Detection System Using Flexible Differential Eddy Current Sensor for Non-destructive Testing

High pressure hydrogen cylinder is an important equipment for hydrogen storage and transportation. Regular nondestructive testing of aluminum liner microcracks of hydrogen cylinder is necessary to ensure the safe use of high-pressure hydrogen cylinder. Due to the small volume and narrow mouth of the hydrogen storage bottle, the traditional detection methods are difficult to implement, so a detection system suitable for the detection of the inner surface of hydrogen cylinders is urgently needed. In this paper, a flexible differential eddy current sensor is designed based on the principle of eddy current testing. The feasibility of the sensor is verified by establishing a finite element model, and the influence of various parameters on the sensor response is analyzed. A scanning system suitable for the detection of the aluminum liner of hydrogen gas cylinders is designed. The scanning system can enter the interior of the aluminum liner of the hydrogen cylinder, and is equipped with an eddy current sensor to fit the inner surface of the aluminum liner for detection. The experimental results show that the sensor can suppress the common mode component in the signal, and has a high signal to noise ratio. What is more, the scanning system can complete the rapid scanning of the hydrogen cylinder liner, which verifies the feasibility of the detection system.