Implementation of hierarchical single surface δ₀ and δ₁ models in finite element procedure

Hierarchical single surface (HISS) δ 0 and δ 1 models are briefly discussed. An algorithm for the implementation of δ 0 and δ 1 models in a finite element code and the associated subroutines, written in FORTRAN 77, are presented. The algorithm is general and can be adopted for other computer codes with minor changes. Detailed steps and subroutines are included for easy implementation of the models in specific codes. Two example problems are also presented to enable the user to verify the implementation.