论文标题
雪的高应变率变形的离散元素模型
Discrete element model for high strain rate deformations of snow
论文作者
论文摘要
在工程应用中,雪经常发生大变形。在这些变形过程中,雪从烧结的多孔材料转变为颗粒状材料。为了捕获此过程的基本机械行为,离散元素(DE)模型在物理上是最合适的。它明确包括所有相关组成部分:由粘合晶粒组成的雪微观结构,键的破裂以及散发谷物的随后重排和相互作用。我们根据开源代码liggghts开发并校准了De Snow模型。在模型中,雪粒由随机分布的弹性球表示,该球由弹性 - 脆性键连接。这种粘合的结构对应于烧结的雪。施加外力后,键中的应力可能会超过其强度,键断裂,并且我们得到的颗粒松散,对应于粒状雪。模型参数可以分为依赖温度的材料参数和依赖雪类的微观结构参数。通过在冷实验室中进行的休息角度和几个高应变速率机械测试来校准该模型。我们通过模拟具有较大菌株的不同雪类型的组合压缩和剪切变形来证明DE雪模型的性能。该模型成功地重现了实验。机械降雪行为的大多数特征是由模型捕获的,例如断裂行为,低密度和高密度降雪之间的差异,颗粒剪切流量或低密度积雪的密度。该模型有望为多种雪类型模拟任意高应变率过程,因此似乎适用于不同的雪工程问题。
In engineering applications snow often undergoes large and fast deformations. During these deformations the snow transforms from a sintered porous material into a granular material. In order to capture the fundamental mechanical behavior of this process a discrete element (DE) model is the physically most appropriate. It explicitly includes all the relevant components: the snow microstructure, consisting of bonded grains, the breaking of the bonds and the following rearrangement and interaction of the loose grains. We developed and calibrated a DE snow model based on the open source DE code liggghts. In the model snow grains are represented by randomly distributed elastic spheres connected by elastic-brittle bonds. This bonded structure corresponds to sintered snow. After applying external forces, the stresses in the bonds might exceed their strength, the bonds break, and we obtain loose particles, corresponding to granular snow. Model parameters can be divided into temperature dependent material parameters and snow type dependent microstructure parameters. The model was calibrated by angle of repose experiments and several high strain rate mechanical tests, performed in a cold laboratory. We demonstrate the performance of the DE snow model by the simulation of a combined compression and shear deformation of different snow types with large strains. The model successfully reproduces the experiments. Most characteristics of the mechanical snow behavior are captured by the model, like the fracture behavior, the differences between low and high density snow, the granular shear flow or the densification of low density snow. The model is promising to simulate arbitrary high strain rate processes for a wide range of snow types, and thus seems useful to be applied to different snow engineering problems.