On-set slow cracking time detection for the Notched Ring Test

Abstract

A Method of detecting on-set of slow cracking (or slow crack initiation) time for the Notched Ring Test (NRT) specimen is proposed and the method was evaluated on plastic pipe resins having high slow crack resistance. The modified displacement technique proposed takes the raw experimental data in the form of load-line displacement of the NRT specimen versus time and modifies the load-line displacement data utilizing a suitable exponential power until the details of slow crack initiation becomes displayed on the modified displacement versus the time curve. It has been demonstrated that the method is promising in detecting on-set slow cracking times in NRT specimens when used on properly obtained experimental data. Whenever applicable, the proposed method was checked with the segmental numerical differentiation method to help better understand the viability of the proposed technique. In all cases, fracture surface examination is required to verify that the crack initiation has indeed occurred. (C) 2010 Elsevier Ltd. All rights reserved.