Method for estimating stress intensity factors of surface cracks on typical welding structure of ship body

Abstract

The invention discloses a method for estimating the stress intensity factors of surface cracks on the typical welding structure of a ship body. The method comprises the following steps: determining the surface maximum opening displacement of crakes according to a certain measuring method; estimating stress intensity factor values in the depth directions of cracks on a plate-plate welding member and a pipe joint structure. By adopting the method for calculating the stress intensity factor of a welding member provided by the invention, the defect that the tip stress intensity factors of cracks cannot be grasped at any time is overcome, a novel thought is provided for the measurement of stress intensity factor values, a stress intensity factor measuring method at a laboratory stage is closer to practical engineering, and a foundation is laid for the grasp of the tip stress intensity factors of cracks containing crake damage practical engineering structures.

Description

Technical field: [0001] The invention relates to a method for estimating stress intensity factors of cracks on the surface of a typical welded structure of a hull. Background technique: [0002] Various microscopic and macroscopic defects that are inevitably produced in the welding process of ships and other large structures, under the action of alternating loads such as wave force, tidal current force, sea wind force and various dynamic forces during operation, welds with serious stress concentration Defects in the toe can easily develop into surface cracks with a shape close to a semi-ellipse. Under the action of continuous external load, surface cracks will continue to expand and penetrate the steel plate to form penetrating cracks. Since the hull structure has a large amount of redundancy, the appearance of surface cracks or even penetrating cracks does not mean the destruction of the cracked area, and only when the fracture parameter of the crack tip—the stress intensi...

AI Technical Summary

Problems solved by technology

However, when solving practical large-scale structural problems, the finite element method still has the following difficulties, such as (1) it is difficult to accurately obtain the external load and deformation data of the complex structure, which may cause the calculation results of the stress field near the crack tip to be large. The error directly affects the calculation accuracy of the stress intensity factor; (2) to discretize the entire three-dimensional structure, and due to the singularity of the stress field near the crack tip, it is necessary to divide a very dense grid, or use special Finite element technology, so the workload of data preparation is very large, such as the typical complex structure of the hull, it is difficult to establish a three-dimensional solid finite element model with surface cracks, which makes it difficult to calculate the stress intensity factor of large structures by finite element method

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