论塑性因子与塑性时间的一般关系

DISCUSSION ON GENERAL RELATIONSHIP BETWEEN PLASTIC FACTOR AND PLASTIC TIME

确定材料特定的内蕴时间表达式,是内时塑性力学建模的难点之一,依据原有的内蕴时间定义,也难以探明塑性增量理论和内时塑性理论之间的联系。为此,给出新的内蕴时间——塑性时间的定义,旧的内蕴时间是塑性时间的特例。根据塑性时间的定义,塑性增量力学理论是内时塑性力学理论的特例,塑性增量理论的塑性因子属于内时塑性理论的塑性时间,因此通过塑性因子的表达式可以获得塑性时间的表达式。材料已有的塑性试验表明,不同材料具有不同的塑性因子,由此确定的塑性时间也因材料而异。众多实例阐明推导塑性时间表达式的具体过程,提供利用塑性时间和脉冲函数把塑性增量力学本构模型推广为积分型内时塑性模型的一般方法。

It is difficult to determine the expression of an intrinsic time for a specific material in the endochronic theory of plasticity. Meantime, according to the definition of the intrinsic time by K.C. Valanis, the relationship between the increment theory of plasticity and the endochronic theory of plasticity becomes ambiguous. In order to overcome the limitations above, the new intrinsic time, which is named plastic time, is defined. The old intrinsic time is a special case of the plastic time. According to the definition of plastic time, it is illustrated that the increment theory of plasticity is a special case of endochronic theory of plasticity. It is proved that the plastic factor in the increment theory of plasticity belongs to the plastic time. The expression of plastic time could be derived from the expression of plastic factor. It has been shown by mechanic tests that the plastic factors are different from material. As a result, the plastic time is not identical for different materials. A lot of instances present the specific method to deduce the expression of a finite plastic time and provide the generalized approach to derive the integral endochronic constitute equations from the increment theory of plasticity by means of the plastic time and the impulse function.