Engineering Adhesive Interfaces to Enhance Dynamic Energy Dissipation within a Mechanical Metamaterial Structure

Mechanical metamaterials manipulate material properties without changing the properties of their constituent material. To accomplish this the geometry of structures has been engineered to improve the impact strength and energy dissipation by introducing a macroscale pattern that can be adjusted to lower the transmitted impact force or improve energy dissipation. Unfortunately for many metamaterials such as foams, these properties are coupled and cannot both be decreased in conjunction. In this work, we move beyond controlling geometry and focus on development and testing of a novel metamaterial structure designed to form new interfaces when placed under compressive strain. These new interfaces will allow us to address individual mechanical elements to gain further control of the overall mechanical response. This configuration allows for the addition of adhesive surfaces that when placed at these temporary interfaces can contribute surface energy that helps to counteract the total mechanical energy transmitted to the metamaterial structure on dynamic impact which is measured through transmitted force and contact time. The addition of adhesive energy decouples some of the material properties from their mechanical response, and is able to lower both the impulse and the impact stress simultaneously which is an extremely unusual property for high impact materials.