  We find a new type of boundary layers that occur at the top and bottom
surfaces of an inhomogeneous plate. The boundary layers of this type never
occur in homogeneous plates or plates made of layers of homogeneous materials.
The thickness of such a boundary layer is usually less than that of a one
single fiber of the plate. Moreover, we introduce a new notion of
representative plate as a plate whose stress-strain state in some parts is
similar to the stress-strain state in the original plate. In addition, every
part of the original plate has a corresponding part in the representative
plate. We demonstrate that a three-layered plate can be representative of a
plate formed of an arbitrary number of layers. We also demonstrate a wrinkling
phenomenon that happens on the top and bottom surfaces of inhomogeneous plates.
This effect does not occur in homogeneous plates or plates made of layers of
homogeneous materials. Such wrinkling can become a significant adverse effect,
and thus should be given utmost attention.
