Development Of Portable Ferro-magnetic Material Stress Testing Equipment

Magnetic Nonstructive testing technology has been widely used in defect,fatigue crack and stresstesting of pressure vessels,railway,aeronautics and astronautics’s structure. And BarkhausenNoise(MBN) testing technology has become a very important method for evaluating and testingdistribution of ferro magnetic materials electromagnetic by the advantages of coupling andnon-contact testing.In the paper,a set of portable stress testing equipment which is based on theBarkhausen effect testing principle for ferromagnetic material and the embedded technology has beendeveloped.Firstly,the Barkhausen Noise mechanism of production and the relation between the BarkhausenNoise and ferromagnetic material stress is discussed,effective features are extracted,model of testingand calibration is constructed.Then based on the theoretical researches and requirement analysis,thewhole design schedule of equipment is supposed. Then the hardware selection,hardware circuit designand debug is completed. The hardware circuit includes signal generating circuit,power amplifiercircuit,stress testing probe,signal conditioning circuit,acquisition circuit,serial communicationcircuit,matrix keyboard circuit,storage circuit and power supply module. Then,the software design ofthe equipment is completed,including the generation of drive signal,the collection and storage ofMBN signal,FIR band-pass filtering and serial communication. The root mean square, averagevalue,peak value and ratio of peak width of MBN signal are extracted as features. And the calibrationof the four features and the equipment’s stress testing is completed with the use of linearfitting,quadratic function and cubic function method. At the same time,conduct the experiment oftemperature stress on the rail,validate the relationship between ferromagnetic material temperaturestress and MBN signal.