Foreign object damage notch calibration method with stress concentration coefficient not smaller than 3

Abstract

The invention provides a foreign object damage gap calibration method capable of ensuring that a stress concentration coefficient is not less than 3. The method comprises the following steps of firstly, prefabricating an FOD notch in a blade, carrying out three-dimensional reconstruction on FOD damage through a three-dimensional optical scanning system to establish an FOD damage model; performingfinite element analysis on the blade model with an FOD, which is reversely obtained by three-dimensional reconstruction, calculating to obtain a stress concentration coefficient of the blade model, and recording a stress concentration coefficient value corresponding to the typical damage size; and building a neural network model by using a programming language, taking the damage size as the inputof the neural network, taking the stress concentration coefficient as the output of the neural network, and training the neural network model through loop iteration; and calibrating the damage size corresponding to the type of blade Kt = 3 through the trained network. When the anti-FOD capacity of the blade is assessed, an FOD notch can be prefabricated in the front edge of the blade through an air cannon method or a notch machining method according to the calibrated damage size.

Description

technical field [0001] The invention belongs to the technical field of damage analysis of aeroengine blades. Background technique [0002] When an aero-engine is running near the ground, it will inhale various foreign objects moving with the high-speed airflow, causing impact damage to engine components (mainly fan / compressor blades). When the foreign object is a stone, gravel, bolt or rivet, etc., it is usually called a "hard object" impact. In domestic and foreign aero-engine design codes, standards and manuals, only the impact damage caused by the impact of "hard objects" is called "Foreign Object Damage" (FOD for short). FOD has four basic characteristics: (1) stress concentration at the damage site; (2) residual stress field near the damage site; (3) tiny cracks at the damage site; (4) microstructural damage at the damage site. [0003] Aiming at the FOD problem of blades, the U.S. military standard JSGS-87231A released in 1995 requires that the anti-FOD design of bla...

AI Technical Summary

Problems solved by technology

However, for the stress concentration factor of the edge notch of complex components such as blades, the corresponding relationship between Kt and the notch size cannot be found through the stress concentration factor manual, and can only be obtained through the finite element calculation of the notch model. FOD damage is often prefabricated only by experience. It will cause the stress concentration factor of the prefabricated damage to be much greater than 3, resulting in an over-assessment situation, causing errors in the assessment results of the blade's FOD resistance, and affecting the blade's FOD resistance design work

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