一种考虑尺寸效应的颗粒材料流变模型及其验证

发布时间：2018-08-06 21:04

【摘要】：经典连续介质理论的粘塑性本构关系缺乏材料尺度的相关性,难以表征颗粒材料流变的尺寸效应,而Cosserat连续体中的内禀特征长度为刻画材料的尺寸效应提供了一种可能途径。该文旨在Cosserat连续体的理论框架下发展Perzyna粘塑性模型,以探讨颗粒材料流变的尺寸效应与影响机制。首先基于Drucker-Prager屈服准则导出了Cosserat连续体粘塑性模型的一致性算法,获得了过应力本构方程积分算法与一致切向模量的封闭形式,并在ABAQUS二次平台上采用用户自定义单元(UEL)予以程序实现。有限元数值算例模拟了软岩试样的三轴压缩蠕变和两种堆石料试样在常规三轴条件下的蠕变和应力松弛,数值预测结果与相应试验结果具有较好的一致性,表明该流变模型的适应性。同时,将颗粒的球型指数、圆度和平均粒径作为表征颗粒材料内禀特征长度的一种度量,以反映颗粒材料的试样尺寸及其颗粒粒径与形状对流变过程中的轴向应变、偏应变和偏应力的影响关系,表明所发展的流变模型可以捕捉颗粒材料流变行为的压力相关性和尺寸效应。
[Abstract]:The viscoplastic constitutive relation of classical continuum theory lacks the correlation of material scale, so it is difficult to characterize the size effect of particle material rheology. The intrinsic characteristic length in Cosserat continuum provides a possible way to characterize the size effect of material. The purpose of this paper is to develop the viscoplastic model of Cosserat continuum in order to study the size effect and influence mechanism of the rheology of granular materials. Based on the Drucker-Prager yield criterion, the consistency algorithm of the viscoplastic model of Cosserat continuum is derived, and the closed form of the integral algorithm of the overstress constitutive equation and the uniform tangential modulus is obtained. And on the second platform of ABAQUS, the user defined unit (UEL) is used to realize the program. Finite element numerical examples are used to simulate the triaxial compressive creep of soft rock samples and the creep and stress relaxation of two kinds of rockfill specimens under conventional triaxial conditions. The numerical prediction results are in good agreement with the corresponding experimental results. It shows the adaptability of the rheological model. At the same time, the spherical index, roundness and average particle size of particles are taken as a measure to characterize the intrinsic characteristic length of particle material to reflect the axial strain of the sample size, particle size and shape of particle material on the rheological process. The relationship between strain and stress indicates that the developed rheological model can capture the pressure dependence and size effect of the rheological behavior of granular materials.
【作者单位】：武汉大学土木建筑工程学院;
【基金】：国家自然科学基金项目(11372230)
【分类号】：TU43;O33

【共引文献】