Method for identifying plate defect and damage based on nonlinear acoustics and time reversal principle

Abstract

The invention relates to a method for identifying plate defect and damage based on a nonlinear acoustics and time reversal principle. In the traditional method, the detection on small cracks in a plate is difficult to satisfy people, and therefore, the accuracy and the sensitivity of the traditional method are lowered. The method comprises the steps of: 1, transmitting transducer pumping signals:arranging a defined quantity of transducer arrays on a plate to be measured, and generating two pulse signals by a random waveform signal generator to be used as pumping signals; 2, selection of timereversal window signals: receiving transmission signals of the step 1 in a medium by a receiving transducer, carrying out nonlinear spectrum analysis on the received signals, and carrying out time reversal on the selected time window signals with nonlinear characteristic parameters; 3, obtained focus signals: loading the signals subjected to the time reversal in the step 2 to the transmitting transducer arrays again, and receiving the focus signals at the receiving part; and 4, defect or damage identification evaluation: analyzing the focus signals in the step 3, and finding out the relation between the defect or damage and the nonlinear characteristic parameters. The invention is applied to detection and identification of a plate structural member.

Description

Technical field: [0001] The invention relates to the field of non-destructive testing, in particular to a plate defect and damage identification method based on nonlinear acoustic modulation spectrum technology and time reversal principle. Background technique: [0002] Sheet structures are widely used and play an indispensable role in the fields of aerospace, automobile industry and civil engineering. Since the plate will produce defects or damage during the forming and use process, when these defects or damage are located in the middle of the plate thickness, it is difficult to find with the naked eye. With the external loading and the change of the environment, the internal small defect source may expand together, resulting in fatigue damage. Therefore, it is very necessary to detect and identify plate-shaped structural members. [0003] Ultrasonic nondestructive testing is one of the methods widely used at present. However, the existing ultrasonic methods mainly use l...

AI Technical Summary

Problems solved by technology

However, if the nonlinearity of the flaws in the plate breaks the symmetry of the time-reversal rule, then the energy will not focus where desired

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