Nonlinear ultrasonic detection method for axial stress of bolt

Abstract

The invention provides a nonlinear ultrasonic detection method for axial stress of a bolt. The method comprises the following implementation steps: step A, establishing a relation model between a second harmonic amplitude and a fundamental wave amplitude on the basis of a propagation theory of ultrasonic waves in an isotropic medium to obtain an expression of relative nonlinear coefficients; stepb, carrying out an axial stress loading experiment on a bolt sample, carrying out nonlinear ultrasonic detection, and calculating relative nonlinear coefficients under different stress states; and step c, fitting the loaded axial stress and the corresponding relative nonlinear coefficients, determining an ultrasonic detection coefficient of the axial stress of the bolt, and finally obtaining a relational expression of the axial stress of the bolt and the relative nonlinear coefficients. By means of the steps, nonlinear ultrasonic detection of the axial stress of the bolt can be realized, the axial stress of the bolt can be rapidly and accurately detected with the method, and the accuracy and the practicability of the axial stress detection technology of the bolt are improved.

Description

[0001] 1. Technical field [0002] The invention provides a nonlinear ultrasonic detection method for bolt axial stress, which relates to the technical field of detection of bolt fasteners. [0003] 2. Background technology [0004] As a common fastener, bolts are widely used in aerospace, railway transportation, ship turbines, armored vehicles, civil manufacturing and other industrial fields due to their advantages of good connection performance, simple disassembly and low cost. Connection performance or sealing effect. During the service process, the bolts are required to maintain sufficient strength and rigidity to meet the stability requirements of the overall structure. However, during the working process, the bolt is inevitably affected by the axial force. As time accumulates, the overall performance of the bolt will degrade, which has a great impact on its service performance and service life. In extreme cases, the bolts may even break suddenly, causing major personnel...

AI Technical Summary

Problems solved by technology

The traditional ultrasonic testing method evaluates the stress of the material through the relationship between sound velocity and stress. However, when the stress changes by 100MPa, the sound velocity only changes by 0.01%. Therefore, it is not accurate enough to reflect the stress of the material through the change of wave velocity.

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