PSI - Issue 38

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

531

6

Figure 7: Global Process – Participation Factor – Instantaneous Computation

It is also necessary to take into account the effect of PCP cycling: indeed, the PCP is applied one the cylinder head at each 720 crankangle, due to each combustion, simultaneously on each cylinder: it means that during a duty cycle of several thousand hours of usage, the number of PCP load is very important and can then have an impact on the damage. Several steps must be implemented: -Estimate the dynamic stress for each operating Point (e.g. 1700rpm at 80%), with a HCF (high cycle fatigue) computation to get the Dynamic/alternated and Mean stresses between Thermal and PCP load cases. The Corrected Dynamic Stress is then computed for each operating point, using the Rm to get a unitary stress, and the second order Goodman Correction. -Corrected Dynamic stresses are then computed for each duty cycle point, based on interpolation defined on §1.3, using the undamped Participation Factor. This Dynamic Stress is then positioned on the Wöhler curve to estimate the damage of one Thermal / PCP cycle. See next paragraphs for more details on the curve description. - Estimate the number of “Thermal / PCP” cycles occurring during the duty cycle, and estimate the cumulative PCP damage for this duty cycle point