Creep fatigue damage assessment method for superheater tube plate

Abstract

The invention provides a creep fatigue damage assessment method for a superheater tube plate. The creep fatigue damage assessment method comprises the steps of correcting a steady-state cyclic analysis method; combining a CAE model, a yield stress and temperature related ideal elastic-plastic model and a temperature related creep constitutive equation, and analyzing the creep cycle plasticity behavior of the tube plate in the steady-state cycle; designing a fatigue curve to evaluate fatigue damage by adopting a general slope method; evaluating creep damage by adopting a time fraction method, a ductility depletion model or a strain energy density depletion model; and evaluating the creep fatigue damage according to a linear damage superposition criterion or a unified creep fatigue equation. According to the creep fatigue damage assessment method for the superheater tube plate, the non-isothermal creep effect, the multiple load holding periods and the stress-strain relaxation history in the load holding periods are considered, creep fatigue total damage assessment can be conducted on the superheater tube plate, and the creep fatigue damage assessment method has the advantages of being visual, high in applicability and high in accuracy.

Description

technical field [0001] The invention relates to the field of creep fatigue damage assessment, in particular to a creep fatigue damage assessment method for superheater tube sheets. Background technique [0002] As a traditional standard shell-and-tube heat exchange equipment, superheaters are key components of steam power plants and are widely used in the petroleum and energy industries. As a typical single-phase heat exchanger, the steam flows in the inner tube and allows the external flue gas to heat the steam in a cross-flow (cross-flow or cross-flow). The production and maintenance of superheaters are relatively simple, inexpensive, and highly adaptable, able to withstand high temperature and high pressure working conditions. Among the many parts of the superheater, the tube sheet is one of the most critical parts attached to both the tube layer and the shell layer. In tube sheets subjected to thermal and mechanical loads, extremely complex loading conditions can often...

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Problems solved by technology

[0004] However, since the linear matching-extended direct steady-state cyclic analysis method (LMM-eDSCA) can only consider the isothermal creep parameters in one load cycle and one dwell period, it does not consider non-isothermal conditions or multi-dwell creep behaviors, etc.

At the same time, this method cannot predict the creep stress relaxation history during the load-holding time in the numerical simulation, and there are certain limitations in solving complex practical problems

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