A multi-axis creep fatigue prediction method based on ABAQUS

Abstract

The invention discloses a multi-axis creep fatigue prediction method based on ABAQUS, and the method comprises the steps of S1, building an ABAQUS finite element model, and defining a viscoplastic constitutive equation of a to-be-tested material through a user subprogram UMAT; S2, determining model parameters required by the viscoplastic constitutive equation; S3, establishing a fatigue damage calculation model and a creep damage calculation model of the multi-axis stress-strain state of the to-be-tested material; S4, establishing an ABAQUS finite element model in a multi-axis stress-strain state, and calculating to obtain a stress-strain tensor of each cycle on the basis of the defined viscoplastic constitutive equation and model parameters; and S5, calculating equivalent stress and equivalent plastic strain through a user subprogram USDFLD, and superposing fatigue damage and creep damage of each cycle through a linear cumulative damage criterion on the basis of the fatigue damage calculation model and the creep damage calculation model in combination with the stress strain tensor to obtain the crack initiation life.

Description

technical field [0001] The invention relates to the field of numerical simulation, in particular to a multi-axis creep fatigue prediction method. Background technique [0002] With the increasing demand for large-scale, high-performance, and long-life high-temperature rotating parts, the structural integrity assessment of structures containing geometric discontinuities in complex and harsh environments has become one of the key technical bottlenecks that need to be solved urgently. The multiaxial stress-strain regimes resulting from geometric discontinuities and complex loading histories inevitably become the limiting service life of such components. In recent years, the development of finite element software can satisfy people's understanding of complex stress-strain behavior and provide the feasibility of accurate life prediction in this state. [0003] Nowadays, creep fatigue analysis and life prediction of complex structures can be mainly divided into three categories. ...

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Problems solved by technology

However, these three types of methods have their own shortcomings: the first type of method is only suitable for describing the stress-strain behavior at the microscopic level, and is not suitable for large high-temperature components at the macroscopic level; the second type of method focuses on describing the creep fatigue in the crack growth stage Behavior, its complex programming, poor convergence, high computational cost and other characteristics determine that this type of method does not have strong universality; although the third type of method has the characteristics of strong operability, it is mostly used to analyze single-axis in a steady state. Stress-strain behavior, not accurate for creep fatigue analysis and prediction under complex stress-strain state and complex loading history

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