Damage mechanics-based high-strength metal material amplitude variation ultra-high cycle fatigue life predication method

Abstract

The invention discloses a damage mechanics-based high-strength metal material amplitude variation ultra-high cycle fatigue life predication method. The method is based on an ultra-high cycle fatigue test result and a damage mechanics model, and the high-strength metal material amplitude variation ultra-high cycle fatigue life predication method is provided. The ultrasonic fatigue test is used to rapidly acquire the ultra-high cycle fatigue performance of a high-strength metal material, the test frequency is 20 kHz, only 13.9 hours are needed to finish 109 cycles; based on the nonlinear damagemechanics theory, a damage factor of the amplitude variation stress level is introduced, a material amplitude variation ultra-high cycle fatigue life predication model is established, and the ultra-high cycle fatigue life is quantitatively predicated on amplitude varied load. The thought of the assessment model is clear, and the computation is simple and fast.

Description

technical field [0001] The invention belongs to the field of engineering structure fatigue, and relates to a method for predicting the fatigue life of metallic materials with variable amplitude ultra-high cycles based on damage mechanics. Background technique [0002] High-strength metal materials, such as high-strength metal materials, have the advantages of high strength and light weight, high temperature resistance, corrosion resistance and excellent formability, and are widely used in aeronautical structures, aeroengine compressor blades, steam turbine blades and other fields. The high-strength metal structure bears high-frequency vibration fatigue loads during high-speed operation, and can withstand cyclic loads of up to 10 during long-term service. 9 Week times, that is, ultra-high cycle fatigue. In the actual service process, high-strength structures are often subjected to variable-amplitude loads, which have a significant impact on ultra-high cycle fatigue damage of...

AI Technical Summary

Problems solved by technology

However, for ultra-high-cycle fatigue of high-strength metal materials, ultra-high-cycle fatigue damage is a nonlinear damage feature, fatigue crack initiation life is the main part, and the linear cumulative damage theory is not applicable

Considering the nonlinear characteristics of fatigue damage, researchers introduced nonlinear factors for correction based on the theory of linear cumulative damage, but lack of theoretical basis

Fatigue nonlinear damage mechanics life models, such as the Chaboche damage mechanics model, are mainly used to study the evolution of fatigue damage under constant amplitude loads. The fatigue life prediction model based on Chaboche damage mechanics under variable amplitude loads is still immature, and many parameters need to be determined , it is difficult to apply in engineering

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