M athilde Renault

Naval Group, Bouguenais, France & IRDL, Brest, France

Mathilde Renault is a second year PhD student at IRDL, Brest. She works in collaboration with Naval Group Nantes, on the influence of the surface condition of parts obtained by WAAM additive manufacturing using thermographic measurements under cyclic loading. This thesis is part of an industrial chair called "Self-Heating", involving two laboratories (IRDL & P' Institut) and four companies (Naval Group Research, Safran Aircraft Engines, Safran Landing Systems, SafranTech) in eight theses and four post-docs on the determination of oligocyclic and very oligocyclic fatigue properties from thermographic measurements under cyclic loading.


Wire Arc Additive Manufacturing is an additive manufacturing process with a high rate of material deposition capable of producing near-net shape parts. This process involves the reduction of production costs (material and lead times) and considers innovative designs.  However, the deposition technique induces heterogeneities in the material, in particular the presence of porosity and a degraded surface finish. The surface condition has a first-order influence on the fatigue life of unmachined parts due to the stress concentrations induced by the presence of the valley.  Various finishing treatments can be considered to reduce the criticality of the surface finish influence over crack initiation and propagation : conventional ones such as hammer, laser or shot peening and some specially developed for Addiditive Manufacturing (AM) processes such as in-situ cooling device or hot-rolling system.  The multitude of AM parameters and the different finishing surface post-treatments entail many configurations that will modify fatigue properties. For this reason, rapid fatigue evaluation methods are an asset for process evaluation.

Thermo-elastic Stress Analysis (TSA) is a non-contact technique for measuring the distribution of stress in the surface of a component subject to cyclic loading by using a sensitive infrared camera. The analysis of the thermo-elastic coupling amplitude maps allows the detection of initiation and monitoring of  crack propagation.  A four-point bending fatigue test protocol is conducted on CuAl9 WAAM specimens. The identification of crack kinetics then allows the assessment of a probabilistic model based on linear elastic fracture.


Room 6Wednesday 29th November17:00-17:30Mathilde Renault
S01-2 Additive Manufacturing
3 - Infrared imaging surface roughness criticality assement of Wire Arc Additive Manufactered specimens
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