Deformation of Engineering Materials Across length and time Scales (DEMAS)

该计划旨在研究工程材料在长度和时间尺度上的变形。该研究计划的长期目标是能够评估和提高用于三个战略行业的金属和非金属复合材料的结构完整性和性能：核，航空航天和运输。在这些行业中使用的材料在承受机械载荷的同时经常暴露于恶劣的环境中。在这样的环境中，材料可逆地（弹性地）或不可逆地（塑性地）变形。塑性变形可以潜在地局部化在工程部件中的特定点处，并且随后导致裂纹成核和灾难性失效。* 有限元是一种强大的数值技术，可用于模拟材料的弹性和塑性变形。晶体塑性作为材料变形的本构模型，可以进一步增强有限元研究变形局部化机理的能力。数值研究往往需要实验观测的发展和验证。例如，电子或X射线显微镜可用于研究纳米和介观尺度的局部变形。** 该程序的目的是表征、公式化和模拟局部塑性变形;申请人提出开发三个数值和实验工具箱，其可以显著提高我们对变形的基本理解：**I）开发温度相关的非局部晶体塑性有限元代码，用于对由滑移带和孪晶的形成引起的塑性变形进行建模。该代码将能够模拟点缺陷和线缺陷之间的相互作用。这是一个独特的和新颖的能力，通过这样的配方，可以研究由缺陷的扩散或线缺陷的爬升导致的空隙形成;因此，该模型可以用于研究和模拟蠕变，疲劳，并最终断裂的多晶体。**II）开发世界领先的运行温度相关原位高分辨率电子背散射衍射和高分辨率数字图像相关技术的能力。这两种技术都是基于扫描电子显微镜的使用;它们可以用于测量纳米、介观和宏观尺度的局部变形，从而验证将在（I）中开发的代码。（一）和（二）的直接应用是在加拿大的核工业。随着CANDU反应堆的老化，辐照增强蠕变已成为一个主要关注的问题。这种变形模式是时间依赖性塑性变形，其建模是（I）的主要目标。这项研究的另一个应用是在航空航天工业。钛和镍合金的抗蠕变和抗疲劳性是制造喷气发动机部件的两个主要因素。

The proposed program aims to study deformation of engineering materials across length and time scales. The long term objective of this research program is to be able to assess and enhance structural integrity and performance of the metallic and non-metallic composites used in three strategic industries: nuclear, aerospace, and transportation. The materials that are used in these industries are very often exposed to hostile environments while carrying mechanical loads. In such environments, materials deform reversibly (elastically) or irreversibly (plastically). Plastic deformation can potentially localize at particular points in engineering components and subsequently lead to crack nucleation and catastrophic failure. ***Finite element is a powerful numerical technique that can be used for simulating elastic and plastic deformation of materials. Crystal plasticity, as a constitutive model for materials' deformation, can further enhance the power of finite element to study mechanisms of deformation localization. Numerical studies often require experimental observations for both development and validation. For instance, electron or X-ray microscopy can be used to study localized deformation at nano and meso scales. ******The aim of this program is to characterize, formulate, and simulate localized plastic deformation; the applicant proposes to develop three numerical and experimental toolboxes that can significantly improve our fundamental understanding of deformation:******I) Developing a temperature dependent non-local crystal plasticity finite element code for modelling plastic deformation caused by formation of slip bands and twins. The code will be able to simulate interaction between point defects and line defects. This is a unique and novel capability as through such formulation, void formation resulting from diffusion of defects or climb of line defects can be studied; hence, the model can be used to study and simulate creep, fatigue, and eventually fracture of polycrystals. ******II) Developing a world leading capability for running temperature dependent in-situ High Resolution Electron BackScatter Diffraction and High Resolution Digital Image Correlation techniques. Both techniques are based on the use of scanning electron microscopes; they can be used for measuring localized deformation at nano, meso, and macro scales and hence validate the code that will be developed in (I).******The immediate application of (I) and (II) is in the Canadian nuclear industry. With the aging of CANDU reactors, irradiation enhanced creep has become a major concern. This mode of deformation is a time dependent plastic deformation the modelling of which is the primarily goal of (I). Another application of this research is in the aerospace industry. Creep and fatigue resistance of titanium and nickel alloys are the two main factors in manufacturing jet engines components.