All over the world, a trend toward electric vehicles is growing in significance. As climate change concerns increase, there is a pressing need to find ways to reduce fossil fuel consumption, and vehicle electrification is one of the most promising initiatives on the table. The United Kingdom plans to eliminate all emissions from on-the-road vehicles by 2050, and France hopes to end sales of gas- and diesel-powered vehicles by 2040. Norway is one of the most ambitious countries of all, with a goal of having all new passenger cars and vans sold in 2025 be zero-emission vehicles.
The move toward vehicle electrification opens up new challenges for engineers and manufacturers. There are more differences between electric and internal-combustion vehicles than simply their sources of power.
One of the main concerns engineers have when designing electric vehicles is the same as when designing traditional cars: that of reducing noise. Electric vehicles (EVs) are naturally quieter than internal-combustion vehicles (ICs), as engine combustion noise is not a factor. At low speeds and when idling, electric vehicles are nearly silent. While accelerating, EVs are much quieter than ICs; however, when they reach highway speeds, they suffer from the same cruising noise issues as traditional vehicles – namely, wind noise, tire/road noise, gear whine and HVAC noise.
While noise at cruise conditions is common to all types of vehicles, there are some key differences with electric vehicles. With a relatively thin and distributed electric battery pack, as opposed to a bulky internal combustion engine, designers now have much more freedom to explore unconventional shapes, which lead to different – and potentially noisy – airflow patterns. A need for low rolling resistance in tire design to increase vehicle range may create more noise at the contact patch with the road. Reduction of sound package weight to offset added mass from battery packs rearranges the importance of noise paths through different parts of the body.
Then there are the process challenges that EVs share with their traditionally powered counterparts: prototypes are not available until too late in the development process and noise sources are difficult to trace.
SIMULIA’s simulation tools can help designers come up with better design solutions by allowing them to assess noise performance early in development, exploring new exterior shapes and noise control strategies while the design is still in its earliest stages. Wind, tire, motor/gear HVAC noise reaching passengers can be checked well before a physical prototype is ever created. Simulation can also screen other new sources of interior noise in EVs, such as the noise created by battery cooling fans and power inverters. Modern simulation tools make it easier to identify noise sources & paths and to optimize them well before designs for hardware prototypes are finalized. By targeting and correcting noise issues earlier, quieter and lower cost solutions are possible, reducing the number and severity of launch delays while improving product value for customers.
Finally, even the acoustic vehicle alerting systems that are being required of electric and hybrid vehicles to warn pedestrians of their approach can be studied in simulation to ensure the audio design meets regulations.
Electric vehicles may be naturally quieter than internal-combustion vehicles, but the absence of engine noise makes other noise sources seem even louder. Noise from wind, tires, powertrain whines or fan noise becomes even more critical to control. Creative solutions and diligent engineering are required to mitigate this noise and to ensure the utmost in passenger comfort.
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