The Sunswift Racing team at the University of New South Wales (UNSW) is a group of innovators, comprising both students and staff, who are working together in the research & development of solar electric vehicles.
The broad aim of the team is to redefine sustainable transport. However, they are probably better known for their success at competing in the World Solar Challenges. Since 1996 the teams of students and academics have built six solar-powered vehicles to enter these challenges – and most recently have been hard at work on the development and manufacture of car number seven.
With some 45 people in the Sunswift team all contributing in different ways, the primary aim is to show the world that innovative technology is available today, not in years to come, and they are setting about to demonstrate their ideas and applications. Sub-teams make up the construction sections of the car-building group, comprising mechanical, electrical, computer science, photovoltaics – in other words, solar cells – and systems engineering. Each of these groups has a defined task that also provides them with opportunities to develop skills that they can use in future work environments.
For example, the photovoltaics team is tasked with designing and optimising performance of the solar array to generate power for the vehicle as it moves along the roadway. Relying on CAD programs, the team must ensure that the solar cell power system provides adequate energy generation, along with monitoring the environmental conditions such as temperature changes and irradiance quality, from which data can be recorded as a form of diagnostic benchmarking.
Ahead of the first shakedown test of the car, a number of engineering tests are run during the Challenges to gather data for research purposes. One such data form is telemetry. When analysing the power requirements needed to drive a solar car, measurements are gathered from three different points: the power required to accelerate the car; the power required to climb a hill that needs extra energy; and the power used to overcome the drag or resistance, created both by the tyres on the road as well as the aerodynamic drag. One key aim of the teams is to minimise drag. A member of a British team has managed to analyse the telemetry data from a car and provided useful efficiency yields that can be used by other teams in their development program.
Linking up with industry
Heading up the UNSW Sunswift team is Professor Richard Hopkins. With a background in Formula 1, Hopkins has already been involved in some 28 eight chassis builds and plies his knowledge in overseeing the teams and the construction of car number seven.
To achieve the team’s goals, partnerships with industry are formed to assist the production process, and to support the students as they build car number seven. In building partnerships with industry, Hopkins has had some interesting successes. One recent industry partnership was with Audi, who when approached to provide a set of headlights, found it easier to give the university a whole car.
As SLM Solutions has extensive experience in testing new innovations, followed in the last few years by a wide installed base among European car manufacturers, the company was a suitable choice for building the student-designed parts using a selective laser melting process. In the automotive industry, SLM Solutions multi-laser systems are being used to print aluminium brackets containing cooling channels. These carry circulated water to provide a heat shield next to an electric pump. Another popular development has been the creation of 3D-printed brake calipers that use lightweight material that reduces running costs. These parts can withstand incredibly high temperatures and exceptional stress levels, yet still satisfy automotive standards in Europe and the USA.
This breadth of experience in the automotive parts sector meant Raymax Applications, the Australian distributor of SLM Solutions’ laser systems, was approached to support the mechanical team responsible for the Sunswift Racing chassis, interior, exterior and moving parts. Raymax was asked to provide advice and assistance with the design and 3D manufacture of the suspension struts.
The students completed the designs and provided the CAD drawings. The drawings were sent to Germany for a 3D build in an SLM 500 multi-laser system. The metal used was aluminium, chosen for its light weight, which is essential to the build of the solar-powered car; lightweight parts would help to reduce the overall load, which in turn would reduce the amount of energy required to keep the car going.
The parts were configured to fit onto single build plates to maximise the time for production. While CAD design provides the foundation for the part, it is essential to consider the way parts are organised on the build plate and the number of supports required. Recently SLM Solutions has released Free Float technology, which enables fewer supports to hold a part, minimising both the amount of metal powder needed as well as reducing the degree of post-processing that will be required.
As the automotive sector grows, demands by the industry mean new developments in processing bring about changes in selective laser melting systems. Using 3D printed aluminium and titanium parts is fast becoming the ‘norm’ in car manufacturing today, specifically for the proven weight reductions it offers, which in turn decreases fuel consumption.
Collaboration is critical
It is essential the Sunswift teams work closely together either at UNSW or the workshops of their partners. To ensure co-ordination of the build, the mechanical team had to work closely with both the electrical and photovoltaic systems groups, making sure the parts that they design and build adequately accommodate each team’s need to successfully fulfil their separate tasks.
In previous races the UNSW Sunswift teams have had great success with their cars – uniquely named Violet (due to the car’s colour), Eve, Ivy, Two, Three and One. Now Number Seven is well on the way, with the 3D printed parts received from Germany and fitted into the car. The whole group is hoping to compete in the Bridgestone World Solar Challenge, a 3,000km race from Darwin to Adelaide right through the centre of Australia, competing against other university entrants from all around the world. Hopefully, given their efforts, their success is assured.