论文标题
脆性断裂的随机相位场建模:计算多个裂纹模式及其概率
Stochastic phase-field modeling of brittle fracture: computing multiple crack patterns and their probabilities
论文作者
论文摘要
在脆性断裂的变分相田间建模中,要最小化的功能不是凸,因此功能的必要平稳性条件可以允许多个溶液。在实际计算中获得的解决方案通常是几个局部最小化器中的一个。有时会记录由数值或物理参数的小扰动引起的多种溶液的证据,但在文献中未明确研究。在这项工作中,我们专注于这个问题,并主张范式转变,从寻找一种特定解决方案到同时描述所有可能的解决方案(本地最小化器),以及它们发生的概率。受到最新方法的启发,提倡测量解决方案(Young措施以及它们对统计溶液的概括)及其在流体力学中的数值近似,我们提出了通过随机扰动功能的变异脆性断裂问题的随机松弛。我们介绍了随机解决方案的概念,其主要优势是可以捕获基础域中裂纹相位字段的点对点相关性。这些随机解决方案由经典确定性解空间中的随机字段或随机变量表示。在数值实验中,我们使用一种简单的蒙特卡洛方法来计算此类随机溶液的近似值。计算的最终结果不是单个裂纹模式,而是几种可能的裂纹模式及其概率。使用不断发展的随机场的随机解决方案框架还允许在中间裂纹模式上调节进一步裂纹路径的概率的有趣可能性。
In variational phase-field modeling of brittle fracture, the functional to be minimized is not convex, so that the necessary stationarity conditions of the functional may admit multiple solutions. The solution obtained in an actual computation is typically one out of several local minimizers. Evidence of multiple solutions induced by small perturbations of numerical or physical parameters was occasionally recorded but not explicitly investigated in the literature. In this work, we focus on this issue and advocate a paradigm shift, away from the search for one particular solution towards the simultaneous description of all possible solutions (local minimizers), along with the probabilities of their occurrence. Inspired by recent approaches advocating measure-valued solutions (Young measures as well as their generalization to statistical solutions) and their numerical approximations in fluid mechanics, we propose the stochastic relaxation of the variational brittle fracture problem through random perturbations of the functional. We introduce the concept of stochastic solution, with the main advantage that point-to-point correlations of the crack phase fields in the underlying domain can be captured. These stochastic solutions are represented by random fields or random variables with values in the classical deterministic solution spaces. In the numerical experiments, we use a simple Monte Carlo approach to compute approximations to such stochastic solutions. The final result of the computation is not a single crack pattern, but rather several possible crack patterns and their probabilities. The stochastic solution framework using evolving random fields allows additionally the interesting possibility of conditioning the probabilities of further crack paths on intermediate crack patterns.