Fissuration des culasses des moteurs diesel de secours du parc 900 MWe Cylinder heads cracking of 900 MWe reactors back- up diesel generators Robin Degeilh , Dominique Geoffroy, Samuel Géniaut, David Haboussa (R&D/ERMES), François Curtit (R&D/MMC) Client : Fréderic Gaudeaux (DPN/UNIE/GMAP) Salome-Meca 2018 users day – March 20 th – EDF Lab Paris-Saclay
INTRODUCTION CONTEXT 30 x start / shut down per year Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 2
INTRODUCTION CONTEXT Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 3
INTRODUCTION CONTEXT Water cooling Valves bridge cracking Crack Combustion chamber Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 4
INTRODUCTION CONTEXT UNIE: Need to define (and justify to ASN) the maintenance program Can bridge cracks propagate up to motor failure ? Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 5
2 Realisation of the CAD model and mesh SUMMARY 1 Thermal simulation of a start / shut 3 down motor cycle Material Thermo-mechanical properties Mechanical simulation of a start / 4 shut down motor cycle 5 Determination of crack growth rate 6 Conclusion Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 6
2 Realisation of the CAD model and mesh SUMMARY 1 Thermal simulation of a start / shut 3 down motor cycle Material Thermo-mechanical properties Mechanical simulation of a start / 4 shut down motor cycle 5 Determination of crack growth rate 6 Conclusion Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 7
IDENTIFICATION OF THERMO-MECHANICAL PROPERTIES EXPERIMENTAL CHARACTERIZATION Cast iron GJL300 from rejected cylinder heads Monotonous tensile test Tests at 20, 220 and 420°C Cyclic compression/tensil test Fatigue propagation test Elastic-plastic behaviour Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 8
IDENTIFICATION OF THERMO-MECHANICAL PROPERTIES EXPERIMENTAL CHARACTERIZATION Growing symmetrical strain controlled test Monotonous tensile test Tests at 20, 220 and 420°C Applied strain 0 Cyclic compression/tensil test Tension/compression dissymmetry Fatigue propagation test Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 9
IDENTIFICATION OF THERMO-MECHANICAL PROPERTIES EXPERIMENTAL CHARACTERIZATION Monotonous tensile test Tests at 20, 220 and 420°C Cyclic compression/tensil test Température C moyen m moyen 20°C 1,77E-12 6,65 Fatigue propagation test 220°C 3,98E-12 6,55 420°C 1,83E-11 6,50 Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 10
IDENTIFICATION OF THERMO-MECHANICAL PROPERTIES CONSTITUTIVE MODEL DEVELOPMENT Development Implementation MFront Identification at 20, 220 and 420°C non-linear kinematic hardening function of sign of trace(σ) code_aster Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 11
2 Realisation of the CAD model and mesh SUMMARY 1 Thermal simulation of a start / shut 3 down motor cycle Material Thermo-mechanical properties Mechanical simulation of a start / 4 shut down motor cycle 5 Determination of crack growth rate 6 Conclusion Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 12
NUMERICAL MODEL 3D CAD Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 13
NUMERICAL MODEL 3D SANE MESH Element size ~2mm 640 000 nodes Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 14
NUMERICAL MODEL 3D CRACKED MESHES Zcracks 28mm One crack per bridge 3 meshes 20mm Maximal measured length according to UNIE Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 15
2 Realisation of the CAD model and mesh SUMMARY 1 Thermal simulation of a start / shut 3 down motor cycle Material Thermo-mechanical properties Mechanical simulation of a start / 4 shut down motor cycle 5 Determination of crack growth rate 6 Conclusion Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 16
THERMAL SIMULATION OF A MOTOR CYCLE T=20°C BOUNDARY CONDITIONS - START Start Shut down Exchange condition = h(r) Exchange Temperature condition Exchange stabilisation condition r 400 350 300 Température (°C) 250 PAA 200 PAE1 PAE2 150 Exchange condition PEE 100 50 0 0 50 100 150 200 250 300 Temps (s) Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 17
THERMAL SIMULATION OF A MOTOR CYCLE T=20°C BOUNDARY CONDITIONS - STABILISATION Start Shut down Exchange condition = h(r) Exchange Temperature condition Exchange stabilisation condition r 500 450 400 Temperature (°C) 350 300 250 Mesure 200 Calcul 150 Exchange condition 100 50 0 0 20 40 60 80 100 120 140 Radius (mm) Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 18
THERMAL SIMULATION OF A MOTOR CYCLE T=20°C BOUNDARY CONDITIONS – SHUT DOWN Start Shut down Temperature stabilisation 400 350 300 Temperature (°C) 250 PAA PAE1 200 PAE2 PEE 150 Exchange condition(water flow /50) 100 50 0 300 2 300 4 300 6 300 8 300 10 300 12 300 14 300 16 300 Time (s) Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 19
THERMAL SIMULATION OF A MOTOR CYCLE RESULT Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 20
2 Realisation of the CAD model and mesh SUMMARY 1 Thermal simulation of a start / shut 3 down motor cycle Material Thermo-mechanical properties Mechanical simulation of a start / 4 shut down motor cycle 5 Determination of crack growth rate 6 Conclusion Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 21
MECHANICAL SIMULATION OF A MOTOR CYCLE BOUNDARY CONDITIONS normal displacement=0 r Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 22
MECHANICAL SIMULATION OF A MOTOR CYCLE RESULT ON SANE MESH End of start End of shut down Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 23
MECHANICAL SIMULATION OF A MOTOR CYCLE RESULT ON SANE MESH End of shut down Linear mesh Quadratic mesh End of start Depth (mm) End of start End of shut down Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 24
MECHANICAL SIMULATION OF A MOTOR CYCLE RESULT ON CRACKED MESH Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 25
2 Realisation of the CAD model and mesh SUMMARY 1 Thermal simulation of a start / shut 3 down motor cycle Material Thermo-mechanical properties Mechanical simulation of a start / 4 shut down motor cycle 5 Determination of crack growth rate 6 Conclusion Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 26
DETERMINATION OF CRACK GROWTH RATE RESULTS IN ΔK Post-treatment with POST_K1_K2_K3 (elastic) Bridge C Bridge A Paris law Bridge D Cracking rate Curvilinear abscise (mm) Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 27
DETERMINATION OF CRACK GROWTH RATE RESULTS IN CRACK GROWTH 1500 start / shut down Margin=7,75mm Margin=7,01mm Margin=7,10mm Bridge A Bridge D Bridge C Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 28
2 Realisation of the CAD model and mesh SUMMARY 1 Thermal simulation of a start / shut 3 down motor cycle Material Thermo-mechanical properties Mechanical simulation of a start / 4 shut down motor cycle 5 Determination of crack growth rate 6 Conclusion Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 29
CONCLUSION Can bridge cracks propagate up to motor failure ? • Experimental mechanical characterisation • New cyclic inelastic behaviour model in MFront • 3D complex shape CAD from plans • Thermo-mechanical study in code_aster Bridge cracks cannot propagate up to motor break down over 1500 start / shut down Note EDF R&D 6125-1716-2017-00547-FR « Projet MODERN - Justification de la tenue des culasses des moteurs diesels des tranches 900 MWe (LP 3.6) » Cylinder heads cracking of 900 MWe reactors back-up diesel generators | 30
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