13th International Conference on Fracture June 16–21, 2013, Beijing, China -10- The camera has two objective lenses, each of which tracing a black-white contrast on the specimen ligament so that two redundant displacement signals can be provided. The camera measurement technique is validated statically by gauge blocks and dynamically by comparison of the results of elongation measurement at rupture in dynamic tensile tests with the corresponding manually determined values. 3. Summary and conclusions Experimental aspects of dynamic fracture mechanics tests on bend type specimens were discussed and different techniques for the measurement of force, displacement and crack initiation were investigated. It can be concluded that the fairly limited recommendations of the test standards may provide significantly different results. Therefore, they cannot simply be transferred to the own specific experimental tasks. It must be considered an absolute essential prerequisite that the used measuring techniques are validated in advance. The detection of unstable crack initiation by crack sensors in KId tests works well. Compared to that, the use of crack sensors to detect stable crack initiation in low blow R-curve tests needs further enlargement of the data base to finally rate the technique. References [1] BS 7448-3, 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, 2005. [2] ASTM E 1820, Standard Test Method for Measurement of Fracture Toughness, 2011. [3] ISO 26843, Metallic Materials – Measurement of fracture toughness at impact loading rates using precracked Charpy specimens, in preparation. [4] D.R. Ireland, Procedures and Problems associated with Reliable Control of the Instrumented Impact Test, Instrumented Impact Testing, ASTM STP 563, 1974, pp. 3-23. [5] D.R. Ireland, Critical review of instrumented impact testing, Dynamic Fracture Toughness: an International Conference arranged by the Welding Institute, London, 5-7 July 1976, published in 1977, pp. 47-62. [6] Trudeau, L.P.: Dynamic toughness – its relevance and measurement, Research report R 275, Department of Energy, Mines and Resources, Mines Branch, Ottawa, Oct. 1974. [7] W. Baer, A. Eberle, D. Klingbeil, The impact of ductile cast iron fracture behaviour on dynamic fracture mechanics R-curve testing using key curve methods, In: Fracture of Materials and Structures from Micro to Macro Scale, 18th European Conference on Fracture ECF18, Editors: D. Klingbeil, M. Vormwald and K.-G. Eulitz, ESIS European Structural Integrity Society, Dresden, Germany, Aug 30-Sep 03, 2010, 8 pages. [8] W. Baer, D. Bösel, A. Eberle, D. Klingbeil, Determination of dynamic crack resistance of ductile cast iron using the compliance ratio key curve method, Engineering Fracture Mechanics 77 (2010), pp. 374-384. [9] W. Baer, P. Wossidlo, B. Abbasi, M. Cassau, R. Häcker, R. Kossert, Large scale testing and statistical analysis of dynamic fracture toughness of ductile cast iron, Engineering Fracture Mechanics 76 (2009) 8, pp. 1074-1086. [10]M. Enderlein, M. Kuna, A. Ricoeur, W. Baer, K. Müller, K. Klein, H.-P. Winkler, Numerische Analyse des Stossbiegeversuches zur Ermittlung der dynamischen Bruchzähigkeit, Proceedings der 35. Tagung des DVM-AK „Bruchvorgänge“, 18.-19.2. 2003, Freiburg, DVM-Bericht 235, 2003, pp. 251-260.
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