Method for determining available limit of crack-type hard object damage of concave and convex of blade by taking high and low cycle fatigue into account

Abstract

The invention discloses a method for determining an available limit of crack-type hard object damage of a concave and a convex of a blade by taking high and low cycle fatigue into account. The methodcomprises the steps: firstly, extracting high-cycle-fatigue loads and low-cycle-fatigue loads from high / low-cycle composite loads borne by the blade, and respectively establishing a crack / tear-type hard object damage crack non-extension equivalent curve relevant to a stress ratio under a series of high-cycle-fatigue loads and low-cycle-fatigue loads; then, determining a static stress and a dynamicstress on a position of each point of the concave and the convex of the blade by using a finite element numerical analysis method; and finally, comparing positions of the static stress and the dynamic stress in the crack non-extension equivalent curve to determine a crack size corresponding to the equivalent curve, namely the available limit of crack / tear-type hard object damage at the point of the concave and the convex of the blade. The invention not only provides the simple and effective method for determining the available limit of the hard object damage, but also forms a normalized available limit formulation process for the crack / tear-type hard object damage of the concave and the convex of the blade.

Description

Technical field [0001] The invention relates to a method for determining the available limit of cracked hard object damage on the blade back of a blade basin considering high and low cycle fatigue, and belongs to the field of hard object damage tolerance design and maintenance of aero engine blades. Background technique [0002] Metal, debris, gravel, stones and other hard objects accompanied by the airflow into the engine airflow channel collide with the high-speed rotating blades, and the impact damage is one of the important reasons that aggravate the fatigue failure of the blades. Although people have proposed preventive measures against external object damage such as the cleaning of the runway and the inspection and control of ground crew maintenance tools, hard object damage is always inevitable. [0003] Regarding the inevitable hard object damage problem, although the engine designer makes the blade have a certain hard object damage tolerance capability, it is also necessar...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a method for determining the usable limit of crack-type hard object damage on the back of the blade basin considering high- and low-cycle fatigue, so as to solve the current lack of reasonable and standardized usable limit formulation process for tear / crack type hard object damage The problem

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