An Experimental and Computational Framework Incorporating Uncertainty for Modeling Ductile Failure of Metals

包含金属延性失效建模不确定性的实验和计算框架

• 批准号: RGPIN-2018-04202
• 负责人: Simha, Hari
• 金额: $ 1.97万
• 依托单位: University of Guelph
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2019
• 资助国家: 加拿大
• 起止时间: 2019-01-01 至 2020-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=681763
• 关键词: Experimental; Computational; Framework; Incorporating; Uncertainty

Policy makers and technical decision makers increasingly rely on results of large-scale computations. Climate change policy, for instance, may be guided by predictions of rise in global temperatures obtained using computational fluid dynamics procedures. Such predictions invariably include uncertainty. This is tantamount to putting error bars on computational results. In contrast, in solid mechanics computations, large-scale automobile crash simulations are carried out, the results post-processed, and metrics to assess passenger safety of the design computed -- but the associated uncertainties are ignored.******Uncertainty stems from the metal's response during failure, the models used to describe the failure behaviour; and uncertainty on account of the algorithms used for discretization of space and time. In the modeling of ductile failure of metals, my research programme will investigate mitigation and quantification of uncertainty stemming these three sources, and the probabilistic (Bayesian) tools used to quantify the uncertainty. ******Personal experience with material testing of conventional engineering alloys has shown that components and structures display more scatter in deformation and failure response than the specimens used for material property evaluation. Accordingly, I propose to develop a novel specimen geometry, in which strategically located cut-outs leads to a sequence of failures when the specimen is loaded under tension. In the specimen, because of the cut outs, multiple failure paths are observed and fewer tests for model calibration are required. Such specimens may be used to characterize the uncertainty in deformation and failure behaviour at the structural-level with a limited number of tests.******The second source of uncertainty is the constitutive description of the deformation and failure. Full-field displacement measurements of the developed specimens will be used to estimate the uncertainty in the deformation and failure parameters. ******A third source of uncertainty is the computational modeling of failure. I propose to develop a novel element, for use in the explicit dynamic computations that uses the floating node method of Chen et al. The implementation will be in a general purpose finite element software such as Abaqus. ***The brute-force computation of uncertainty and associated statistical parameters requires a large number of computations especially in the context of dynamic loading. I propose to investigate techniques such as response surface (also called surrogate model analysis) to quantify the uncertainty and Bayesian methods for model calibration. ******All of the above developments constitute a framework for application in sectors such as dynamic fracture of pressurized oil pipelines, response of armor and layered armor systems, and failure of multi-material welds.

决策者和技术决策者越来越依赖大规模计算的结果。例如，气候变化政策可以由使用计算流体动力学程序获得的全球气温上升预测来指导。这样的预测总是包含不确定性。这相当于在计算结果上设置了误差栏。相比之下，在固体力学计算中，进行了大规模的汽车碰撞模拟，结果进行了后处理，计算了评估设计乘客安全性的指标--但相关的不确定性被忽略了。*不确定性源于金属在故障期间的响应，用于描述故障行为的模型；以及不确定性，因为用于空间和时间离散化的算法。在金属延性失效的建模中，我的研究计划将调查这三个来源的不确定性的缓解和量化，以及用于量化不确定性的概率(贝叶斯)工具。传统工程合金材料试验的个人经验表明，与用于材料性能评估的试件相比，部件和结构在变形和失效响应方面表现出更大的离散性。因此，我建议开发一种新的试件几何结构，在该几何结构中，当试件在拉伸下加载时，位于策略性位置的断口会导致一系列故障。在试件中，由于切割，可以观察到多条失效路径，并且需要较少的模型校准试验。这种试件可以用来通过有限数量的试验来表征结构层面上的变形和破坏行为的不确定性。第二个不确定性源是变形和破坏的本构描述。开发的试件的全场位移测量将用于估计变形和破坏参数的不确定性。*不确定性的第三个来源是对故障的计算建模。我建议开发一种新的单元，用于显式动力计算，使用Chen等人的浮动节点方法。该方法将在ABAQUS等通用有限元软件中实现。*对不确定性和相关统计参数的暴力计算需要大量计算，特别是在动态加载的情况下。我建议研究一些技术，如响应面(也称为替代模型分析)来量化不确定性，以及贝叶斯方法来进行模型校准。*所有上述发展构成了一个框架，可用于压力输油管道的动态断裂、装甲和分层装甲系统的响应以及多材料焊接失效等领域。