Thèse Hélène MORCH

Thermomechanical modelling of the creep-fatigue behaviour and damage of Nickel-alloy receiver tubes used in Concentrated Solar Power plants

The receivers in Concentrated Solar Power (CSP) plants of this study are made of vertical panels of metallic tubes in which molten salt flows. The salt is heated by the solar radiation hitting the surface of the tubes and the heat it carries is then used to produce electricity. The daily thermal loading/unloading of the solar receivers causes a combination of high temperature creep and fatigue in the receiver tubes. Additionally, the presence of molten salt inside the tubes can lead to severe corrosion. For this technology to be profitable, the lifetime of the solar receiver should be at least of 25 years. The objective of this thesis is the modelling of the thermomechanical behaviour of receiver tubes made of nickel alloy 230 and the prediction of their lifetime under the conditions encountered in the field of CSP.
In a first stage, an extensive experimental campaign was launched to assess the mechanical behaviour of alloy 230 at different temperatures and under various loading conditions. Additionally, a metallographic analysis of part of the tested samples was conducted to understand the micro-scale phenomena responsible for the macroscopic behaviour of alloy 230. In a second stage, based on the results of the experimental campaign and on results found in the scientific literature, a behaviour model based on the Chaboche framework was selected and implemented in the finite-element code Lagamine developed at the University of Liège. A specific formulation was proposed for the temperature-dependence of the model parameters. Consecutively, a damage model was associated to the behaviour model to predict the lifetime of the tubes under fatigue and creep, and the combination of both. This damage model is based on the unified Lemaitre damage model which is compatible with the Chaboche framework. In a third stage, the modelling of corrosion was added, for which a simplified model was created based on limited experimental data from the literature to simulate uniform corrosion. The resulting full model (behaviour, damage, and corrosion) is highly complex and requires long computational times for the precise modelling of the receiver tubes. In this respect, two methods were developed to make calculations faster using simplifying hypotheses. Both methods proved to be efficient for the reduction of computational time, but only one of the methods is really reliable in terms of accuracy of the results.
Finally, one receiver tube was modelled using the finite-element model and its lifetime was evaluated for a specific loading case. The results showed that the estimated lifetime exceeded the target of 25 years, and that uniform corrosion did not have a significant impact on the lifetime and behaviour.

 Publications

A review of higher order Newton type methods and the effect of numerical damping for the solution of an advanced coupled Lemaitre damage model
Morch, Hélène  ; Yuan, Sibo  ; Duchene, Laurent ; Harzallah, Ridha; Habraken, Anne Marie
2022 • In Finite Elements in Analysis and Design, 209, p. 103801
https://hdl.handle.net/2268/292643

Efficient temperature dependence of parameters for thermo-mechanical finite element modeling of Alloy 230
Morch, Hélène  ; Duchene, Laurent  ; Harzallah, Ridha ; Tuninetti, Victor; Habraken, Anne Marie
2021 • In European Journal of Mechanics. A, Solids, 85
https://hdl.handle.net/2268/255741

Identification method of an advanced constitutive law for nickel-based alloy Haynes 230 used in solar receivers
Morch, Hélène  ; Duchene, Laurent  ; Habraken, Anne Marie
2018 • In Journal of Physics. Conference Series, 1063
https://hdl.handle.net/2268/227779

Visco-plastic Chaboche model for nickel-based alloys under anisothermal cyclic loading
Morch, Hélène  ; Duchene, Laurent  ; Habraken, Anne Marie
2017 • In Proceedings of the XIV International Conference on Computational Plasticity
https://hdl.handle.net/2268/213640