COBEM99

S24 Mecânica dos Sólidos

Title:

PARAMETER DETERMINATION FOR MODELLING THE ASTM A471 STEEL BEHAVIOUR IN A ELASTO-PLASTIC CONTINUUM APPROACH

Summary :

THE PRESENT WORK IS CONCERNED WITH THE DETERMINATION OF MATERIAL PARAMETERS TO MODEL THE INELASTIC BEHAVIOUR OF AN ASTM A 471 STEEL (24CRNIMOV14-6, VACUUM-TREATED ALLOY STEEL FORGINGS) VERY OFTEN UTILISED FOR TURBINE GENERATOR SHAFTS, TURBINE ROTOR DISKS AND WHEELS. TURBOALTERNATOR SHAFTS SUFFER VERY HEAVY LOCAL STRAIN DURING TRANSIENTS AND ACCIDENTAL EMERGENCIES (SHORT CIRCUITS, OUT OF PHASE SYNCHRONISATION, ETC.). THE EXPERIMENTAL WORK HAS BEEN PERFORMED BY STRAIN CONTROLLED, COMPLETELY REVERSED PUSH-PULL LOW CYCLE FATIGUE TESTS, AT ROOM TEMPERATURE, TO DETERMINE THE STABLE HYSTERESIS LOOPS AND THE CYCLIC CURVE. THE TESTS HAVE BEEN PERFORMED WITH A SERVO-HYDRAULIC INSTRON TESTING MACHINE ON ASTM STANDARD SPECIMENS. THE AIMS OF THE STUDY ARE THE CHARACTERISATION OF HARDENING PARAMETERS FOR AN ELASTO-PLASTIC CONTINUUM MODEL, TAKING INTO ACCOUNT THE USE OF CONTINUUM DAMAGE MECHANICS MODELS INTO DESIGN AND STRUCTURAL INTEGRITY ASSESSMENT OF MECHANICAL COMPONENTS. GOOD CORRELATION HAS BEEN FOUND BETWEEN THE CURVES MODELLED BY THE KINEMATIC HARDENING PARAMETERS AND THOSE OBTAINED BY EXPERIMENTAL FATIGUE TESTS. KEY WORDS: CONTINUUM MECHANICS, ELASTO-PLASTIC BEHAVIOUR, CYCLIC HARDENING, STRAIN CONTROL, HYSTERESIS LOOP AND KINEMATIC HARDENING.

Author :

Caligiana, Gianni 0
Chimisso, Fulvio E. G.

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