Engineers at the U.S. Army Research Laboratory and the University of Maryland have developed a technique that causes a composite material to become stiffer and stronger on-demand when exposed to ultraviolet light.
This on-demand control of composite behavior could enable a variety of new capabilities for future Army rotorcraft design, performance and maintenance.
ARL”s Dr. Frank Gardea, a research engineer, said the focus of the research was on controlling how molecules interact with each other. He said the aim was to “have them interact in such a way that changes at a small size, or nanoscale, could lead to observed changes at a larger size or macroscale.”
Dr. Bryan Glaz, chief scientist of ARL”s Vehicle Technology Directorate said,”an important motivation for this work is the desire to engineer new structures, starting from the nanoscale, to enable advanced rotorcraft concepts that have been proposed in the past, but were infeasible due to limitations in current composites. One of the most important capabilities envisioned by these concepts is a significantly reduced maintenance burden due to compromises we make to fly at high speeds.”
The technique consists of attaching ultraviolet light reactive molecules to reinforcing agents like carbon nanotubes. These reactive reinforcing agents are then embedded in a polymer. Upon ultraviolet light exposure, a chemical reaction occurs such that the interaction between the reinforcing agents and the polymer increases, thus making the material stiffer and stronger.
The researchers said the chemistry used here is generally applicable to a variety of reinforcement/polymer combinations thereby expanding the utility of this control method to a wide range of material systems.