Poland: Inter-Faculty Project Yields 3D Printed Parts for Silesian Greenpower Racecar

3D printing has the potential to become a driving force in automobiles of the future. Allowing for exponentially more economical design and production, as well as invaluable rapid prototyping, this technology has been in use for many of the bigger names in car production for decades; in fact, companies like BMW have employed 3D printers for over 25 years and continue to invest further.

Racing enthusiasts have caught on quickly to the benefits of 3D printing also. With their own hardware on site—or in working with other parties to create and fabricate parts—those involved in building cars in a more DIY fashion can design parts, evaluate them as prototypes, and then continue to go back to the drawing board as often as needed without breaking the bank.

Building a racecar is not an uncommon endeavor for university students engaged in engineering studies, but with the addition of 3D design and 3D printing, their education and skillset for the future is expanded significantly. In a new twist, faculty at the Silesian University of Technology in Gliwice, Poland not only created several 3D printed parts for a bolide (also known as a fast-racing vehicle) but they became immersed in studying the dynamics of 3D printing and testing its true fortitude for their needs.

In ‘Studies on optimization of 3D-printed elements applied in Silesian Greenpower vehicle,’ authors A. Baier, P. Zur, A. Kolodziej, P. Konopka and M. Komander explain their process for creating 3D printed parts for their Silesian Greenpower electric racing vehicle, as well as the reasoning behind the project overall. The Silesian Greenpower Bullet SGR’s main parts (the frame and body) were created using Siemens NX software, while all cars competing at Greenpower were required to use identical electric motors with two 12-volt batteries for power.

The model of the fairing for back wheels of SG electric vehicle.

Model of the mirror case.

In testing 3D printing processes in the creation of both the fairing and mirror casing for their car, the team used a 3DGence 3D printer with a .5 mm nozzle. Test parts were created in PLA (1.75mm), chosen due to its more environmentally friendly nature, and its ability to decompose within 18 to 24 months. The team made 56 samples, allowing them to examine temperatures, cooling rates, and layer heights.

The model of the frame of Silesian Greenpower electric vehicle.

 “It can be seen, that Young’s modulus varies between of 721 – 1274MPa with the percentage relative deviation in the range of 1.52 – 28.91 % – 2 out of 8 results are more than 25 %, therefore, these results obtained for Young’s modulus are not accurate,” state the researchers in their paper. “However, each of the results is in the range of the reference value for PLA. Maximum forces applied vary between 1.14 – 2.39 kN.”

“Percentage relative deviation for tensile strength is between 1.61 – 14.22 %, so results are accurate. Values of tensile strength are in the range of 29 – 57 MPa. Percentage relative deviation is the same as of maximum force for the corresponding series since tensile strength value is derived from force value. Most of the results of tensile strength are on the higher end of reference value range – 6 out of 8 results are above 45 MPa with the upper limit of 60 MPa. On the contrary, results of the elongation value are on the very low end of reference range with the value between 3.90 – 5.57 %.”

The model of the body of Silesian Greenpower bolide.

On conclusion, the team realized that while lower 3D printing temperatures do not have as much of an impact on quality, layer height is much improved.

“Smaller layer height provides better connection of the outline with the filling, and of the filling itself,” stated the researchers.

Higher temperatures, however, led to improved tensile strength—a requirement for creating car parts.

“At higher printing temperature and lower layer height, the higher cooling rate influences fragility of the material – lowers tensile strength significantly,” concluded the team. “The material is cooled down too rapidly whereby individual strokes did not connect enough with each other. Low printing temperature and high layer height cause a decrease in tensile strength by almost half, also the outline of the specimen is not well connected with the filling.”

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