Method and system for detecting looseness of bolt joints based on nonlinear excitation characteristics

Abstract

The invention discloses a bolt joint part looseness detecting method and system based on a nonlinear shock excitation feature. The method comprises the following steps: carrying out simulated modal analysis on a three-dimensional model of a test piece, and determining the arrangement positions of a vibration exciter and a sensor of a local part of a bolt joint part; arranging the vibration exciterand the sensor according to the determined arrangement positions of the vibration exciter and the sensor, and determining a vibration excitement parameter of the vibrator exciter according to the simulated modal analysis result of the three-dimensional model; maintaining the vibration excitement parameter unchanged, carrying out preliminary experiment on the same kind of test pieces to obtain a corresponding relation between a bolt pretightening force and a high harmonic scaling factor, and generating a relation data base; and carrying out test on a test piece to be tested to obtain a high harmonic scaling factor, querying the relation data base, determining the bolt pretightening force of the test piece to be tested, and judging whether the bolt joint part of the test piece to be testedis loosen or not according to the bolt pretightening force of the test piece to be tested. The method has the advantages of wide applicability, flexibility and convenience in use, high sensitivity andthe like, implements nondestructive detection, and is suitable for actual production.

Description

technical field [0001] The invention relates to the technical field of mechanical state detection and maintenance, in particular to a method and system for detecting looseness of a bolt joint based on nonlinear excitation characteristics. Background technique [0002] Bolted connections are widely used in various mechanical structures due to their advantages of being able to withstand large loads and can be assembled and disassembled repeatedly. For example, the main force-bearing parts of engineering structures such as spacecraft, machine tools, and steel bridges all contain bolted joints. For a bolted joint that bears an important load, there are strict requirements on its preload, because the preload largely determines the reliability, bearing capacity, and stiffness of the bolted connection, and has an important impact on the structural dynamics. . However, in practical applications, due to long-term fatigue, shock, vibration and other loads, the pre-tightening force of...

AI Technical Summary

Problems solved by technology

This is also a dynamic detection method, but because the peak amplitudes and corresponding frequencies of different structures are different, it is necessary to establish a complete signal feature database for the structure to be tested before detection, which is costly

And in the actual test, it is found that during the process of bolt loosening, obvious nonlinear phenomena may be brought about, resulting in a greater impact on the characteristics of the measured vibration signal due to the magnitude of the knocking force, but the magnitude of the knocking force cannot be accurately controlled, so a large The measurement error reduces the detection accuracy

In short, the existing bolt loosening detection methods have problems such as high cost and poor detection accuracy, and it is necessary to explore new low-cost, high-precision bolt loosening detection methods

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