A 3D-printed polymer-based foam structure was developed that responds to the force of a shock wave to act as a oneway switch, a long sought-after goal in shock research. The material configuration 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.
The material is a foam-like structure that contains a series of specifically engineered tiny holes that determines the overall behavioral characteristics. Computer modeling was used to determine the most effective hole geometries to achieve the desired material response. Small test articles — flat plates not much bigger than a pencil eraser — were printed. Tests were then conducted and the specimens were imaged using X-rays to determine performance.
Results were reviewed and the material configuration was fine-tuned to further refine the product through additional modeling and testing. The end product contains 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.