According to Goldman Sachs Research, electric vehicles (EVs) will account for almost half of new car sales worldwide by 2035. As their development undergoes transformation, so too are conversations around sound.

A solution for structure-borne noise

Liquid-applied sound damping, or LASD, is a solution for structure-borne noise. Targeting low frequency vibrations between 0 and 1,500 Hz, it's a sprayable, robot-applied solution that suppresses vibration and creates a quieter ride. It's also used outside of the automotive industry, with positive results in appliances like sinks and dishwashers.

With the climate crisis a continued concern, EVs are on the rise. While internal combustion engines typically help to dampen noise in the cabin of a non-EV, noise in EVs without that engine could become more noticeable, particularly at higher speeds. Thanks to the localization possibilities of LASD, that's changing.

"LASD is fully customizable and can be sprayed wherever necessary," says Akbar Hussaini, Senior Technical Account Manager for LASD and NVH Coatings at BASF. "The automotive engineer can localize a damping solution at the noise source, rather than die cutting and gluing in an asphaltic pad. It is especially effective for parts with complex geometries."

A powerful solution for EVs

The LASD works via a latex emulsion with a molecular backbone that converts vibration energy into thermal energy. LASD entraps low frequency noise and keeps it within the LASD's viscoelastic interior.

Beyond applying LASD to an EV's floor pan, which sees significant vibrations, automakers increasingly see low frequency vibrations of 200-400 Hz on parts like brackets, e-motor mounts and housings, and battery trays.

LASD is ideal for aluminum or coated substrates, including those with primer or e-coat. This is especially important for electric vehicles, which tend to be made of thinner gauge metal to reduce weight and extend vehicle range. Thinner gauge materials inherently have higher vibrations. LASD also has good adhesion to nylon substrates without any surface pre-treatments.

There are other noise damping solutions available in the market, including expensive materials like quiet steel and aluminum. LASD is both more cost effective and enables 100% coverage of a part while minimizing air gaps, offering more efficient noise cancellation.

EV parts are specifically challenging as they operate at a much broader temperature range than internal combustion engine vehicles. LASD helps extend the damping range to -5° to 55°C, which asphaltic pads cannot achieve.

As something that's very versatile, LASD can also be applied to a vehicle's exterior to treat road noise in the wheelhouse, axel, transmission tunnel, and in the underbody area. It is gravel resistant and can help minimize corrosion, all while operating at low exterior temperatures.

LASD is also water-based and low VOC, making the solution friendly for the environment and supporting automakers' sustainability goals.

With thermal runaway for electric vehicle batteries a major concern for automakers, LASD can be tuned with flame retardants to help minimize the risk and can be applied directly to battery housings.

"LASD has a strong track record in conventional internal combustion engine production and recent development work has shown tremendous promise for EVs as well," says Hussaini.

Optimizing vibration damping for each EV part

Each LASD application is its own technical project, and no application or part is the same.

LASD has a strong track record in conventional internal combustion engine production and recent development work has shown tremendous promise for EVs as well.

Akbar Hussaini

Senior Technical Account Manager for LASD and NVH Coatings at BASF

To ensure the chemistry is working as powerfully as possible, specialists like Hussaini put it through its paces with state-of-the-art test equipment that can reproduce automakers' noise problems and create loss factor curves, which shows what happens to noise across a temperature range.

This information, paired with BASF's track record in the industry, enables Hussaini to recommend the right coat weight and correct emulsion to achieve optimal damping. Finished parts can also be coated and tested.

Other considerations to identify the most efficient emulsion selection include oven availability, drying processes, and how quickly parts are handled or packaged downstream.

A developing sector

In the coming years, EVs are only going to become more prevalent.

With that comes more opportunity but also challenges and questions around specifications and needs. Thanks to our work on innovations like LASD and constant work with automotive suppliers and OEMs, BASF isn't just leading the charge but shaping the future of EVs.

"Conventional LASD has been in the paint shop but we're moving that out to new parts and applications," Hussaini says. "LASD holds a lot of promise to create a quieter EV ride."

Find out more about BASF's automotive sound damping portfolio here.

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