Liquid self-coupling ultrasonic transducer for composite material T-shaped connection area and detection method

Abstract

The invention belongs to the technical field of non-destructive inspection, and relates to a liquid self-coupling ultrasonic transducer for a composite material T-shaped connection area and a detection method. The liquid self-coupling ultrasonic transducer consists of an ultrasonic sensing unit, a shell, a coupling cavity, a connecting base, a liquid coupling agent and a close cover. According to geometrical characteristics and defect possible orientation of the T-shaped connection area, and based on a broadband narrow impact pulse reflection detection principle, the liquid self-coupling ultrasonic transducer is invented, and the acoustic coupling effect between the ultrasonic transducer and the surface of a detected composite material structure T-shaped connection area, the stability of detection signals and the accuracy of a detection result are obviously improved; and by adopting a manual or mechanical automatic scanning mode, a method for performing coverage detection on the composite material structure T-shaped connection area and performing defect distinguishing can be implemented. According to the ultrasonic transducer and the detection method provided by the invention, the defects of layering, air holes, inclusions, super-fatting and the like of the T-shaped connection area can be accurately detected, and the ability of ultrasound for detecting defects of the composite material structure T-shaped connection area is significantly improved.

Description

technical field [0001] The invention belongs to the technical field of non-destructive testing, and relates to a liquid self-coupling ultrasonic coupling transducer in a T-shaped connection area of ​​a composite material and a testing method. Background technique [0002] T-shaped connection is a very important connection form in composite wall panels and overall structures, and is also an important part of composite material load-bearing structures. The T-shaped connection area plays a role in load transfer and structural support in this type of composite material structure. T-shaped connections have been widely used in composite material structures in aerospace, transportation and other industrial fields. Reliable non-destructive testing of T-joint regions of composite structures is often required. At present, the non-destructive testing of the T-shaped connection area of ​​the composite material structure is based on the ultrasonic method: one is the ultrasonic manual co...

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Problems solved by technology

At present, the non-destructive testing of the T-shaped connection area of ​​the composite material structure is based on the ultrasonic method: one is the ultrasonic manual contact scanning method, the transducer is coupled with the T-shaped connecting rib through the solid delay block, and the ultrasonic A - Displaying signals for defect discrimination, the main disadvantage is that (1) this hard contact is difficult to ensure the acoustics between the transducer delay block and the surface of the T-shaped connection area during the scanning process, which will lead to normal emission of ultrasonic waves and reception, and thus easily lead to misjudgment and missed detection of defects; (2) It is necessary to prepare corresponding transducer delay blocks according to the curvature characteristics of different T-shaped connection areas, which is low in efficiency and high in cost; (3) for some curvature comparisons Small T-shaped connection area, using this solid delay block method, it is difficult to form a reasonable ultrasonic detection signal in the T-shaped connection area, so it is difficult to realize the coverage detection of the T-shaped connection area; (4) resolution

In order to improve its shortcomings, another detection method is to realize the scanning detection of the T-shaped connection area of ​​the composite material structure by designing some special ultrasonic automatic scanning detection systems or ultrasonic phased array methods. The main disadvantages are: (1) the cost It is very high and technically difficult, and it is necessary to design different scanning detection systems according to the geometric characteristics of the T-shaped connection area of ​​different composite material structures; (2) Due to the complexity of the automatic scanning mechanism and the limitation of the site environmental conditions, it is difficult to realize; ( 3) The requirements for the testing site are high, and a large dedicated testing site needs to be occupied; (4) The real-time verification of the test results is not good; (5) For some T-shaped connection areas in composite material structures with poor openness, Difficult to achieve detection; (6) There are surface detection blind spots

In order to improve its shortcomings, the Chinese patent "an ultrasonic scanner and scanning method for detecting the R-zone of the inner cavity of the composite material structure" (ZL 201210235056.6) is used to solve the detection of the R-zone of the inner cavity of the composite material structure, and its main shortcomings : (1) The soft-membrane-coupled R-zone ultrasonic probe is used. The soft-membrane is easily damaged during the scanning process, resulting in the inability to achieve acoustic coupling. In addition, the soft-membrane of the R-zone probe needs to be replaced continuously during the scanning process, which affects the detection effect and detection. efficiency

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