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How Thermoplastic Composites Reduce Vehicle Weight?

Mark DeMeuse – Jul 11, 2017

Reducing Vehicle Weight by Thermoplastic CompositesLight weighting or mass reduction is a core focus in automotive markets where a weight reduction facilitates increased fuel economy and decreased emissions.

The high strength-to-weight ratio of thermoplastic composites makes them a suitable replacement for metals for those seeking to reduce weight in vehicles. In conjunction with the proper design of the vehicle components, the composites can provide the same level of mechanical performance as many metals. For example:

  • Carbon fiber-reinforced polyamide composites facilitate significant weight reduction in automotive body and chassis parts
  • Glass-fiber reinforced composites are being used to achieve a reduction of the weight of semi-structural components

In both of these cases, the weight reduction leads to an increase in the fuel efficiency and reduced emissions of carbon dioxide.

Now let's see how weight reduction is achieved using thermoplastic composites.

How weight reduction is achieved?

Lightweight thermoplastic composite materials can generally be divided into two main groups:

  1. Structural composites with or without a textile reinforcement, and
  2. Low-weight reinforced thermoplastics or LWRT’s

Structural composites have a density in the range of 1.1 - 1.7 g/cm3 while the areal weight of LWRT’s ranges from 1,300 to 2,100 g/m2.

Structural Composites

The majority of the structural materials have a PP resin matrix, but other matrix systems are also available. The reinforcement fibers are mainly chopped or continuous glass fibers. Chopped fiber lengths range from at least 25 mm up to 100 mm, which is one of the main differences with other fiber-reinforced materials and processes. Additional fabric reinforcement can be used to achieve tailor-made material properties and significantly higher mechanical properties.

  • For structural applications, mineral-filled grades for non-textile reinforced materials with mechanical properties that are 25% better are used
  • For front-end applications, the use of a multi-layer design for fabric-reinforced materials makes it possible to eliminate additional steel reinforcements

In addition, the use of heat-resistant materials such as PP / PA blends, PA or PBT as the resin matrix material are opening up new application fields.


Their primary applications are in interiors and under-bodies. To further save weight in under-body uses, there is a tendency to replace the hard materials that are produced by various other technologies with these low density materials. A significant reduction in the weight of the automobiles is achieved through the use of that approach.

Weight Reduction that is Achieved!

If all of the potential applications for the use of thermoplastic composites in an automobile are combined in one vehicle, the weight savings potential would be over 50 kg for just the structural applications. These applications include:
Weight Saving Potential using Structural Composites
  • Bumper carriers
  • Pedestrian beams
  • Engine cradles
  • Front-end carriers
  • Instrument panel carriers
  • Seating hatchback structures, and
  • Under-bodies

The maximum weight saving is achieved by using thermoplastic composites in all of these applications 

For automotive interiors, the weight-saving potential that is provided by LWRT’s is not as high as with the structural materials. Roughly 8 kg of weight can be saved by using LWRT’s. Applications for the LWRT materials include:

Weight Saving Potential by LWRT's
  • Instrument panel toppers
  • Tunnel covers
  • Door panel inserts
  • Headliners
  • Parcel shelves
  • Load floors
  • Seat back covers, and
  • Trunk liners

Thus, the combination of LWRT’s with structural materials enables a weight-saving potential of more than 60 kg total. It is important to note that radical innovations are not necessary to observe these weight reductions. This is because:

Achieving Maximum Weight-Saving Potential

Lightweight designs can be achieved with existing systems and without excessively long pre-development phases and development times

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