MOSAICS

The MOSAICS project (Modelling of an austenitic weld inspected by ultrasonic testing) aims at developping modelling codes in order to improve the predication of the ultrasonic propagation in austenitic welds and to help to an inspection diagnosis. The welded components of EDF and DCNS equipments are subject to mechanical and thermal stresses that can generate in-service defects. Therefore Regulatory requirements enforce a volumetric inspection of these components. The ultrasonic (UT) techniques are advocated for their ability to simultaneously detect and size defects. However, for this type of material, the existing industrial processes are neither as effective nor as reliable as is needed. In fact, the multi-pass austenitic welds are characterized by anisotropic and heterogeneous structures which lead to numerous disturbances of the ultrasonic beam. So far, studies have been limited to 2D configurations and to one specific welding process (SMAW). However new industrial applications, with increasing complexity in terms of geometry and material (various welding processes), are emerging . As a consequence, there is a great need for taking into account complex 3D configurations in order to understand the wave/microstructure interaction and then to optimize the UT inspection configurations. . Ultimately, the goal is to provide key elements for decisions relating to the integrity of high-risk structures. The development of several complementary codes (finite elements and semi-analytical models, hybrid model combining the two approaches) will achieve, at all stages of development, a numerical benchmark on perfectly controlled configurations. This task will be supported by all project partners. Moreover, the increasing requirements in terms of inspection performances necessitate an accurate assessment of all influencing parameters in order to reproduce as precisely as possible the propagation phenomena. As the material description is an essential input data, a task of the project will be specifically dedicated to a multiscale welds characterization approach. Various innovative techniques developed by the academic partners of the project will be used in this task. In particular, an ultrasonic measurements device has been designed in order to simultaneously determined the elastic and attenuation coefficients of the wave in an heterogeneous material. Furthermore, an inversion process based on ultrasonic data has been developed to optimize a weld description firstly derived from a phenomenological model. The last task of MOSAICS will be dedicated to the validation of the codes through a direct comparison with experimental results. . Reference data will be acquired using advanced experimental technologies, including phased-array probes,applied on representative mock-ups containing calibrated defects. For all these reasons, MOSAICS is an industrial research project proposed in parts 1 (Modelling and simulation of complex systems) and 5 (Uses and Applications) of the Digital Models Program. The challenges of these developments for the industrial partners concern both the safety, the availability and the lifetime of their facilities. The results will be directly usable in the qualification process of the ultrasonic techniques. The valuation of the project will largely come from the integration of developments in the CIVA software platform and its distribution by the EXTENDE company.