Errors are everywhere, and mechanical failures are especially common: buckled grain silos and cracked support columns are, justly, seen as an issue to be avoided. But flaws can also be used to... Show moreErrors are everywhere, and mechanical failures are especially common: buckled grain silos and cracked support columns are, justly, seen as an issue to be avoided. But flaws can also be used to design materials with unique functionalities. In the work presented here, we use two types of imperfections to create functional structures. First, we design materials that are locally stiff or soft, depending on how they are actuated, using topological imperfections: mistakes in their underlying architecture. Second, we create structures that shape-morph, because their individual elements fail, buckle, and snap- features that should be avoided otherwise. Show less
This thesis explores how rheology and statistical mechanics can be used to describe driven granular materials. Chapter 1 is an overview of the current knowledge of slow granular flows. In Chapter 2... Show moreThis thesis explores how rheology and statistical mechanics can be used to describe driven granular materials. Chapter 1 is an overview of the current knowledge of slow granular flows. In Chapter 2 we characterize the liquid-like behaviour of a granular system excited by flow in a split-bottom geometry. In Chapter 3 we describe the fluctuations experienced by an object floating in our granular liquid and compare these fluctuations to the Brownian motion of particles in a thermal system. In Chapter 4 we characterize the motion of objects moving in a granular system excited by oscillatory flow. Finally, in Chapter 5, we describe both the microscopic and macroscopic motion of pucks on an air hockey table. We find the the system exhibits equipartition of rotational and translational energy and that the system can be described by van der Waals' equation of state. Show less
We study the shear flow of two-dimensional foams, i.e., a monolayer of bubbles floating on a soapy solution. We successfully connect local and global flow behaviour
