SULLA STIMA DELLA VITA A FATICA DI GIUNTI SALDATI
SOGGETTI A CARICHI MULTIASSIALI AD AMPIEZZA
VARIABILE
L. Susmel1,2, R. Tovo1 and D. Benasciutti3
1Dipartimento di Ingegneria, Università di Ferrara, Ferrara (Italy)
2Department of Mechanical Engineering, Trinity College, Dublin (Ireland)
3Dipartimento di Ingegneria Elettrica Gestionale Meccanica, Università di Udine, Udine, (Italy)
E-mail: ; roberto.tovo@unife.it,
ABSTRACT
This paper summarises an attempt of devising an new engineering approach, based on the socalled
Modified Wöhler Curve Method, suitable for estimating fatigue lifetime of both steel
and aluminium welded connections subjected to variable amplitude multiaxial fatigue
loading. The Maximum Variance Method is used to determine the orientation of the critical
plane and the cycle counting is directly performed in terms of shear stress resolved along the
maximum variance direction. The accuracy of the proposed methodology was checked by
using two different datasets taken from the literature and generated by testing both steel and
aluminium tube-to-plate welded connections under in-phase and 90° out-of-phase variable
amplitude bending and torsion. The proposed fatigue life assessment technique was seen to be
highly accurate, resulting in estimates falling within the scatter bands of the curves used to
calibrate the Modified Wöhler Curve Method. This seems to strongly support the idea that the
proposed approach can be considered as an effective engineering tool, capable of performing
multiaxial fatigue assessment under variable amplitude loading by fully complying with
recommendations of the available standard codes.