Issue 38

M.A. Meggiolaro et alii, Frattura ed Integrità Strutturale, 38 (2016) 67-75; DOI: 10.3221/IGF-ESIS.38.09 67 Focussed on Multiaxial Fatigue and Fracture Incorporation of Mean/Maximum Stress Effects in the Multiaxial Racetrack Filter 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 . This work extends the Multiaxial Racetrack Filter (MRF) to incorporate mean or maximum stress effects, adopting a filter amplitude that depends on the current stress level along the stress or strain path. In this way, a small stress or strain amplitude event can be filtered out if associated with a non-damaging low mean or peak stress level, while another event with the very same amplitude can be preserved if happening under a more damaging high mean or peak stress level. The variable value of the filter amplitude must be calculated in real time, thus it cannot depend on the peak or mean stresses along a load event, because it would require cycle identification and as so information about future events. Instead, mean/maximum stress effects are modeled in the filter as a function of the current (instantaneous) hydrostatic or normal stress along the multiaxial load path, respectively for invariant- based and critical-plane models. The MRF efficiency is evaluated from tension-torsion experiments in 316L stainless steel tubular specimens under non-proportional (NP) load paths, showing it can robustly filter out non- damaging events even under multiaxial NP variable amplitude loading histories. K EYWORDS . Multiaxial racetrack filter; Mean/peak stress effects; Non- damaging events; Multiaxial loads. Citation: Meggiolaro, M.A., de Castro, J.T.P., Wu, H., Incorporation of Mean/Maximum Stress Effects in the Multiaxial Racetrack Filter, Frattura ed Integrità Strutturale, 38 (2016) 67-75. Received: 12.05.2016 Accepted: 10.06.2016 Published: 01.10.2016 Copyright: © 2016 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 nlike frequency filters that clean but distort originally noisy signals, the uniaxial racetrack filter [1, 2] is an efficient and well-proven amplitude filter. It can eliminate non-damaging events from uniaxial load histories without changing the original loading order and its overall shape, much improving the efficiency of practical fatigue U