Structure fatigue life calculation method based on non-linear cumulative damage theory

A technology of cumulative damage and fatigue life, applied in the testing, measuring devices, instruments, etc. of machine/structural components, which can solve problems such as poor engineering applicability

Inactive Publication Date: 2015-08-12
DALIAN UNIV OF TECH +4
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Problems solved by technology

Although these model methods are more accurate than Miner's law, they have been applied to a certain extent...

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  • Structure fatigue life calculation method based on non-linear cumulative damage theory
  • Structure fatigue life calculation method based on non-linear cumulative damage theory
  • Structure fatigue life calculation method based on non-linear cumulative damage theory

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Embodiment Construction

[0057] The present invention will be further described in detail below in conjunction with the drawings and embodiments.

[0058] Case selected Figure 5 The welded structure shown is taken from a dangerous section of the truss boom of a rubber-tyred crane. The material parameters are: when the material is Q345B, the elastic modulus E = 200741MPa, the fatigue strength index b = -0.0943, the fatigue ductility index c = -0.5395, the fatigue strength coefficient σ f '=947.1MPa, fatigue ductility coefficient ε f '=0.4644, with cycle hardening characteristics.

[0059] Determine its fatigue life by calculating its complete cumulative damage. Specific steps are as follows:

[0060] Step 1: Determine the fatigue risk area of ​​the component through the finite element analysis software. By right Figure 5 Establish a finite element model, analyze two typical working conditions in Ansys, and obtain multiple points with larger stress values. Two typical working conditions are shown in Table...

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Abstract

A structure fatigue life calculation method based on the non-linear cumulative damage theory comprises the following steps: firstly, performing a stress analysis on a metal structure through the finite element technology and determining a large-stress-value area as a dangerous area, secondly, determining initial damage of the structure according to a served age and surface quality detection of the structure, thirdly, measuring a stress spectrum of the structure in a certain period through a stress detector, fourthly, calculating cumulative damage of the structure under the stress spectrum through the non-linear cumulative damage theory, and fifthly, calculating a fatigue life of the metal structure through the cumulative damage. According to the method, the multi-stage load loading sequence and an influence of the size of a load on the cumulative damage are taken into account, and precision of the fatigue life is higher than the precision of a fatigue life calculated according to the linear cumulative damage theory. The method only needs a small amount of material performance data such as a cyclic stress-strain curve and a constant-amplitude strain life curve, calculation is simple, and the method is suitable for engineering applications.

Description

Technical field [0001] The invention provides a structural fatigue life calculation method based on nonlinear cumulative damage theory, which belongs to the technical field of fatigue damage analysis and reliability evaluation. Background technique [0002] According to statistics, fatigue fracture damage in engineering practice accounts for 50%-90% of all mechanical damage and is one of the most common forms of mechanical and structural failure. The product will have fatigue damage under the anti-corrosion cycle of the load. When the damage value reaches a certain threshold, the structure will fatigue failure. [0003] At present, the Palmgren-Miner linear law is often used to calculate the damage of variable amplitude load, but the calculation result has a large dispersion rate, so the life evaluation accuracy is low. In recent years, some models based on various fracture mechanics theories and real-time observation techniques have been developed, taking into account the residua...

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Application Information

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IPC IPC(8): G01M99/00
Inventor 蔡福海王兴权潘志毅罗建国李树清丁国林张玉林李梦然商国旭何映仁姜官斌
Owner DALIAN UNIV OF TECH
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