Isabelle J. Berger, Andreas Frank, Gerald Pinter, David Nitsche, Dirk Petry
Papers # 2018 Las-Vegas
Electrofusion (EF) sockets constitute a well-established and practically proven technology for the joining of polyethylene (PE) pressure pipes. As for the pipes, the potential lifetime of such welding connections is beside other properties also depending on the resistance against slow crack growth (SCG). The current paper presents a scientific approach for a fracture mechanics lifetime prediction based on quasi-brittle failure behavior of EF sockets made of polyethylene. Therefore, various internal pressure tests on EF sockets were conducted under elevated test conditions with focus on generating quasi-brittle failure curves and investigating characteristics of crack initiation and SCG. In combination with internal pressure tests, a numerical simulation (FEM) model for the stress intensity factor characteristics in EF sockets was created to predict the time to brittle failure. The results demonstrate that with the fracture mechanics approach a reliable prediction of minimum lifetimes of EF sockets for internal pressure loading situations and application oriented installation situations is possible.
