Micro-crack nondestructive detection system and detection method thereof

Abstract

The invention discloses a micro-crack nondestructive detection system and a detection method thereof. The micro-crack nondestructive detection system comprises a signal generator, a low frequency vibration exciter, a high frequency exciter, a detected member, a piezoelectric sensor, a preamplifier and a signal acquisition and analysis system; the signal generator is electrically connected with the detected member through the low frequency vibration exciter and the high frequency exciter, the piezoelectric sensor is fixed on the detected member through an adhesive, and the signal acquisition and analysis system is electrically connected with the piezoelectric sensor through the preamplifier; and the signal-generator can simultaneously output two paths of simple harmonic excitation signals with different frequencies. Defect detection is carried out by using the non-linear modulation effect of a crack structure under multi-frequency excitation, and whether the existence or not of the micro-crack and the micro-crack damage of the detected member are directly determined according to the quantity and amplitude of side frequencies in a response spectrum without complex signal processing, so the system and the method have the advantages of use convenience, sensitive detection and high detection efficiency.

Description

technical field [0001] The invention belongs to the technical field of non-destructive detection, and in particular relates to a micro-crack non-destructive detection system and a detection method based on the nonlinear modulation response effect under multi-frequency simple harmonic excitation. Background technique [0002] Fatigue cracks are one of the main ways of structural damage. It is of great significance to develop real-time and reliable early nondestructive detection methods for structural fatigue cracks to avoid accidents caused by fatigue cracks. At present, scholars at home and abroad have proposed many non-destructive testing methods for structural cracks, such as acoustic emission method, eddy current method, vibration-based method and ultrasonic testing technology. [0003] Ultrasound is an important non-destructive testing method. When it propagates in the structure, it causes the vibration of the material itself. The discontinuity or inhomogeneity of the te...

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Problems solved by technology

These linear parameters do not change significantly when the damage size is small or a closed crack, so conventional linear ultrasonic methods cannot reliably detect these defects

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