论文标题

概率的植物动力框架,并应用于研究统计尺寸效应

A probabilistic peridynamic framework with an application to the study of the statistical size effect

论文作者

Hobbs, Mark, Rappel, Hussein, Dodwell, Tim

论文摘要

数学模型对于理解和预测自然和工程产生的系统至关重要。然而,数学模型是对真实现象的简化,从而使预测受到不确定性。因此,量化不确定性的能力对于任何建模框架都是必不可少的,使用户能够评估某些参数对关注量的重要性,并通过对不确定性的严格了解来控制模型输出的质量。 Peridyanic模型是一类特定的数学模型,事实证明,对于大量的材料故障问题而言,非常准确且健壮。然而,perid肌模型的高计算费用仍然是一个主要限制,阻碍了需要大量模拟的外环应用,例如,不确定性量化。这项贡献提供了一个使此类计算可行的框架。通过采用多级蒙特卡洛(MLMC)框架,其中大多数模拟是使用粗网格进行的,并且使用细网格进行相对较少的模拟,可以实现计算成本的显着降低,并且可以估算结构性故障的统计数据。结果表明,在标准的蒙特卡洛估计器上,速度为16倍,从而在计算昂贵的peridensic模型中实现了不确定参数的正向传播。此外,多级方法提供了离散误差和采样误差的估计,从而提高了对数值预测的置信度。通过检查准脆性材料中的统计尺寸效应来证明该方法的性能。

Mathematical models are essential for understanding and making predictions about systems arising in nature and engineering. Yet, mathematical models are a simplification of true phenomena, thus making predictions subject to uncertainty. Hence, the ability to quantify uncertainties is essential to any modelling framework, enabling the user to assess the importance of certain parameters on quantities of interest and have control over the quality of the model output by providing a rigorous understanding of uncertainty. Peridynamic models are a particular class of mathematical models that have proven to be remarkably accurate and robust for a large class of material failure problems. However, the high computational expense of peridynamic models remains a major limitation, hindering outer-loop applications that require a large number of simulations, for example, uncertainty quantification. This contribution provides a framework to make such computations feasible. By employing a Multilevel Monte Carlo (MLMC) framework, where the majority of simulations are performed using a coarse mesh, and performing relatively few simulations using a fine mesh, a significant reduction in computational cost can be realised, and statistics of structural failure can be estimated. The results show a speed-up factor of 16x over a standard Monte Carlo estimator, enabling the forward propagation of uncertain parameters in a computationally expensive peridynamic model. Furthermore, the multilevel method provides an estimate of both the discretisation error and sampling error, thus improving the confidence in numerical predictions. The performance of the approach is demonstrated through an examination of the statistical size effect in quasi-brittle materials.

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