Fatigue microcrack propagation prediction method based on EBSD characterization and crystal plasticity

Abstract

The invention discloses a fatigue microcrack propagation prediction method based on EBSD characterization and crystal plasticity. The fatigue microcrack propagation prediction method comprises the following steps: acquiring a stress-strain hysteresis loop; compiling a macroscopic viscoplastic constitutive model, and determining parameters of the macroscopic viscoplastic constitutive model; establishing a finite element model of the macroscopic component, endowing the finite element model with viscoplastic constitutive material parameters, carrying out fatigue loading to obtain a macroscopic stress field and a displacement field of the component, and preliminarily determining a dangerous part of the component; compiling a crystal plastic constitutive model, and determining parameters of the model; establishing a local mesoscopic model; dangerous crystal grains are determined; initial cracks are introduced, and the initiation life is determined through a crack initiation model; the accumulated strain energy dissipation density distribution of the cracked crystal grains and the adjacent crystal grains is judged at the tip of the crack, the end point of the initial crack serves as the starting point, and a new crystal penetrating crack continues to be introduced into the slippage system with the maximum accumulated strain energy dissipation density; and determining the microcrack propagation life. The method can consider the influence of the microstructure features of local grains on the crack propagation behavior.

Description

technical field [0001] The invention relates to a fatigue micro-crack propagation prediction method based on EBSD characterization and crystal plasticity, and belongs to the field of structural strength and finite element numerical simulation. Background technique [0002] As the core hot-end component of aero-engine turbine disk, it serves in extreme environmental conditions and bears complex loads, including alternating mechanical load, vibration load and thermal stress. The resulting low-cycle fatigue failure has become a threat to the structural integrity of aero-engine turbine disk. one of the main failure modes. The development of reliable low-cycle fatigue failure prediction and evaluation methods is of great significance to the structural integrity design of aero-engines. [0003] The low-cycle fatigue total life can be divided into three main stages according to the physical development process of fatigue cracks, namely micro-crack initiation, micro-crack propagati...

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Problems solved by technology

At present, there is still no unified method for the evaluation of microcrack initiation and growth, and it is urgent to develop a life prediction model for fatigue crack initiation and full-stage crack growth that takes into account the characteristics of local microstructures.

Patent CN 113435099A proposes a fatigue life prediction method based on a multi-scale fatigue damage evolution model, but its mesoscopic model is based on the Voronoi model, which does not consider the local real microstructure characteristics, and the microcrack growth model does not explicitly introduce cracks, so it cannot consider the crack tip The effect of stress redistribution

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