Issue 33

F. Castro et alii, Frattura ed Integrità Strutturale, 33 (2015) 444-450; DOI: 10.3221/IGF-ESIS.33.49 449 Estimated and observed number of cycles to failure is shown in Fig. 5. The solid diagonal line corresponds to a perfect correlation between estimated and observed fatigue lives, and the two dashed lines define the factor of 2 bandwidth. As can be clearly seen in this figure, most of the life estimates fall within a error band given by a factor of 2. Considering the well known scatter that characterizes the fatigue phenomena this can be considered a very good correlation. Figure 5 : Observed and estimated fatigue lives for fretting fatigue tests conducted by Nowell [1]. C ONCLUSIONS n engineering methodology for fatigue life estimation of mechanical couplings subjected to fretting fatigue was presented in this paper. Constants for the methodology are relatively simple to determine, as only experimental data from conventional fatigue tests on plain and sharply notched (or cracked) specimens are required. It can also be easily incorporated in a Finite Element Method based software for fast assessment of fretting fatigue life in more realistic type of mechanical couplings. Fatigue life estimates correlated well with the experimental results [1], falling in most cases within a factor of two bandwidth. Although some of the required material constants were obtained either from literature or from empirical relations, the methodology was still capable of producing satisfactory life estimates. However, further assessment considering different contact configurations and other materials is still required to corroborate the proposed life methodology. A CKNOWLEDGMENTS he supports provided by CNPq (contracts 310845/2013-0 and 309748/2013-5) and by FINATEC are gratefully acknowledged. R EFERENCES [1] Nowell, D., An analysis of fretting fatigue. Ph.D. thesis, Oxford University, (1988). [2] Amargier, R., Fouvry, S., Chambon, L., Schwob, C., Poupon, C., Stress gradient effect on crack initiation in fretting using a multiaxial fatigue framework, Int J Fatigue, 32 (2010) 1904–1912. [3] Nowell, D., Dini, D., Hills, D.A., Recent developments in the understanding of fretting fatigue, Eng Fract Mech, 73 (2006) 207–222. A T