Simulation Predicts Where a Car Will Be Struck by Lightning

Simulation of the Fiat Mobi being struck by lightning

A side effect of the electrification trend in the automotive industry is that when cars are struck by lightning, there is an increased risk of damage.

Lightning follows the path of least resistance around the frame of the vehicle. Like a Faraday cage, the car will keep its occupants safe. However, the same can’t be said for the electrical components within the car.

Considering that these electrical components — batteries, sensors and integrated circuits — control autonomous and advanced driver-assistance systems (ADAS), lightning damage can be extremely dangerous.

Because lightning strikes are frequent in tropical regions, Fiat Chrysler Automobiles (FCA) Brazil has started to test vehicle lightning performance. This research would be hard to physically replicate due to the cost associated with lightning simulation facilities. Therefore, FCA teamed up with ESSS, an ANSYS channel partner, to simulate how lightning affects the Fiat Mobi.

Simulation Determines the Spots Where Lightning is Likely to Hit

Electrostatic simulation of the Fiat Mobi confirms that the antenna is the most likely place for the car to be struck by lightning.

Lightning tends to strike an area with a high charge density, this can be a sharp rod or corner on an object. As a result, car antennas can act like a lightning rod in a storm.

As the lighting travels around the car, it can create an electric field that destroys onboard electronic components. This electric field will be dependent on the vehicle’s conductivity and geometry.

FCA and ESSS used ANSYS Maxwell’s electrostatic solver to estimate the likely places for the car to be struck by lightning.

Their first step was to generate an electric field through a solution domain. An evenly distributed charge was created in the solution domain by placing a 100-coulombs boundary condition at the top and a zero-coulombs boundary condition at the bottom.

Next, FCA and ESSS added Fiat Mobi’s computer-aided design (CAD) model and electrical conductivity data to the solution domain and conducted a new simulation. This simulation confirmed that strong electrical charges showed up at sharp tips and elevated points. Therefore, the most likely place to be hit by lightning was also confirmed to be the antenna.

The next step was to determine how the lightning strike affected the electrical systems within the Fiat Mobi. This assessment was done by conducting a transient electromagnetic simulation in ANSYS HFSS. To learn how Fiat and ESSS performed this simulation, read: The Path of Least Resistance.