SAE - Biocomposites in Automotive Applications

Organization: SAE
Publication Date: 13 August 2015
Page Count: 139


Lightweight materials are an integral component in product design and integration across several industries, including aviation and automotive, where driving dynamics and efficiency are key factors. The automotive sector has taken a keen interest in lightweighting, from 1941 when Henry Ford unveiled his plastic bodied car made from hemp, sisal, and cellulose-based plastics. Currently, the Boeing 787 and the BMW I series are constructed largely of carbon fiber reinforced plastic (CFRP) support structures. Additionally, the use of CFRP based bearings for an Airbus A340 horizontal tail and car fenders have led to a weight reduction of 50 and 30 percent, respectively [1]. Legislation and regulations in the form of Corporate Average Fuel Economy (CAFE) standards first enacted by Congress in 1975 have been a major driver in improving the fuel economy of automobiles and reduction in greenhouse gas emissions. The CAFE standard for 2025 (Figure 1) is set to have a fleet-wide average of 54.5 mpg, which would translate to over $1.7 trillion in consumer savings and prevent emissions of 6 billion metric tons of CO2 [2].

Automakers employ several approaches to meet their CAFE targets, chief among which are transmission, electrification, hybrid technologies, and lightweighting. However, as seen in Figure 2, vehicle weight has been generally increasing because OEMs have been adding features [4]. The CAFE standards for 2025 have propelled the automotive industry to renew their focus on lightweighting materials.

While steel has traditionally played a major role in the automotive industry, it is increasingly being replaced by alternatives in the form of aluminum, magnesium alloys, and plastics. The replacement of metals by composites in automotive core structure, body, or powertrain offers significant weight reduction, as shown in Figure 3. Greater reduction can be achieved in structural and nonstructural components such as underbody cover, dashboards, roof, frontend, and door modules.