A Method of Establishing Surface Crack Intensity Factor Database Based on Point Weight Function Method

Abstract

The invention discloses a method for establishing a database of surface crack intensity factors based on point weight functions. By integrating the stress and weight functions of all points on the surface crack surface, the stress intensity factors of surface cracks under complex stress gradients are calculated at high speed, thereby Provides the basis for linear elastic fracture mechanics analysis in surface probabilistic damage tolerance assessment. Specifically, finite element parametric modeling is used to establish a cubic structure configuration. Based on the J-integral stress intensity factor theory, the reference stress intensity factor under a given stress gradient is calculated. The calculation accuracy is not affected by the number of crack tip grids. The calculation results Accurate; compared with the general weight function method, the point weight function method overcomes the limitation of only considering the unidirectional change of stress at the crack depth, is suitable for more complex stress situations, and makes up for the limitations of the stress intensity factor manual. The probabilistic damage tolerance assessment of life parts provides technical support, which has important engineering significance and practical value.

Description

technical field [0001] The invention belongs to the technical field of probabilistic damage tolerance evaluation of aero-engines, and in particular relates to a method for establishing a surface crack intensity factor database based on a point weight function. Background technique [0002] The life-limited parts of aero-engine are the key safety parts of aero-engine. In the process of processing and maintenance, small-probability defects will inevitably be introduced into life-limited parts, which will pose a great threat to the safety of aero-engines. Therefore, the FAR-33 part of the U.S. airworthiness regulations and the 33.70 article of the R2 edition of the CCAR-33 part of the Chinese airworthiness regulations propose a set of enhanced life management procedures, using the probabilistic damage tolerance evaluation method to consider Impact of flaws on security. This evaluation method regards surface defects as surface cracks in the structure, is based on linear elasti...

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Problems solved by technology

However, the general weight function method is only suitable for the case where the stress changes in a single direction of the crack depth, and for cracks where the stress distribution on the two-dimensional plane is not uniform in the two dimensions of crack depth and length, the general weight function method is not applicable.

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