Integrated Experimental- Computational Modeling of Deformation and Fatigue in Advanced Structural Materials

先进结构材料变形和疲劳的综合实验计算模型

• 批准号: 1136219
• 负责人: Somnath Ghosh
• 金额: $ 9.43万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-04-01 至 2013-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1136219&HistoricalAwards=false
• 关键词: Integrated; Experimental; Computational; Modeling; Deformation

In this collaborative effort, the PI?s will develop a system of 3D image-based computational models for finite deformation crystal plasticity modeling that incorporates morphological features and crystallographic orientations of real material microstructures. An innovative grain-based adaptive finite element model will be created for accurate and efficient analyses, overcoming limitations of conventional FE methods. Each grain in a polycrystalline aggregate will be represented by a single super-element incorporating a special hybrid assumed stress-plastic strain formulation. The element will feature adaptive augmentation of resolution to represent evolving localization zones and nascent cracks in the microstructure. Crystallographic dislocation densities will also be incorporated as spatial field variables, which can convect and localize to affect plastic hardening. Effective multi-scaling schemes for coupling the dislocation density model with efficient coarse-grained crystal plasticity models will be developed. The GAFEM developments will also be accompanied by a multiple time scale model for simulating large number of cycles required to capture initiation and evolution in fatigue crack simulations. New strategies for the measurement of microstructural response to mechanical loading will be incorporated for calibrating constitutive models. Novel, complementary experiments at different scales, will use a combination of focused ion beam (FIB) micromachining of test articles coupled with testing in a modified nanoindentor and other testing methods, enabling extraction of high quality uniaxial and simple bending constitutive data, and state-of-the-art SEM and TEM observations. Interfaces will be characterized with pillar/cantilever testing of bicrystals and with a combination of orientation microscopy (OM) analysis, surface strain mapping and optical interferometry. These procedures will form a basis for the development of property databases necessary for verification and validation of microstructure-sensitive deformation and damage modeling. The program, upon completion, will provide an unprecedented detailed and integrated understanding of the role of microstructure on deformation and failure characteristics in Ti alloys. This is critical to reliable materials design, especially with respect to creep and fatigue characteristics. Success of this new paradigm will be of great interest to industries such as GE Aviation since the time and cost saving for inserting advanced alloys in safety-critical applications will be tremendous and will allow industry to leapfrog present technologies.

在这场合作中，PI？s将开发一个系统的三维图像为基础的有限变形晶体塑性建模，结合形态特征和晶体取向的真实的材料微观结构的计算模型。一个创新的基于颗粒的自适应有限元模型将被创建为准确和有效的分析，克服传统的有限元方法的局限性。多晶聚集体中的每个晶粒将由一个单一的超单元表示，该超单元包含一个特殊的混合假设应力-塑性应变公式。该元素将具有分辨率的自适应增强功能，以代表微观结构中不断变化的局部区域和新生裂纹。晶体位错密度也将被纳入空间场变量，它可以对流和本地化，影响塑性硬化。有效的多尺度计划耦合位错密度模型与有效的粗晶晶体塑性模型将被开发。 GAFEM的开发还将伴随着一个多时间尺度模型，用于模拟在疲劳裂纹模拟中捕获萌生和演变所需的大量循环。 新的策略，用于测量的微观结构响应机械载荷将被纳入校准本构模型。在不同规模的新的，互补的实验，将使用聚焦离子束（FIB）微加工的测试物品加上测试在一个修改后的nanoindentor和其他测试方法的组合，使提取高品质的单轴和简单的弯曲本构数据，和国家的最先进的SEM和TEM观察。界面的特点是柱/悬臂梁测试的双晶体和取向显微镜（OM）分析，表面应变映射和光学干涉相结合。 这些程序将形成一个基础，为验证和验证微观结构敏感的变形和损伤建模所需的属性数据库的发展。该计划完成后，将提供一个前所未有的详细和综合的理解微观结构的作用，变形和失效特征的钛合金。这对于可靠的材料设计至关重要，特别是在蠕变和疲劳特性方面。这种新模式的成功将对GE航空等行业产生巨大的兴趣，因为在安全关键应用中插入先进合金所节省的时间和成本将是巨大的，并将使行业跨越现有技术。