Method for nonlinear quantitative non-destructive inspection of bonding interface cohesive force using contact sound

Abstract

The invention discloses a method for nonlinear quantitative non-destructive inspection of bonding interface cohesive force using contact sound, wherein the base frequency signal generating system energizes a base frequency longitudinal wave energy converter to produce a longitudinal sound wave which is propagated in the composite material, contacting sound non-linearity will occur when reaching the bonding layer, the sound wave penetrating the bonding layer is received by the secondary harmonic longitudinal wave energy converter and transformed into electrical signal for display on a digital oscilloscope, obtaining base frequency and secondary harmonic frequency constituents through FFT, the energy converter calibration curve then converses them into sound amplitude, the crack width in the bonding layer is determined by the input sound amplitude when sound transmission is present, the input amplitude is set by the laser interferometer measurement or energy converter calibration curve, and the bonding force T0 is obtained through formula (2). The method can realize high sensitivity, reliable quantity value without damaging the bonding layer.

Description

1. Technical field: [0001] The invention relates to an acoustic non-destructive testing method, in particular to a non-destructive non-destructive testing method for non-destructive testing of adhesive interfaces using contact sound nonlinearity. 2. Background technology [0002] In aviation, petroleum industry, military and other fields, composite materials are often used (bonded by one or several materials, so there is a bonding interface inside), and the quality of composite materials is not affected by the material itself , and more importantly, is determined by the bonding strength between layers of composite materials. Before using these materials, it is necessary to consider whether the bonding is intact to prevent accidents caused by the use of damaged materials; and after using these materials for a period of time, there will be cracks and voids in the adhesive layer. The existence of these defects will have a decisive impact on the material. destructive effect. T...

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Problems solved by technology

Some people propose to directly destroy the bonding layer of composite materials to obtain the size of the bonding force [Edited by Gao Xuemin et al., "Handbook of Bonding and Bonding Technology", Sichuan Science and Technology Press, 470-486], although this method can obtain The quantitative value of the adhesive force, but the material is damaged, so this method cannot be detected online and is not an ideal method to obtain the quantitative value of the adhesive force; some ultrasonic methods have also been proposed for the measurement and application of the adhesive strength in the adhesive layer. Detection of various types of defects [C.C.H.Guyott, P.Cawley and R.D.Adams, "Thenondestructive testing of adhesively bonded structure: a review," J.Adhesion, 20 (1986), 129], but these techniques mainly use linear acoustic quantities when measuring the bonding strength, these quantities are often only indirectly related to the bonding strength of materials, and must also rely on a lot of information that needs to be further confirmed. Empirical relationship of measurement parameters such as sound velocity and attenuation

Therefore, these methods can only qualitatively estimate the bonding strength, and cannot give quantitative values. Even if some methods give quantitative values, they are also inferred from indirect empirical relationships, and the test results are not convincing.

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