Industrial 3D Computation of Cracked Nozzles or Elbows

摘要

The ASCOUF [1] software has been developed by EDF to allow the quick analysis of defects contained in pipes orelbows of the primary and the secondary loops. In the same way, the ASPIC software allows the quick analysis of defectscontained in nozzles of the primary and secondary loop. These two pre-processing tools of Code_Aster, the structural analysisfinite element code of EDF [2], have been used to carry out with an increase of productivity a series of numerical studiesproving the mechanical strength of these components. Their validation, taking into account the feedback from previousstudies, leads us to rely on the results. ASCOUF can also solve the problems of under-thickness of pipes of the secondaryloop. These two software have been developed by EDF R&D in order to enable the engineer to make a 3D mesh, includingthe crack or the under-thickness zone, within one hour. And thanks to these tools called ? ASCOUF ? and ? ASPIC ? the timeneeded for a complete study has dropped by more than 80%.ASCOUF and ASPIC are divided into two parts. The first one produces the mesh and the second one carries out 3Dfinite element computations. From the main geometrical parameters the first part generates an accurate mesh of the structurecontaining a crack or an under-thickness. The meshing part of ASCOUF and ASPIC can generate a circumferential or alongitudinal elliptical crack (short crack) and a long crack. At the moment, only ASCOUF can generate circumferential orlongitudinal short or long under-thickness. Thanks to the second part we can compute large (225000 DOF) 3D thermo-elastoplasticfinite element calculations of cracked bodies (elbow or nozzle) to evaluate the energy release rate G (or J).Several studies were also made to validate the meshes coming from the software when they are submitted to complexloadings like pressure, bending moments and thermal shock, even in a wide range of plasticity extension. And thanks to thisvalidation, ASCOUF and ASPIC have allowed us to perform 3D assessment of cracked elbows and cracked nozzles in a veryshort time.