The Magnetic Dipole Theory for Non-Destructive Testing in China

摘要

A survey of the generai situation and progress of the magnetic dipole theory research in China is given in this paper. These include the following contents: 1) Magnetic field of a magnetic dipole, a linear magnetic dipole of finite length and a strip magnetic dipole of finite length; 2) Magnetic force acting upon a magnetic particle; 3) The effect of magnetizing field orientation on the revelation of defects by magnetic particles; 4) Longitudinal magnetization of a rod, tube and cuboid steel component; 5) Magnetic leakage field yielded by a slot on the workpiece surface; 6) The analytic expressions for some results of classical experiments ( made by Japanese Society for NDI and Dr. F. F?rster ) ; 7) Theoretical explanation of some strange magnetic particle patterns ( around a square hole, near corners of a keyslot and over cylindrical surface of a pin with throughout hole ) and abnormal phenomena in magnetic NDT ( reversing of magnetic poles in a slot after discontinuation of magnetization, non-relevant magnetic particle indications along the lateral edges of a cuboid steel component magnetized longitudinally and along the base apex lines of a workpiece magnetized circumferentially ); 8) Seeking new electromagnetic law and conception for NDT; 9) The distribution of magnetic charges in a region on the plane; 10) Approximate theory for the ring standard specimens ( magnetic leakage field from a subsuface flaw ) and so on.