Shock isolation performance of a negative stiffness honeycomb with an integrated fluid damping system

In this thesis, the design, modeling, and shock testing of a monolithic curved beam negative stiffness honeycomb with an integrated air damping system is presented. The purpose of this research was to explore the potential to introduce one way damping into negative stiffness honeycombs by exploiting the geometry changes of the honeycomb during deformation. By adhering an elastomeric diaphragm to the open ends of the honeycomb, the volume of air displaced by the beams during compression is exhausted to the atmosphere from the interior of the honeycomb reservoir through a direction biased check valve system. During rebound, the extension of the honeycomb causes air to be drawn in through an orifice resulting in a damping force. A mathematical model of the system was derived using the theory of compressible flow through an orifice and the constitutive force-displacement relationship of the negative stiffness honeycomb was obtained through quasi-static compression testing of a sample negative stiffness honeycomb. A prototype integrally-damped negative stiffness honeycomb was created using the Selective Laser Sintering additive manufacturing process. A latex rubber diaphragm with a differential check valve system was adhered to the open ends of the honeycomb. The honeycomb was subjected to shock loadings using a drop-test apparatus, and the flow control orifice diameter was varied to observe the effect of orifice size on both compressive, or snap-through accelerations, and rebound or snap-back accelerations. By decreasing the rebound flow control orifice diameter, the snap-back accelerations were reduced, but not as effectively as predicted in the mathematical model, providing an incentive to further investigate the concept of integrated damping systems for negative stiffness honeycombs.