Lamb wave engineering structure multi-crack damage monitoring method

Abstract

The invention discloses a Lamb wave engineering structure multi-crack damage monitoring method. The method comprises the following steps: arranging a piezoelectric array on a to-be-monitored structural member, dividing a monitoring area into a plurality of fan-shaped areas, collecting a Lamb wave response signal of each monitoring path in the piezoelectric array, and calculating an SDC value of the monitoring path; determining a fan-shaped sub-region where the damage is located through an SDC value of a radius monitoring path of a fan-shaped region; determining the approximate direction of the damage through a three-point positioning method, and then conducting SDC value correction on the monitoring paths passing through a plurality of fan-shaped sub-region at the same time; and finding out the crack direction of a single fan-shaped sub-region through a cross method according to the action mechanism of cracks on Lamb waves, conducting imaging of the fan-shaped sub-region through an elliptical weight model, and finally overlapping images of all the fan-shaped sub-regions to obtain a crack damage image of a to-be-monitored structural part. According to the method, the direction of the crack damage can be reliably and stably judged, and accurate monitoring and evaluation of the multi-crack damage are realized.

Description

technical field [0001] The invention relates to a multi-crack damage monitoring method for a Lamb wave engineering structure, belonging to the technical field of structural health monitoring. Background technique [0002] With the continuous improvement of the safety and reliability requirements of structural components, structural health monitoring technology has achieved unprecedented development. During the use of materials, under the action of external cyclic stress and strain, structural parts may gradually produce local permanent cumulative damage in one or several places. After a period of time, too many cycles will cause cracks or complete fracture. In order to prevent the damage and loss caused by structural damage, it is necessary to carry out an effective assessment of the structure. [0003] The Lamb wave is generated on the premise of the free boundary of the plate. When the thickness of the plate is of the same order of magnitude as the wavelength of the monit...

AI Technical Summary

Problems solved by technology

[0004] Due to the dispersion characteristics of Lamb waves and the mode conversion caused by the end effect during propagation, when Lamb waves are used for crack damage monitoring of structural parts, the monitoring signal can be greatly affected, resulting in inaccurate monitoring results and improving the reconstruction of cracks. The difficulty of damage, therefore, needs to be improved on the existing Lamb-wave tomography-based structural crack damage monitoring technology

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