Daily Archives: April 20, 2018

Adaptive Materials

Engineers at the U.S. Army Research Laboratory (ARL) 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”, he said. The reduced scheduled maintenance of future Army aviation platforms is an important technological driver for future operating concepts.

Army researchers imagine a rotorcraft concept, which represents reactive reinforcements that when exposed to ultraviolet light will increase the mechanical behavior on-demand. The engineers said control of mechanical behavior could potentially lead to increased aerodynamic stability in rotorcraft structures.

The enhanced mechanical properties with potentially low weight penalties, enabled by the new technique, could lead to nanocomposite based structures that would enable rotorcraft concepts that we cannot build today,” Glaz said.

The joint work, recently published in Advanced Materials Interfaces (DOI: 10.1002/admi.201800038), shows that these composite materials could become 93-percent stiffer and 35-percent stronger after a five minute exposure to ultraviolet light. 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.

ource: https://www.arl.army.mil/