Study On Stress Detection Method Based On Magnetoelastic Effect

Stress detection method based on magnetoelastic effect as a kind of developing nondestructive testing technology, can be widely use in military and civil domain. The planar flexible eddy current sensor design and the magnetic permeability measurement method based on grid database as the key technology was studied. The main contents include the following aspects.(1)The theory of stress detection method based on magnetoelastic effect was studied. Aimed at the lift-off effect, the magnetic permeability measuring method based on measuring grid was proposed. Through establishing the finite element simulation model of the planar flexible sensor and the under test material, this method can attain the concrete relationship between trans-impedance and magnetic permeability with the influnce of the lift-off. Thus, In this way, the lift-off effect on accuracy and the requirement on calibration are reduced.(2)A new planar flexible eddy current sensor which was used in the domestic stress monitoring method based on magnetic permeability for the first time, was designed based on the finite element method. This sensor can be accurately modeled, flexibly used, expediently mounted and easily executed. Furmore, it is adaptive to any shape and small space. Besides, it can measure stress without mounted on the material.(3)The stress monitoring system is designed and implemented. The test system was established under laboratory condition and a series of static and dynamic experiments were carried out. Through the analysis of the exprimental results, the linear relationship between the tensile force and the magnetic permeability was attained and the added residual stress was measured. The results proved the feasibility and validity of stress monitoring method based on magnetic permeability, and also the good performance of the sensor. This method has great potential in application and development.