一种基于应变能理论的黏弹塑性蠕变本构模型

A new visco-elastoplastic creep constitutive model based on strain energy theory

从内能角度分析发生蠕变的机制,基于应变能理论,采用Perzyna黏塑性理论与西原正夫元件模型相结合,建立了一种能描述衰减蠕变、稳定蠕变和加速蠕变3个阶段全过程的蠕变统一本构模型。该模型考虑了应力状态对加速蠕变的影响,通过定义加速蠕变临界应变能密度值可以有效判断加速蠕变发生时刻,并在统一蠕变本构模型基础上进行简化,采用Drucker-Prager(D-P)屈服准则结合相关联流动法则,用过屈服应力比反映加速阶段蠕变应变速率变化,建立了一个实用的能预测加速蠕变并能反映蠕变3阶段全过程的简化蠕变本构模型,结果表明,数值模拟结果与试验数据基本吻合,研究成果为岩石蠕变断裂过程研究提供了一种新的思路。

The mechanism of creep from the perspective of internal energy is analyzed. Based on the strain energy theory, a creep constitutive model is established by combining the Perzyna viscoplasticity theory and Nishihara model, which can describe the whole process of transient creep, steady state creep, and accelerated creep. The model takes into account the influence of stress state on the accelerated creep, and defines the critical strain energy density to effectively judge the occurrence time of accelerated creep. On the basis of the unified creep constitutive model, a practical simplified creep constitutive model is built by adopting Drucker-Prager yield criterion and associated flow rule; and using the yield stress ratio to reflect the creep strain rate change of accelerated creep, which can predict the accelerated creep and reflect the whole process of the three stages of creep. As the simulation result is basically consistent with the test data, the research results provide a new idea for the study of rock creep fracture process.