A Hybrid Iterative Solver for Robustly Capturing Coulomb Friction in Hair Dynamics
A Hybrid Iterative Solver for Robustly Capturing Coulomb Friction in Hair Dynamics
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DOI：
10.1145/2024156.2024173
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发表时间：
2011-12-01
影响因子：
6.2
通讯作者：
Boissieux, Laurence
中科院分区：
文献类型：
--
作者：
Daviet, Gilles;Bertails-Descoubes, Florence;Boissieux, Laurence
头发纤维之间的干摩擦在集体头发动态行为中起着主要作用，因为它解释了典型的非光滑特征，如粘滑不稳定性。然而，由于非光滑摩擦的建模带来的挑战，以往的头发力学模型要么忽略了摩擦，要么使用了近似的平滑摩擦模型，从而失去了重要的视觉特征。在这篇文章中，我们提出了一种新的通用稳健求解器，用于捕获紧密堆积的纤维(如头发)的大型组件中的库仑摩擦。我们的方法基于迭代算法，通过引入一种混合策略来高效而稳健地解决每个单接触问题，该混合策略结合了(精确)库仑摩擦的新的找零公式和作为故障安全的解析求解器。事实证明，我们的全局解算器非常健壮且高度可扩展，因为它可以以合理的计算成本处理多达数千个密集堆积的纤维，受到数万个摩擦接触的影响。它可以方便地组合到任何具有不同静止形状的纤维模型，从光滑到卷曲。我们的结果与真实的头发运动进行了视觉验证，描绘了典型的头发集体效果，并极大地增强了标准头发模拟器的真实感。
Dry friction between hair fibers plays a major role in the collective hair dynamic behavior as it accounts for typical nonsmooth features such as stick-slip instabilities. However, due the challenges posed by the modeling of nonsmooth friction, previous mechanical models for hair either neglect friction or use an approximate smooth friction model, thus losing important visual features. In this paper we present a new generic robust solver for capturing Coulomb friction in large assemblies of tightly packed fibers such as hair. Our method is based on an iterative algorithm where each single contact problem is efficiently and robustly solved by introducing a hybrid strategy that combines a new zero-finding formulation of (exact) Coulomb friction together with an analytical solver as a fail-safe. Our global solver turns out to be very robust and highly scalable as it can handle up to a few thousand densely packed fibers subject to tens of thousands frictional contacts at a reasonable computational cost. It can be conveniently combined to any fiber model with various rest shapes, from smooth to curly. Our results, visually validated against real hair motions, depict typical hair collective effects and greatly enhance the realism of standard hair simulators.