Crack Failure Mode Judgment Method and Fatigue Life Prediction Method Based on the Method

Abstract

The invention discloses a crack failure mode determination method and a fatigue life prediction method based on the method, which are applied in the field of reliability and determine the component crack failure mode based on the contribution of normal strain and shear strain to fatigue damage, combining energy and The critical surface method establishes the fatigue life prediction model under the two modes of tensile-dominant failure and shear-dominant failure, which can effectively control the problem of excessive prediction error caused by material dispersion, so that the predicted life will not deviate from The test life is too far away; and the critical surface stress-strain curve relationship and related material constants are introduced in the process of model establishment, which can reflect the influence of average stress. At the same time, the model can also predict fatigue under proportional and non-proportional, symmetrical and asymmetrical loads life.

Description

technical field [0001] The invention belongs to the field of reliability, in particular to a fatigue life prediction technology of aviation metal materials or structural components. Background technique [0002] As the thrust device of the aircraft, the aero-engine is known as the "heart" of the aircraft, and its reliability and life prediction are of great significance to the safety of the aircraft. Among the mechanical failures in my country's aviation field in recent years, 80% are caused by the failure of rotating parts. With the development of the aviation industry, the requirements for the performance of aero-engines continue to increase, and the thrust-to-weight ratio continues to increase, which makes the temperature and speed of aero-turbine engines continue to increase, resulting in more complex thermal loads and mechanical cycles of aero-engine components, especially turbine rotor components. The failure problem of working under load is becoming more and more pro...

AI Technical Summary

Problems solved by technology

Although some multiaxial fatigue life prediction models in recent years can predict the multiaxial fatigue life under proportional and non-proportional loads, and can properly characterize the influence of mean stress, due to the dispersion of materials, in the absence of experimental conditions, its The crack failure mode is often uncertain, which eventually leads to unsatisfactory prediction results of some multiaxial fatigue life

For the fatigue model considering the two crack failure modes, simply choosing the lower predicted life as the final predicted life can easily lead to its model prediction being too conservative and the result not accurate enough

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