An Ultrasonic Inspection Method of Composite Foam Structure Based on Reflection Principle

Abstract

The invention belongs to the technical field of lossless detection, and relates to a composite material foam structure ultrasonic detection method based on a reflection theory. According to the method, ultrasonic echoes are formed in a composite material foam structure by utilizing broadband narrow pulse waves, and a mathematical relation between the ultrasonic echoes and defects in different parts of the composite material foam structure is constructed by constructing a transmission function of the ultrasonic waves in the composite material foam structure, so that defect judgment and ultrasonic detection are carried out; different types of the broadband narrow pulse ultrasonic waves with different sizes and frequencies can be selected; ultrasonic detection on different composite material foam structures can be realized by adopting an ultrasonic reflection detection method. An actual detection result shows that the detection sensitivity and the resolution as well as the detection capacity for the composite material foam structure are obviously improved, and the defects and the combination conditions of the skins and skin / foam cementing regions can be accurately detected, and therefore, the detection reliability is greatly improved, the surface detection blind region is up to 0.13mm, and the detection sensitivity is phi3mm.

Description

technical field [0001] The invention belongs to the technical field of non-destructive testing, and relates to an ultrasonic testing method for a composite material foam structure based on the principle of reflection. Background technique [0002] Composite foam structure, as an ultra-light structure, has been widely used in aerospace, transportation and other industrial fields. By selecting different composite materials and foam materials and designing foam bonding processes of different shapes and thicknesses, various forms of foam can be produced. Composite foam structure. In order to improve the process of composite foam structure and ensure the quality of composite foam structure, non-destructive testing of composite foam structure is usually required. A relatively common composite material foam structure is that the foam is directly bonded to the composite material skin to form a composite material foam structure for various purposes. Usually, this kind of composite m...

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Problems solved by technology

Currently feasible non-destructive testing methods are: (1) Soft X-ray testing method, its main disadvantages are: 1) It is difficult to detect the defects in the foam bonding interface and composite skin of the X-ray beam vertically oriented; 2 ) The detection efficiency is low, the cost is high, and special radiation protection is required; (2) The conventional ultrasonic detection method has the main shortcomings: a) The ultrasonic surface detection blind area is large (usually 1-3mm), and the mask in the composite foam structure The thickness of the skin is usually 0.5-3mm, so it is very easy to cause missed detection; b) the detection signal echo is multi-cycle characteristic, the resolution is low, it is difficult to accurately determine the depth and nature of the defect in the foam composite material; c) when using solid When the time-delay transducer scans the detection means, the blind area of ​​the surface detection is improved (up to 0.8-2mm), but the solid time-delay block and the surface of the composite foam structure are hard-contact coupled, which is likely to cause problems due to poor coupling. Missed detection, which makes it difficult to achieve reliable detection and accurate defect location of composite skin and composite skin / foam adhesive interface defects, which will also lead to difficulties in defect identification and location

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