Multi-step metamaterials with two phases of elastic and plastic deformation

Abstract

From the landing of lunar probes and airplanes to the collision of cars, energy absorption materials are needed to mitigate impact and reduce the damage of the objects to be protected. Traditionally, either elastic or plastic deformation can be harnessed to achieve the function. Elastic deformation-based metamaterials have the ability of recoverable deformation, but their energy absorption efficiency is usually low. On the other hand, plastic deformation-based metamaterials can have improved energy absorption capacity, but are not reusable due to induced permanent deformation. In this paper, a multi-step deformation metamaterial (MSM) is designed with an elastoplastic material and can realize multiple stress plateaus. The first stress plateau involves only recoverable elastic deformation and is reusable, and higher order stress plateaus are associated with plastic deformation to improve energy absorption efficiency. The deformation mechanism and the effect of geometric dimensions are investigated through a combined theoretical, numerical, and experimental approach. Impact experiments are performed to demonstrate the cushion performance. The developed MSM can be employed for shock isolation, vibration control, and multi-task impact attenuation.