Fatigue cracks in airplane gear detected by the magnetIc-particle method 202128 & Dr Jonathan c.Y. Chung: NDE 今16
Fatigue cracks in airplane gear detected by the magnetic-particle method ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖16
Orientation of magnetic fields Leakage field at crack NIS Crack Current Current Leakage field at cracK Current (a) Longi tudinal field produced b) Circular field produced by circular current by longitudinal currents 202128 & Dr Jonathan c.Y. Chung: NDE
Orientation of magnetic fields ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖17
Some cracks are more difficult to detect Direction of current 3-5 Turn Coil Dif ficult to Detect Crack Detectable Crack Direction of Magnetic Field Longitudinal magnetization induced by coil magnetization
Some cracks are more difficult to detect ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖18
Threshold indications of near-surface cavities 1200 800 400 Dry-dc 0 3 2021/2 Depth of hole below surface, mm 19
Threshold indications of near-surface cavities ❖2021/2/8 ❖Dr. Jonathan C.Y. Chung: NDE ❖19