Issue 47

D. Rigon et alii, Frattura ed Integrità Strutturale, 47 (2019) 334-347; DOI: 10.3221/IGF-ESIS.47.25 334 Fracture and Structural Integrity: ten years of ‘Frattura ed Integrità Strutturale’ Analysis of dissipated energy and temperature fields at severe notches of AISI 304L stainless steel specimens D. Rigon, M. Ricotta, G. Meneghetti University of Padova, Department of Industrial Engineering, via Venezia 1 – 35131 Padova, Italy daniele.rigon.1@phd.unipd.it , http://orcid.org/0000-0003-0315-6628 mauro.ricotta@unipd.it, http://orcid.org/0000-0002-4212-2618 giovanni.meneghetti@unipd.it , http://orcid.org/0000-0002-3517-9464 A BSTRACT . In the last years, a large amount of fatigue test results from plain and bluntly notched specimens made of AISI 304L stainless steel were synthetized in a single scatter band by adopting the specific heat loss per cycle (Q) as a damage parameter. During a fatigue test, the Q parameter can be evaluated measuring the cooling gradient at a point of the specimens after having suddenly stopped the fatigue test. This measurement can be done by using thermocouples; however, due to the high stress concentration at the tip of severely notched components analysed in the present paper, an infrared camera achieving a much improved spatial resolution was adopted. A data processing technique is presented to investigate the heat energy distribution close to the notch tip of hot-rolled AISI 304L stainless steel specimens, having notch tip radii equal to 3, 1 and 0.5 mm and subjected to constant amplitude cyclic loads. A thermal finite element analysis was also performed by assigning heat generation in the appropriate region close to the notch tip. Then the numerical temperature values were compared with the experimental measurement. K EYWORDS . Energy Distribution; Fatigue; Notch Effect. Citation: Rigon, D., Ricotta, M., Meneghetti, G., Analysis of dissipated energy and temperature fields at severe notches of AISI 304L stainless steel specimens, Frattura ed Integrità Strutturale, 47 (2018) 334-347. Received: 01.11.2018 Accepted: 03.12.2018 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 atigue is an irreversible process, accompanied by microstructural changes, localized plastic strains and energy dissipation. The temperature increase of a metallic material undergoing a fatigue test is a manifestation of the thermal energy dissipation. Therefore, in the last decades; temperature has been used for the rapid estimation of fatigue limit in metallic materials and components [1–4] , the detection and propagation of damage in metal materials and composites in [5–8] and the investigation of fatigue life under constant amplitude [9–11] and block loading [12,13]. Nevertheless, since temperature depends on the mechanical and thermal boundary conditions, the specific heat energy per cycle, Q, was assumed as a fatigue damage indicator in [14], because it is expected to be a material property, similarly to the plastic strain hysteresis energy [15,16]. F