Create lightweight, durable underbody components for EVs with Tepex composite material

As vehicle electrification accelerates, lightweighting plays a significant role in creating optimal driving experiences. The batteries of electric vehicles (EVs) on average weight 454 kg (1,000 pounds), with bigger models weighing as much as 900 kg (2,000 pounds) and some even up to 1,800 kg (4,000 pounds).

To compensate for the heavy batteries, engineers need to design as many lightweight components as possible for EVs. Thankfully there are materials, which are much lighter then metal, that designers can utilize. These materials also ease logistics and transportation and allow fewer secondary operations—no milling/drilling, painting, corrosion protection—with lower energy consumption, less waste streams in production and less hazardous production steps.

You can make stronger and more rigid energy-absorptive underbody components 

When designing underbody paneling, the engineering materials that are about 30 percent lighter than a steel design are Envalior’ s Tepex® Dynalite branded continuous-fiber-reinforced thermoplastic composite materials (CFRTP). Tepex is the composite material family of Bond-Laminates, a 100% daughter company of Envalior. Not only are these materials lightweight, but they are also highly effective and mechanically stable for underbody paneling components.

The materials are resistant to penetration and help to increase energy efficiency. Batteries are especially vulnerable to damage because they are usually installed in the floor panel. Thus, the underbody paneling components protect the batteries against stone impacts or other damages when the vehicle underside gets hit.

Underbody paneling components made of Tepex can be found among a multitude of  modern cars in the models Li L9, Li L8 and Li 7, from Li Auto Inc., a Chinese carmaker offering extended-range electric vehicles. These six-seater premium family SUVs include a gas-powered engine that charges the battery on the go, and their underbody paneling protects the tanks.

The panels consist of a robust, thermoplastic composite structure and are manufactured using the compression molding process with a reinforcing insert made of the composite Tepex Dynalite and a DLFT (Direct Long Fiber Thermoplastic) mass. When compared to other material concepts–such as pure DLFT–the Tepex reinforcement makes the paneling component stronger as well as more rigid and energy-absorptive.

Enabling an efficient production process

The underbody paneling component is around 1.5 meters long, 1 meter wide and just 3 to 4 millimeters thick. It is manufactured with a 1 mm thick insert made from Tepex Dynalite 104-RG600 as a top layer and an additional extruded DLFT mass. Both materials are heated and plasticized and then placed in a compression tool, where they are molded together in just one single step.

The matrix of the Tepex insert consists of polypropylene and is reinforced with 47 volume percent of continuous-glass-fiber-rovings. The polypropylene DLFT mass contains 40 weight percent of long glass fibers. As both components are compatibly PP based, they form a perfect bonding.

This material combination fulfills the high mechanical requirements and shows a high level of resistance to penetration. The underbody paneling component can be manufactured on a conventional compression molding tool.