Thermal Stress Filed When Crack Arrest in an Axial Symmetry Metal Die Using Electromagnetic Heating
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摘要: 为求解金属模具脉冲放电止裂瞬间裂纹尖端附近的热应力场，选择具有半埋藏环形裂纹的金属凹模为研究对象，采用复变函数方法求解了凹模内外环面均匀通入强脉冲电流放电止裂时的热应力场．理论分析结果证实：由于放电瞬间脉冲电流的绕流集中效应，使金属凹模内部环形裂纹尖端附近金属迅速升温，金属熔化形成堆焊，并由于瞬间温升产生热压应力场．研究结果表明：应用电磁热效应止裂技术可以减小裂纹尖端的应力集中，形成的热压应力场有效地阻止金属模具中干线裂纹源的开裂趋势，达到了裂纹止裂目的．Abstract: In order to solve the thermal stress field around crack tip in metal die when crack prevention using electromagnetic heating,a metal die with a half-embedded round crack was selected as the study object.The complex function method was used as a basis for the theoretical model of the space crack prevention in metal dies using electromagnetic heating.The crack arrest was accomplished by a pulse current discharge through the inner and outer.The theoretical analysis results show that the temperature around the crack tip rises instantly above the melting point of the metal.Small welded joints are formed at a small sphere near the crack tip inside the metal die by metal melting as a result of the heat concentration effect when the current pulse discharged.The thermal compressive stress field appears around the crack tip at the moment.The research results show that the crack prevention using electromagnetic heating can decrease the stress concentration and forms a compressive stress area around the crack tip,and also prevents the main crack from propagating further,and the goal of crack preventing can be reached.
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Key words:
- crack /
- crack arrest /
- pulse current discharge /
- complex function /
- thermal stress field
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