RESEARCH ON RELATIONSHIP OF CRACK ARRESTING EFFECT USING ELECTROMAGNETIC HEAT EFFECT WITH DIMENSION OF CURRENT PATH

The technique of crack arresting is badly in need of current industry production and practice application. The preventing for a current conductor with a crack by the heat effect of the electromagnetic field is an effective method to extend its service life, to improve its security and reliability. The experiment study, theoretical analysis and numerical calculation are proposed for researching the different distribution of the temperature field and temperature gradient field near the crack tip in edge crack preventing inside a current carrying plate by electromagnetic heat effect under the different dimension of current path. Complex function is applied in theoretical analysis and the thermal electrical coupled theory applied in numerical simulation. Meanwhile, crack arresting experiments are also conducted by using a super density pulse current generator (model ZL 1) developed by authors. Theoretical analysis, experiment surveys and numerical calculations show that due to the heat concentration effect around the crack tip, small welded joints are formed by metal melting. The curvature of the crack tip will be increased by some orders of magnitude instantly and the stress concentration will be decreased remarkably. The superfine microcosmic structure was found around crack tip, so that the intensity, ductility and wearing capacity around crack tip have been promoted under the influence of superfine structure. Micro crack will be prevented and the spreading of the crack be arrested too. The dimension of current path is one of the main factors that effect the distribution of temperature field and temperature gradient field of crack tip.