Research of Crack Depth Detection Method Based on Frequency Scanning Technique

After introducing some familiar methods of crack depth detection, frequency scanning technique is applied to alternative current field measurement. The ratio of the upright magnetic intensity divided by total magnetic intensity is used as a characteristic value to achieve crack depth detection. The influence of encouraging frequency to crack depth detection is analyzed and the rule of characteristic value varying with scanning frequency is observed. It is found that at first when encouraging frequency increases, the characteristic value increases too. When encouraging frequency continue to increase, the characteristic value decrease instead. The scanning frequency when the characteristic value obtains minimum is recorded and named as inflexion frequency. Thus a crack depth detection model is established based on frequency scanning technique. At the same time quantitative relationship of crack depth and inflexion frequency is analysed. Experimental results prove that crack depth detection can be achieved commendably using frequency scanning technique.