In this thesis we will look at the implementation and results of the APS program. The program computes the accumulated plastic strain in a umbilical tube for the deformations axial tension, bending and internal pressure. The computation is based on solving incremental problems with the finite element method and the return-mapping algorithm. The return-mapping algorithm encountered convergence failure for large strain increments, this was solved by using the strain increment of $1.0e\sp{-4}\%$.The implementation of axial tension and bending was consistent with the results provided by Nexans Norway.While the plastic behaviour of the internal pressure proved to be more complex, so the implementation requires improvement.