Defect Signal Analysis For Nondestructive Testing Assesment

For fast assessment of defects in conductive materials, Eddy current testing is a most widely non-destructive testing (NDT) evaluation methods utilized in industry, especially in oil and gas, aircraft, nuclear and coating industries. Experimental studies of eddy current testing have emerged as an important approach alongside numerical modelling. This paper focus on investigating the defect signal characteristics of carbon steel pipe weld coating inspection using different frequency eddy current testing. The optimum frequency of carbon steel pipe weld coating is verified. Tests have been conducted utilizing positive and negative scanning method with frequency between 10 kHz to 100 kHz. Artificial defect use of this test is the horizontal affected zone (HAZ), centre line and transverse crack. Experimental results showed the frequency can be impression to the amplitude and phase angle eddy current testing signal. The optimum frequency for carbon steel weld plate is 100 kHz

Challenges in improving the performance of eddy current testing: Review

Eddy current testing plays an important role in numerous industries, particularly in material coating, nuclear and oil and gas. However, the eddy current testing technique still needs to focus on the details of probe structure and its application. This paper presents an overview of eddy current testing technique and the probe structure design factors that affect the accuracy of crack detection. The first part focuses on the development of different types of eddy current testing probes and their advantages and disadvantages. A review of previous studies that examined testing samples, eddy current testing probe structures and a review of factors contributing to eddy current signals is also presented. The second part mainly comprised an in-depth discussion of the lift-off effect with particular consideration of ensuring that defects are correctly measured, and the eddy current testing probes are optimized. Finally, a comprehensive review of previous studies on the application of intelligent eddy current testing crack detection in non destructive eddy current testing is presented

Vibration signal for bearing fault detection using random forest

Based on the chosen properties of an induction motor, a random forest (RF) classifier, a machine learning technique, is examined in this study for bearing failure detection. A time-varying actual dataset with four distinct bearing states was used to evaluate the suggested methodology. The primary objective of this research is to evaluate the bearing defect detection accuracy of the RF classifier. First, run four loops that cycle over each feature of the data frame corresponding to the daytime index to determine the bearing states. There were 465 repetitions of the inner race fault and the roller element fault in test 1, 218 repetitions of the outer race fault in test 2, and 6324 repetitions of the outer race in test 3. Secondly, the task is to find the data for the typical bearing data procedure to differentiate between normal and erroneous data. Out of 3 tests, (22-23) % normal data was obtained since every bearing beginning to degrade usually exhibits some form of a spike in many locations, or the bearing is not operating at its optimum speed. Thirdly, to display and comprehend the data in a 2D and 3D environment, Principal Component Analysis (PCA) is performed. Fourth, the RF algorithm classifier recognized the data frame's actual predictions, which were 99% correct for normal bearings, 97% accurate for outer races, 94% accurate for inner races, and 97% accurate for roller element faults. It is thus concluded that the proposed algorithm is capable to identify the bearing faults

Lift-off detection system using Error Compensated Eddy Current Testing based on fuzzy logic

Nondestructive testing (NDT) deals with the inspection of an object for determining its properties without destroying its usefulness. Applications include detection of cracking in coating industries, steam generator tubing in nuclear power plants, aircraft and etc. As a method for NDT, the eddy current testing is also used for detection the lift-off in the pipe or plate due to several factors resulting from lift-off including the thickness of the coating on the pipe, the probe is lifted and the angle of pipe joining is small. In this thesis, the development of Error Compensation of Eddy Current Testing system (ECECT) and combining of the Absolute probe (AP) and Differential probe (DP) is used in measurement for actual defect measuring. From here the probe design (2D and 3D) and development are used for integrating with the system design and at the same time, the comparison between conventional technique and ECECT technique can be executable. Besides, the comparison between simulation and actual devices is used for accuracy of measurement in this system. The ECECT system design has higher sensitivity and less noise comparing conventional technique. As the complementary in this system, the Mamdani Fuzzy Logic is used as an intelligent technique in ECECT for high accuracy results. In system development, the graphical interfacing (GUI) is used for graph display on the computer by using MATLAB software and from here the value of defect and lift-off can be identify based on graph display. Based on the results was obtained ECECT system will achieve 99.90% accuracy without lift-off and 99.00% with the different types of lift-off. This shows that the merger of the probe and intelligence system are built will affect the accuracy of the results and it's very useful for the defects classification aside from the accuracy of the reading displayed. In addition, the comparison between the simulation and actual devices by using ECECT is also conducted to obtain the desired result accuracy

Multi-Excitation Signal for Depth Crack Defect in Eddy Current Testing

Eddy current Non Destructive Evaluation (NDE) is one of the more commonly used techniques in measure electrical conductivity and thickness of plate and pipes. In recent years, several works have reported the sensitivity of probe in measuring the depth of crack according the input excitation. To extract relevant features for input excitation types of waveform, range frequency and depth of crack have been proposed. In this paper, a method to getting clear signal output for crack detection and data for differential depth of crack identified is reported. The measuring method Mulit-Excitation Signal (MES) is based on ac current signal, pulse signal and triangle signal. A frequency signal is set from 10KHz until higher 90KHz by following the probe’s limitation. Otherwise the calibration block is used as a defect plate with the depth of crack is 0.5mm, 1mm and 1.5mm. As a result the depth of cracks signal were clearly shown by using the three types of waveform with different levels of frequency and could be concluded when frequency of input excitation is high then the ability of signal to measure the crack on the material will decrease and if frequency is low then travelling signal in defect measuring is high but the responses time is low

Adaptive Neuro-Fuzzy Inference System Model Based on the Width and Depth of the Defect in an Eddy Current Signal

Non-destructive evaluation (NDE) plays an important role in many industrial fields, such as detecting cracking in steam generator tubing in nuclear power plants and aircraft. This paper investigates on the effect of the depth of the defect, width of the defect, and the type of the material on the eddy current signal which is modeled by an adaptive neuro-fuzzy inference system (ANFIS). A total of 60 samples of artificial defects are located 20 mm parallel to the length of the block in each of the three types of material. A weld probe was used to inspect the block. The ANFIS model has three neurons in the input layer and one neuron in the output layer as the eddy current signal. The used design of experiments (DOE) software indicates that the model equations, which contain only linear and two-factor interaction terms, were developed to predict the percentage signal. This signal was validated through the use of the unseen data. The predicted results on the depth and width of defect significantly influenced the percentage of the signal (p < 0.0001) at the 95% confidence level. The ANFIS model proves that the deviation of the eddy current testing measurement was influenced by the width and depth of the defect less than the conductivity of the materials

Construct coil probe using GMR sensor for eddy current testing

Eddy current testing is a widely applied non-destructive technique in different sections of industries. Nowadays eddy current testing is an accurate, widely used and well-understood inspection technique, particularly in the aircraft and nuclear industries. The main purpose of this paper is to construct an eddy current probe by using transmission coil and using a Giant Magneto resistance (GMR) sensor for detection medium. This probe only use a magnetic field to operational in detection of flaws. A transmission coil is an object made from a material that is magnetized and creates its own persistent magnetic field. A GMR-coil probe has been used to inspect two different material of calibration block. Experimental results obtained by scanning A GMR-coil probe over Brass calibration block has 10 slots with different depth from 0.5mm to 5mm and mild steel has 8 slots with different depth from 0.5mm to 4mm are presented. The result prove that GMR-coil probe that operated using a magnetic field and sensor more effective on ferromagnetic material

An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design

The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient

A Review on System Development in Eddy Current Testing and Technique for Defect Classification and Characterization

Eddy current testing (ECT) is one of the non-destructive evaluation techniques widely used, especially in oil and gas industries. It characterized noisy data to the less-than-perfect detection and as an indication of serious false alarm problem. However, not many researchers have described in detail the intelligent ECT crack detection system. This paper introduces a review of ECT technique and factors that affect the signal fundamental according to the hardware and software development. First, describe the magnetic excitation resources including the sinusoidal and pulse exciting signal. Second, outlines explanation about the ECT probe. The explanations are more about the probes development for air core probe and giant magnetoresistance probe. Third, there is discussion on ECT circuit that used including ECT system, ECT rotating magnetic field and application measurement for optimal control parameters. The defect in characterizations and measurement are discussed on the fourth part of this paper. The fourth part discusses the ECT lift-off compensation including the lift-off and application of intelligent technique in ECT. The limitations of lift-off for coil probe and compensation techniques also discussed in this part. Finally, a comprehensive review of previous studies on the application of intelligent ECT crack detection in nondestructive ECT is presented

Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper