Issue 38

T. Morishita et alii, Frattura ed Integrità Strutturale, 38 (2016) 281-288; DOI: 10.3221/IGF-ESIS.38.38 288 (2) In the circle loading test (non-proportional loading test), failure life depends on the strain rate. The increase in the failure life can be explained by the reduction in the intensity of strain non-proportionality caused by stress relaxation due to creep. Conversely, the decrease in the failure life can be explained by the increase of creep damage. (3) The modified non-proportional strain range considering the strain rate can correlate the failure life very well. A CKNOWLEDGEMENT his work was supported by the Japan Atomic Energy Agency under the Joint Work contract #27K400, as a part of the work assigned to the Japanese Implementing Agency under the Procurement Number IFERC-T3PA4-JA-RP- 1b within the "Broader Approach Agreement" between the Government of Japan and the European Atomic Energy Community. R EFERECES [1] Doong, S.H., Socie, D.F., Robertson, I.M., Dislocation substructures and nonproportional hardening, Journal of Engineering Materials and Technology, 112 (1990) 456-464. [2] Wang, C.H., Brown, M.W., A path-independent parameter for fatigue under proportional and non-proportional loading, Fatigue & Fracture of Engineering Materials & Structures, 16 (1993) 1285-1297. [3] Itoh, T., Nakata, T., Sakane, M., Ohnami, M., Nonproportional low cycle fatigue of 6061 aluminum alloy under 14 strain paths, European Structural Integrity Society, 25 (1999) 41-54. [4] Socie, D.F., Marquis, G.B., Multiaxial Fatigue, Society of Automotive Engineers International, (2000). [5] Sakane, M., Itoh, T., Kida, S., Ohnami, M., Socie, D.F., Dislocation structure and non-proportional hardening of type 304 stainless steel, European Structural Integrity Society, 25 (1999) 130-144. [6] Itoh, T., Fukumoto, K., Hagi, H., Itoh, A., Saitoh, D., Low cycle fatigue damage of Mod.9Cr-1Mo steel under non- proportional multiaxial loading, Procedia Engineering, 55 (2013) 457-462. [7] Manson, S.S., A complex subject: some simple approximations, Experimental mechanics, 5 (1965) 193-226. [8] Itoh, T., Sakane, M., Ohnami, M., Socie, D.F., Nonproportional low cycle fatigue criterion for type 304 stainless steel, Journal of Engineering Materials and Technology, 117 (1995) 285-292. [9] Itoh, T., A model for evaluation of low cycle fatigue lives under nonproportional straining, Journal of the Society of Materials Science, 50 (2001) 1317-1322. [10] Itoh, T., Sakane, M., Hata, T., Hamada, N., A design procedure for assessing low cycle fatigue life under proportional and non-proportional loading, International Journal of Fatigue, 28 (2006) 459-466. [11] Itoh, T., Sakane, M., Shimizu, Y., Definition of stress and strain ranges for multiaxial fatigue life evaluation under non-proportional loading, Journal of the Society of Materials Science, 62 (2013) 117-124. [12] Itoh, T., Sakane, M., Ohsuga, K., Multiaxial low cycle fatigue life under non-proportional loading, International Journal of Pressure Vessels and Piping, 110 (2013) 50-56. [13] Itoh, T., Sakane, M., Morishita, T., Evaluation and visualization of multiaxial stress and strain states under non- proportional loading, Frattura ed Integrita Strutturale, 33 (2015) 289-301. [14] Coffin, L.F., Mechanical Behavior of Materials, 2 (1972) 516. T