PSI - Issue 3

Wolfram Baer et al. / Procedia Structural Integrity 3 (2017) 25–32 Author name / Structural Integrity Procedia 00 (2017) 000–000

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consequences of the discussed effect would be of secondary importance. In case of a nearly horizontal J-R curve, the effects influence on the crack initiation toughness value would disappear, Fig. 9(b).

Fig. 9. Scheme on the influence of small amounts of additional crack extension on the multiple specimen J-R curve and the crack initiation toughness value, (a) material with steeper R curve, i.e. higher crack growth resistance, (b) material with flat R curve, i.e. very low crack growth resistance. 3. Summary It can be concluded from the investigation of the crack propagation sensor signal, the force-displacement records and the loading level, that additional crack extension in the specimen due to bouncing strikes is not to be expected under the given conditions of test setup, material and loading. Therefore, it can be seen as a major experimental advantage that the striker does not have to be catched after the low blow test. References ASTM E 1820, 2013. Standard Test Method for Measurement of Fracture Toughness, ASTM International, West Conshohocken, PA. BS 7448-3, 2005. Fracture mechanics toughness tests, Part 3: Method for determination of fracture toughness of metallic materials at rates of increase in stress intensity factor greater than 3 MPa √ m s -1 . ISO 26843, 2015. Metallic Materials - Measurement of fracture toughness at impact loading rates using pre-cracked Charpy specimens, ISO, Switzerland. ISO 12135, 2002. Metallic materials - Unified method of test for the determination of quasi-static fracture toughness, ISO, Switzerland. Baer, W., 2012. Adequate Measurement of Force, Displacement and Crack Initiation in Dynamic Fracture Mechanics Experiments, In: Fracture Mechanics for Durability, Reliability and Safety, Proceedings of the 19th European Conference on Fracture ECF19, Editors: R. Goldstein and V. Shlyannikov, ESIS European Structural Integrity Society, Kazan, Russia.