Papers by Keyword: Nondestructive Testing (NDT)

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Authors: Miloš Drdácký, Michal Kloiber
Abstract: The paper presents a novel concept and a prototype of a diagnostic tool for in-situ assessment of timber in existing structures and buildings. The device enables direct determination of conventional compressive strength and modulus of deformation in arbitrary depth along timber profile. The measurement of the stress-deformation relationship is performed in a prepared hole of a very small diameter by means of a special small size symmetrical loading jack. Testing and verification of the new device behaviour during loading of wood along the fibres has been carried out on fir which is the most frequent wood species in European buildings. The comparison of stress-strain diagrams acquired by means of the new device with those measured in compliance with the European standard for testing of wood shows a very good correlation including the determination of the compressive strength values. This semi-destructive method causes a very gentle damage and can be also used for the assessment of historic timber structures.
Authors: Qiang Song
Abstract: Magnetic flux leakage (MFL) is a non-destructive testing method used to inspect ferrous materials. However, apparatus parameters could affect the MFL inspection tool’s ability to characterize anomalies. In this paper, MFL signals obtained during the inspection of pipes have been simulated using three-dimensional finite element analysis and the effects of magnet assembly on MFL signals are investigated. According to numerical simulations, an increase in the leakage flux amplitude is observed with an increase in the permanent magnet size and the inflexion point may indicate the presence of magnetizing pipe wall to near saturation. It clearly illustrates degradation in the MFL with increasing backing iron length. The relationship between MFL apparatus parameters and MFL signals could be utilized in the MFL technique to characterize the defect.
Authors: Yun Gyeong Choi, Jung Hee Suh, Nu Ree Han, Ji Hyang Choi, Young Ho Cha
Abstract: We have chosen the GPR method for investigating the inner structure of a stone pagoda in a non-destructive way. The selection of a suitable source frequency of the GPR antenna is the key because the main frequency of its pulse controls the resolution and the depth of the investigation. Through theoretical consideration and numerical simulation, we found that 500 to 800 MHz is suitable for a field model with a foundation part of 3 to 4 m. To image the inner structure we selected 3-D Kirchhoff prestack depth migration technique used in seismic processing. We have used the modified migration algorithm for the source and receiver configurations of common offset GPR data. To verify the scheme, we calculated the synthetic data using the 3-D FDTD algorithm and applied the migration technique to it. Through these experiments, we confirmed that the 3-D Kirchhoff prestack depth migration technique is a very powerful tool to image the inside of a stone pagoda with high resolution. We have also applied the technique to the field data of the foundation of a five-story stone pagoda at Jeongnim temple site in Buyeo City, Korea. Based on the 3-D migrated images, we inferred that the structure of the foundation of this pagoda seemed to be preserved quite well and the thickness of the outer wall was about 0.5 m.
Authors: Gede Arya Wiguna, Gede Bayu Suparta, Andreas Christian Louk
Abstract: An imaging procedure for developing a 3D X-ray micro-radiography system has been developed. The idea arose due to the necessity of performing internal inspection and testing nondestructively on a small specimen. The image is generated from multiple x-ray radiograph that were acquire from multiple angle of view. Each radiograph was taken for every one degree. The total angle covers up to 360 degree so that a set of 360 image were collected for each specimen. Then, for those images were rendered to be a 3-D image. A set of image processing procedures were applied such as background subtraction and noise reduction. From the experiment, this manner is very useful for assessing a small specimen nondestructively prior to perform a tomography inspection.
Authors: Rong Li Li, Xiao Yong Liu, Shou Qin Zhang
Abstract: A review of conventional and optical measurement methods of ultra high pressure vessels (UHPVs) in-service was introduced. Typical engineering applications of these technologies were illustrated. The new trends of inspection methods of UHPVs were discussed. Owe to full-field, non-destructive imaging characteristics with high precision and sensitivity, optical measurement methods had gained more and more attention in recent years. Therefore, DIC was suggested to be developed for experimental inspection of UHPVs in 2D or 3D surface shape and deformations.
Authors: Zhao Ming Zhou, Fu Wan, De Sin Mao, Quan Chuan Xu, Chen Xing Wei
Abstract: Many of the NDT methods used for casing, tubing, drill pipe and line pipe are applicable, with some minor modifications, to CT. This article describes the requirements of an ideal in-service inspection. This paper presents a new wall thickness and ovality measuring method engineered for reliable field use. This method based on flux gate testing technology discussed in this paper .This method not only will detect internal flaws and the density of micro-cracks, but also wall thickness measurements will be made. This paper discusses the development of this new method, the detection of eddy current testing program is used in coiled tubing ovality measurements. The key technology is the production of amorphous alloy core. Using this method measure diameter, wall thickness and ovality of CT, is currently being developed.
Authors: Utku Buyuksahin, Ahmet Kirli
Abstract: Nondestructive testing (NDT) methods has been increased within recent years depending on the needs of industry, parallel to new technological developments. Many studies have focused on thermal imagining, magnetic flux analysis or both, which are used in order to detect the deformation on surface and under the surface. In this study a new technique is suggested to eliminate the perturbations which are distorting effects of one point cameras in terms of perspective. A new integration is also proposed in this research such as using image recognition with magnetic flux analysis. Taking advantage of this integration and the new approach to image processing, both the surface and the inside of a mechanical product can be tested properly.
Authors: Gang Huang, Lu Ming Li, Yi Ping Cao, Xing Chen
Abstract: The issue of nondestructive testing in aeronautical structures is of considerable importance in the aviation industry today. And a high sensitivity magnetic field sensor, which has recently been developed is designed for non-destructive stress testing. It is based on idea of the magnetic field produced by pulsed currents and perturbed by the presence of stress. The sensor can be effectively utilized for the detection of defects and stress concentration in conducting materials using eddy current testing measurements. The principle of the measuring technique is based on the unbalance of the magnetic field where the stress or cracks exist. Also, the excited input-signal is special designed. A pulsed current was inputted and changed into a self-attenuation signal which does the effect in the probe.
Authors: Roland Hessert, Wilhelm Satzger, Alfried Haase, Achim Schafmeister
Abstract: For industrial applications concerning the nondestructive characterization of the nearsurface material condition in terms of residual stresses, work hardening, phase transformation and formation of reaction compounds there is a strong demand for X-ray diffraction measurements on large components with complex geometry. Because many regions of interest on these components are not accessible with conventional laboratory or even mobile X-ray diffractometers, a novel center- free diffractometer with two cooperating robots named "Charon XRD" has been developed at MTU Aero Engines. Using a special optical measuring system to synchronize the two six-axis robots it was possible to achieve positioning accuracies that are comparable to those of conventional stationary diffractometers. This paper describes the design and functionality of Charon XRD and presents calibration and reference measurements, along with first measurements on aero-engine components.
Authors: Li Li Gao, Zhen Hong Jia, Xi Zhong Qin, Xiao Hui Huang, Yong Bo Yao
Abstract: A nondestructive measurement approach is presented in this paper, which is capable of determining sugar content in cantaloupe from the dielectric property. The approach is based on measured equivalent capacitance and equivalent resistance of the cantaloupe, and on data analysis using quantum-behaved particle swarm optimization (QPSO) and Grey radial basis function (RBF) neural network. First, accumulated generating operation (AGO) in Grey forecasting is used to convert the initial observed data to obtain the accumulated data with strong regularity, which are employed to model and train the radial basis function neural network. Second, it adopted quantum-behaved particle swarm optimization algorithm to train the centers and widths of radial basis function. This model not only prevented the problem that the parameters of neural network are hard to be tuned, but also improved the network precision of prediction. Experimental results revealed that the predictive model as proposed has good predictive effect for the measurement of sugar in cantaloupes.
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