This paper presents the results of notch tests on single edge notch specimen under condition corresponding to the PENT approach, i.e. at temperature 80°C and nominal stress 2,4 MPa. Tests were performed for one monomodal and two bimodal HDPE materials, both from structural and fracture mechanics point of view. Under conditions corresponding to the PENT test the dependence of a crack opening displacement COD vs. time was measured and the values of the rate of the stable crack growth rate da/dt and time to fracture t_f were estimated. To estimate the residual life of pipes the finite element model with an initial defect was suggested and the values of the stress intensity factor K have been calculated. The computation took into account the change of the crack shape during its growth in the pipe. For assessment of the residual service life of pipes the relation da/d_t = A (K)~m was applied. The values of the pipe lifetime for three studied materials are compared and diagram of the hoop stress versus failure time is presented. The results show that slow crack growth tests can rank qualitatively different pipe grades.
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