PSI - Issue 7

Igor Varfolomeev et al. / Procedia Structural Integrity 7 (2017) 359–367 Igor Varfolomeev et Al./ Structural Integrity Procedia 00 (2017) 000–000

367

9

• The UT indications found in the material blocks were of a size which usually requires a fracture mechanics assessment. Thus, the experimental results on the specimens with defects demonstrate a substantial conservatism of the flaw characterization rules incorporated in the fracture mechanics codes (e.g. BS 7910, 2013; FITNET, 2008; FKM, 2009). • The numerical approach adopted for modeling damage evolution at defects yields a reasonable prediction of the crack formation around a defect field. In particular, this may improve the overall life time assessment by combining the damage and fracture mechanics methods.

1,000 cycles

3,000 cycles

2,000 cycles

4,000 cycles

5,000 cycles

Fig. 8. Progressive damage ( 34 ≡ ) at the defect field with increasing number of load cycles; maximum stress 800 MPa. Permission for Use Statement The content of this paper is copyrighted by Siemens Energy, Inc. and is licensed to Structural Integrity Procedia for publication and distribution only. Any inquiries regarding permission to use the content of this paper, in whole or in part, for any purpose must be addressed to Siemens Energy, Inc. directly References ASTM E647-15e, 2015. Standard test method for measurement of fatigue crack growth rates. West Conshohocken, PA: ASTM International. BS 7910, 2013. Guide to methods for assessing the acceptability of flaws in metallic structures. British Standards Institution. FITNET, 2008. Fitness-for-Service Procedure. Kocak, M., et al. (Eds.), GKSS Research Center, Geesthacht. Ellyin, F., Xia, Z., 1989. A rate-independent constitutive model for transient non-proportional loading. Journal of Mechanics and Physics of Solids 37, 71–91. FKM Guideline, 2009. Fracture Mechanics Proof of Strength for Engineering Components. 3rd revised edition, VDMA Verlag GmbH, Frankfurt a.M.