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采用Gourdin的电磁动力学方法对金属电磁膨胀环动态拉伸过程进行分析,探讨了电流截断方式、加载过程欧姆温升对实验数据处理的影响。结果表明:按自由膨胀假设的实验模型分析,短路电流截断方式会引入较大误差,断路方式符合较好;试样环感应电流产生的欧姆温升很大,材料本构参数拟合时应考虑温度历史的变化。考虑电磁加载过程试样环的温度和应变率不断变化,提出采用单个实验应力-应变曲线来拟合得到应变率敏感系数及热软化系数的方法,结果与给定的本构参数符合较好。研究为电磁膨胀环动态拉伸实验设计及数据分析提供参考。
The dynamic stretching process of metal electromagnetic expansion ring was analyzed by Gourdin’s electromagnetic dynamics method. The effects of current truncation mode and ohmic temperature rise on the experimental data processing were discussed. The results show that according to the experimental model of the free expansion assumption, the short-circuit current truncation method will introduce larger errors and the circuit breaking method is in good agreement. The ohmic temperature rise caused by the induced current in the sample ring is very large, and the material constitutive parameters should be considered when fitting Changes in temperature history. Taking into account the changing temperature and strain rate of the specimen ring during the electromagnetic loading process, a method of obtaining the strain rate sensitivity coefficient and thermal softening coefficient using a single experimental stress-strain curve is proposed. The results agree well with the given constitutive parameters. The research provides a reference for the dynamic tensile experimental design and data analysis of electromagnetic expansion ring.