Nondestructive Testing Devices Research Articles

Design of Automatic Control System for NDT Device

The article designed a kind of new nondestructive testing device control system to increase the test efficiency and improve the reliability of computed tomography. This system could not only precisely locate and control the turntable and lifting platform by adopting digital control, servo control and other advanced control methods, but also develop a high-precision servo turntable by using a three-layers closed-loop controller. This system, whose workpiece rotate platform is particularly suitable for small-space detection, has an increasingly improved automatic detection efficiency of 20 work-pieces at a time and a wider detection scope of maximum height of up to 50cm. By the means of pre-setting parameters, high-precision servo turntable can rotate to any regulated angle, offering a satisfactory platform for computed tomography. The system, as a new type of automatic non-destructive testing platform, adapts to the digital transformation of traditional X-ray detection device as well.

Construction of the inverse transformation function for eddy current multiparameter testing devices

We have developed a method for constructing a nonlinear multiparameter model of the inverse transformation function for eddy current nondestructive testing devices. The new means of multiparameter eddy current testing, created on the basis of nonlinear processing of the response of primary eddy current converter by the inverse transformation function of the system, simplify, in principle, their implementation, software, and metrological assurance, enhancing simultaneously the accuracy of estimating the parameters of a controlled object.

Concept of Active Measurement

In an ideal situation, good measuring system can be designed if exact information is known concerning performance and structures involved during the lifetime of the measuring object. But in the real world uncertainties of object exist in this information as well as in the method of measurement. To account for these uncertainties, concept of active measurement has been presented in this paper. Nowadays, scale transform and smart sensor have been applied for realizing elementary active measurement technique, the objective herein is to present measuring method of actively adjusting structure based on these factors. The practicality of this concept is illustrated with an engineering system using wire rope nondestructive testing device, double-point measurement device with eddy current probe as sensors is designed. Mathematical model of the rope’s characteristics and real-time quantity to trim of measure device is established according to relative spacing between sensors and rope. The idea of active control is introduced here, adjusting instrument structure timely based on mathematical relationships and feedback information will achieve the active measurement.

Validation of Backcalculated Modulus Values from Falling Weight Deflectometer through Instrumentation on I-35 in Oklahoma

Several state departments of transportation evaluate the modulus of pavement layers from nondestructive deflection tests such as the falling weight deflectometer (FWD). Although the FWD is a widely used nondestructive testing device, it still does not fully represent the loading conditions generated by moving vehicular traffic. Therefore, the modulus values backcalculated from FWD data may be different from those values backcalculated from vehicular traffic loading data. A comparison is presented of modulus values backcalculated from FWD and strain gauge measurements collected on a 1,000-ft-long instrumented section of I-35 in central Oklahoma. The FWD data were captured at different temperatures with different loading configurations. Meanwhile, longitudinal and transverse strain data were captured from May 30, 2008, through October 28, 2009, over a wide range of middepth pavement temperatures (40°F to 110°F) under actual vehicular traffic loading. The influence of different backcalculated modulus values is demonstrated through the prediction of remaining life in terms of number of equivalent single-axle loads of the existing pavement. Also presented is a description of the testing program, data collection efforts, and subsequent analysis for the I-35 instrumented section. Overall, modulus values backcalculated from the FWD and from longitudinal strain gauges showed close agreement at temperatures above 50°F.

20712 磁気車輪を用いた鉄橋非破壊検査装置のための移動機構の開発(一般講演 ロボット)

20712 磁気車輪を用いた鉄橋非破壊検査装置のための移動機構の開発(一般講演 ロボット)

Magnetosensitive transducers for nondestructive testing operating on the basis of the giant magnetoimpedance effect: A review

Experimental data on and model representations of the physical processes in small detectors operating on the basis of the magnetoimpedance effect are analyzed and generalized for conditions adapted to systems of magnetic nondestructive testing. The principles of measuring the high-frequency magnetoimpedance effect in electronic circuits including a sensitive element of a detector of weak magnetic fields are briefly described. The data on the available devices for nondestructive testing (NDT) based on the magnetoimpedance effect are systematized and examples of typical approaches are presented.

PFWD, DCP and CBR correlations for evaluation of lateritic subgrades

The evaluation of subgrade strength plays a major role in pavement design. An understanding of subgrade properties enables the selection of road materials for sub-base and base courses. In developing countries like India, apart from the use of well-established traditional pavement evaluation techniques such as the California bearing ratio (CBR) test and the dynamic cone penetrometer (DCP) test, the use of non-destructive testing devices such as the portable falling weight deflectometers (PFWDs) has gained popularity in recent years. This is mainly because of the inherent capability of PFWDs in obtaining quick estimates of the modulus of subgrade in addition to their simplicity in design and portability. Thus, there exists a need to correlate the results obtained using PFWDs with those obtained using traditional approaches such as the CBR and the DCP for the benefit of road engineers. This work focuses on exploring the correlations between these approaches for lateritic soils in Dakshina Kannada district, India.

Measurement of residual stress of magnetic substance by surface acoustic waves

In magnetic substances under oscillating stress due to the application of acoustic waves (such as ultrasonic waves), an oscillating anisotropic field may be generated by the inverse effect of magnetostriction. If this magnetic field oscillation can be detected, the stress state inside the magnetic substance can be determined. Based upon this principle, we have set up an apparatus for stress measurements, applied it to Ni plates with different residual stresses, and have obtained output signals corresponding to different stresses. This measuring technique makes it possible to know the stress state in structures before the formation of cracks, and hence offers a very promising nondestructive testing device.

RELATIONSHIP BETWEEN ULTRASONIC PULSE VELOCITY AND STANDARD CONCRETE CUBE CRUSHING STRENGTH

In Jordan as well as in most countries, many concrete structures are becoming old. The question of whether they are safe to be utilized by people or is it feasible to spend money to rehabilitate them, requires conducting a quality survey to assess the integrity of all critical structural items without undermining the safety of the structures. Moreover the nondestructive testing is beneficial for the quality control of new constructions. One of the most effective and least expensive techniques is using Ultrasonic Pulse Velocity (UPV), utilizing Pulse ultrasonic nondestructive indicator tester (Pundit) - a simple non-destructive testing device – that is used to assess the integrity of the structures without causing any damage. Thus the aim of this study is to give forth a mathematical relationship that relates UPV with standard concrete cube crushing strength ( cu f ) in a step to reinforce the credibility of nondestructive compressive strength investigations on concrete containing local materials. To accomplish this task, 135 standard concrete cubes of 150 mm dimensions were prepared using various concrete mixes in order to cover all types of concrete locally produced. The UPV and the relevant crushing strength for each cube were documented. Regression analysis was carried out to study the correlation among observed data. Finally a mathematical relationship between Pundit readings and the corresponding cube compressive strengths was derived.

Device for determining the diffuse-reflection spectra of various kinds of wood

This paper discusses questions of the use of spectral devices to obtain the diffuse-reflection spectra of various samples of wood. Information is given on the importance of the problem of determining the kind and quality of trees by means of nondestructive testing devices. A portable monochromator is described that operates in the spectral range from 0.4 to 2.5 µm, developed for taking the diffuse-reflection spectra of various samples of wood under field conditions. Examples of the recorded spectra are demonstrated.

Detection of gas pipe wall thickness based on electromagnetic flux leakage

Based on electromagnetic flux leakage (EMFL), a nondestructive testing (NDT) technique for the detection of gas pipe wall thickness is presented, and its principle and feasibility is evaluated by means of equivalent magnetic circuit analysis and finite element analysis. An online NDT device adopting this technique is developed, and its structure and working principle are introduced in detail. This device is composed of a detector array with 32 pipe wall thickness sensors that employ a Hall element as the element for sensing the magnetic flux density, and it can be adapted to pipe diameters from O400mm to O650 mm. On the basis of the experimental investigation for this device, the influences of some factors on thickness measurement, namely the excitation current, excitation coil turns, gap distance, concentrator of the magnetic field, magnetization time, and number of sensors in the detector array, are revealed and the optimal excitation voltage for the sensors of the detector array is selected. The measuring calibration is given to establish the relationship between the pipe wall thickness and the output voltage of the sensors. The results show that the proposed EMFL for measuring the wall thickness of ferromagnetic pipe is feasible, the technical parameters of the sensor are important for improvement of measurement precision and resolution, and the developed device has precision, resolution, and a linear output curve. Carried by the developed gas pipeline inspection robot through a universal joint, this NDT device can move inside the gas pipeline and monitor the state of the pipe wall.

Portable Neutron Source Using by Spherically Convergent Beam Fusion Device for Nondestructive Testing

This paper presents experimental and simulation results of discharge in spherically convergent beam fusion device. The deuterium-deuterium (D-D) fusion reaction in that device will generate neutron. The experimental device is consists of a vacuum chamber made of stainless steel, spherical mesh type anode and concentric grid cathode of 5cm diameter. The pressure of chamber maintained constant by injecting gas and pulsed voltage applied to grid cathode. A star mode discharge which has possibility of neutron generation was observed.

Simulation of radiation characteristics of pulse X-ray devices for non-destructive testing the semiconductor materials

Simulation of radiation characteristics of pulse X-ray devices for non-destructive testing the semiconductor materials

Recognizing imperfections with an artificial neural network of a special type

Recognition of imperfections with the use of signals from nondestructive testing devices is considered. A new type of neural network that allows separation of signals from imperfections of different types is proposed. Concepts of the neural network’s operation are considered. An example of recognition of signals from an ultrasonic flaw detector is given.

Neural Networks for Rapid Reduction Interpretation of Spectral Analysis of Surface Waves Results

Nondestructive testing (NDT) of pavements has made substantial progress during the past two decades. Most algorithms currently used to determine the remaining life of pavements rely on stiffness parameters determined from NDT devices. One major area of continual improvement is the reliable extraction of stiffness parameters from nondestructive field data. The spectral analysis of surface waves (SASW) method is one of the more frequently used NDT methods because of its capabilities in characterizing the near-surface layers effectively. In this method, time records obtained with vibration sensors are used to obtain an experimental dispersion curve, which, through an inversion procedure, provides an estimate of the elastic modulus profile of the pavement. The inversion process requires a significant computational effort or frequent operator intervention. To improve the user-friendliness of the inversion process, an algorithm for the rapid reduction of the SASW data was developed. Thickness and modulus of each pavement layer are estimated in real time using artificial neural network models. These models serve a dual purpose: (a) the results from the neural network models can be used to approximate the layer properties of a given pavement section and (b) it can be used as a first approximation to the traditional inversion process. The reduction algorithm appears to be robust and to yield consistent results in almost real time.

Evaluating Potential for Reflection Cracking with Rolling Dynamic Deflectometer

A common rehabilitation strategy used for repairing aged concrete pavement is to place a hot-mix asphalt (HMA) overlay on the existing concrete pavement. However, reflection cracks are often found to propagate from the underlying cracks and joints through the HMA layer. As such, much reflection cracking is believed to be caused by differential vertical and horizontal movements in the concrete pavement. A common method of determining the differential vertical movements is by measuring the load transfer efficiency (LTE) at the joints by using nondestructive deflection testing devices. A study was conducted with a rolling dynamic deflectometer (RDD) to evaluate the movement of joints in concrete pavements. Evaluation of joint movements by RDD testing permits estimation of the LTE of each joint or transverse crack. On the basis of the assumption that reflection cracks are more likely to form at joints or cracks with low LTE than with high LTE, pavement engineers can use the results to identify areas with low LTE and perform necessary repairs at these locations to reduce the potential for creating reflection cracking. Field data collected before rehabilitation work on US-82 near Gainesville, Texas, are presented as a case study, and the benefits of continuous deflection profiling for use in the district’s rehabilitation strategy are discussed.

Feasibility of Backcalculation of Nonlinear Flexible Pavement Layer Parameters from Nondestructive Testing

Nondestructive testing (NDT) methods are typically used to measure the variations in the modulus of different pavement layers. The falling-weight deflectometer (FWD) and the seismic pavement analyzer (SPA) are two of the NDT devices used for this purpose by the Texas Department of Transportation. Since the loads applied by the FWD to the pavement are similar to those exerted by traffic, the FWD moduli are used in pavement design and analysis without adjusting them for the nonlinear behavior of the materials. Seismic moduli are similar to linear elastic moduli since they correspond to small external loads. A constitutive model that considers nonlinear behavior of pavement materials is essential in order to convert seismic moduli to those appropriate for the state of stress applied by a truck. Nonlinear parameters needed for these models can normally be obtained from laboratory testing. A study was carried out to determine whether these nonlinear parameters can be estimated from the FWD deflection basin alone or from integration of the seismic and FWD data. FWD deflection alone in most cases does not seem to contain enough information to reliably provide the nonlinear parameters of the layers. Combining the seismic and deflection data would allow the estimation of some of the nonlinear parameters for weaker pavement structures. In the authors’ experience, the most reliable way to estimate the nonlinear parameters of base and subgrade is still laboratory testing.

Recycling and Overlay of Portland Cement Concrete Pavement—a Case Study

A broken and seated portland cement concrete pavement (PCCP) was analyzed using destructive and nondestructive testing (NDT). The paper focuses on the results of a series of NDT methodologies by which the effective structural capacity of the overlaid pavement was estimated. The NDT included Falling Weight Deflectometer (FWD) and Road Rater (RR), followed by back-calculation and verification routines. A comparison was performed between the FWD and RR deflection bowls, which demonstrated a close correspondence between the two NDT devices. The effective modulus of the broken and seated PCCP was estimated and it showed close agreement with previous work conducted by other investigators, A large-stone hot mix asphalt (HMA) overlay was placed on top of the broken and seated PCCP; this decision was made based upon rutting resistance of this type of mix as reported in previous studies.

Integrating Seismic and Deflection Methods to Estimate Pavement Moduli

Nondestructive testing (NDT) of pavements has made substantial progress during the past two decades. Most algorithms currently used to determine the remaining life of pavements rely on stiffness parameters determined from NDT devices. One major area of continual improvement is the reliable and rapid extraction of stiffness parameters from nondestructive field data. Two of the most common NDT methods used are the deflection and seismic-based methods. The spectral analysis of surface waves tests are the most common seismic method. In this method, time records obtained with vibration sensors are used to obtain an experimental dispersion curve, which, through an inversion procedure, provides an estimate of the elastic modulus profile of the pavement. Deflection bowls are also used to backcalculate modulus profiles of pavements through the inverse theory. The inversion processes used in both methods are complex and require either a significant computational effort or frequent operator intervention. Each method, of course, has its own limitations and strengths. To improve the accuracy of the predicted moduli, an algorithm for joint reduction of the deflection and seismic-based data has been developed. Thickness and modulus of each pavement layer are estimated in real time using artificial neural network models. An overview of a proposed joint inversion and its practical use in pavement analysis and design is presented. The joint reduction algorithm shows promise since it appears to be more robust and to yield more consistent results when compared with the process and results from each method independently.

Intracore fiber Bragg gratings for strain measurement in embedded composite structures

An intracore Bragg grating written on a photosensitive fiber core is used for strain measurement in composite specimens under load. The strain information is directly related to the absolute change in the Bragg-reflected wavelength. Fiber Bragg grating (FBG) sensors (fibers with intracore gratings) are thus sensitive to strain that is caused by changes in temperature as well as to load-induced changes. Thus these sensors can be made to be independent of source intensity variations and losses. FBG sensors used for load-induced strain sensing in composite structures and the effects of temperature on them are discussed. A detailed account of the use of such embedded structures as self-monitoring nondestructive testing devices is given.