  The governing equation for elastic waves in flexural plates is not form
invariant, and hence designing a cloak for such waves faces a major challenge.
Here, we present the design of a perfect broadband cloak for flexural waves
through the use of a nonlinear transformation, and by matching term-by-term the
original and transformed equations. For a readily achievable flexural cloak in
a physical setting, we further present an approximate adoption of our perfect
cloak under more restrictive physical constraints. Through direct simulation of
the governing equations, we show that this cloak, as well, maintains a
consistently high cloaking efficiency over a broad range of frequencies. The
methodology developed here may be used for steering waves and designing cloaks
in other physical systems with non form-invariant governing equations.
