Numerical analysis of asymmetric fatigue crack growth behaviors of circular notched bar specimen resulting from various geometric misalignments

• Root causes of asymmetric crack growth of circular notched bar specimens are clarified.
• Crack contour under combined geometric misalignments is successfully simulated.
• The variation of fatigue lifetime due to asymmetric crack growth is verified.

The effects of various misalignments of circular notched bar (CNB) specimens on the fatigue crack propagation behavior of pipe grade polyethylene were investigated by finite element analyses. Generally, as the misalignments increased, the asymmetric crack growth accelerated with a consequent decrease in the time taken to reach the critical stress intensity factors. It was therefore confirmed that the lifetime to failure of CNB specimens varies noticeably when they are misaligned. Going by our study results, the fatigue crack growth behavior of CNB specimens, including their lifetime estimations, should be considered by addressing the effects of their misalignments.