A New Device Of Residual Stress Measurement Based On Pulse Method

Ferromagnetic material is used extensively in the national economy.It is the mainbuilding and manufacturing materials. The quality of ferromagnetic material isdirectly related to national economic development.even to the many practialproblems,such as personal safety and people’s property.The detection of the internalforce of ferromagnetic material is particularly important.The measurement of residual stress in ferromagnetic material develop rapidly inrecent years.There are a dozen methods of measurement.They can be divided intodetrimental testing and non-destructive testing. It’s need damage to material fordetrimental testing. So there are lots of limitations for testing. We could not damagegood material for testing the residual stress.We take lots of time to reseach thenon-destructive testing and has been closely following the development ofnon-destructive testing in worldwide.Non-destructive testing (NDT) technique is to study the changes of electric、magnetic、optical and thermal signals caused by structure changes or defects ofmaterial to measure the internal features and defects of the measured pattern in orderto evaluate the current use of state of the material. With the development of scienceand technology, especially computer technology, NDT has become an importantmethord of monitoring and assurance of the materials quality in industrial production.In the paper,the pulse method is a kind of non-destructive testing. Compared withX-ray diffraction、Barhsusen effect and magnetic memory,the pulse method canmeasure internal stress of mechanical components repetitively and portability.The new equipment is divided into two systems, a hardware system and asoftware system. Hardware system is a pulsed magnetic field generating device. Thesoftware system is a signal acquisition system based on Labview. We do a lot of teststo get the pulse magnetic field after we study the principle of the pulse magnetic field and the operability of the program. Finally, we determine to use four insulated gatebipolar transistor(IGBTs)、two capacitors、the excitation coil and power resistorscomposed the the pulse magnetic field generating device. The capacitor discharge tothe low resistance of excitation coil to generate the pulse magnetic field. We use fourIGBTs as switchs to control the order of discharge to generate two pulses in oppositedirections. The related signals are directly fed to high-speed data acquisition card. Thesoftware platform based an Labview process the acquired signal and plot thehysteresis loopsHysteresis loops obtained is directly related to the stress change of the internalstructure of the ferromagnetic material. The material stress cause changes in thehysteresis loops. So we establish the relationship between the stress and the materialmagnetic signal.This method achieve the purpose of non-destructive measurement. Itcan measure the stress of components repeatability and portability. It has a goodprospect of application...