PSI - Issue 38

Hubert Blondet et al. / Procedia Structural Integrity 38 (2022) 526–537 Hubert Blondet, Kamilia Barthoux/ Structural Integrity Procedia 00 (2021) 000 – 000

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5. Conclusion It is now possible to have a complete FEA mapping, all over the cylinder head, of the damage created by a duty cycle. All areas can be then checked and compare, whereas in the previous Volvo methodology, only few areas are analyzed due to the long time process. This new methodology for LTA computation takes into account several parameters that also allow having a better estimation of the damage for Cylinder Head simulations than previous in-house methodologies: - Participation factors of computed stresses allow describing a full duty cycle. Nevertheless, the computed load cases have to be well chosen to describe the best possible the duty cycle points. - Time of engine loading during duty cycle has an impact of the thermal behaviour (and thus on the stress behaviour) of the cylinder head. It is now taken into account by the latency parameter (tau) , which applies on thermal stresses - PCP loadings are instantaneous, and do not depend of this latency. This is also taken into account, as well as t he number of cycle for each “combustion” that induces potential High Cycle Fatigue behaviour (100% load @ 2200rpm makes ~18 Thermal / PCP cycle per second) All those factors are implemented into a SOFAST analysis that allow computing the cumulative damage for each element or node of the cylinder head mesh.

References

[7] Rainflow counting (2011, Pär Johannesson) [8] Rainflow counting algorithm (1991, L. L. Schluter, H. J. Sutherland) [9] Simple rainflow counting algorithms (1982, S. D. Downing and D. F. Socie) [10] Simple Equivalence of four-point and three-point rainflow cycle counting algorithms (2007, C.H. McInnes, P.A. Meehan) – International Journal of Fatigue [11] Review and application of Rainflow residue processing techniques for accurate fatigue damage estimation (2016, Gabriel Marsh, Colin Wignall, Philipp R. Thies, Nigel Barltrop, Atilla Incecik, Vengatesan Venugopal, Lars Johanning) – International Journal of Fatigue