Composite material plate layering defect air coupling ultrasonic detection method based on HHT and neural network

A composite material board, ultrasonic detection technology, applied in neural learning methods, biological neural network models, neural architectures, etc. Effects of secondary pollution problems

Pending Publication Date: 2022-04-12
HARBIN INST OF TECH
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Problems solved by technology

[0005] The traditional Lamb wave information extraction method is the Cross-borehole method. This method has achieved good results in many industrial technical projects, but it requires a large number of sensors and densely arranged sensors. further optimization

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  • Composite material plate layering defect air coupling ultrasonic detection method based on HHT and neural network
  • Composite material plate layering defect air coupling ultrasonic detection method based on HHT and neural network
  • Composite material plate layering defect air coupling ultrasonic detection method based on HHT and neural network

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specific Embodiment 1

[0070] according to Figure 1 to Figure 4 As shown, the present invention determines the center frequency of the air-coupled transducer as f and the inclination angle as θ according to the Lamb dispersion curve and Snell's law. On one side of the composite material plate, the air-coupled transducer is placed according to the requirement of the inclination angle, and the distance between the exciting and receiving air-coupled transducer is set as L. The same-side-to-face detection method is adopted, and the A0 mode is used to detect the delamination defect of the composite material plate. The received signals obtained by air-coupled ultrasonic Lamb wave detection on artificially set composite plates with layered defects of different depths, widths, and lengths are subjected to HHT to obtain Hilbert spectrum, HHT marginal spectrum, and instantaneous energy spectrum, etc., and then the damage Features such as time delay and energy loss in detection. The above eigenvalues ​​are ...

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Abstract

The invention relates to a composite material plate layering defect air coupling ultrasonic detection method based on HHT and a neural network. The invention relates to the technical field of composite material defect detection. The method comprises the following steps: determining an excitation frequency and an inclination angle of an air coupling transducer; eMD decomposition is carried out, and an intrinsic mode function is extracted; a BP neural network is established, and network learning is carried out; and identifying the depth, width and length of the layered defect based on the established BP neural network. In the detection process, air is used as a transmission medium to replace a coupling agent in traditional ultrasonic nondestructive detection, so that the problem of secondary pollution of a coupling material to a to-be-detected piece can be fundamentally avoided, the air coupling ultrasonic transducer has the advantages of no contact, no invasion and no damage in the detection process, and the service life of the air coupling ultrasonic transducer is prolonged; therefore, the air-coupled ultrasonic Lamb wave detection realizes on-line rapid detection, and is suitable for ultrasonic detection of layering defects of composite material plates which cannot be subjected to contact detection by using a coupling agent.

Description

technical field [0001] The invention relates to the technical field of composite material defect detection, and relates to an air-coupled ultrasonic detection method for layered defects of composite material plates based on HHT and neural networks. Background technique [0002] Nowadays, the various single metal materials and alloy materials that people relied on in the early days are increasingly difficult to meet people's high requirements for the materials used, especially in the field of cutting-edge scientific and technological research. Composite materials have emerged as the times require, and are being widely used in various fields such as aerospace engineering, bridges, ships, automotive engineering, and medical equipment. Composite materials have the characteristics of low density, high strength, high modulus, wear resistance, high temperature resistance, strong antimagnetic, strong corrosion resistance, and fatigue resistance, and have been widely and maturely use...

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01N29/04G01N29/44G06N3/04G06N3/08
Inventor 史维佳王丙泉赵勃谭久彬
Owner HARBIN INST OF TECH
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