利用焦耳效应提高含裂纹金属构件抗裂性能问题的研究

ENHANCEMENT OF FRACTURE TOUGHNESS OF A THIN METAL PLATE WITH A LINE CRACK UNDER TENSION/ELECTRIC CONDITIONS

设一无限大金属薄板中含有一个线裂纹 ,对金属板施加恒定的电流场 ,在两个裂尖处产生的热量远远大于其余地方产生的热量 ,可简化成两个点热源 .经求解得到了问题的解析解 ,包括裂纹尖端附近区域温度、应力、应变、应变能密度因子的解析表达式 .计算结果表明 ,裂纹尖端处的材料发生熔化而形成一个焊点 ,裂纹尖端明显纯化 ,可抑制裂纹的进一步扩展 ,提高含裂纹金属构件的抗裂性能 .

When a line crack is subjected to an electric field, the electric current density will be intensified to change the material microstructure near the crack tips and as a result, the local fracture toughness will be enhanced. The object of this paper is to explore this idea by analysis. To this end, the problem of an infinite thin metal plate with a line crack is formulated. A thermoelastic solution is obtained by assuming that the effect of electric field concentrated at the crack tips is equivalent to two heat sources. The temperature, stresses and the strain energy density factors in the vicinity of the crack tip for different electric current density, different crack length and different plate thinkness are numerically computed. The results show that the material in the region very close to the crack tips may be molten to suppress crack initiation.