The design of combustion chambers for space launchers, particularly in the context of launcher re usability, needs to be optimized to ensure multiple safe flights while keeping costs and mass budget under control. To this end, these complex and critical components are now designed to be manufactured using additive manufacturing processes that allows for innovative combustion chamber designs, particularly when integrating a regenerative cooling system.

To optimize this design effectively, it is essential to understand the impact of additive manufacturing (L-PBF process) on the thermomechanical and fatigue properties of the copper alloys used. This requires a deeper understanding of the cyclic behavior (thermomechanical, damage, etc.) of combustion chamber liners. These components are subjected to extremely high thermal gradients, with temperatures ranging from -200°C to 400-700°C (depending on the application) during each operational cycle.

To withstand such cyclic thermal gradients, these liners are often made from copper-chromium-zirconium and/or niobium alloys, a family of alloys developed in the 1980s for this specific purpose and more recently produced via additive manufacturing. The development of reusable launchers introduces considerations of very low-cycle fatigue for these materials. While some recent studies have been published, the behavior and damage mechanisms due to creep and thermal fatigue of these alloys remain poorly documented, particularly in the case of additively manufactured materials. However, such data are crucial for modeling behavior and damage to design these critical components effectively.

The objective of this PhD work is to characterize and model the cyclic behavior of a CuCrZr alloy over a wide temperature range, as well as the predominant failure mechanisms. 

The first step will involve conducting cyclic testing campaigns combining material hardening and creep/relaxation. Then, based on these results, a viscoplastic modeling approach will be proposed. Anisothermal thermomechanical uni axial fatigue tests will be performed. Finally, a technological representative test (anisothermal thermomechanical fatigue) will be designed, performed and modeled to validate the proposed modeling approach.

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - eric.charkaluk@polytechnique.edu

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 13th, 2026 Midnight Paris time !