نشریه فناوری آزمون های غیرمخرب
سال دوم شماره 3 (پیاپی 4، پاییز و زمستان 1397)

The shearography method is one of non-contact and full-field method for non-destructive testing of parts and sets. In this method the displacement gradient is directly measured. After processing the image, the surface fringe patterns are earned. It is used mainly in detecting surface and sub-surface defects of parts. Other applications include strain measurement, characterization of material properties, evaluation of residual stresses, leakage detection, structural vibration studies and three - dimensional measurements. Due to the measurement of displacement derivatives and not sensitive to the vibrations of the environment, in addition to experimental environments, it has a wide application in industrial environments, which makes this method discriminate with other optical methods. This method is used mostly in composite and metal components for defect detection. In this paper, we study techniques, equipment, method of operation, image processing, type of loading according to the materials and type of defect with emphasis on some practical researches in this regard.

Ultrasonic imaging using phased arrays is a crucial non-destructive test. In this paper, a phased array ultrasonic system is designed and implemented. It is implemented using integrated electronic circuits which results in higher image quality and lower noise, lower cost, lower weight and smaller dimensions with respect to current systems. The implemented system supports all phased array probes with standard connector up to 16 elements and its sampling rate is 40MHz and is capable of upgrading to higher number of elements and sampling frequencies. Imaging is implemented using total focusing method which results in higher quality images with lower noise in comparison to regular phased array images. Portability, development to use in all non-destructive imaging tests and a lower price in comparison to current imaging systems, are major features of this product. The experimental results demonstrate that the system easily distinguishes between three holes with 0.8mm, 0.6mm and 0.3mm diameter.

There are many approaches for food quality and safety evaluation and adulteration detection of agro-food products. These ways include destructive and non-destructive. After non-destructive tests, foods can be used and also we can apply all experiment case studies for testing but in destructive test we can test just afew samples. Ultrasound is one of non-destructive tests which can use in quality evaluation and fraud detection of agricultural, livestock and poultry products. Also from detection of foreign body in packaged and canned foods to microbial contaminant detection by ultrasound technique is available. Diagnostic ultrasound in food science is fast, low cost, portable and easy to lean. In this work, evaluation and application of diagnostic ultrasound has been classified in three parts which include: a. agricultural products b. livestock and poultry products and c. vegetable oils, juices and other drinking. At the end on paper challenge and some difficulties in ultrasound are given and some problems for solve and reduction of these challenges are given.

In this research, the possibility of evaluating non-destructive materials using terahertz waves was investigated. For this purpose, the results of determining the specific defects dimensions on the samples of aluminum, plexiglas and ceramic zirconium dioxide with the results of dimensional measurements with methods such as Coordinate Measuring Machine (CMM), micro-X and Visual Measurement Machine (VMM) was compared. In order to conduct research, depending on the nature of the sample and the required information, two configurations (transmission and reflection) of the terahertz imaging system based on the terahertz time domain spectroscopy system were used in which the generation and detection of terahertz waves pulses were performed using a femto-second laser. The results showed that non-destructive terahertz test was used to identify defects (very shallow surface defects and hidden defects in sample tissue) and measurements were superior to some of the common methods. In the final, the terahertz wave imaging method is a non-destructive test that can compete with conventional methods.

In this paper, we examine the method of Digital Image Correlation (DIC) and introduce a new theory for measuring residual stresses in non-destructive mechanical parts. In this regard, with the aim of scientific proof, the new theory introduced into the review of the article related to the idea presented in this study and its details have been discussed. First, the principles of the method of digital image correlation and methods for calculating correlation coefficients are presented. With the aim of evaluating the authenticity of the outputs of digital imaging, by constructing the required equipment and performing empirical tests to perform the process, comparing the output results of the digital imaging overlap method and the finite element simulation results. In the following, the proposed theory is presented to measure residual stresses in mechanical parts by applying loads in the elastic and non-destructive regions. The proposed relationship, which is based on Hooke's law, is capable of evaluating and calculating residual stresses in a non-destructive, full-screen, and high-precision manner. Finally, In order to prove the theoretical theory, steel samples have been welded by the SMAW process and the amount of residual stresses in the compartments has been calculated.

The spot welding process is one of the most common and oldest methods of electric welding, which is widely used today in various industries, especially automotive, aerospace, electronics and some parts of the nuclear industry. It has a point in the construction of an automobile body of between 2000 and 5000 bits. Spot welding quality control is carried out according to international standards, which is often accompanied by demolition of samples. The use of a destructive method in controlling the quality of spot welding created on different parts or the entire body of the car costs a lot. Which will be saved in case of quality control of these points using non-destructive method and sales of welded parts. Accordingly, a non-destructive method should be used to evaluate and control spot welds. One of these methods is a non-destructive ultrasonic test that has been successfully used in this project. The ultrasonic waves measure the diameter of the boiling button, which is an important indicator of boiling quality. In this study, a large number of healthy and defective point welds were made and these specimens were tested by ultrasonic non-destructive methods and destructive testing of pull-shear testing. The results of these experiments showed that the ultrasound test can detect defective welds well and its results in the production line also improve the test method. Keywords: Spot resistance welding, Welding nugget, Ultrasonic Test, Automotive Industry

Nondestructive testing has a special status as one of the main safety components in nuclear power plants. Given the importance of safety and integrity of nuclear power plant circuits, especially the primary circuit equipment and pipelines, the application of a series of non-destructive tests can be assured Improved performance of these equipment. It should not be forgotten that timely inspections can prevent very disastrous national, regional and global events. For example, the LOCA, or the loss of coolant accident, which is the first failure of the primary circuit prevented. The first circuit equipment, such as the generator, steam generator, pressurizer, pumps and main circuit pipes, are based on a general inspection plan during operation periodically and regularly under non-destructive testing. Based on the above-mentioned equipment, the steam generator has a special position. This equipment as the first and second circuit boundary plays a critical and complex role in the power plant's operation. There are approximately 11,000 U-shaped tubes for heat exchange between the first and second circuits, which confirms the importance of controlling these levels. The presence of pores in this number of tubes and the heat exchanger level can have many environmental and economic problems. Therefore, accurate and efficient non-destructive checks and inspections on this equipment can solve many problems