Issue 47

R. Fincato et alii, Frattura ed Integrità Strutturale, 47 (2019) 231-246; DOI: 10.3221/IGF-ESIS.47.18 231 Fracture and Structural integrity: ten years of ‘Frattura ed Integrità Strutturale’ Ductile damage evolution law for proportional and non-proportional loading conditions Riccardo Fincato, Seiichiro Tsutsumi University of Osaka, JWRI, Japan fincato@jwri.osaka-u.ac.jp, tsutsumi@jwri.osaka-u.ac.jp Hideto Momii Nikken Engineering Corporation, Fukuoka, Japan hideto.momii@nikkencorp.com A BSTRACT . The characterization of ductile damage evolution, and its description, have been the object of extensive research in the continuum damage mechanic field. Many different models have been developed since the pioneering works carried out a few decades ago. In detail, the stress triaxiality and the Lode angle parameters have been identified as the two main variables that affect the material ductility. The literature offers a great number of investigations under monotonic loading conditions, however, a proper characterization of the damage evolution under cyclic loading or non- proportional loading is still missing. In this paper, an unconventional coupled elastoplastic and damage constitutive model with a Mohr-Coulomb failure criterion is presented. The novelty of this study is represented by the modification of the ductile damage law in order to consider the damage evolution under non-proportional loading conditions. Therefore, the idea is to investigate the structural response of a steel bridge column subjected to a cyclic non-proportional loading, showing how, a different approach in the description of the ductile damage evolution, is necessary for a realistic description of the pier behavior. K EYWORDS . Ductile damage; Elastoplasticity; Non-proportional loading; Damage Subloading Surface model. Citation: Fincato, R., Tsutsumi, S., Momii, H., Ductile damage evolution law for proportional and non-proportional loading conditions, Frattura ed Integrità Strutturale, 47 (2019) 231-246. Received: 08.08.2018 Accepted: 27.09.2018 Published: 01.01.2019 Copyright: © 2019 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 n the recent years, many authors tried to characterize the ductile behavior of metals by means of different types of numerical models (coupled elastoplastic and damage models, uncoupled models, phenomenological, etc.). The large campaign of experimental investigations carried out in the last decades (Algarni et al. [1]; Bai et al. [2]; Bao and Treitler I