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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Figure 9: Global Process – Participation Factor – Latency explanation

Using this evolution of stress, the participation factors “with latency” can be computed: †ƒ’‡† ൌ Ǥ •–ƒ„ ൅ ሺͳ − ሻǤ − ͳ †ƒ’‡† With ൌ ∆ ,  t the time increment, and n the considered increment

In order to estimate a “reasonable” value of Tau, Damped Participation factors are computed for a TC303 cycle (standard durability test at Volvo for hot components), where state of the cylinder head is known as stabilized near fire face at some moments of the cycle. With Tau=25s, the participation factors reach a stabilized state

Note that the value of Tau is probably dependant of the location on the Cylinder Head. It couldbe an improvement of the method

3. C ombination and “LTA Thermal” damage computation

Next step consists in combining the Participation Factors and the Unitary Stresses to get a history of equivalent stresses for each point in the cylinder head. This history of equivalent stresses is then treated with a Rainflow counting damage calculation using SOFAST analysis software, based on a Dimensionless Wohler curve