Issue34

F. Berto, Frattura ed Integrità Strutturale, 34 (2015) 11-26; DOI: 10.3221/IGF-ESIS.34.02 14 based SED approach together with a final synthesis of more than 1900 experimental data from static and fatigue tests. Very different materials have been considered with a control radius, R 0 , ranging from 0.4  m to 500  m. A wider and complete synthesis of this work can be found in [64]. A SUMMARY OF THE CAREER OF PROF . P AOLO L AZZARIN aolo Lazzarin, Professor at the University of Padova, Vicenza (Italy), outstanding scientist in theoretical and applied notch mechanics, has passed away on September 14, 2014. Paolo Lazzarin was born on April 21, 1957 in Conegliano near Treviso (Italy). He was graduated at the University of Padova, Faculty of Mechanical Engineering, in 1982 and obtained his PhD in ʽ Mechanical Behaviour of Materials ʼ at the University of Pisa in 1986. In 1992 he became associate professor of ʽ Machine Design ʼ at the University of Cassino and, afterwards, at the University of Ferrara. Since 2000 he has been full professor of ʽ Machine Design ʼ at the University of Padova, Department of Management and Engineering in Vicenza. In this position, he has presided the master course in Mechanical Engineering since 2012. Paolo Lazzarin is the author of about 100 significant scientific articles in renown scientific journals. Additionally, he has gained merit in the publication sector as a reviewer on demand of these journals. Also, he was a member of the board of the journal ʽ Fatigue and Fracture of Engineering Materials and Structures ʼ since 2002 and became its co-editor in 2012. Paolo Lazzarin was also the organiser of international conferences which aroused considerable attention – the Crack Path Conference in 2009 and the Mesomechanics Conference in 2011, both conferences held in Vicenza. The appreciation hereafter of Paolo Lazzarin’s scientific achievements cannot specify the respective collaborators and coauthors because of space restrictions. More than 200 pioneering articles in scientific journals are available, all written together with well-known colleagues or talented disciples. Paolo Lazzarin’s scientific achievements can be assigned to three areas of notch mechanics: notch stress intensity factors, local strain energy density and fictitious notch rounding. Paolo’s scientific career started in the mid-eighties of the last century with Bruno Atzori as his mentor. His challenge was the mathematical analysis of the stress field at fillet weld toes, modelling them as pointed V-notches for assessment of the fatigue limit of these joints within a worst case scenario. The asymptotic stress distribution ahead of the stress singularity at pointed V-notches was available from Williams’ linear-elastic solution. It was later on quantified by means of notch stress intensity factors (NSIFs), separating the contribution of the three loading modes (in-plane tensile and shear loading as well as out-of-plane shear loading) to the overall stress distribution ahead of the V-notch tip. The NSIFs were derived for weld-like geometries and cross-sectional models of various fillet-welded joints. The scale effect, i.e. the influence of specimen size on the level of the asymptotic stresses is already included in the NSIFs. Fatigue strength values in terms of the NSIF amplitudes dependent on number of loading cycles for fillet-welded joints made of steel or aluminium alloys were presented as a scatterband, evaluating a large body of test results in the open literature. The scatterband widths and the curve gradients were well in agreement with comparable nominal stress relationships in the codes. Additionally, a mixed-mode failure criterion in terms of the NSIFs was derived. Also, the relationship to the standardised structural stress at the wed toe was clarified. The elementary NSIF concept for pointed notches has been extended by Paolo Lazzarin to sharply rounded (blunt) or root-holed V-notches. Notch rounding removes the stress singularity, but the asymptotic stress distribution connected with the singularity remains largely unchanged at distances from the notch root larger than one half of the notch radius. It was shown that generalised NSIFs can be defined as the governing field parameters. These are related to the maximum notch stresses which constitute the conventional stress concentration factors (SCFs). In contrast to the SCFs, the generalised NSIFs characterise not only the maximum stress at the notch root but the whole stress field in the vicinity of the notch root. The field information is needed for assessing local failure processes, but it is not possible in general to express the fatigue limit of sharply rounded notches solely by critical NSIF amplitudes. A remarkable by-product of these efforts were the in-plane and out-of-plane stress field solutions for V-notches with root hole. Under certain conditions such as low sheet thickness in lap joints, the radial distance from the slit tip, where the second order approximation of the stresses (inclusive of the T-stress) is appropriate, may be very small, so that higher order approximations are needed. Stress equations for the in-plane loading modes at slit tips up to the seventh order have been derived. The conventional loading modes 1, 2 and 3 refer to singular stress fields at V-notches which can be considered as two- dimensional (plane or anti-plane). It is presumed that the corresponding NSIFs do not vary along the straight notch tip line. At the intersection with lateral free surfaces, an abrupt change of the homogeneous conditions takes place. A complex three-dimensional, generally singular stress state occurs near the intersection point. It may be described by the P