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

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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Problems solved by technology

Although these model methods are more accurate than Miner's law, they have been applied to a certain extent, but due to the need for a large amount of experimental data to fit, the engineering applicability is not strong

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