铝合金薄板中裂纹的电磁热效应局部跨越止裂

 讨论了电磁热裂纹止裂时脉冲放电瞬间的电流、温度和热应力的耦合关系。通过自制的 ZL-1型强脉冲放电止裂装置进行了模拟实验研究;理论分析中采用了复变函数的研究方法给出了跨越止裂后裂纹尖端附近的温度值和热应力值;通过热 -电耦合和热 -机械耦合 2个过程对脉冲放电瞬间的电流 -温度 -热应力的演变进行了数值模拟,数值模拟的结果与理论分析和实验研究有较好的吻合。三方面的研究结果均表明 :通过电磁热效应局部跨越止裂可以使铝合金薄板中裂纹在裂纹尖端处很小的范围内熔化形成微小焊口,减小了裂纹尖端的应力集中,并在裂尖处形成压应力区,从而遏制了裂纹的扩展。该方法可应用于飞机机翼疲劳裂纹的止裂中。

CRACK ARREST IN ALUMINUM ALLOY PLATE BY PART CROSSOVER USINGELECTROMAGNETIC HEAT EFFECTS

The coupling of current, temperature and stress has been proposed in crack arresting by the electromagnetic heat effect at the moment when a pulse current is switched on. A simulation experiment has been conducted using a super density pulse current generator (model ZL 1) developed by the authors. Complex function analysis is applied in the theoretical analysis; the temperature and stress at the crack tip are solved in analytical solution after crack arresting. The numerical analysis process was finished by two ways of the thermal electrical coupled and thermal mechanical coupled. The results of the numerical simulation are in good agreement with the results of theoretical analysis and experiment. Theoretical analysis, experiment surveys and numerical calculations show that the tip of crack may be melted and the crater can be formed by metal melting when the crack is arrested by part crossover using the electromagnetic heat effect, which decreases the stress concentration and forms a compressive stress area. Therefore, the goal of crack preventing can be reached. This method can be applied in the fatigue crack prevention of the aerofoil root.