What makes a material bendable? A thickness-dependent metric for bendability, malleability, ductility

The requirement for materials that can bend is proliferating with the growing interest in flexible electronics and devices. The terms bending and flexing are often used interchangeably even though flexing is usually meant to be elastic while bending often involves plastic deformation. Materials can be compared with a simple “bendability figure-of-merit” through the fracture strain—that is, how much a material can be bent plastically once before breaking—for a given thickness of material, which is similar to the way that yield strain serves as a figure-of-merit for flexibility.