Effect of Eddy Currents on Discontinuity of Different Metals

Abstract

The objective of thesis to inspect discontinuities such as cracks, scores, Corrosion pits, seams, laps, inclusions etc. will disrupt the eddy currents and may cause an indication. Study design: The learner will use the descriptive analytic and experimental approaches to carry out this research. Alternating electrical current is passed through a coil producing a magnetic field. When the coil is placed near conductive material, the changing magnetic field induces current flow in the material .these currents travel in closed loops and are called eddy currents. Eddy currents produce their own magnetic field that can be measured and used to find flaws and characterize conductivity, permeability, and dimensional features. In this study eddy current testing technique was used Defect meter 2.837 to study defect on some selected samples and report was considered. This thesis reviews the state-of-the-art methods of eddy current testing which is one of the most widely used non-destructive forms of testing. Eddy current testing permits crack detection and measurements that are beyond the scope of other techniques such as non-conductive coating thickness, alloy composition and hardness in a large variety of materials. The only need is that the materials being tested must be electrical conductors where eddy currents can flow. Eddy current sensors are insensitive to dirt, dust, humidity, oil or dielectric material in the measuring gap and have been proven reliable in a wide range. In conclusion, as researchers and developers of solutions based on eddy current testing, it was found that eddy current techniques can provide the industry with reliable quality control systems. Although there are excellent improvements due to the effort of the many scientists during the last several years, we believe that more research in eddy current techniques, in terms of sensors, equipment and signal processing, will lead to even more applications of these techniques. From inspection done in the Khartoum V International Airport it was concluded that there is defect on the samples that inspected under Defect meter 2.837 as prescribed in the report. It is necessary trying to develop new coil probes and research the use of other magnetometers such as superconducting quantum interference devices (SQUIDs), Hall-effect and magneto resistive sensors that also provide very interesting responses.