Bolt axial stress detection method based on ultrasonic spectrum energy attenuation

Abstract

The invention discloses a bolt axial stress detection method based on ultrasonic spectrum energy attenuation. The bolt axial stress detection method comprises the following steps: 1) clamping a bolt on a tensile sample machine; 2) adjusting the clamping length of the bolt; 3) adjusting axial stress sigma borne by the bolt; 4) exciting one end face of the bolt to generate ultrasonic waves, and collecting voltage signals of the ultrasonic waves reflected from the other end face of the bolt; 5) selecting a primary bottom surface echo f1 (t) and a secondary bottom surface echo f2 (t) containing all cylindrical surface guided wave signals; 6) calculating an energy attenuation coefficient R (sigma); 7) circulating the step 3) to the step 6) to obtain a nonlinear fitting curve of the axial stress sigma and the energy attenuation coefficient R (sigma); 8) circulating the step 2) to the step 7) to obtain a nonlinear fitting curve of the axial stress sigma and the energy attenuation coefficient R (sigma) of the bolt under different clamping length conditions; and 9) carrying out linear fitting between the slope of the nonlinear fitting curve and the corresponding clamping length to obtain a linear relation of the slope of the nonlinear fitting curve along with the change of the clamping length.

Description

technical field [0001] The invention belongs to the technical field of ultrasonic nondestructive testing, in particular to a bolt axial stress testing method based on ultrasonic spectrum energy attenuation. Background technique [0002] Loose bolts may lead to abnormal mechanical vibration or even partial disintegration, resulting in serious safety accidents. Accurate measurement and control of the force state of bolts and other joints in precision machinery is of great significance to ensure the continuous and reliable operation of the system. At present, common bolt stress monitoring methods include electrical strain gauge method, piezoelectric impedance method and ultrasonic testing method. Although the first two detection methods have simple principles and high reliability, they have many restrictions on the installation position of the sensor, so their versatility is limited. Ultrasonic testing is currently the most widely used and relatively mature general-purpose st...

AI Technical Summary

Problems solved by technology

In addition, when the bolt is short, its mounting eccentricity, plastic deformation under heavy load, and uneven stress distribution can adversely affect the transit time measurement

It can be seen that in some cases the transit time method is not suitable for measuring bolt stress

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