SUMMARY

Since its introduction more than 50 years ago, pulse shaping played a key role in the Split Hopkinson Pressure Bar (SHPB) test, a fundamental experiment in the assessment of materials under impact and high amplitude excitation. At its basis, pulse shaping is a wave propagation phenomenon, depending on the material and geometry through which the pulse propagates to modify select pulse characteristics. As such, pulse shaping represents a ripe area for the application of phononic metamaterials which has conventionally been applied to elastic vibration mitigation and isolation. As metamaterials display properties atypical of their constitutive elements, we can exploit metamaterial-based pulse shapers to realize pulse shaping properties not possible with conventional pulse shapers. We explore herein the application of metamaterial-based pulse shapers in the elastic and the plastic regimes. We first develop a procedure to experimentally verify previous numerical work optimizing the design of elastic metamaterials for a pulse shaping application. We then aim to develop metamaterial pulse shapers which will operate in the plastic regime as plastic inputs are common in the SHPB test. To achieve this goal, we first develop a semi-analytical (SA) procedure by which we predict plastic wave propagation in a metamaterial, a topic sparsely covered in literature. With this SA procedure, we also investigate the applicability of an elastic metamaterial's bandgap on plastic waves. Our proposed work extends naturally from the SA procedure by first experimentally verifying its numerical results through the use of experimental slider (or Jenkins) elements to imitate a hysteretical elastic-plastic constitutive curve. Our second proposed work returns to numerical optimization by utilizing both the SA procedure and a finite element model to numerically design a metamaterial-based pulse shaper in the plastic excitation regime. The combination of these works not only contributes valuable tools and insights to wave propagation in metamaterials in elastic and plastic regimes but also realizes the concept of metamaterial pulse shapers for a range of amplitudes.