Welding structure multi-axial fatigue life evaluation method

Abstract

The invention discloses a welding structure multi-axial fatigue life evaluation method. The method includes the following steps that a finite element model of a welding structure to be measured is established; multiple test loads are applied to the welding structure, and structural stress tensors [sigma] of all joints of the end face of a weld toe in the board thickness direction are obtained through solving; corresponding load proportionality coefficients R of the joints are worked out according to the structural stress tensors [sigma] of the joints, and then the position of a stress peak critical point is determined; the structural stress tensor [sigma CPSP] of the stress peak critical point is obtained through the interpolation method; the maximum shear stress and normal stress range of a fatigue life critical damage plane are worked out according to the structural stress tensor [sigma CPSP] of the stress peak critical point, and multi-axial fatigue life evaluation is carried out through the union multi-axial fatigue life evaluation method MWCM.

Description

technical field [0001] The invention relates to a method for analyzing a welding fatigue structure, in particular to a method for evaluating the multiaxial fatigue life of a welding structure. Background technique [0002] The welded structure of the offshore platform is in a state of multiaxial fatigue damage. One is that the welded structure itself is subject to the joint action of different types of loads; the other is that the complex geometry of the welded part leads to a multi-directional stress state in the local area. [0003] At present, the standards are mainly based on the uniaxial fatigue method to evaluate the fatigue life of offshore platforms, which is one of the main reasons why fatigue fracture accidents have not been fully controlled. Internationally, although a variety of multiaxial fatigue life assessment methods have been proposed, so far, there is no method that can be applied to the actual complex welded structure of offshore platforms. [0004] The ...

AI Technical Summary

Problems solved by technology

From the perspective of engineering application, the latest achievement in the world is based on the hot spot stress method combined with the modified Waller curve method MWCM to evaluate the multiaxial fatigue life of welded joints, but this method can only deal with welding with very simple load types and structural forms The main reason is that the stress obtained by interpolating the surface stress of the structure is difficult to deal with the complex and changing stress state at the weld toe of the actual offshore platform welded structure

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