Abstract
The combination of cyclic (due to startup and shutdown) thermal and mechanical stresses can result in thermomechanical fatigue (TMF) failures in aero engine and power plant components (for example).
Unified viscoplastic constitutive models have been successfully used to describe the macroscopic behaviour of materials where both rate-independent and rate-dependent effects occur simultaneously, e.g. high temperature cyclic loading. One of the most well known physical-phenomelogical models using state variables, developed in the framework of the thermodynamics of irreversible processes, was formulated by JL Chaboche. The Chaboche model includes combined nonlinear isotropic and kinematic hardening, with a viscoplastic flow rule for time-dependent effects, including creep.
This paper uses Z-mat software to implement the multiaxial form of the Chaboche constitutive equations into the ABAQUS finite element (FE) code. The evolution of complex stress and strain fields within a grade P91 steel notched bar specimen are investigated in detail for different TMF loading conditions. The results of this work can be used to determine suitable test conditions for notched specimens by providing predictions of the stress-strain history local to the notch. In future, such tests will be used along with the FE analyses to develop and validate multiaxial TMF lifing models.
Unified viscoplastic constitutive models have been successfully used to describe the macroscopic behaviour of materials where both rate-independent and rate-dependent effects occur simultaneously, e.g. high temperature cyclic loading. One of the most well known physical-phenomelogical models using state variables, developed in the framework of the thermodynamics of irreversible processes, was formulated by JL Chaboche. The Chaboche model includes combined nonlinear isotropic and kinematic hardening, with a viscoplastic flow rule for time-dependent effects, including creep.
This paper uses Z-mat software to implement the multiaxial form of the Chaboche constitutive equations into the ABAQUS finite element (FE) code. The evolution of complex stress and strain fields within a grade P91 steel notched bar specimen are investigated in detail for different TMF loading conditions. The results of this work can be used to determine suitable test conditions for notched specimens by providing predictions of the stress-strain history local to the notch. In future, such tests will be used along with the FE analyses to develop and validate multiaxial TMF lifing models.
| Original language | English |
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| Title of host publication | 11th International Conference on the Mechanical Behavior of Materials (ICM11) |
| Place of Publication | Lake Como, Italy |
| Publication status | Published - 2011 |
| Event | 11th International Conference on the Mechanical Behavior of Materials (ICM11) - Como, Italy Duration: 5 Jun 2011 → 9 Jun 2011 |
Conference
| Conference | 11th International Conference on the Mechanical Behavior of Materials (ICM11) |
|---|---|
| Country/Territory | Italy |
| City | Como |
| Period | 5/06/11 → 9/06/11 |