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Image of 3-D printed polymer-based foam
An AFRL research team has developed a 3-D printed polymer-based foam structure that responds to the force of a shock wave to act as a one-way switch. These images show the material’s formation of jets, which localize shock wave energy in one direction, but not the other. (Los Alamos National Laboratory photo illustration)

The Air Force Research Laboratory, along with research partners at Los Alamos National Laboratory, are working to change the shape of materials technology with a breakthrough development that could open up a new range of possibilities for the military and beyond. The collaborative team has developed a 3-D printed polymer-based foam structure that responds to the force of a shock wave to act as a one-way switch, a long sought-after goal in shock research.

According to AFRL Senior Materials Research Engineer Dr. Jonathan Spowart, this novel material configuration, although in the early stages of development, has the potential to be scaled up in order to be used in different ways for a variety of applications, including for the protection of structures.

Spowart describes the material as a foam-like structure that contains a series of specifically-engineered tiny holes that determine the overall behavioral characteristics. Over a period of months, AFRL experts used computer modeling to run trials to determine the most effective hole geometries to achieve the desired material response. When they would arrive at a promising configuration, Spowart says the team would print a small test article, a flat plate not much bigger than a pencil eraser. With the help of Los Alamos National Laboratory, working on-site at the Dynamic Compression Sector user facility at Argonne National Laboratory, they would then conduct tests and image the specimen using X-rays to determine performance.

From there, the AFRL team would review results and fine-tune the material configuration to further refine the product through additional modeling and testing. Spowart described the end product as containing a series of hollow cones. When these cones encounter a shock wave, they collapse inward, forming jet protrusions that project from the opposite side. These jets localize the shock wave energy, which is the origin of the material’s unique directional behavior.

Spowart said the team plans to publish their findings and work toward transitioning the technology for further maturation and integration into existing systems, where he believes this technology has tremendous potential.

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