IBFE examples should have an option to output stress and strain about ibamr HOT 1 OPEN

  /**
   * Postprocessor for the Cauchy stress, defined as
   *
   *     C(FF) = PK1(FF) FF^T / det(FF)
   *
   * Only implemented for dim == spacedim.
   */
  template <int dim, int spacedim = dim>
  class CauchyStressPostprocessor : public PostprocessorBase<dim, spacedim>
  {
  public:
    CauchyStressPostprocessor(
      const std::vector<fdl::ForceContribution<dim, spacedim> *>
        &force_contributions);
  // ...
  };