Issue 33

M.A. Meggiolaro et alii, Frattura ed Integrità Strutturale, 33 (2015) 368-375; DOI: 10.3221/IGF-ESIS.33.40 374 Fig. 7(c) compares the (dashed) original history with the filtered one. The filtered data tends to the original one as the filter amplitude r decreases, at the cost of increasing the number of unfiltered points, see Fig. 7(d) and (e). In practice, a relatively large r value can be initially chosen, and then decreased until the calculated damage converges. Note that the adopted 6D space can be defined for example by the normal and by the effective shear components, 3 3 3 T y z x xy xz yz           or 3 3 3 T y z x xy xz yz           , respectively for stress or strain histories. Figure 7 : Multiaxial racetrack filter applied to a tension-torsion history path with 16 points, showing (a) the translating hyper-spheres, (b) the static and dynamically-filtered points (respectively × and triangles), and the effect of decreasing the filter amplitude r , resulting in histories with (c) four, (d) seven, and (e) fourteen points. C ONCLUSIONS mplitude filters are most important in practical fatigue analyses to manage their computational cost when (as usual) the input history is oversampled, too long, and/or contains too many non-damaging low-amplitude cycles. The proposed multiaxial racetrack algorithm is very versatile, allowing the synchronous filtering of stress and strain histories acting at a given material point, based on a single scalar amplitude value. R EFERENCES [1] Fuchs, H.O., Nelson, D.V., Burke, M.A., Toomay, T.L., Shortcuts in Cumulative Damage Analysis, SAE Automobile Engineering Meeting Paper 730565, (1973). [2] Nelson, D.V., Fuchs, H.O., Predictions of cumulative fatigue damage using condensed load histories, in Fatigue Under Complex Loading, SAE, (1977). A