At a recent demonstration at the Detroit Arsenal, a group of 25 U.S. Army program managers and engineers voluntarily spent their time watching glue and were delighted to do it. In an effort to lightweight tactical vehicles, the Army is replacing certain metal vehicle components with composite. Adopting composite materials bring several benefits such as lower corrosion and erosion vulnerabilities, as well as a significant reduction in overall weight. Securely joining these various substrates takes a powerful adhesive. But what happens when maintainers need to work on these composite parts? In order to separate the conjoined parts, it could take hours of grinding, chiseling, or even using forklifts to separate them. These tactics may seem extreme but until the demonstration at the Detroit Arsenal, there was no other choice.
The Reversible Adhesive System for Spall-Liner Applications CTMA initiative is focused on ensuring the new adhesive retains the highest performance levels to increase crew safety while offering a facile reversibility process for maintenance activities. The goal of this new adhesive is to be transportable, and operable in the field and expeditionary locations, although the main focus, for now, is maintenance and sustainment at the depot level.
Using a new compound developed by Michigan State University (MSU) in partnership with PPG, the aim was to have a reversible adhesive that is reliable, reusable, and adaptable to work with various components, focusing on the spall liner as a demonstration. The Army, or any commercial entity that relies on trucks, airplanes, ships, and trains, all of which are undergoing lightweighting and corrosion prevention efforts, would benefit greatly from this initiative.
The MSU/PPG team is evaluating the reversible bonding behavior of thermoplastic adhesive reinforced with graphene nanoplatelets and ferromagnetic nanoparticles for a combination of steel, aluminum, and glass-fiber reinforced composite substrates.
During the demonstration, the team from MSU stood nervously waiting for their joining material to react. The goal was to validate a new adhesive compound that is mechanically sound, safe, strong enough to withstand high energy, and reversible. Incredibly, the new adhesive came apart within 60 seconds.
“You could have heard a pin drop it was so silent,” says Mahmood Haq, Associate Professor in Civil Engineering at MSU and one of the leads on the CTMA initiative. “We thought something was wrong, but it was a shocked silence.”
With the ability to reverse the joining adhesion, maintainers will be able to repair a small part rather than an entire component, saving time, money, and quickly getting critical equipment mission-ready.
“Reversibility is the holy grail!” says Rob Jensen, former acting regional lead, Army Research Laboratory Northeast. “The results from the demonstration were amazing.”
After the successful demonstration, the team is working toward testing to bring the reversible adhesive out of the lab phase, from a Technology Readiness Level (TRL) 4 to TRL 7; from a laboratory product into pre-production.
“It was validating to see the demonstration so well received,” says Erik Stitt, MSU Ph.D Candidate who has been working on this project for the last two years. “We knew the limitations of previous reversible adhesive systems and we were happy to see our advancements create a product to fulfill the needs of the DOD.”