Scientists have theorized that paper-thin composite nanomaterials could stop bullets just as effectively as heavy weight body armor, but progress has been hampered by their inability to reliably test such materials against projectile impacts. Researchers at MIT and Rice University have developed a breakthrough stress-test that fires microscopic glass beads at impact-absorbing material. Although the projectiles are much smaller than a bullet, the experimental results could be scaled up to predict how the material would stand up to larger impacts.

The glass beads, described as "millionths of a meter in diameter," are propelled using a laser pulse technique developed by MIT's Keith Nelson over several years. His technique was modified with the help of scientists from Rice University in experiments conducted at MIT's Institute for Soldier Nanotechnologies. Their work, reported in the journal Nature Communications, was supported by the U.S. Army Research Office, which is keen to reduce the burden on soldiers who currently wear armor that contains cumbersome plating an inch thick.

An electron-microscope image shows a cross-section of a layered polymer and the crater left by a glass bead in an edge-on impact (Photo: Thomas Lab, Rice University)

The team's self-assembling polymer is made by alternating flexible and rigid material layers just a nanometer thick, which can be seen clearly in cross-section with an electron microscope. This allows them to see precisely how the material has deformed after an impact. By studying multiple impacts, the team found that their material was 30 percent more resilient to head-on (rather than edge-on) collisions, a discovery which could change how current protective materials are made.

"It’s a novel and useful approach that will provide needed understanding of the mechanisms governing how a projectile penetrates protective vests and helmets," said Donald Shockey, director of the Center for Fracture Physics at SRI International (unaffiliated with the project), as quoted by David Chandler of the MIT News Office.

The researchers still need to develop a way to record these impacts in real time in order to best understand them, but their tests could accelerate the development of paper-thin military body armor or shielding for satellites, space suits, and shuttles, and more.

View gallery - 2 images