Issue 49

J.A.O. González et alii, Frattura ed Integrità Strutturale, 49 (2019) 26-35; DOI: 10.3221/IGF-ESIS.49.03 34 strain-based DIC techniques were all used to identify K op by far and by near field measurements. The decreasing behavior of the crack opening ratio K op /K max obtained by these 4 redundant methods showed no discrepancy in the testing results, confirming the reliability and repeatability of the data obtained in previous works. Since the ∆K eff measured along those tests augmented significantly with the crack size, whereas the measured FCG rates da/dN remained practically constant, it can be concluded that Elber’s effective stress intensity factor range is not the actual FCG driving force for the analyzed tests. A CKNOWLEDGEMENTS ulián Andrés Ortiz González would like to gratefully acknowledge the support of the FAPERJ-Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (Process N° 201.699/2017). R EFERENCES [1] Elber, W. (1971). The significance of fatigue crack closure. ASTM STP 486, pp. 230-242. DOI: 10.1520/STP26680S. [2] Elber, W. (1970). Fatigue crack closure under cyclic tension. Engineering Fracture Mechanics, 2(1), pp. 37-45. DOI: 10.1016/0013-7944(70)90028-7. [3] Ferreira, S.E., Castro, J.T.P., Meggiolaro, M.A. (2018). Fatigue crack growth predictions based on damage accumulation ahead of the crack tip calculated by strip-yield procedures. International Journal of Fatigue, 115, p.p. 89-106. DOI: 10.1016/j.ijfatigue.2018.03.001. [4] Ferreira, S.E., Castro, J.T.P., Meggiolaro, M.A., Miranda, A.C.O. Crack closure effects on fatigue damage ahead of crack tips. International Journal of Fatigue, under review. [5] Kemp, P.M.J. (1990). Fatigue crack closure – a review. TR90046, Royal Aerospace Establish. [6] Skorupa, M. (1999). Load interaction effects during fatigue crack growth under variable amplitude loading - a literature review part II: qualitative interpretation. Fatigue & Fracture of Engineering Materials & Structures, 22(10) pp. 905 – 926. DOI: 10.1046/j.1460-2695.1999.00158.x. [7] Williams, J.J., Yazzie, K.E., Padilla, E., Chawla, N., Xiao, X., de Carlo, F. (2013). Understanding fatigue crack growth in aluminum alloys by in situ X-ray synchrotron tomography. International Journal of Fatigue, 57, pp. 79-85. DOI: 10.1016/j.ijfatigue.2012.06.009. [8] Castro, J.T.P., Meggiolaro, M.A., Miranda, A.C.O. (2005). Singular and non-singular approaches for predicting fatigue crack growth behavior. International Journal of Fatigue, 27 (10-12), pp. 1366-1388. DOI: 10.1016/j.ijfatigue.2005.07.018. [9] Castro, J.T.P., Meggiolaro, M.A., González, J.A.O. (2015). Can ΔK eff be assumed as the driving force for fatigue crack growth? Frattura ed Integrità Strutturale, 33, pp. 97-104. DOI: 10.3221/IGF-ESIS.33.13. [10] González, J.A.O., Castro, J.T.P., Gonzales, G.L.G., Meggiolaro, M.A., Freire, J.L.F. (2017). On DIC measurements of ΔK eff to verify if it is the FCG driving force. Frattura ed Integrità Strutturale, 41, pp. 227-235. DOI: 10.3221/IGF-ESIS.41.31. [11] Chen, D.L., Weiss, B., Stickler, R. (1994). The effective fatigue threshold: significance of the loading cycle below the crack opening load. International Journal of Fatigue, 16(7), pp. 485-491. DOI: 10.1016/0142-1123(94)90199-6. [12] Vasudevan, A.K., Sadananda, K., Holtz, R.L. (2005). Analysis of vacuum fatigue crack growth results and its implications. International Journal of Fatigue, 27(10-12), pp.1519-1529. DOI: 10.1016/j.ijfatigue.2005.07.026. [13] Vasudevan, A.K., Sadananda, K., Louat, N.A. (1994). Review of crack closure, fatigue crack threshold and related phenomena. Materials Science and Engineering, 188(1-2), pp. 1–22. DOI: 10.1016/0921-5093(94)90351-4. [14] ASTM E399. (2013). Standard test method for linear-elastic plane-strain fracture toughness K Ic of metallic materials. ASTM Standards 03.01. [15] ASTM E647. (2013). Standard test method for measurement of fatigue crack growth rates. ASTM Standards 03.01. [16] Yamada, Y., Newman Jr., J.C. (2009). Crack closure under high load-ratio conditions for Inconel-718 near threshold behavior. Engineering Fracture Mechanics, 76 (2), pp. 209-220. DOI: 10.1016/j.engfracmech.2008.09.009. [17] Castro, J.T.P. (1993). A circuit to measure crack closure. Experimental Techniques, 17(2), pp. 23-25. DOI: 10.1111/j.1747-1567.1993.tb00720. [18] Castro, J.T.P. and Meggiolaro, M.A. (2016). Fatigue Design Techniques, vol. 3: Crack Propagation, Temperature and Statistical Effects. USA: CreateSpace, 110-110. J