Abstract In applying discrete numerical methods to model large-displacement problems, such as rockslides, accurate contact force calculation requires correct representation of the evolving contact status. In the discontinuous deformation analysis (DDA), open-close iteration (OCI) serves the crucial role of ascertaining that contact status is properly updated throughout an assembly of discrete blocky elements. OCI is a simple, straightforward and intuitive procedure but has shortcomings that affect analysis accuracy. Alternatives are generally computationally involved and have other issues, and OCI with its large installed base can still be one of the most desirable ways to track contact state with proper improvements. This is exactly this study aims to achieve. This study proposes an augmented open-close iteration (AOCI) algorithm that amends the shortcomings of OCI through: (1) it enhances the modeling of transition between contact states; (2) it provides the control mechanism for improving shear forces and shear movement direction also during OCI iteration. The AOCI is easy to add to the existing structure of OCI. The improved performance of AOCI over the traditional approach is demonstrated using both static and dynamic test cases.

中文翻译：

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在不连续变形分析中使用增强的开闭迭代公式改进摩擦力计算

摘要 在应用离散数值方法模拟大位移问题时，如岩石滑坡，精确的接触力计算需要正确表示不断变化的接触状态。在不连续变形分析 (DDA) 中，开闭迭代 (OCI) 起着至关重要的作用，以确定接触状态在整个离散块状元素组装过程中是否正确更新。OCI 是一个简单、直接和直观的程序，但存在影响分析准确性的缺点。替代方案通常涉及计算并存在其他问题，并且拥有庞大安装基础的 OCI 仍然是通过适当改进跟踪接触状态的最理想方法之一。这正是本研究旨在实现的目标。本研究提出了一种增强开闭迭代（AOCI）算法，该算法通过以下方式修正了 OCI 的缺点：（1）它增强了接触状态之间转换的建模；(2) 它也提供了在 OCI 迭代过程中改善剪切力和剪切运动方向的控制机制。AOCI 很容易添加到 OCI 的现有结构中。使用静态和动态测试用例证明了 AOCI 优于传统方法的性能。