中文摘要：

多维虚内键（VMIB）模型是基于虚内键（VIB）理论的一种多尺度力学模型。依据VIB和VMIB观点,有裂纹材料与无裂纹材料的微观组构是相同的,即在微观上都是由随机分布的质量微粒与虚内键所组成的网络结构构成。两种材料不同之处在于有裂纹材料在裂纹处的微粒距离很大,以至于微粒的相互作用（虚内键刚度）几乎为零,宏观上表现为裂纹。为了再现宏观裂纹效应,赋予裂纹处微粒集合体一初始变形,使微粒之间的距离（虚内键变形）增大,从而使微粒的相互作用（虚内键刚度）可以忽略不计。通过该方法,有裂纹材料可以通过统一的本构方程来描述,而不用将宏观裂纹当作不连续面来处理,使问题变得简单化。同时,由于VIB和VMIB模型在本构层次上就是离散的,材料的断裂破坏准则已包含于本构关系之中,所以应用该方法避免了网格重新划分及外部断裂准则选取的问题,提高了计算效率。通过对两条不同排列的平行裂纹开裂过程进行模拟,得出本方法可以再现多裂纹的扩展过程。

英文摘要：

Virtual multidimensional internal bonds （VMIB） was a multiscale mechanical model based on the Virtual Internal bond （VIB） theory. From the view of VIB and VMIB, the microstructures of intact materials and cracked materials were consistent in that both the two materials consisted of network constructed by the randomized materials particles and virtual internal bonds in micro scale. For the cracked materials, the distance of material particles at the pre-existing crack was so large that the interaction （bond stiffness） between particles becomes negligible in micro scale, leading to the macro crack. To simulate the pre-existing crack, an initial deformation was assigned to the aggregate of material particles at the pre-existing crack. The assigned initial deformation was large enough to make interaction between material particles negligible, so as to represent the behavior of the pre-existing crack, By use of this method, the effect of the pre-existing crack was incorporated into the constitutive relation of materials, hence, the cracked materials could be described by the uniform constitutive relationship, which made the present method free of the special treatment of cracks on the element discretization level as the conventional continuum mechanics method did. Moreover, the VlVIIB was discrete at the constitutive level and the failure criterion had been embedded into the constitutive relation by the bond evolution function, so it was free of the problem of remeshing and choice of external fracture criterion when the failure process was simulated. By simulating the fracture process of a square plate containing two parallel pre-existing cracks, the present method is indicated to be capable of representing the fracture propagation and the failure process of multi-cracked rock materials.