsand the one used by TUGdansk`s FSAE team is the doublewishbone design.
The double wishbones, shown in figure2?1 on thefollowing page are most commonly called A?arms because of theirresemblance to the letter”A”. Figure21: Front Aarms on PGR 2017 formulacar Itis also important to understand the concepts of sprung and unsprung masses inorder to design and engineer an effective suspension system. In a suspension system,the sprung massis the part of the car that is supported by the car’s suspension system.
The engine,the frame, and everything withinthe frame of thecar are part of the sprung mass system of the car.The unsprung mass on the other hand is the part of the carthat is not supported by the suspension. This generally includes the wheels,brakes, tires, and a few other components outside theframe of the car.The A?arm designuses a totalof 16 tubes, 4 on each wheelof the car.These tubes, historically made of steelon formula car suspensions and especially on PGRformula cars make up a significant portionof weight of the car.PGR’s 2017 car’sA?arms weighed a total of 6.49 lbs.
In a competition wherethe weight to power ratiomatters significantly, FSAE teams always strive to design and engineer a car that is as light as possible yet stillstructurally sound and that deliversmaximum power to the wheels.By using carbon fiber tubes to replace the 16steel tubes the total weight of the A?armscan be reduced by at least 50% and the overall stiffness of the tubescan be maintained or even increased.While theA?arms act as structural members of the suspension, the push rod, also shown in figure 2?1, acts as the spring?damper component of the car’s suspension.The A?arms,push rod, and sprung and unsprung masses of the suspension systemall need to be carefully designed so thatoptimal car performance is reached on the race track. 3.
0Carbon Fiber Tubes 3.1Types of carbon fiber Carbon fibertubes are mostcommonly manufactured usingtwo methods: Pultruding and roll?wrapping. Pultruded – Pultrude Carbon Rods and Tubes aremanufactured for maximum rigidity with minimum mass. Pultrusion orients thefibers lengthwise down the shaft for maximum structural rigidity. Carbon fibercontributes to the rigidity, while minimizing weight.
Carbon is 70% lighterthan steel, 40% lighter than aluminum, and three times the stiffness of eitherfor the same weight.The Carbon fiber has a negative coefficientof thermal expansion, meaning it expands as the temperature lowers. The resinmatrix, on the other hand, has a positive coefficient.
The net result isvirtually no expansion or contraction of the composite over a wide range oftemperatures. Figure 31: Pultrudedtube (left) and rollwrapped tube (right) Flexural Modulus 18.5 msi / 127 GPa Fiber Volume 60% Thermal Expansion Coefficient -0.1 ppm/cm3 / -0.
2 ppm/°C Glass Transition Temperature 100° C Matrix Material Bisphenol Epoxy Vinyl Ester Roll?wrapped–Roll-wrapping involves the applying of resin pre-impregnatedcomposite fiber cloth (Pre-Preg) around a mandrel. The outer diameter of themandrel thus determines the inner diameter of the final tube. The mandrel andcloth are then spiral wrapped with a consolidation tape under tension to holdthe laminate in place during the curing phase. After curing, the mandrel isextracted to leave the tube ready for machining or finishing as necessary. 3.
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