The 3D-printed NV-8 (left) and carbon fiber NV-9 (right). (Image courtesy of NTU.)
Since 2009, students at the Nanyang Technology University School of Mechanical and Aerospace Engineering (MAE) have been designing efficient, economical and ecologically friendly vehicles for entry into the annual Shell Eco Marathon contest with their Nanyang Venture (NV) series of vehicles. The first incarnation, NV-1, resembled a low-riding recumbent tricycle with spoked wheels. As you will see, thanks to the magic of CAD, the NV vehicles have evolved a lot since 2009!
The first iteration, NV-1, in 2009. (Image courtesy of NTU.)
The most recent iterations, dubbed NV-8 and NV-9, were designed specifically to be entered into the 2015 Shell Eco-Marathon Asia heat, which was held in 2015 in Manila, Philippines.
Both cars were originally designed to be battery-powered with the option to charge from solar panels. However, due to a last-minute change of regulation by Shell which excluded use of solar power, both cars were switched over to run exclusively on battery power. Each car has a top speed of over 24 mph (40 km/h). Because they’re designed specifically for the Eco Marathon track, the cars are optimized in terms of weight, speed and power tradeoff to allow the car to complete the 7.5-mile (12-km) circuit on a single charge.
The NV-8: A First for Singapore
NV-8 has created quite a stir in the media, for good reason. Many of the car’s parts, including the upper body shell (cockpit area), scissor doors and other hardware parts were manufactured using 3D printing. All in all, the car featured over 150 3D-printed components, which were printed mainly on-site with some components printed at the Stratasys office in Singapore.
It is Singapore’s first 3D-printed electric car.
Designed using SOLIDWORKS, the NV-8’s upper body shell is made from over 100 individual ABS plastic segments, which fit together to make a single component much like a huge three-dimensional jigsaw puzzle. Stiffeners are printed within the panels in-situ, providing a honeycomb-like interior and adding strength to the structure while keeping weight down. The entire car weighs in at just over 264 lbs (120 kg), making it lighter than most motorcycles. The chassis is made from carbon fiber and contains all of the car’s motors, the individual suspension systems and running gear.
The NV-9: Improving Aerodynamics
While NV-8 is a radical departure from the evolution of the other NV vehicle lineage, the carbon fiber composite NV-9 bears a much closer resemblance to preceding entries over the years.
The NV-9 in action. (Image courtesy of NTU.)
It has a tricycle design, with two wheels at the front and one at the rear for greater stability. The two front wheels also tilt, allowing for more efficient cornering—just like a motorcyclist would lean when rounding a corner. The rear wheel is driven by a 1-kW DC motor.
The panoramic canopy is made from clear polycarbonate and is tinted to protect the driver from the sun’s rays when racing at the track. Load-bearing structures are made from aluminum. In addition to all the cool mechanical innovations, NV-9 also features a computerized image recognition system for increased situational awareness.
One thing that stands out even to the casual observer is that NV-9 was designed very much with aerodynamics in mind. The overall shape is that of an aerodynamically efficient teardrop. Additionally, the interior of the vehicle uses NACA ducts, which circulate exterior air around the cabin, to keep the driver cool. NV-9 is incredibly light, weighing in at around 93 lbs (42 kg). making it weigh only slightly less than its diminutive test driver!
Both cars managed to scoop up a cumulative score of six awards for Singapore at last year’s Eco Marathon, a record haul for the university. NV-8 was also selected by judges at the event to compete with five other teams in the Shell Drivers’ World Championship in London in July 2016.
Designing the Vehicles
The design of both vehicles took only six months, with a further four months to build and test. This rapid turnaround time was made possible due to the usage of CAD and SOLIDWORKS in particular.
Modeling NV-8 in SOLIDWORKS. (Image courtesy of NTU.)
Associate Professor Ng Heong Wah is the supervisor of the NV project. I asked Ng why SOLIDWORKS was the preferred choice for the NV vehicles. “Students use SOLIDWORKS as it is the default licensed software available to all students at MAE,” remarked Ng. “Most students who come onto the NV projects have experience in other CAD software, but are quick to make the switch to SOLIDWORKS.”
In addition to modeling the car components in SOLIDWORKS, the team subjected both the NV-8 and NV-9 designs to flow and stress analysis within SOLIDWORKS Simulation. This allowed the students to determine the best shape to minimize drag and weight within allowable stresses respectively. Even at relatively low speeds of 25 to 30 mph (40 to 50 km), drag force is quadratic (meaning that drag force increases with the square of the velocity), so it helps to have some form of CFD simulation to get a more accurate view of the vehicle aerodynamics before committing to the manufacturing process.
NV-8 in Flow Analysis simulation in SOLIDWORKS. This was used to optimize aerodynamics. (Image courtesy of NTU.)
The multiple components were mated together within SOLIDWORKS Assembly. Once the assembly was complete, the motion study and animation features were used in order to show that moving components were free from collisions.
NV-9 in SOLIDWORKS assembly mode. Note the carbon fiber composite wheels. (Image courtesy of NTU.)
You can see the evolution of all of the Nanyang Venture vehicles at this link and given the success of the school in previous Eco Marathons, you can be sure that there will be plenty more iterations over the next few years.
Image of NV-8, rendered in PhotoView 360. (Image courtesy of NTU.)
About the Author
Phillip Keane is currently studying his PhD at the School of Mechanical and Aerospace Engineering at Nanyang Technological University, Singapore. His background is in aerospace engineering, and his current studies are focused on the use of 3D-printed components in spaceflight. He previously worked at Rolls-Royce and Airbus Military and served as an intern for Made In Space and the European Southern Observatory.