PSI - Issue 19

Yoichi Yamashita et al. / Procedia Structural Integrity 19 (2019) 123–129 Yamashita et al./ Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 1. Schematic of “ crack growth arrest and retardation system ” using “ gourd-shaped-insert-plate ” .

3. Crack growth tests to verify performances of the crack arrester

3.1. Test method

Various cracks can be assumed in the practical welded structures. First the simplest case is assumed as plate through-thickness crack as shown in Fig. 1. Arresters were applied to CT (Compact Tension) specimen in order to validate performance of the system. For example, CT specimen with three insert-plates is shown in Fig. 2. Fatigue crack growth rate tests were performed with 2-inch compact-tension (CT) specimens regularized in ASTM E647. CT specimens with and without few insert-plates were used in the tests. Also CT specimen with ∅ 5mm stop hole at the fatigue pre-crack tip was used for the fatigue crack growth test for the comparison. Material used for CT specimen is rolled steel for welded structures, JIS SM490YB, which is typical in steel bridges. Also the material used for insert-plate is quenched and tempered high strength steel JIS SCM435 to avoid the fatigue failure of insert plate itself.

30mm

Fig.2. Photograph of CT specimen with three through-thickness gourd-shaped-insert-plates.