Surface crack strength factor database establishment method based on point weight function method

Abstract

The invention discloses a surface crack strength factor database establishment method based on point weight function method, which comprises the following steps of: carrying out integration on stress and weight functions of all points on a surface crack surface, and calculating stress strength factors of the surface crack under a complex stress gradient at a high speed; therefore, providing a basis for linear elastic fracture mechanical analysis in surface probability damage tolerance evaluation. Specifically, finite element parametric modeling is adopted, a cubic structure configuration is established, a reference stress intensity factor under a given stress gradient is calculated based on a J integral stress intensity factor theory, the calculation precision is not influenced by the number of grids at the tip of the crack, and the calculation result is accurate; compared with a general weight function method, the method overcomes the limitation that only one-way change of stress in the crack depth is considered, is suitable for more complex stress conditions, makes up for the limitation of a stress intensity factor manual, provides technical support for probability damage tolerance evaluation of the aero-engine service life limiting piece, and has important engineering significance and actual 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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