Application of the Potential Drop Method in Brittle Fracture Tests

Steel structures are typically designed for the upper toughness-temperature curve, but reduced toughness in the transition range requires fracture mechanics assessments to prevent brittle fracture.The current standards exhibit discrepancy in this regard concerning bridge bearings. Therefore, a research project by the German Center for Rail Traffic Research aims to address these deficiencies. To achieve this, large-scale component tests are being conducted in which brittle failure of bearing components is induced under dynamic loading. One of the key challenges in these experiments is the detection of crack initiation and the desire to measure crack depth in large specimens undergoing fatigue loading, in order to generate pre-cracks for subsequent testing against brittle fracture. The chosen methodology to do this is the DC electrical potential drop method (DCPD). Here we present preliminary results for a series of tests conducted on representative specimens.