EFFECT OF NOTCH ROOT RADIUS ON THE CREEP FAILURE MECHANISMS ON PALYAMIDE 6: APPLICATION OF FRACTURE MECHANICS APPROACHES

摘要

The polyamide 6 (PA6) under study exhibits non-linear time dependent (viscoplastic) deformation when submitted to steady load (creep) at room temperature. An experimental database consisting of creep tests performed on notched round bars with various notch root radii was built. Failure mechanisms of the PA6 material were investigated thanks to comprehensive microscopic examinations of deformed and broken specimens. Global approach of fracture mechanics for creeping solids was applied and showed its limits. Alternatively, the local approach of fracture mechanics was attempted, with the help of finite element analysis. It was shown that this approach could successfully capture main features of creep damage mechanisms of the PA6 material, which lead to complete failure.