PROVINI DI FATICA PER LA VALUTAZIONE DELL’EFFETTO SCALA IN CAMPO GIGACICLICO

According to Furuya, gigacycle fatigue properties of materials are strongly affected by the volume of material subjected to stress amplitudes above the 90% of the maximum stress (risk volume at 90%, %). The experimental results obtained by Furuya are analyzed, showing a non uniform distribution of failures in the %. Therefore, a limitation in the range of the stresses considered for the definition of the risk volume must be introduced (i.e, a risk volume at 96%, %). The analysis of dog-bone specimen behavior shows that the stress distribution in the specimen part with constant cross-section is not uniform and, as a consequence, the maximum attainable risk volume value is limited. In order to obtain larger % values, a new specimen shape is designed analytically and verified numerically through a finite element analysis.