Ranking Amongst the Top Three with HyperWorksThe University of Stuttgart Formula Student Team, “GreenTeam”, Optimizes and Develops Winning Electrical Formula Student Car with HyperWorks

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Case Study

„We use HyperWorks throughout the entire development process of our car, for concept design and optimization, from meshing to solving and post-processing and it has helped us to significantly reduce the weight of our car, to make it better and faster. In addition to the benefits we gain from using HyperWorks as a software tool it is also a great pleasure to work with the Altair Engineering team. The support they provide us with is outstanding and from everything they do with us – software, training, events, or support – you can always tell that they are just as enthusiastic about the Formula Student projects as we are.”

Marco Mohl, Homepage and FEM Support, GreenTeam, University of Stuttgart

Overview The Formula Student competitions are international, collegiate design contests, launched in 1981 by the “Society of Automotive Engineers” (SAE) in the U.S. and established in Europe in 1998. The category for electrical vehicles was introduced in 2010. The GreenTeam of the University of Stuttgart is participating with its car in the Formula Student Electric competition since the start of this category three seasons ago. The goal of the Formula Student competitions reads as follows: “The Formula SAE ® Series competitions challenge teams of university undergraduate and graduate students to conceive, design, fabricate and compete with small, formula style, vehicles (Article A1.1 of the Formula Student regulations).”Since 2011 the Team is using HyperWorks to engineer their cars and has achieved a weight reduction on certain components of up to 32% compared to the previous design tool integrated in their CAD system.

Business/Team ProfileThe GreenTeam of the University of Stuttgart is a nonprofit organization with about 35 active student members to develop and to manufacture electric race cars based on Formula SAE rules. The GreenTeam students are responsible for the entire process – concept stage, design stage, fabrication, assembly and testing the prototype. In 2010, the first Formula Student Electric competition, in which only purely electrically powered race cars are allowed, took place in Germany and Italy. In its first year 15 teams participated in this category. The GreenTeam of the University of Stuttgart was one of them and contested with their first car E0711-1. For season 2010 the team reports a successful debut in Germany and Italy with the overall victories. In 2011 (when already 37 teams participated in this category) the team reached a good second place in Italy and currently holds 3rd place on the overall worldwide ranking list for the electric competition. More information about the GreenTeam of the University of Stuttgart can be found at: www.greenteam-stuttgart.de.

ChallengeSince the Formula Student Competition has established a category specialized on electric vehicles it has been the goal of several participating student teams to address the newly involved challenges and to develop winning cars that fit into this category. Traditionally electric vehicles are, due to the integrated rechargeable batteries that drive the cars, heavier than cars with combustion engines. To compensate this weight disadvantage a common need for all teams is to identify the possible weight saving potential in the car, which was unused so far. With the given development process and the used tools, the students would have to do much more virtual design iterations and more physical testing. Due to the limited resources the students needed to employ new development methods to optimize the weight of each component as far as possible, while keeping the components stiff and functional, before the car was built.

The GreenTeam car lists rank three on the world wide ranking list of the Formula Student electrical car competition.

The weight of the rear rocker arm was reduced by 68%.

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SolutionThe GreenTeam uses Altair’s HyperWorks software suite and the various educational offerings of the software and service company and deploys Altair’s concept design philosophy successfully. The team has access to the broad range of software tools from meshing to optimization to advanced reporting, all of them leading to a more streamlined workflow. The virtual testing of the race car was done on component as well as on a system level. Especially on rotating masses significant weight savings have been achieved lowering the energy consumption of the car and leading to a much better vehicle dynamic behavior. Since the car itself is more or less a running prototype, the first design direction is a basic decision. Due to the lack of time and budget the student teams have less or no access to hardware testing except the mandatory ones, such as safety tests of the structure. Being able to bring the components to an optimized shape and weight right from the beginning is a strong competitive advantage for the GreenTeam.

Results/BenefitsBy using HyperWorks, the GreenTeam was able to maximize the performance of its electric race car. With OptiStruct, the optimization tool of the HyperWorks suite, the team has been able to achieve significant weight savings especially on rotating masses. While the monocoque structure was calculated analytically in 2011, the team is already working on enhanced simulation models for the optimization of the overall composite structure. With all the needed virtual software tools in place the team expects considerable additional weight savings in the next car generation.

HyperWorks and the included optimization solution OptiStruct helped to:

• open up the way for an advanced and highly integrated engineering workflow• significantly reduce weight while keeping or increasing the component stiffness• save time and costs• save material and real-world testing• reach weight goals

Topology optimization of the wheel carrier.

The hybrid wheel rim consists of aluminum and composite material and has undergone a topology optimization.

The two symmetric spur gear units are placed in an aluminium gear box.

Wheel carrier and brake desk showing von Mises stresses in a contour plot.

Topology optimization of a gear wheel. Picture is showing the von Mises stresses before and after the optimization process.