Virtual Vehicle Research GmbH, Rail Systems, Inffeldgasse 21/A, A-8010, Graz, Austria.
The University of Sheffield, Department of Mechanical Engineering, Mappin Street, S1 3JD, Sheffield, UK.
Sci Rep. 2020 Apr 8;10(1):6045. doi: 10.1038/s41598-020-62827-w.
Particle shape analysis is conducted, to compare two types of railway ballast: Calcite and Kieselkalk. Focus lies on the characterisation of particle angularity using 3D scanner data. In the literature, angularity is often characterised using 2D data, as these types of data are easier to collect. 3D scanner data contain a vast amount of information (e.g. curvatures) which can be used for shape analysis and angularity characterisation. Literature approaches that use 3D data are often not thoroughly tested, due to a lack of test cases. In this work, two new curvature-based angularity indices are introduced and compared to one from the literature. Analytical test bodies with shapes ranging from spherical towards cubic are used for a first plausibility test. Then, 3D scans of ballast stones are compared to artificially rounded meshes. Only one out of three evaluated angularity indices seem to be suited to characterise angularity correctly in all of the above tests: the newly introduced scaled Willmore energy. A complete shape analysis of the scanned ballast stones is conducted and no difference between the two types of ballast can be seen regarding form, angularity, roughness, sphericity or convexity index. These findings of shape analysis are set in the context of previous works, where experimental results and DEM simulations of uniaxial compression tests and direct shear tests were presented for the same ballast types.
进行颗粒形状分析，比较两种类型的铁路道砟：方解石和硅质石灰岩。重点在于使用 3D 扫描仪数据对颗粒棱角进行特征描述。在文献中，棱角通常使用 2D 数据进行特征描述，因为这类数据更容易收集。3D 扫描仪数据包含大量信息（例如曲率），可用于形状分析和棱角特征描述。由于缺乏测试案例，使用 3D 数据的文献方法往往没有经过彻底测试。在这项工作中，引入了两个新的基于曲率的棱角指数，并与文献中的一个进行了比较。使用形状从球形到立方体形的分析测试体进行了初步可行性测试。然后，将道砟石的 3D 扫描与人为圆形的网格进行比较。在所有上述测试中，只有三个评估的棱角指数中的一个似乎适合正确地描述棱角：新引入的缩放威尔莫尔能量。对扫描的道砟石进行了完整的形状分析，在形状、棱角、粗糙度、球形度或凸度指数方面，两种类型的道砟之间没有差异。这些形状分析的结果与之前的工作相结合，其中展示了相同类型的道砟的单轴压缩试验和直接剪切试验的实验结果和 DEM 模拟。
