PSI - Issue 57

Jacopo Pelizzari et al. / Procedia Structural Integrity 57 (2024) 817–823 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

822 6

D=∑

(3)

1.E+02

Failure location

1.E+01

1.E+00

 max .  a [MPa]

Spettro banco M-C SWT PS50% Axle fatigue test Fatigue design curve PS 50%

1.E-01

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E+07

Number of reversals, 2N

Fig. 6. Comparison of the Smith-Watson-Topper fatigue design curve for machined surface and PS50% with the axle fatigue test spectrum.

5. Conclusions The static and strain-controlled fatigue mechanical properties of EN-GJS-500-7 cast iron have been evaluated using specimens taken from a trumpet of an off-highway axle. The static tensile properties of the material resulted in agreement with EN 1563:2018. The cyclic stress-strain curve and the Manson-Coffin fatigue design curve have been fitted over the experimental data. In parallel, the axle has been equipped with a strain gauge rosette placed in the region with the highest strains and subjected to a simplified bench fatigue test used for product validation. The strain gauge data have been processed and the resulting local strain spectrum has been evaluated in terms of Smith-Watson Topper (SWT) fatigue design parameter to account for mean stress effects. Accordingly, the original Manson-Coffin life equation has been updated and the Palmgren-Miner damage index to failure resulted equal to 0.48. Finally, a comparison between the simplified bench load spectrum and actual spectra measured during in-field tests is planned to assess the significance of bench tests adopted for product validation. Acknowledgements Carraro S.p.A. is gratefully acknowledged for financial support to the present research. References [1] F. Scacco, A. Campagnolo, M. Franceschi, G. Meneghetti, Strain-Controlled Fatigue Behavior of a Nodular Cast Iron in Real Off-Highway Axles: Effects of Casting Skin and Strain Ratio, Metals (Basel). 12 (2022). https://doi.org/10.3390/met12030426. [2] P. Hübner, H. Schlosser, G. Pusch, H. Biermann, Load history effects in ductile cast iron for wind turbine components, Int J Fatigue. 29 (2007) 1788 – 1796. https://doi.org/10.1016/j.ijfatigue.2007.01.012. [3] R. Tovo, P. Lazzarin, F. Berto, M. Cova, High cycle multiaxial fatigue strength of cast iron: experimental investigation under uniaxial and biaxial loading, The Tenth International Conference on Multiaxial Fatigue & Fracture (ICMFF10). (2015). [4] ISO 12106:2017, Metallic materials - Fatigue testing -Axial-strain-controlled method, International Organization for Standardization (ISO), Geneva, Switzerland, 2017. [5] ASTM E606/E606M - 12, Standard Test Method for Strain-Controlled Fatigue Testing, American Society for Testing and Materials, West Conshohocken, PA, United States, 2012. [6] ISO 6892-1:2019, Metallic materials, Tensile testing, Part 1: Method of test at room temperature,