Heat sink materials are used in nuclear applications for the construction of high heat flux components that can experience high temperature and high stress-strain conditions. The operations of these components are verified by numerical simulations that require the knowledge of the material modelling parameters. This paper deals with the determination of the material hardening parameters by carrying out optimization procedures integrated in finite element analyses that reproduce the testing conditions and results. The values of the hardening parameters are obtained by developing and applying a numerical optimization process that compare the hysteresis loops calculated by finite element analyses with experimental data of the cyclic stress-strain curves. Two hardening models have been considered to verify the matching of the parameters, both parametric in temperature: the first is a multi-linear kinematic hardening model to be used to simulate material hardening at stable hysteresis loops (for fatigue verifications); the second is the Chaboche's nonlinear hardening model that simulates non-symmetric hysteresis loops (for ratcheting and shakedown analyses). The materials considered for the characterizations are CuCrZr alloy and OFHC copper that are typical heat sink materials in fusion applications. The parameters presented in this paper can be used with hardening models to simulate numerically the thermo-mechanical behaviour of materials operating under cyclic loadings such as fatigue, ratcheting and cold work treatments.
Hardening Parameters for Modelling of CuCrZr and OFHC Copper under Cyclic Loadings
Dalla Palma M
2011
Abstract
Heat sink materials are used in nuclear applications for the construction of high heat flux components that can experience high temperature and high stress-strain conditions. The operations of these components are verified by numerical simulations that require the knowledge of the material modelling parameters. This paper deals with the determination of the material hardening parameters by carrying out optimization procedures integrated in finite element analyses that reproduce the testing conditions and results. The values of the hardening parameters are obtained by developing and applying a numerical optimization process that compare the hysteresis loops calculated by finite element analyses with experimental data of the cyclic stress-strain curves. Two hardening models have been considered to verify the matching of the parameters, both parametric in temperature: the first is a multi-linear kinematic hardening model to be used to simulate material hardening at stable hysteresis loops (for fatigue verifications); the second is the Chaboche's nonlinear hardening model that simulates non-symmetric hysteresis loops (for ratcheting and shakedown analyses). The materials considered for the characterizations are CuCrZr alloy and OFHC copper that are typical heat sink materials in fusion applications. The parameters presented in this paper can be used with hardening models to simulate numerically the thermo-mechanical behaviour of materials operating under cyclic loadings such as fatigue, ratcheting and cold work treatments.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
