MSE PhD Final Defense: Jairaj Narendran

MSE PhD Final Defense: Jairaj Narendran

TITLE: Functional Nonlinearities Enable Compliance-Switching in Elastogranular Structures

ADVISOR: Douglas Holmes ME, MSE

CHAIR: Joerg Werner ME, MSE

COMMITTEE: James Bird ME, MSE; Abigail Plummer ME, MSE; Harold Park ME, MSE

ABSTRACT: Mechanical metamaterials are engineered structures that exhibit mechanical properties that differ from their constituent parts. They often consist of repeating unit cells of a structural component, such as beams, plates, and shells, that introduce geometric nonlinearities (e.g. buckling, large rotations, stress stiffening) which can be leveraged to create a structure with unique attributes (e.g. negative Poisson’s ratio; chirality). The combination of elastic components (shells and rods) and granular components (spheres and rocks) allows for the creation of a new set of metamaterials, where the relative – and often tunable – stiffness of each component dictates the resultant physical behavior. These elastogranular materials combine the geometric nonlinearities of mechanical metamaterials with a jamming-like phase transition to allow for new, functional behaviors. In this dissertation, experiments and scaling analyses are used to create and investigate elastogranular shells and knit columns for their tunable behavior. The elastogranular shells showcase compliance-switching, functionalization of defects, and shape locking behavior while elastogranular knit columns exhibit load-bearing capability, tunable stiffness, and shear resistance.