Safety Margin Assessment Model for Surface Cracks Based on Path Rate Integral Method

Pressure vessel is a common important equipment in industrial production, in the production process by the equipment itself material properties, pressure environment, work in the medium and other complex effects, resulting in the emergence of different defects in the form of surface cracks is a common form of defects in pressure vessels. Although the safety assessment of crack defects has already formed a certain system, most of them are quantitative judgments, and there are fewer studies on the quantitative characterisation of the safety margin or remaining life of crack defects in pressure equipment. In this paper, an extended study is carried out on the basis of the theory of failure assessment diagram, and the remaining safety margin of surface crack defects in the whole process of fatigue failure is investigated. Using the numerical characterisation calculation method of the failure assessment diagram, the safety margin model of the path rate integral is established by analysing the transient relation equation and differential calculation, and further exploring the safety decay path with the help of practical examples. The results show that the model characterises the safety margin more accurately and is more in line with engineering applications.