Carbon nanotubes may soon be ready for EWIS
Carbon nanotube (CNT) technology has been a big topic in many industries for more than a decade. Although it has been around for a while, the application has been hindered by the inability of the manufacturing process to create long, continuous CNTs. Recent developments have improved processes and are generating products that may soon be ready for application.
By weaving CNT fibers together, it is possible for the created thread to be used at the macroscopic engineering scale for applications such as wires and cables. These fibers have incredible properties that make them ideal for aerospace.
Aerospace Applications
Researchers at Rice University have found that, on a pound-per-pound basis, CNT-based fibers are much stronger and have a greater capacity for carrying current than copper cables of the same mass. According to the study, CNT fibers can carry up to four times as much current for the same weight. Given the current technology, the reduced weight comes with an increased cross section. This technology is another option for those designing aerospace Electrical Wire Interconnection Systems (EWIS) where weight is a significant factor.
The study also found that CNT fibers have the highest current carrying capacity (CCC) for any other carbon-based fibers and could more easily dispel heat through convection. The strength of the fibers was also observed by other researchers. They found that wires made from CNT could withstand more than 200,000 bending cycles without increasing resistivity to current (Note: the researchers were evaluating only a conductor and not an insulated wire). In addition, no increase in resistivity was observed when the wires were exposed to corrosive environments.
Many companies in the military and aerospace fields are funding research into new Electromagnetic Interference (EMI) shielding that can effectively protect sensitive electronic sensors and other equipment. EMI can interrupt an aircraft’s electronic equipment and telecommunications, lose data, and may even result in requiring the equipment to be replaced. The Rice University study has found that a more effective EMI shield can be created from a composite material infused with CNT fibers. Not only is this new material effective at resisting high frequency EMIs, but it is also lightweight (the shield weight of a coax cable with CNT shielding was found to be 96% lower compared to the shield weight of a typical copper conductor shielding). Currently researchers are testing how the material’s shielding properties can be strengthened by various factors such as the CNT fibers’ density and applied thickness.
Potential Replacement for Power Distribution Cables
Present-day power distribution cables are heavy large gauge wires with limited flexibility. Designers could remove these cables and replace them with either a lighter substitute (to achieve the same amount of current) or gain the ability to push more current through the system. The additional flexibility could also mean the cables could be routed in ways not possible with copper conductor wires.
Maintenance
Among the biggest struggles for aircraft maintainers is maintaining an airworthy EWIS. Without proper maintenance, essential EWIS components fail and may result in hazardous or catastrophic events. Because of this, it is necessary that any new material or technology is thoroughly examined before it is placed on any platform. The introduction of stronger, more flexible wires with high resistance to corrosion will likely reduce the likelihood of EWIS failure. When finally put into applications, the hopes that these new CNT wires will reduce maintenance costs will likely materialize.
Emma Schwoerer
info@lectromec.comEmma is a full time engineering student at The George Washington University. She works at Lectromec as a junior engineer on a variety of projects including wire testing, aged platform assessment, and arc damage modeling.