Numéro : 2781 - Year : 2022
High cycle fatigue design of a propeller blade fabricated by WAAM
Lorenzo BERCELLI, Cédric DOUDARD, Sylvain CALLOCH, Sylvain MOYNE, Matthieu DHONDT - ENSTA Bretagne, IRDL - UMR CNRS 6027, Brest, France
Julien BEAUDET - Naval Group Research, Bouguenais, France
Jean-Loup HEUZÉ - MinArm DGA, Paris, France
Additive manufacturing processes act as an alternative to the production of complex geometries and high added value parts. It is the case in the naval industry for which the Wire and Arc Additive Manufacturing (WAAM) process is used to fabricate hollow structures. WAAM materials usually show a heterogeneous microstructure, internal defects, a strong residual stress field and rough as-built surfaces. The objective of the present work is to propose a method for fatigue life prediction taking into account both the internal defects and the rough as-built surfaces. The material parameters of probabilistic models are determined through the use of thermometry in fatigue tests. Firstly, it is shown that the self-heating of machined samples is not affected by the presence of rare pores, allowing for the identification of the fatigue properties of a virtually defect-free WAAM material. Secondly, the use of infrared thermography allows for the detection and the tracking of fatigue cracks on rough as-built surfaces of samples, giving useful information to the modelisation of crack propagation. Finally, these tests results are confronted to the case of a hollow WAAM structures with rough as-built internal surfaces. The fatigue testing of these structures allow to set the basis of a fatigue dimensioning method.
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