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[en] Among the applications of Materials Science and Engineering carried out by the Center for Technological Applications and Nuclear Development (CEADEN) is the use of various physical techniques to support the restoration and maintenance of buildings and other work objects of historical, cultural and social interest in Havana city. The field of Defectoscopy is addressed in this paper, where the applied Nondestructive testings also contributed to restore the cultural heritage, to upgrade the structural conditions at an important sport facility in Havana, and in a greater extent, to the safety of facilities of social significance, such as amusement parks. In this regard, three examples are presented: the inspection of structures during the restoration of the City Hall in the Museum of the Havana City at the Palace of Captains General; the welded joints testing during the restoration of the lighting system and the installation of the digital screen at the Latin American Stadium in Cerro municipality; and finally, the inspection systematically performed at maintenance works to critical elements and related devices at amusement parks.
[en] We set up a reflective nonlinear acoustic microscope to contour the quantitative adhesion at a bonded solid-solid interface by a contact acoustic nonlinearity (CAN) method. The principle of the reflective nonlinear acoustic microscope is described. After the vibration amplitude of the incident, focusing wave at the bonded interface is calculated, the standard adhesion with a complete bonding state is established by the tension test, the reflective CAN parameter is calibrated, and the quantitative contour of the adhesion at the interface can be obtained. The experimental contours of two samples are also presented. Compared with the transmitted microscope, the reflective one is more convenient and more suitable for practical applications. (authors)
[en] Applications of additive manufacturing (AM) are diversified, but found with preponderance in the automotive, aerospace, and medical fields. The field of additive manufacturing/material 3D printing is advancing extremely fast, and covers a broad range of materials, spanning from plastics to metals, ceramics, and even to biological tissue. In the aerospace industry one of the main points of attraction is that parts with complex shapes can be built on demand while reducing the weight at the same time. The process can also aid in the fabrication of rare parts and replacement components that are no longer in production. It is commonly understood that AM parts would have different types of defects than those found in conventionally manufactured ones, while major gaps in knowledge exists in terms of the defect type, the effect-of-defect, and the critical defect size and location. One of the shortcomings is related to the lack of physical reference blocks for calibration and performance verification of proposed non-destructive evaluation (NDE) techniques. Also, there are no standards for NDE techniques as applied to AM. This article discusses how NDE could better position itself to help AM gain the trust of aerospace industry. (author)
[en] Structural health monitoring has been a growing business in the past few decades in infrastructure sector, particularly when multi-billion-dollar structures were built. These may include television towers, over hundred storey high skyscrapers, suspension bridges, cable stayed bridges, tunnels and dams. In the industrial sector, owners' mindset has also gradually changed from reactive maintenance to proactive monitoring and preventive measures. In smelting industries, each day of shutdown due to maintenance can cost millions of dollars. This provides the incentive for owners to take the proactive approach to reduce the frequencies and periods of unscheduled shutdowns. In view of the demand, Hatch Ltd. has developed a package for structural health assessment for smelters and various industrial structures. This included a non-destructive testing (NDT) program to identify the weak zones of a structure and a structural assessment to check the soundness of the major-structural components. The non-destructive testing program include the determination of remaining lining thickness or vessel shell thickness, and the determination of the extent of damaged zones and potential runout/leak regions. Furthermore, ground penetrating radar and impact echo are used for identifying corrosion and delamination of reinforced concrete and to locate any voids and cracks within the concrete structures. A case study is provided in this paper to illustrate the effectiveness of the structural health assessment program on silo structures. (author)
[en] In this study, 3D shape measurement and path design methods for automatic nondestructive testing were investigated. A rotation was added to the 2D shape measurement sensor, and the point cloud data obtained from the measurements was visualized using a mesh generated in MATLAB. The visualized data was re-meshed to generate inspection points and inspection directions to produce a uniform mesh size. The inspection path obtained using the calculated data is zigzag in shape, since this path was inefficient, optimization was performed. The optimization method aims to minimize the path by maintaining the inspection direction and aligning the inspection position to the same height, thereby eliminating the problem of continuous shaking. Through this study, we have confirmed the possibility of automated, non-destructive inspection systems using shape information
[en] To ensure the quality of material, nondestructive testing is necessary, and radiography testing is the nondestructive technique most commonly used today. For inspection, the quality of a radiographic image is critical, and there are many image artifacts that can reduce inspection accuracies such as noise or blurring. The deterioration in spatial resolution caused by blur in both the X-ray imaging itself and the noise reduction process are particular problems. To tackle them, we implemented a non-blind deconvolution method that employs the alternating direction method of multipliers (ADMM) after noise reduction. Experimental results confirm that the proposed algorithm effectively restores edge sharpness. The 50% modulation transfer function of the restored image of a slit-camera was about 3.54 line-pairs per mm, which is about 2.5 times higher than that of the denoised image. Moreover, the edge preservation index values are about 0.82, 0.54, and 0.75 for the restored, denoised, and acquired images, respectively. Consequentially, the proposed method has the potential to increase inspection efficiency in industrial applications.
[en] This paper accounts axisymmetric contact problems of interaction between rigid punch and poroelastic layer based on Cowin–Nunziato poroelastic theory. It is supposed that punch’s foundation shape is a flat or a paraboloid and there is no contact friction. Using Hankel’s integral transform the formulated contact problems are reduced to the integral equations with unknown contact stress. To solve these integral equations we used the collocation technique. In the case of parabolic punch the values of the contact stress and the contact area have been determined and discussed. The relationship between the force acting on the punch and the punch displacements is investigated, which is one of the main characteristics in determining the mechanical parameters of a material by the indentation method. A comparative analysis of the studied characteristics of the contact problem is carried out for various values of the porosity and layer’s thickness.
[en] This paper presents an application of the linear sampling method to ultrasonic non destructive testing of an elastic waveguide. In particular, the NDT context implies that both the solicitations and the measurements are located on the surface of the waveguide and are given in the time domain. Our strategy consists in using a modal formulation of the linear sampling method at multiple frequencies, such modal formulation being justified theoretically in Bourgeois et al (2011 Inverse Problems 27 055001) for rigid obstacles and in Bourgeois and Lunéville (2013 Inverse Problems 29 025017) for cracks. Our strategy requires the inversion of some emission and reception matrices which deserve some special attention due to potential ill-conditioning. The feasibility of our method is proved with the help of artificial data as well as real data. (paper)
[en] Most of the conventional Non-Destructive Evaluation (NDE) techniques are in the process of continuous technological upgradation and many sophisticated techniques have evolved in the recent years, to meet the challenges of quality and reliability requirements in the high technology areas such as, atomic energy, aerospace and defense. The conventional Nondestructive Testing techniques are being transformed into Quantitative Non-Destructive Evaluation by the introduction of computer technology. In the field of radiography also, the conventional film technique has changed considerably by the introduction of digital technology, such as digital radiography and Computed Tomography (CT). CT has established itself as a leading tool in diagnostic radiology in medical field over the past twenty five years and is catching on fast in the NDE area in a variety of situations. The design of the CT machine for industrial and scientific applications is more complex than medical systems since, it has to accommodate large variation in density and achieve finer resolution. (author)