Large deflection of a bilayer soft strip due to incompatibility of isotropic volumic expansion.

Since the traditional bending theory of bilayers was mainly for linear elastic materials with the assumption of infinitesimal deformation, here we study the bending of a bilayer soft strip with large deformation. The strip under investigation is comprised of an active layer and a passive layer, where only the active layer is assumed to be subjected to an isotropic volumic expansion. A bending theory for the large deformation of the strip is then developed. The subsequent analysis indicates that our theoretical predictions agree well with the finite element simulation, which, however, can significantly diverge from those predicted by the traditional theory under certain circumstances. With our theory, it is also shown that there exists an optimal modulus ratio or thickness ratio for a bilayer strip to achieve a maximal curvature. We suggest that our theory may greatly facilitate the design of soft bilayer strips that can be potentially employed in varied fields. [ABSTRACT FROM AUTHOR]