PSI - Issue 38

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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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Figure 8: Global Process – – “HCF” Damage C omputation / Method

2.4.2 Damped Participation Factor computation

The instantaneous Participation Factor computation cannot be used for Thermal loading, where a phenomenon of latency exists: temperature field on the cylinder heat does not increase instantly when the engine goes, for instance, from “1200rpm / 20% Load” to “2200rpm / 100% Load”: There is a lag between heat changes from outside and temperature inside, due to thermal inertia.

On a first approach: - a Time Constant (Tau) is taken into account to consider that latency - Stresses Fields are considered to evolve the same way as temperatures

A graph can be plotted to explain the main idea:

- Yellow Dash Line: instantaneous Stress - Green Line: latency evolution of “exact” Stress = σ inst (1- − ) - Blue Line: latency evolution of Stress approximated by finite difference (discrete description)