Jacopo Pelizzari is a Ph.D. student at the Department of Industrial Engineering of the University of Padova. The research project is in collaboration with Carraro S.p.A. where Jacopo works as Virtual Validation Specialist. Jacopo focused is research activities on fatigue assessment of steel welded structures by the application of local design approaches and it is now working on fatigue assessement of components made of cast iron, mainly axles and transmissions for off-highway vehicles.
Nodular cast irons are commonly adopted in Off-highway applications, owing to the possibility to shape complex components and to guarantee good mechanical properties. In the fatigue strength assessment of axles made of nodular cast irons, engineers have to deal with external loads that turn into local strain spectra at the fatigue crack initiation zones, which are usually located in areas weakened by notch-like geometrical details. Moreover, Off-highway axles are subjected to variable amplitude load histories during their service life; during the design phase, the field load histories are usually applied to the axles in the form of simplified bench load spectra. In this paper, the mechanical properties of EN GJS 500-7 have been investigated through static tensile tests and strain-controlled fatigue tests performed on specimens with machined surface extracted from a real axle. Furthermore, a local strain-based load spectrum has been derived by means of strain gauges which have been applied at the failure location of the axle during the bench tests. The bench load spectrum has been replicated on the specimens to define the damage index based on the linear damage rule proposed by Palmgren and Miner. Finally, by using the Miner’s damage index at failure returned from the specimens’ testing and the mean stress corrected life equation according to Smith, Watson and Topper, the theoretical fatigue life of the axle has been compared with the experimental fatigue life obtained from bench load spectra.
|Poster Session||00:00-00:00||Jacopo Pelizzari|
33 - Fatigue behavior of a nodular cast iron subjected to a variable amplitude strain-based load spectrum applied in bench tests of an Off-highway axle