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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。
The multi-dimensional virtual internal key (VMIB) model is a multi-scale mechanical model based on the virtual internal key (VIB) theory. According to VIB and VMIB, the microstructures of cracked material and crackless material are the same, that is, they are microscopically composed of network structure composed of randomly distributed mass particles and virtual internal bonds. The difference between the two materials is that the cracked material has a large distance between the particles at the crack, so that the interaction of the particles (virtual internal bond stiffness) is almost zero and the crack shows macroscopically. In order to reproduce the macroscopic crack effect, an initial deformation is given to the particle assembly at the crack site, so that the distance between the particles (virtual internal key deformation) is increased so that the interaction of particles (virtual internal key rigidity) is negligible. With this method, the cracked material can be described by a unified constitutive equation without the macrocracking being treated as a discontinuity, simplifying the problem. At the same time, since the VIB and VMIB models are discrete at the constitutive level and the fracture failure criterion of materials is included in the constitutive relation, this method avoids the problems of re-division of grids and selection of external fracture criterion, Computational efficiency. By simulating the cracking process of two parallel cracks with different arrangement, it is concluded that this method can reproduce the propagation of multiple cracks.