  The bifurcation of an incompressible neo-Hookean thick block with a ratio of
thickness to length {eta}, subject to pure bending, is considered. The two
incremental equilibrium equations corresponding to a nonlinear pre-buckling
state of strain are reduced to a fourth-order linear eigenproblem that displays
a multiple turning point. It is found that for 0 < {eta} < {infty}, the block
experiences an Euler-type buckling instability which in the limit {eta} ->
{infty} degenerates into a surface instability. Singular perturbation methods
enable us to capture this transition, while direct numerical simulations
corroborate the analytical results.
