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In this paper a new concept based on signal periodicity about AR model is presented, many problems which are difficult to be resolved in classical viewpoint such as order selection, pseudo frequency recognizing, relation determination between coefficient and signal amplitude, and relation determination between order and signal length are investigated profoundly by the new viewpoint, in the last, a...
In this paper, a multi-magnetizer comprise of three units was introduced, of this multi-magnetizer, permanent magnet, poke, brush, and pipeline form a closed magnetic circuit in each unit, and each unite can be adjusted relative angle to meet the requirement for detection of pipes with different size. The investigation focuses on the interaction due to the introduction of multiple magnetic circuits...
High strength flange are widely used in the petroleum and petrochemical industries, flange seal failure may lead to leakage and unexpected incidents. Currently, the flange seal detection in-service lacks an effective method. A lot of tests to study magnetic force behavior and characteristics of flange bolts have been conducted. In test, the bolt axial, radial magnetic field under the tensile stress...
This paper presents a novel flexible eddy-current probe specifically designed to inspect small defect for material with planar or complex geometry. The proposed eddy-current probe has a planar design and a multilayer structure using flexible printing circuit board technology. The fundamentals on the sensor operation are presented and explained in the presence of a metallic part to be inspected with...
Quantitative evaluation of cracks is the critical issue of eddy current stimulated thermography. In this paper, numerical simulation study on the quantitative evaluation of cracks with eddy current stimulated thermography is introduced. The simulation works are conducted using COMSOL software. Sequential images are obtained during the heating and cooling periods of the test process. By processing...
One of the most common gear damages is contact fatigue damage, which is difficult to be detected at an early stage. As one of the integrative non-destructive testing and evaluation techniques (NDTE) of eddy current and thermography, eddy current pulsed thermography (ECPT) has been applied for fatigue damage characterization. However, quantitative material state characterization before microcrack initiation...
3D ultrasound has got considerable development in medicine, but in the field of non-destructive testing of industry still lags behind. Three-dimensional ultrasound images can visually display spatial distribution of defects, make the test results easier to be understood and evaluated. This paper presented a 3D imaging method, which using linear phased array probe detection system to collect scan data,...
The materials of testing specimen are nonuniform, which leads to phase aberration in ultrasonic signal. The resolution of ultrasonic image decreases as a result of phase aberration, this paper proposes a method that can correct the phase aberration through calculating signal correlation. In this method, we calculate the correction function between the reference signal and other signals and choose...
The main objective of this work is to assess the possibility of improving the achievable image quality using synthetic aperture (SA) approach and to evaluate the performance of the modified algorithm. The modified algorithm is based on the coherent summation of back-scattered RF echo signals with weights calculated for each point and for all possible combinations of transmit-receive pairs. Weights...
The Total Focus Method (TFM) is a post-processing algorithm which uses all elements in the array to focus in both transmission and reception at every image point. The time-domain signals is captured in a process termed Full Matrix Capture (FMC). In this paper, the main objective is to research the effects of directivity function on the TFM. The TFM algorithm is based on the FMC data with weights calculated...
This paper presents a study on edge effect of radiographic inspection for Titanium alloy joint structure with large thickness difference. And due to the existence of the defects undetected caused by edge effect in practical situation, it is significant to investigate the impact of edge effect on radiographic examination of joint structure with such a large difference in thickness. The conventional...
During the long-time working circle, railroad transport system will be damaged to a certain degree caused by the wearing, the impact, the loads, the climate and so on. In order to monitor the health of the railways and reduce the potential losses, many effective methods are used in railway health monitoring, but few of the techniques can reach the demand of the comprehensive inspection such as operating...
In this paper, the author aims to use the Fourier transform profilometry(FTP), a three-dimensional non-contact optical measurement method, for recovering the rail profile and defects on the rail web. In phase unwrapping, the least square algorithm based on the specific characteristic of the rail is used. Simulation is done to manifest the feasibility of the method. Results of the experiments show...
In order to eliminate the shot noise and extract precise wheel contour line in online dynamic detection system for locomotive, threshold denoising method and smooth spline fitting are proposed in the paper. Furthermore, cubic B-spline interpolation is used to do subsequent processing on the principal curve. Before math processing on the curve, in advance the light-section image pixels are transformed...
Irradiation embrittlement appears due to Reactor Pressure Vessels (RPV) service under strong neutron irradiation for a long time. It is an important reason of accelerating the aging of RPV. As a special part of nuclear power plant (NPP), it decides the life of the whole NPP. Thus, it is necessary to estimate the current state of embrittlement and predict the trends of embrittlement through a new method...
The ability of acoustic emission detection is enhanced by electromagnetic stimulation with external magnetic field. Different magnetic field directions, which are generated by permanent magnet, produce various vibrations of defect itself. In this paper, the deformation characteristics of electromagnetically induced acoustic emission (EMAE) are studied by the finite element method (FEM). The experimental...
Three-dimensional reconstruction of objects with smooth surface has poor results. In this paper, a method of the online rail profile with smooth surface based on Fourier Transform Profilometry (FTP) is put forward. After analyzing the reflective polarization, phong illumination model and FTP method, the online rail shape with smooth surface are reconstructed, after eliminating the highlight region...
This paper is dedicated an eddy current test research plan in order to evaluate the eccentricity for the sandwich structure conductor used in ITER in-vessel coils. Important parameters, such as signal, frequency, lift-off effect and probe direction, are analyzed by using a numerical simulation method, and sample experiments are carried out for verification. Eventually, optimized parameters will be...
Rolling contact fatigue (RCF) has become a pervasive and insidious problem on all types of railway system, especially a safety challenge for high speed railway. This paper introduces eddy current pulsed thermography (ECPT), a non-destructive testing and Evaluation (NDT&E) technique, for RCF detection and characterization in rail. The theory and simulation for RCF detection using ECPT are described,...
Because the section of aluminum alloy extrudate used in high-speed train is complex, lots of structural echoes and noise will be received when using array ultrasound to detect the flaws in friction stirring welds (FSW). Therefore, phased array acoustic field model and acoustic rays propagation model were introduced to simulate the acoustic field pressure distribution and the sound beams propagation...
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