Research On The Key Technology Of Defect Inspection Under Velocity Based On Multi-physical Sensors

The non-destructive testing technology is a safe,reliable and effective testing method and technology,which has been widely used in railway,oil,aerospace,nuclear power and other fields.The non-destructive testing(NDT)technology has the advantages of non-destructive testing,high sensitivity and mutual compatibility.The small diameter and thin-wall tube and rail are the key components for nuclear industry and railway transportation.Both of them are base metal and need to do pre-service or in-service inspection.It is required to do high-precision,high-efficiency and whole-section inspection due to the particularity of the industry.The non-destructive testing technology has various testing methods.Each testing method has its own advantages and limitations.How to overcome the limitations of a single NDT method and achieve effective and high-precision detection is a difficulty.This paper will focus on the ultrasound and eddy current thermography nondestructive testing technology under the velocity effect.The purpose is to study the defects detection of small-diameter and thin-walled tube,the precision measurement of wall thickness and diameter,and the inspection of rail under the scanning mode.The main contents and innovations of this paper are summarized as follows:1)The propagation process,defect detection and energy distribution of ultrasound in the small diameter and thin-walled tube are studied.The optimization method of acoustic parameters for ultrasonic probe is proposed based on physical perspective forward and inverse learning.The acoustic parameters and formulas for the probe are analyzed and deduced from the end corner formed by the defects and the surface of the tube.The frequency and size of the crystal element which are difficult to calculate directly are optimized by using sound field,reverse learning and digital image processing.The simulation and experiment shows that the proposed method is effective.2)The high-precision ultrasonic measurement method of wall thickness and diameter for small-diameter thin-walled tube under the condition of high-speed scanning is studied.Based on the measurement errors analysis of the high-speed rotating probe device and the previous research on ultrasonic resonance method,a new embedded neural network intelligent compensation sensing architecture is proposed.The experimental results show that the new ultrasonic sensor architecture can eliminate the error caused by the change of water temperature.It is able to reduce the influence of tube deformation and mechanical vibration during the scanning process.3)The dynamic scanning experiment of eddy current thermography is carried out,and the spatial fusion tensor model of infrared thermography is studied.By comparing the results of rectangular and double circular excitation coils under the velocity effect,the double excitation coil is suitable for dynamic scanning due to the effective detection for defects in different distribution directions.The hidden relationship between the location and time is mined by tensor decomposition.The superposition effect of thermal diffusion and motion blur is reduced and the contrast between defect and background noise is enhanced.It is a foundation for eddy current thermagraphy inspection under the elocity effect.4)A multi-sensor data fusion model based on the feature layer is proposed under the velocity effect.The mapping relationship between ultrasonic data,thermal image and the detection position is established,and the relationship between ultrasonic B-scan imaging and motion,thermal image sequence and time is analyzed.The ultrasonic B-scan image,thermal image and the testing area are unified by position mapping.The three-dimensional thermal image sequences are converted to two-dimensional thermal image.The one-dimensional ultrasonic A-scan signal is reconstructed to two-dimensional B-scan image.The method of redundant data fusion is proposed.The fusion result and ultrasonic bulk wave are fused to achieve complementary detection.The compensation and verification of defects inspection are completed by the proposed method.The 3D model of thick metal plate is reconstructed by DirectX technology.The whole-section of the specimen is exhibited from surface to interior.The above research will help to solve some practical problems in industrial production process,provide a theoretical basis for the implementation of rapid dynamic testing,and contribute to the comprehensive testing of various non-destructive testing methods.