Advancements in the aerospace industry are tied to the need for improved fuel efficiency. Jet fuel prices almost doubled to $112/barrel in 2012 from $65/ barrel in 2006. Companies are working to reduce cost and improve material performance in airframes. For example, Lockheed Martin is evaluating carbon nano-reinforced polymers (CNRP) to replace approximately 100 components made with other composites or metals throughout the F-35’s airframe. CNRP offers a 20 to 30 percent weight reduction at one tenth of the cost of carbon fiber reinforced plastics (CFRP) and several times higher strength. Recently, Hexcel came up with a carbon fiber/epoxy sheet molding compound that enables complex shapes to be manufactured in series production.
The benefits of using composites in up to 50 percent of the structural parts of the 787 are shown in Figure 6.
The aerospace industry is moving toward automated tape laying (ATL) and automated fiber placement (AFP) to fabricate parts. Both ATL and AFP machines are very costly and complex to operate. Mikrosam AD has developed a new line of automated fiber placement machines that apply both technologies (ATL and AFP) on a single mandrel. From a single computer, producers can program both technologies. This has resulted in no downtime to change from one machine to another, low manpower and drastic savings in machine investment.
Advancements in the wind energy industry focus on blade length, which has continuously increased in the last 10 years and is expected to increase at an even faster pace in the future. The average turbine size in the United States was 0.89 MW in 2000: This reached 1.94 MW in 2012. All major OEMs are working on large size turbines. For example, Vestas has launched an 8 MW wind turbine and Samsung Heavy Industries introduced a 7 MW turbine. Mitsubishi, Sinovel, Goldwind, Guodian United Power, Sway and Clipper have plans to develop 10 MW turbines, while GE energy will develop turbines ranging from 10 to 15 MW. In addition, Gamesa plans to make a 15 MW turbine.
Increasing blade length requires the use of high-performance materials to increase stiffness and reduce weight. Vestas and Gamesa were early innovators and started using carbon fiber in spar sections. After seeing the benefits, other players followed suit, including GE Energy via Tecsis, Samsung Heavy industries via SSP Technology and ETI via Blade Dynamics. Figure 7 demonstrates the spar cap mass and spar-to-blade weight ratio at various blade lengths.