MODELLING AND SIMULATION
Electric vehicles are developed using Catia g Modelling the flow of the electrical
power from the battery and across the vehicle is also an issue, as Vincent Marche, marketing director at Altair, explained: ‘You need to choose the best path to ensure you reduce the weight and size of the vehicle and this requires electric and thermal physics to be taken into account [and] the designer must make some technical choices on what technology to use during the design process.’ For example, when incorporating the
battery into the vehicle, such technical decisions must be made by the designer, as Yen added: ‘The weight of the battery is hard to bring down, so we need to make savings on the structural side by using materials such as aluminium and composites instead. The designer can select different materials and optimise the battery design using C123 to achieve this.’
Lightweight designs Lightweight materials are often used to help both traditional and electrical vehicles make the necessary weight reductions. For example, engineers at ARRK took a conventional electric transmission housing, made of aluminium, and substituted this with a housing made from fibre reinforced thermoplastics in an electric vehicle. The design consisted of an optimised organo-sheet layer and UD- Tapes placement, with ribs overmolded by a standard injection process. The ESI PAM-FORM simulation module gave a first indication of the manufacturability of the organo sheet and highlighted the problematical areas in the stamping process. Stamping and injection molding simulation techniques were further used to assess and optimise the manufacturability and a weight reduction of 30 per cent was realised in the design. Hervé Motte, R&D innovation manager at ARRK, said: ‘Function complexity of electrical gearboxes is mostly lower compared to conventional gears because
28 Scientific Computing World October/November 2017
it is not necessary to have a high number of gears (i.e. conventional vehicles have up to seven gears and electricals have one or two gears).’ Motte added: ‘Most challenging for electrical gearboxes is the acoustics because there is no combustion engine, only a silent electrical engine, which makes the gearbox acoustics dominant, especially at low velocity. The sound of a transmission (usually a whining sound) itself is annoying for the customer, so it has to be optimised. Also, weight is really essential for electrical cars to improve their range as much as possible by appropriate costs.’
Flying high Electric cars are not the only form of vehicle under development. Electric aircraft also rely on simulation and modelling tools to optimise such designs. Electric aircraft company Ampaire, is developing a high-performance, zero- emission aircraft with the assistance of such techniques. The company’s director of Powertrain Engineering, Omar Laldin, said: ‘The most significant challenge on an aircraft is mass, which constrains the power-to-weight ratio of the vehicle. While also important in the car, aircraft systems may require five to ten times more power per kg from the overall system for take-off, including the battery and motors. ‘As a result, increasing range is
significantly more challenging as the battery is limited primarily by mass, instead of available package volume. Our simulation tools allow us to investigate every early-stage innovation, even if it is not yet implemented in an industrial setting,’ he added. The reduced development times
facilitated by simulation and modelling are key, according to Laldin: ‘Models and their simulations allow for rapid development of the vehicles, significantly reducing design iterations down to one or two. As such,
the overall cost and time of the projects become a fraction of what they had been. Detailed simulations allow engineers to develop more targeted solutions, often triggering the creative genius of ‘out-of- the-box’ thinkers.’ Simulations will also aid market
acceptance of electric vehicles, as Laldin explained: ‘Modelling and simulations tend to facilitate wide-scale acceptance by providing visualisation to the mathematics, making it easier to convey the message to non-technical personnel and over a wide range of media.’ Sometimes you need to be in the driving
seat to truly understand their integration into the automotive industry, as Laldin said: ‘Acceptance for an individual is most significantly tied to the user experience during, for instance, a test drive.’ This is why the optimisation of the user
experience using simulation and modelling tools is a vital component of the design
“Our simulation tools allow us to investigate every early-stage innovation, even if it is not yet implemented in an industrial setting”
process – but proving that an electric vehicle provides a comfortable and enjoyable drive is one area where such tools cannot compete with the real world. So, while simulation and modelling
tools optimise electric vehicles to reduce the complexity of the design process and ensure real cost and energy saving capabilities, they can only take this work so far. The automotive industry needs to get drivers in such vehicles to ensure they never get stuck on the starting line again. As Moseley said: ‘I don’t think people will ever believe it until they drive it.’
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