Lighter, farther, faster, greener: TUfast Eco team drives to success

The TUfast Eco team of Technical University Munich uses simulation and optimization to develop energy-efficient vehicles. In addition to being very successful at the international Shell Eco-Marathon, the team recently celebrated achieving a new world record for energy efficiency of electrically powered vehicles.

For the Shell Eco-marathon, an international contest for sustainable mobility, student teams from schools and universities all over the world design vehicles that are as energy-efficient as possible. After passing a technical check, the vehicles compete for energy efficiency. In this discipline the vehicles are evaluated for the vehicle’s reach per kWh. To compete in this category, a driver with a minimum weight of 50 kg has to drive a distance of 17.9 km in less than 43 minutes. The average speed must therefore be at least 25 km/h. Teams can also compete for additional “Off-Track-Awards,” which include safety concepts, marketing activities, or technical innovations. Each team can compete in three categories and will be questioned and rated by the jury on site.
Team TUfast Eco
In the last few years, the TUfast Eco team from the Technical University Munich has been one of the most successful teams in the Shell Eco-marathon. The team consists of about 30 highly motivated students from various fields of study, aiming to design, develop and manufacture a vehicle that is as energy efficient as possible to compete in various energy-efficiency contests.

The TUfast Eco team consists of one administrative and three technical groups – chassis, suspension and powertrain.

The students design and develop all vehicle components and assemblies, which are then manufactured in the team’s workshop or in cooperation with external partners. The students rely on Altair Engineering’s HyperWorks software suite to develop, analyze and optimize the vehicle's components prior to production.
The challenges – create an all-new lightweight vehicle
The statute of the TUfast Eco team demands that each year an entirely new vehicle has to be developed. No component of the previous year is allowed to be used for the new competing vehicle. This is to ensure that the technical expertise and development approaches of previous years are used to develop the new vehicle and passed on to the new team.

One of the most important aspects in the development of an energy-efficient vehicle is to reduce the mass of the vehicle. Therefore the team members are constantly looking for weight-saving potentials, especially when designing the suspension and chassis.

A lightweight vehicle can only be developed when all components and assemblies have an efficient design, and in this effort the TUfast Eco team works with Altair and uses its HyperWorks software suite. Team members have access to Altair’s CAE software as well as to the support and training resources the company offers.
The approach – each component is subject to simulation
Almost every part of each vehicle of the TUfast Eco team’s eLi series is designed, simulated and optimized with CAE software prior to production. To do so, the team employs the tools of the HyperWorks suite, including HyperMesh for geometry creation and meshing, OptiStruct as their FEA solver and optimization tool, and HyperView for post-processing tasks.

The use of simulation tools was very important for eLi15. In 2015, new Shell Eco-marathon regulations required that the steering had to be at the front of the vehicle. In addition to the development of the new vehicle, HyperWorks was also used in two master theses related to the project.

The first master thesis focused on the design and shape definition of the vehicle itself, while the second thesis' subject was the evaluation of the basic structure of the vehicle. The team used simulation to investigate how the plies of the vehicle could be positioned best to fully benefit from the chosen material, carbon (CFRP). To optimize the composite material and components, the students applied a three-step optimization approach, developed by Altair especially for the design and optimization of composite materials.

After the exterior shell was determined, the size, shape, and position of the plies were defined. The team then conducted a sizing optimization, during which they were able to determine which loads would occur and how many layers would be needed. The last step was a shuffling optimization to identify the optimal layer sequence. With this simulation step, the students determined which fiber orientations should be used (0, 90, 45 degrees), where the core material should be placed, and how many layers had to be above and beneath the core material.

In addition to optimizing the vehicle's chassis, the Altair tools were also applied to optimize the suspension system.
The successes – driving into the winner’s circle
Thanks to the use of simulation and optimization, the eLi15 vehicle was the lightest vehicle participating in the 2015 Shell Eco-marathon. All other vehicles, with masses between 30-38 kg, were considerably heavier. The eLi15 drove the TUfast Eco team to its most successful year to date – first place at the Shell Eco-marathon in the battery-powered vehicle category and the Shell Eco-marathon’s design award, along with three Off-Track Awards, and another first place in the French Educ-Eco competition with a result of 1888 km/kWh.

In 2016 the team was again successful, winning first place in France and a very good third place in London at the Shell Eco-marathon contest. Building on the success of 2015, the TUfast Eco team was able to save an additional 10 percent of weight, leading to a final official vehicle weight of only 24 kg. This was made possible by applying simulation and optimization methods again – this time in the development of the monocoque.

The front suspension underwent further optimization, leading to an additional weight saving of 25 percent. To reach this result, the students conducted the calculations including the new track and adjusted load cases, enabling them to determine the ideal structure.

The world record – achieving a greater goal
Not content to rest on these laurels, the TUfast Eco team and its alumni were striving for a greater goal. Using the eLi14 vehicle as a base, the team took on the challenge of breaking the official world record for the most efficient electric vehicle.

eLi14 has aerodynamic advantages compared to the newer vehicles, while being very light and equipped with a suspension system that could be easily adapted – ideal conditions for the world record. The team also used their experience with the eLi15 and eLi16 vehicles to modify the vehicle running for the world record, such as the use of a custom-built motor controller in combination with an optimized magnet placement and silver wire coils to reduce electric losses. Acceleration and the speed progression were simulated upfront, and new wheel rims and extremely low friction bearings were installed. An aerodynamically optimized top cover without solar cells was also developed and manufactured.

On July 16, 2016, shortly after half past nine the time for the world record had come. The students and alumni involved met at the Audi test track in Lower Bavaria. After a first false start, the successful attempt to break the world record started at 9:40 am under the watchful eye of a Guinness World Records representative. After five laps, each with a distance of 4573 meters, the team reached the goal and now can officially call itself the world record holder for the most efficient electrical vehicle. The team reached a top value of 1232 km/kWh, equal to a range of 10965 km per one liter of Super 95 fuel.
The future – more competitions, more success
Since its founding in 2011, the TUfast Eco team has participated in three different contests: the Shell Eco-marathon, the Solar Race Region de Murcia in Spain, and the Educ-Eco challenge. In the future, the team plans to participate in other challenges such as the “Urban Concept” category of the Shell Eco-marathon, building additional vehicles to do so.

The team of TU Munich will continue to employ the HyperWorks suite to develop all new vehicles and to design, optimize and analyze components and assemblies, to create even lighter, more efficient vehicles in the future and stay on the road of success.

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