Non-Destructive Testing Technology
Year:2019 | Volume:2 | Issue:4|Papers Count:7

Fractures and damages can be resulted from physical stresses in the flawed parts of an aircraft. The exact detection of internal defects is possible by radiography testing. The determination of the defects locations by the experts depends on the accuracy, skill and quality of the radiographs. Many of the produced images by industrial radiography are not clear, and it is difficult to accurately detect their defects; hence, the processing methods can help to better investigation of the defects. These images suffer from some opaqueness due to the inherent dispersion of X-rays. In this study, a non-local mean method based on the detection of similar pixels in a neighboring area is used to identify corrosion areas. In the method, the image is split into smaller windows and the similar pixel is found on these parts. The results of the method show that, due to the lack of noise function in radiographic images, the background elimination method is more suitable for this algorithm. In this research, the large amount of standard deviation of the noise is considered and background is extracted, the obtained image was reduced from the original radiographic image. The reconstructed image has sharp edges that more clearly indicates the defect area. The evaluation of the results by radiography experts showed that this method has the efficiency to detect defects.

Pipelines are widely used in transporting large quantities of water and sewage over long distances. These valuable infrastructures attract public attention only when they fail. The quantitative and early detection of defects in sewer pipelines is very important in order to avoid severe consequences. In many countries, sewer pipeline inspection is usually carried out using CCTV (Closed-Circuit TV) cameras and off-line human surveys through raw image assessment for failure identification. CCTV-based techniques have some limitations that restrict their implementation. One of the disadvantages of CCTVbased techniques is the lack of visibility in the interior of the pipes. The other disadvantage of CCTVbased techniques is the poor quality of the obtained images because of difficult lighting conditions. In consequence, CCTV-based techniques can only detect gross defects reliably. In recent decades, thermography, microwave, laser, and sonar-based techniques have been proposed to complement the conventional CCTV-based technique and to improve inspection results. Also, new inspection devices employing multiple sensors and being capable of carrying out remote sewer inspection tasks have been proposed. This paper presents an overview of the conventional and novel inspection technologies for sewer pipelines. Furthermore, different types of robots for in pipe inspection tasks are discussed.

Usage of composite materials in aircrafts is increasing because of lightweight, strength and other appropriate physical properties. Vertical Rudder and Horizontal Elevator usually made by Honeycomb composite sandwich panels. These surfaces may be affected by defects due to crossing different climatic conditions and aging. In addition, detection of accumulated water droplets is so important. Although the using of conventional nondestructive inspection test methods such as Ultrasonic is so common, but concerning the restrictions, would not be enough. Checking for the changes of elastic properties cannot lead to the detection of water droplets in the internal network and defects too. The most common way to ensure the absence of these defects is using the Thermography method. Thermography is based on the specific thermal properties of materials and thermal equilibrium point. Airbus has used the two methods of Lock-in Thermography and Pulse Thermography in order to inspect possible defects in Rudders and Elevators. As well as describing the inspection principals in using this method, the current article studies the possibility of using the Air Injection for inspecting these surfaces.

Among various types of radiation practices, industrial radiography is one of the highest risk activities due to handling high activity sources. Thus, the exposure control of the radiographers is of great importance in this regard. In this study, while presenting the occupational exposure situation of this group in the period from the years 2007 to 2016 in Iran, the effectiveness of the measures taken for the workers who received doses higher than the investigation level has been evaluated. Moreover, a comparison between the averaged individual and collective doses of this radiation practice in Iran with those of some other similar counties has been performed. The results show that all the interventional actions in the field of optimization of protection have been significantly effective. However, to achieve a better level of radiological safety, establishment of a dose constraint can have a significant effect on the further and continuous reduction of this radiation practice

Thermography is one of the new, fast and low-cost methods for nondestructive testing. In this method, the workpiece is subjected to heating under the modulated heat source, and the images of the process are stored by the thermal camera. In this research, the feasibility of this method was performed on a plastic cutter. The results showed that deeper and smaller defects are better identified in the image of the amplitude of the heat wave amplitude. It was also found that the quality of phase images is higher than the image of the domain and is less affected by the test conditions, such as asymmetric heating and light reflection. By optimizing the test conditions, the defects can be displayed with the use of domain images. Also, two different frequencies with a relatively high spacing of 0. 5 Hz and 1 Hz were used to obtain a suitable frequency for the workpiece. Due to the appropriate heat transfer, lower frequency use in the test is recommended to provide a more appropriate time interval for detecting defects.

There are two destructive and nondestructive inspection methods to ensure the operation of pipelines, pressure vessels and defects in industrial sheets. One of the important issues in oil and gas transmission lines and pressure vessels is leakage issue. The leak test is one of the nondestructive testing methods that relates to the entry or exit of a fluid from a high pressure environment to a low pressure environment. Acoustic emission is one of the nondestructive methods which is used for leakage locating. The jet produced due to leakage causes the pipe to vibrate and so acoustic waves will propagate through the pipe. Due to different source-sensor distances, acoustic sensors will capture the signals with time delay. In this study the first arriving time and so time delay between sensors can be estimated using Akaike Information Criteria method. Acoustic signals will capture using two R15a sensors located on two sides of leakage. In this study, first leakage tests were carried out on a pressurized pipe. The results showed that using AIC technique leakage location can be done with a mean error of 1. 4%. In the next step, experiments were carried out to locate the acoustic source on a steel sheet. The results showed that using AIC method, an acoustic source location can be estimated with an average error of 3. 92%.

The electronic nose technique is a novel and nondestructive method used for grading odorant materials including essence (oils) of medicinal plants. This technique works based on chemical sensors and resembles the human olfactory system. On the other hand, the medical and aromatic plant industry (MAPs) is a new and growing industry that lacks quality control devices. In this study, an electronic nose device is introduced and then the possibility of identifying and grading 8 species of basil is investigated. An electronic nose system based on eight metallic oxide semiconductor (MOS) sensors was used. First, the main constituents of the essential oils of 8 species were extracted from the basil and were determined using standard laboratory methods, their type and percentage. Then, the grading of these classes was evaluated using a nondestructive electronic nose test. Results of PCA principal component analysis showed that using the first two principal components (PCA1, PCA2), 88% of the variance can be justified. Also, loading diagram showed that the MQ135 sensor had a greater effect on class separation. The precision present of grading was 89 %. The results showed that e-nose as an inexpensive, accurate, easy tool to identify species of basil is effective.