Scaling Up the Next Generation of Body Armor

The next generation of body armor might be lighter, more flexible and much stronger thanks to its scaly structure.

armor, scales, material, military, securityDermal mod­i­fi­ca­tion is a sig­nif­i­cant part of evo­lu­tion, says Ranajay Ghosh, an asso­ciate research sci­en­tist in the Col­lege of Engi­neering. Almost every organism has some­thing on its skin that pro­vides impor­tant sur­vival prop­er­ties such as pro­tec­tion from preda­tors, cam­ou­flaging, thermal reg­u­la­tion, and sen­so­rial func­tions. In many ani­mals, this evo­lu­tion has led to the for­ma­tion of scales.

This is why Ghosh and his col­leagues in North­eastern University’s High Per­for­mance Mate­rials and Struc­tures Lab­o­ra­tory are looking to the prop­er­ties of animal scales to help them develop the next gen­er­a­tion of armor sys­tems. The lab studies the mechan­ical behavior and per­for­mance of mate­rials and struc­tures, at var­ious scales from nanowires and living cells to ships and buildings.

Led by asso­ciate pro­fessor Ashkan Vaziri, the lab’s find­ings were recently pub­lished in the journal Applied Physics Let­ters, being fea­tured on the cover of one of December’s issues. Hamid Ebrahimi, PhD’17, who is pur­suing her doc­torate in mechan­ical engi­neering, was also a co-​​author.

Ranajay Ghosh holds a 3-​​D printed model of a fish scale he used in his armor system research. Photo by Matthew Modoono

“The next gen­er­a­tion of armor sys­tems are light, per­form a lot of func­tions, and at the same time do not com­pro­mise on pro­tec­tion,” Ghosh said, “and nature pro­vides very impor­tant infor­ma­tion in terms of armor development.”

The research, which is sup­ported by the National Sci­ence Foun­da­tion and Qatar Foun­da­tion, involved exam­ining dif­ferent strate­gies for gen­eral pro­tec­tive sys­tems that are light­weight and multi-​​use across industries.

The researchers chose to mimic the prop­er­ties of fish scales because fish, like a person wearing armor, need a fine bal­ance between mobility and pro­tec­tion, Ghosh explained. Using 3-​​D printing, the researchers cre­ated models of fish scales that were embedded in a soft sub­strate. Adding these scales caused the soft sub­strate to stiffen up, a response the researchers found could be achieved rather quickly because of the scales’ size and place­ment within the substrate.

“This is very dif­ferent from what people have been working on before, which is focusing on the very nature of the scales them­selves, how they will behave, and whether they break easily or not,” he added. “Here, our focus is simply the effect of simple scales and their mutual con­tact and inter­ac­tion with the soft substrate.”

Ghosh said the research also iden­ti­fies that even with pedes­trian mechan­ical prop­er­ties, nature has devel­oped very com­plex systems.

In this project, the researchers’ work focused on exam­ining the impact that adding scales would have on the substrate’s elas­ticity. Having found this makes the sub­strate stiffer and less pen­e­trable, the next step is deter­mining how this work can help create tougher armor. The lab plans to con­tinue with more advanced testing on fish scales’ pro­tec­tive prop­er­ties, with the ulti­mate goal of com­bining the prop­er­ties of sev­eral dif­ferent ani­mals’ scales into one armor system. The mobility of snake scales and the optics of but­terfly wings are among these intriguing prop­er­ties the lab hopes to inves­ti­gate, he said.

“We can syn­the­size what nature could not do because we have more flexibility with the materials we use,” Ghosh said.

Source: Northeastern University