Effect of ball scribing on magnetic Barkhausen noise （MBN） of conventional grain-oriented （CGO） and high- permeability grain-oriented （HGO） electrical steel was investigated. The results showed that after ball s...Effect of ball scribing on magnetic Barkhausen noise （MBN） of conventional grain-oriented （CGO） and high- permeability grain-oriented （HGO） electrical steel was investigated. The results showed that after ball scribing, root mean square of MBN （MBNrms） of CGO electrical steel increased 9.8% with 4 mm scribing spacing at 1.2 T, and that of HGO electrical steel apparently decreased 17.3% with 16 mm scribing spacing at 1.2 T. Through the formation and development of free magnetic poles and secondary magnetic domains due to compressive stress, primary magnetic domain space of grain-oriented electrical steel becomes smaller, which reflects as a variation of MBN in the macroscopic magnetic properties. Through correlation formula derivation of MBNrms and equilibrium distance between domain walls, effect of domain refinement on grain-oriented electrical steel was also interpreted, and optimum equilibrium distance between domain walls was determined.展开更多
<span style="font-family:Verdana;">In Nigeria, most welding activities are carried out by road side welders, majority of this welders are ignorant of weld residual stress and its adverse effect on weld...<span style="font-family:Verdana;">In Nigeria, most welding activities are carried out by road side welders, majority of this welders are ignorant of weld residual stress and its adverse effect on weldment. Residual stress (RS) measuring device </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> vital in the measurement of inherent stresses in material. The aim of this research was to employ proof of principle in analyzing the weld residual stresses in a material. This was achieved by measuring samples with magnetic residual stress device and then subjecting the weld samples to mechanical tensile test with hope that materials with more residual stresses fail first. Finally the result from both procedures w</span><span style="font-family:Verdana;">as</span><span style="font-family:Verdana;"> compared to establish </span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">relationship</span><span style="font-family:""><span style="font-family:Verdana;">. Four (4) pieces of mild steel coupons measuring 100 × 40 × 3 mm were welded, producing two specimens, A</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> and B</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> of 200 × 40 × 3 mm</span></span><span style="font-family:Verdana;">,</span><span style="font-family:""><span style="font-family:Verdana;"> respectively. The specimens were measured using the Magnetic device developed and 37 signals were obtained per specimen, thereafter, the welded specimens were subjected to tensile testing and results analyzed. From the results obtained, Specimen A</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> was observed to have the highest signal peak at the weld zone with RS signal of 20.3983 mV compared to B</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> with 19.358 mV. While und展开更多
Magnetic Barkhausen noise （ MBN） is a phenomenon of electromagnetic energy due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic fiel...Magnetic Barkhausen noise （ MBN） is a phenomenon of electromagnetic energy due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic fields. According to Faraday＇s law of electromagnetic induction, the noise can be received by the coil attached to the surface of the material being magnetized and the noise carries the message of the characteristics of the material such as stresses, hardness, phase content, etc. Based on the characteristic of the noise, researching about the relationship between the residual stress in the welding assembly and the noise are carried out. Furthermore, data process is performed by RMS （Root Mean Square） equation and Power Spectrum analysis.展开更多
A GMR（giant magneto-resistive） spin valve sensor for magnetic recording has been designed in an attempt to solve the Barkhausen noise problem in small-sized GMR sensors.In this study,the GMR ratio of the top-pinned ...A GMR（giant magneto-resistive） spin valve sensor for magnetic recording has been designed in an attempt to solve the Barkhausen noise problem in small-sized GMR sensors.In this study,the GMR ratio of the top-pinned spin valve is optimized to a value of 13.2%.The free layer is magnetized perpendicular to the pinned layer by a CoCrPt permanent magnetic bias so that a linear magnetic field response can be obtained.An obvious improvement on performance is observed when the permanent magnetic bias is magnetized,while the GMR sensor has a steadier MR-H loop and a smaller coercive field.展开更多
Hardened depths on steel samples are evaluated using a non-destructive technique based on the measurement of surface magnetic Barkhausen noise (MBN). Based on the results or experiments, the relation betweeu hardened ...Hardened depths on steel samples are evaluated using a non-destructive technique based on the measurement of surface magnetic Barkhausen noise (MBN). Based on the results or experiments, the relation betweeu hardened depth and MBN is found, and a conclusion that the hardened depth can be measured by the way of measuring the MBN slgnals is obtained.展开更多
Rolling path squeezes and rolling residual stresses of large diameter circular saw body for wood, generated by rolling pressure from 10 up to 120 bar were examined. X-ray diffraction, Barkhausen noise (BN) and Full Wi...Rolling path squeezes and rolling residual stresses of large diameter circular saw body for wood, generated by rolling pressure from 10 up to 120 bar were examined. X-ray diffraction, Barkhausen noise (BN) and Full Width of the peak at a Half Maximum (FWHM) (o) methods for evaluation of residual stresses were used. Dependencies of a tangential rolling residual stresses inside rolling paths upon rolling pressure p (bar) and rolling area A (mm2) were evaluated. The rolling pressure, as large as 60 bar, resulting in the rolling squeeze as high as 0.04 mm2, and, tangential residual compression stresses inside a rolling path, as large as ?TI = ?822 MPa, was considered to be the largest for the practical application.展开更多
Magnetic Barkhausen Noise (MBN) is a phenomenon of electromagnetic energy emission due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magneti...Magnetic Barkhausen Noise (MBN) is a phenomenon of electromagnetic energy emission due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic field. According to Faraday’s law of electromagnetic induction, the noise can be received by the coil attached to the surface of the material being magnetized and the noise carries the message of the characteristics of the material such as stresses, hardness, phase content, etc. Based on the characteristic of the noise, research about the relationship between the welding stresses in the welding assembly and the noise, the fatigue damage of the plate structure and the noise, and the influence of heat treatment and the variation of phase content to the noise are carried out in this paper.展开更多
The Magnetic Barkhausen Noise （MBN） technology is a non-destructive method to measure the neutral temperature of thc CWR track. A series of in-field verifications and data comparison on Australian mainline tracks ha...The Magnetic Barkhausen Noise （MBN） technology is a non-destructive method to measure the neutral temperature of thc CWR track. A series of in-field verifications and data comparison on Australian mainline tracks have shown the results from that system are highly accurate and reliable. The system can be an accuracy and cost-effective tool to prevent the potential buckling and break of CWR rails. The physical backgrounds and features of the system are represented in this paper. The Darwin-Alice Springs Line is a newly constructed main line in Australia which is linked from the north and middle of Australia. Originally, this rail line is designed and constructed in a ＂cost-effective＂ way to a lower price, and the key parameters are relatively low. To maintain the stability of the CWR tracks in a very harsh environment, some new technologies such as the MBN technology were utilised. From the results of neutral temperature, it is found that the majority of them are very high. Combined with the calculation and finite element analysis, these problems evidenced that it is caused by the low toe load fastening system and high sleeper spacing. After that some suggestions are given to improve the stability of the CWR on the railway line.展开更多
Acoustic Barkhausen Emission (ABE) and Electromagnetic Barkhausen Emission (EBE) have been measured. Explanations of the response of nickel to an applied magnetic field are considered using energy density diagrams and...Acoustic Barkhausen Emission (ABE) and Electromagnetic Barkhausen Emission (EBE) have been measured. Explanations of the response of nickel to an applied magnetic field are considered using energy density diagrams and critical fields deduced using Kersten's modified theory. These theoretical models are correlated with ABE and EBE measurements, providing further confirmation of the origins of ABE being non-180° domain wall motion. This paper also shows that the motion of domain walls, on increasing the magnetising fields from saturation to satu -ration, follows the sequence of 71°-180° - 109°. Values of critical fields correponding to 71°, 180° and 109° wall motions in nickel are determined using these techniques .展开更多
基金The financial support of the National Natural Science Foundation of China(Nos.51174057 and 51274062)the National High Technology Research and Development Program (No.2012AA03A503)
文摘Effect of ball scribing on magnetic Barkhausen noise （MBN） of conventional grain-oriented （CGO） and high- permeability grain-oriented （HGO） electrical steel was investigated. The results showed that after ball scribing, root mean square of MBN （MBNrms） of CGO electrical steel increased 9.8% with 4 mm scribing spacing at 1.2 T, and that of HGO electrical steel apparently decreased 17.3% with 16 mm scribing spacing at 1.2 T. Through the formation and development of free magnetic poles and secondary magnetic domains due to compressive stress, primary magnetic domain space of grain-oriented electrical steel becomes smaller, which reflects as a variation of MBN in the macroscopic magnetic properties. Through correlation formula derivation of MBNrms and equilibrium distance between domain walls, effect of domain refinement on grain-oriented electrical steel was also interpreted, and optimum equilibrium distance between domain walls was determined.
文摘<span style="font-family:Verdana;">In Nigeria, most welding activities are carried out by road side welders, majority of this welders are ignorant of weld residual stress and its adverse effect on weldment. Residual stress (RS) measuring device </span><span style="font-family:Verdana;">is</span><span style="font-family:Verdana;"> vital in the measurement of inherent stresses in material. The aim of this research was to employ proof of principle in analyzing the weld residual stresses in a material. This was achieved by measuring samples with magnetic residual stress device and then subjecting the weld samples to mechanical tensile test with hope that materials with more residual stresses fail first. Finally the result from both procedures w</span><span style="font-family:Verdana;">as</span><span style="font-family:Verdana;"> compared to establish </span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">relationship</span><span style="font-family:""><span style="font-family:Verdana;">. Four (4) pieces of mild steel coupons measuring 100 × 40 × 3 mm were welded, producing two specimens, A</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> and B</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> of 200 × 40 × 3 mm</span></span><span style="font-family:Verdana;">,</span><span style="font-family:""><span style="font-family:Verdana;"> respectively. The specimens were measured using the Magnetic device developed and 37 signals were obtained per specimen, thereafter, the welded specimens were subjected to tensile testing and results analyzed. From the results obtained, Specimen A</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> was observed to have the highest signal peak at the weld zone with RS signal of 20.3983 mV compared to B</span><sub><span style="font-family:Verdana;">11</span></sub><span style="font-family:Verdana;"> with 19.358 mV. While und
文摘Magnetic Barkhausen noise （ MBN） is a phenomenon of electromagnetic energy due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic fields. According to Faraday＇s law of electromagnetic induction, the noise can be received by the coil attached to the surface of the material being magnetized and the noise carries the message of the characteristics of the material such as stresses, hardness, phase content, etc. Based on the characteristic of the noise, researching about the relationship between the residual stress in the welding assembly and the noise are carried out. Furthermore, data process is performed by RMS （Root Mean Square） equation and Power Spectrum analysis.
文摘A GMR（giant magneto-resistive） spin valve sensor for magnetic recording has been designed in an attempt to solve the Barkhausen noise problem in small-sized GMR sensors.In this study,the GMR ratio of the top-pinned spin valve is optimized to a value of 13.2%.The free layer is magnetized perpendicular to the pinned layer by a CoCrPt permanent magnetic bias so that a linear magnetic field response can be obtained.An obvious improvement on performance is observed when the permanent magnetic bias is magnetized,while the GMR sensor has a steadier MR-H loop and a smaller coercive field.
文摘Hardened depths on steel samples are evaluated using a non-destructive technique based on the measurement of surface magnetic Barkhausen noise (MBN). Based on the results or experiments, the relation betweeu hardened depth and MBN is found, and a conclusion that the hardened depth can be measured by the way of measuring the MBN slgnals is obtained.
基金support of the Poznan Networking&Supercomputing Center(PCSS)calculation grant
文摘Rolling path squeezes and rolling residual stresses of large diameter circular saw body for wood, generated by rolling pressure from 10 up to 120 bar were examined. X-ray diffraction, Barkhausen noise (BN) and Full Width of the peak at a Half Maximum (FWHM) (o) methods for evaluation of residual stresses were used. Dependencies of a tangential rolling residual stresses inside rolling paths upon rolling pressure p (bar) and rolling area A (mm2) were evaluated. The rolling pressure, as large as 60 bar, resulting in the rolling squeeze as high as 0.04 mm2, and, tangential residual compression stresses inside a rolling path, as large as ?TI = ?822 MPa, was considered to be the largest for the practical application.
文摘Magnetic Barkhausen Noise (MBN) is a phenomenon of electromagnetic energy emission due to the movement of magnetic domain walls inside ferromagnetic materials when they are locally magnetized by an alternating magnetic field. According to Faraday’s law of electromagnetic induction, the noise can be received by the coil attached to the surface of the material being magnetized and the noise carries the message of the characteristics of the material such as stresses, hardness, phase content, etc. Based on the characteristic of the noise, research about the relationship between the welding stresses in the welding assembly and the noise, the fatigue damage of the plate structure and the noise, and the influence of heat treatment and the variation of phase content to the noise are carried out in this paper.
文摘The Magnetic Barkhausen Noise （MBN） technology is a non-destructive method to measure the neutral temperature of thc CWR track. A series of in-field verifications and data comparison on Australian mainline tracks have shown the results from that system are highly accurate and reliable. The system can be an accuracy and cost-effective tool to prevent the potential buckling and break of CWR rails. The physical backgrounds and features of the system are represented in this paper. The Darwin-Alice Springs Line is a newly constructed main line in Australia which is linked from the north and middle of Australia. Originally, this rail line is designed and constructed in a ＂cost-effective＂ way to a lower price, and the key parameters are relatively low. To maintain the stability of the CWR tracks in a very harsh environment, some new technologies such as the MBN technology were utilised. From the results of neutral temperature, it is found that the majority of them are very high. Combined with the calculation and finite element analysis, these problems evidenced that it is caused by the low toe load fastening system and high sleeper spacing. After that some suggestions are given to improve the stability of the CWR on the railway line.
文摘Acoustic Barkhausen Emission (ABE) and Electromagnetic Barkhausen Emission (EBE) have been measured. Explanations of the response of nickel to an applied magnetic field are considered using energy density diagrams and critical fields deduced using Kersten's modified theory. These theoretical models are correlated with ABE and EBE measurements, providing further confirmation of the origins of ABE being non-180° domain wall motion. This paper also shows that the motion of domain walls, on increasing the magnetising fields from saturation to satu -ration, follows the sequence of 71°-180° - 109°. Values of critical fields correponding to 71°, 180° and 109° wall motions in nickel are determined using these techniques .
