Causes of scatter in high rate fracture testing of polymers

A method based on the measurement of failure time is being developed by the European Structural Integrity Society to determine high rate fracture toughness of polymers. The test method appears reasonably straightforward but produced unacceptably high scatter, due to failure time data scatter. In this work an experimentally based sensitivity study was performed by fracture tests at 1 ms−1 in order to determine the causes of scatter and to seek to improve the test protocol. No single cause of scatter was identified but the quality and repeatability of the notching technique was identified as a major contributor.

► High rate fracture toughness tests based on a failure time method are studied.
► Failure time is measured on polymeric specimens by strain gauges.
► The goal is to determine the reason of high scatter of failure time measurements.
► The accuracy of strain gauge signal is confirmed by high speed video recording.
► The pre cracking process is identified as a major contributor to data scatter.