  The approximation properties of a quadratic iso-parametric finite element
method for a typical cavitation problem in nonlinear elasticity are analyzed.
More precisely, (1) the finite element interpolation errors are established in
terms of the mesh parameters; (2) a mesh distribution strategy based on an
error equi-distribution principle is given; (3) the convergence of finite
element cavity solutions is proved. Numerical experiments show that, in fact,
the optimal convergence rate can be achieved by the numerical cavity solutions.
