Determination of fracture toughness and resistance curves by three methods on armoured steelManjgo, Mirza (Avtor) Glodež, Srečko (Avtor) Lojen, Gorazd (Avtor) Vuherer, Tomaž (Avtor) Protac 500fracture mechanicsKJICresistant curvesParameters of EPFM are used as relevant parameters in structural integrity assessments. In this research, the fracture toughness of armoured steel was determined. The resulting resistance curves and KJIC obtained according to the ASTM E1820 standard with normalization, compliance and multi-specimen methods were compared. Also, the KIC was verified according to the ASTM E399 standard as the most precise method for obtaining the KIC, which also requires a lot of knowledge. For the experiment, the multi-specimen method was used, which is the most expensive and most accurate method, where the least assumption and crack size is measured on the specimen. A fractographic analysis was also presented, and this heat-treated high-strength steel, which is used for anti-ballistic protection, was fully characterized.MDPI20252025-07-03 10:09:11Članek v reviji93579UDK: 539.3COBISS_ID: 241213443DOI: 10.3390/jmmp9070212ISSN pri članku: 2504-4494sl