Issue 41

M. A. Meggiolaro et alii, Frattura ed Integrità Strutturale, 41 (2017) 1-7; DOI: 10.3221/IGF-ESIS.41.01 1 Focused on Multiaxial Fatigue A two-step multiaxial racetrack filter algorithm for non-proportional load histories Marco Antonio Meggiolaro, Jaime Tupiassú Pinho de Castro Pontifical Catholic University of Rio de Janeiro, PUC-Rio, R. Marquês de São Vicente 225, Rio de Janeiro, 22451-900, Brazil meggi@puc-rio.br, jtcastro@puc-rio.br Hao Wu School of Aerospace Engineering and Applied Mechanics Tongji University, Siping Road 1239, 200092, Shanghai, P.R.China wuhao@tongji.edu.cn A BSTRACT . The recently proposed multiaxial racetrack filter (MRF) is able to deal with general non-proportional multiaxial load histories. While only requiring a single user-defined scalar filter amplitude, the MRF is able to synchronously eliminate non-damaging events from any noisy multiaxial load history without changing the overall shape of its original path, a necessary condition to avoid introducing errors in fatigue damage assessments. The MRF procedures are optimized here by the introduction of a pre-processing “partitioning” step on the load history data, which selects candidates for the reversal points in a robust partitioning process, highly increasing the filter efficiency and decreasing its computational time. The improved MRF is evaluated through the fatigue analyses of over-sampled tension-torsion data measured in 316L stainless steel tubular specimens under non-proportional load paths. K EYWORDS . Multiaxial racetrack filter (MRF); Partitioning operation; Multiaxial variable amplitude loading; Amplitude filter. Citation: Meggiolaro, M.A., Castro, J.T.P., Wu, H., A two-step multiaxial racetrack filter algorithm for non-proportional load histories, Frattura ed Integrità Strutturale, 41 (2017) 1- 7. Received: 28.02.2017 Accepted: 15.04.2017 Published: 01.07.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION atigue load histories measured under actual field conditions usually are noisy, over-sampled, and contain too many non-damaging low-amplitude events that can largely increase the subsequent fatigue damage calculation burden. This problem has long been recognized and properly dealt with in traditional uniaxial analyses, but it is still much more important for multiaxial fatigue damage calculations, which can even become impractical if not properly filtered to remove from the data non-damaging events before performing such complex calculations, in particular under non- proportional (NP) loading conditions, so common in practical applications. F