三维模拟高温高静水压下矿物颗粒边界应力分布

3D modeling of stress distribution at mineral grain boundaries at high temperature and high hydrostatic pressure

为探讨矿物颗粒边界应力分布规律,采用有限元程序ANSYS三维模拟、计算高温(800℃)、高静水压(1.6GPa)下,立方体结构的镁橄榄石和透辉石矿物集合体在加压瞬间各向同性完全弹性变形时的应力场。通过改变矿物颗粒边界层组成物质的弹性模量与泊松比,进一步计算、分析边界层的等效应力和组分矿物的体积模量系数。研究结果表明:两矿物颗粒边界具有应力集中现象,边界层内部应力分布不均,颗粒边界层的等效应力等值线随着颗粒边界组成物质的弹性模量的微小改变而变化明显;2种不同矿物颗粒构成的过渡边界层的等效应力与其组分矿物的体积模量系数呈高斯函数关系;矿物颗粒边界层的等效应力与其组成物质的弹性模量之间具有高斯分布规律。

To study the stress distribution law, stress field at grain boundaries of cube forsterite and cube diopside was modeled with three dimensional finite element technique at 800 ℃ and 1.6 GPa hydrostatic pressure, where the mineral grains and grain boundaries were all considered as elastic isotropy. Adjusting elastic modulus and Poisson’s ratio of mineral grain boundary layer, equivalent stress and the bulk modulus coefficient of the composition were calculated and analyzed. The results show that stress concentrates on the boundaries and its inner distribution are uneven. The equivalent stress contours at grain boundaries change apparently with the small variations of its elastic modulus. Gaussian distribution exists between equivalent stresses and the bulk modulus coefficient of the composition for the grain boundary layers by the transition from the minerals. The same relationship is found between the equivalent stresses and elastic modulus of the compositions in the mineral grain boundary layers.