The Research Of Metallic Magneto-Elasticity And Magnetic Memory Testing Signal Acquisition And Processing System

Ferromagnetic material has very good elasticity and plasticity and many other good qualities, such as unyielding and enduring,etc.It is a widely used industry material now and in the future and can't be replaced.But breakdown of the products made from ferromagnetic material sometimes may occur which can cause serious problems and may endanger people's life sometimes.Therefore,testing of various properties of ferromagnetic material, such as stress, hardess and fatigue, etc,is very important.With the development of modern industry,actualizing stress testing for ferromagnetic material structural member has become an important means to ensure the safety of the equipments as well as the quality of products.In comparison with other common stress testing methods,metallic magneto-elasticity and magnetic memory testing methods,which were developed in recent years,were two kinds of advanced nondestructive testing technology.They both have the superiority in testing residual stress,fatiguelife,hardness,microstructure,surface state of the ferromagnetic material and they can also be used to analysis and evaluate the state of a whole product or equipment.They are very promising nondestructive testing methods.In this paper,mechanism of the generation of metallic magneto-elasticity and magnetic memory signals and their relations to the various properties of ferromagnetic material are discussed thorougthly and carefully.And on the foundation,an instrument for testing the stress of ferromagnetic material using metallic magneto-elasticity and magnetic memory technology has been developed.The instrument mainly consists of three parts:the sensor,the signal alignment circuit and the signalchip.For high-frequency interference signals in metallic magneto-elasticity testing,this paper proposes a scheme of low pass digital filter with Field-Programmable Gate Array(FPGA).The filter is programmed with VHDL and simulated.It is also applicated in online testing of magneto-elasticity with higher precision.