基于J-A力磁耦合模型的压力磁测系统研究

Research on pressure magnetic measurement system based on J-A model of force-magnetic coupling

提出了基于磁机械效应的在役容器压力测量方法,利用磁信号与器壁应力之间存在稳定对应关系,实现非侵入无损检测。采用J-A力磁耦合模型分析了弱地磁环境下钢材磁导率和应力的关系,在理论上证明了利用容器外部磁场测量内部压力的可行性。设计了一套多通道磁信号同步采集系统,能够完成多传感器3个分量的磁信号的同步获取,实验验证了本方法的性能和优势。实验表明,在压力设定范围内,容器附近磁场与内部压力符合线性模型。压力容器表面的不同部位的磁场对压力变化的灵敏度差别较大,因此需要多点布置、标定优选。对于实验的低碳钢压力容器,磁场测量灵敏度可达131.4 mGs/MPa,并通过轴对称布置一对传感器叠加,可以减弱旋转容器对测量精度的影响。

A pressure measurement method for in-service vessel based on magneto-mechanical effect is proposed.Non-intrusive and non-contact pressure measurement are realized by using the stable correspondence between magnetic signals outside the vessel and the stress on the vessel wall.The relationship between magnetic permeability and stress of steel in weak geomagnetic field is analyzed by using J-A coupling model,and the feasibility of using external magnetic field of vessel to measure internal pressure is theoretically proved.A multi-channel synchronous magnetic signal acquisition system is designed,which can simultaneously acquire the magnetic signals of three components of the multi-sensor.Experiments are carried out to verify the performance and advantages of this method.The results show that in the range of 0~3 MPa,there is a good linear relationship between the magnetic field near the surface and the internal pressure of the vessel.The sensitivity of the pressure change of the magnetic field at different parts of the vessel surface is different,so multi-point deployment and calibration optimization are required.For low carbon steel pressure vessel with an outer diameter of 275 mm and a wall thickness of 7.5 mm,the sensitivity of magnetic measurement can reach up to 131.4 mGs/MPa.Via axis-symmetrically arranging a pair of sensors and adding their output up,the influence of rotating vessel on measurement accuracy can be significantly weakened.