Finite Element Simulation of Polypropylene Pipe Damage Tolerance

A PP material producer needed the assessment of the damage tolerance  of a PP pipe with applied internal pressure. He was particularly interested in the time dependent stress state at an imperfection.

We created a geometric 3D model of a pipe section with an imperfection specified by the material producer and computed a load case with internal pressure. In order to take stress redistribution at the imperfection into account, we used a viscoelastic-viscoplastic material model, which was calibrated from material tests performed in-house by us.

We compared results using the viscoelastic-viscoplastic material model with linear elastic computations. The comparison showed, that an adequate material model is absolutely necessary for a faithful stress analysis at the imperfection. Pipes can be damaged during transport and laying. An adequate material model makes the prediction of a pipe’s damage tolerance possible.

finite element mesh of pipe with imperfection finite element mesh of pipe with imperfection
finite element mesh of pipe with imperfection fea contour plot of stress field at imperfection in a polypropylene pipe Computed stresses at imperfection for two different material models. Two finite element computations are compared. One uses a linear elastic material model. The other uses a visco-elastic visco-plastic material model, which describes the behavior of plastics more faithfully..