Method for monitoring multi-axial fatigue stress of ocean engineering structure

Abstract

The invention discloses a method for monitoring multi-axial fatigue stress of ocean engineering structure, which comprises the following steps of: analyzing the stress of a fatigue key position of the structure, and finding out a main loading form of the structure; establishing a fatigue key position finite element model to obtain hot spot stress at a fatigue hot spot; arranging a strain sensor at a position far away from the fatigue hot spot to obtain characteristic stress representing each simple loading form; obtaining a conversion matrix according to the linear relations between the simple loading forms and the column stress conversion equation; and multiplying the characteristic stress monitored by the actual load of the structure by the conversion matrix to obtain the stress at the fatigue hot spot under the action of the actual load. The sensor is arranged in the area far away from the hot spot, all stress states at the fatigue hot spot can be obtained at a time, the obtained monitoring result can be directly used for multi-axial fatigue evaluation, and the multi-axial fatigue stress can be evaluated through mutual superposition of different load linear combinations. Fatigue stress monitoring of various structures in different forms can be realized on the basis of accurate stress analysis.

Description

technical field [0001] The present invention relates to the technical field of marine engineering, in particular to a monitoring method for multi-axis fatigue stress of marine engineering structures. Background technique [0002] Ocean engineering structures have been in a complex and changeable marine environment for a long time, and the long-term action of wind and waves makes fatigue damage an important form of damage that cannot be ignored. At present, the finite element method is mainly used in engineering to calculate the stress state of the fatigue hot spots, and the fatigue life of ships and ocean engineering structures is evaluated based on the S-N curve and combined with the spectral analysis method. However, the simplification of the finite element model and constraint conditions will produce calculation errors, and the accumulation of various errors will make the stress calculation results inconsistent with the real stress response of the structure, resulting in ...

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Problems solved by technology

In addition, since the sensor is generally arranged perpendicular to the weld when monitoring the hot spot stress, only the unidirectional stress component at the hot spot can be obtained, which is difficult to use for multiaxial fatigue life assessment

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