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提出塑性时间的定义,Valanis K C提出的内蕴时间是其特例。分析了一类积分型塑性时间内时模型“现时近似式”的基本性质,揭示了此类“现时近似式”存在屈服面和塑性位势的必要条件。当“现时近似式”存在屈服面和塑性位势时证明了“现时近似式”的塑性因子等于塑性时间与其Pfaffy型积分分母之积。当Pfaffy型积分分母为正常数时塑性因子等于塑性时间。从经典塑性增量理论出发,采用塑性因子作为塑性时间,建立了一个小应变条件下干砂的内时模型,该模型能够考虑砂土的剪胀性,能够较好地拟合循环荷载作用下干砂的应力-应变响应。
Put forward the definition of plastic time, the intrinsic time proposed by Valanis K C is its special case. This paper analyzes the basic properties of a type of integral plasticity in time model “the present approximation ”, and reveals the necessary conditions for the existence of yield surface and plastic potential in such “current approximation ”. The existence of the yield surface and plastic potential when the “present approximation” has proved that the plastic factor of “present approximation” is equal to the product of plastic time and its Pfaffy type integral denominator. The plasticity factor is equal to the plastic time when the Pfaffy-type integral denominator is a positive constant. Based on classical plastic incremental theory, plasticity is used as plasticity time to establish an internal model of dry sand under small strain. The model can consider the dilatancy of sand and can well fit the cyclic loading Stress-strain response of dry sand.