Trimming the Fat: Advancing Vehicle Lightweighting Solutions
Vehicle lightweighting—the practice of replacing conventional materials like carbon steel with low-mass alternatives—offers the single biggest opportunity for automakers to boost the fuel efficiency of their fleets while reducing greenhouse gas emissions. More than one-third of the fuel consumed by fossil fuel-powered vehicles is a function of their mass, and tailpipe emissions of CO2 and other pollutants are, to a large degree, a byproduct of getting and keeping all of that bulk in motion.
With the average U.S. auto tipping the scales at around 4,000 pounds (2010 figure), there is ample opportunity to introduce weight-saving innovations all along the automotive supply chain. A recent survey of more than 900 industry representatives by WardsAuto documented a rising appetite for lightweighting as a means of reaching fuel economy targets. In part, it’s a question of self-preservation: By reducing the weight of their vehicles, automakers can go a long way toward meeting emerging global emissions and fuel economy standards, including CAFE.
Fortunately, DuPont long ago recognized the promise of thermoplastic composites as foundational materials for improved vehicle performance and sustainability. Today, DuPont is working hard to advance the adoption of lighter, stronger materials for automotive design—collaborating with automakers and tier-one component manufacturers to develop and test thermoplastic composites for use in structural, load-bearing, and even heat-exposed components.
The DuPont flagship material for vehicle lightweighting is its DuPont™ Vizilon® thermoplastic composite (TPC). The DuPont thermoplastic composite technology offers a holistic approach—an approach which includes design, materials, and processing—all working together to take out the weight. Vizilon® TPC refers to a growing family of complementary technologies that today includes continuous-glass fiber woven reinforced consolidated sheets in a polyamide matrix. DuPont™ Vizilon® TPC combines the virtues of strength and stiffness in a lightweight structure that offers an attractive alternative to most metals in structural applications. In addition, DuPont™ Vizilon® TPC absorbs more energy than metals, making it well suited to crash components. It also performs better in crash applications than other thermoplastics. In tests, a beam made of Vizilon® TPC delivered 5.4 times more energy absorption than a short-glass fiber polymer beam. And for large structural items like floor pans, glass fiber reinforced DuPont™ Vizilon® TPC sheets offer stiffness properties that can’t be achieved with standard thermoplastic resins, creating further opportunities to reduce vehicle mass.
Still, realizing the full benefits of lightweighting technology isn’t a simple matter of swapping out steel parts for plastic. It requires a fundamental shift in the way we design our vehicles. The most effective way to reduce weight is to design for plastic first, rather than using plastics in parts that are designed for metal. Designing for plastic requires a different approach in order to capture all the lightweighting, strength, and functional benefits.
To support these objectives, DuPont is deploying advanced FEA (finite element analysis) technology for more accurate design and performance prediction, and has installed manufacturing capabilities for better process development, prototyping, and demonstration.
DuPont’s partnerships with automakers are beginning to deliver on the promise of thermoplastic composites for vehicle lightweighting. Working with PSA Peugeot Citroën recently, DuPont tested a side-impact beam using DuPont™ Vizilon® TPC with continuous-woven glass fiber. The Vizilon® TPC beam demonstrated a 40% weight reduction compared to ultra-high strength (UHHS) steel, while absorbing more energy than both metal and short glass-fiber polymer beams. As a result, DuPont™ Vizilon® TPC passed its crash tests, making it well suited for application in crash-prone components. Vizilon® TPC also showed excellent stiffness, responding favorably in temperatures from -40°C to +90°C, and outperforming polypropylene-based composites above 80°C.
Structural members aren’t the only place where thermoplastic composites shine. DuPont has a long history of application development and collaboration programs that have led to breakthrough metals replacement, including the world’s first high-volume manifold of plastic and the world’s first commercial volume oil pan made of thermoplastic resin for passenger vehicles.
DuPont continues to invest in global collaboration through its network of 11 Innovation Centers, which connect customers to 10,000 DuPont scientists and engineers. With four of the DuPont Innovation Centers focused on the automotive industry, thermoplastic composites for lightweighting—and the sustainability gains that accompany them—are sure to be a feature of next-generation vehicle fleets around the world.
DuPont is committed to finding ways to reduce dependence on fossil fuels. We are working aggressively with automakers on bringing to market fuel-efficient, low-emissions vehicles that are safe, affordable, and fun to drive.