CAREER: Time-Dependent Multi-Scale Frameworks for Mechano-Thermo-Hygro-Visco and Damage Behaviors of Composite Materials and Structures

职业：复合材料和结构的力学-热-湿-粘和损伤行为的时间相关多尺度框架PI：Anastasia Muliana（德克萨斯A& M大学）纤维增强聚合物（FRP）复合材料结构的长期力学性能和耐久性受到其微观结构演变的强烈影响。 复合材料结构的多尺度分析框架，认识到由于耦合的时间-应力-温度-湿度效应的微观结构恶化，需要结合实验工作的微观结构表征，以了解和预测材料/结构行为。 建议的CAREER计划旨在开发一种方法，用于将复合材料成分（纤维-基体-界面）的演变与FRP结构的整体粘弹性和损伤行为联系起来，并有效地建模和表征微观结构特性。 研究计划包括（1）分析/计算公式化阶段，以开发多尺度材料和结构建模框架。 该框架是基于三个主要组成部分的合成：与湿热，应力和损伤的影响，在组分（基质界面）水平，层次化的微观力学本构模型的时间相关的本构模型的数值算法的几个复合材料增强，分层结构元素，包括通过厚度材料的变化和横向剪切变形。 该框架是实现在一个通用的三维（3D）非线性有限元（FE）代码。 (2)实验阶段，以表征原位微观结构特性，并验证所提出的多尺度框架。 宏观尺度测试包括FRP试样的轴向和剪切蠕变测试，并使用数字图像相关（DIC）记录全场表面位移。 微尺度测试包括对纤维、基体和界面区域的蠕变压痕和划痕测试。 虽然在多尺度材料本构建模方面取得了重大进展，但所提出的研究计划是重要和独特的，因为它提供了一个整体的微观结构-全球材料和结构框架，该框架将时间，机械，湿热和损伤行为从微观水平（微米尺度）耦合到结构水平（米尺度）的非线性响应。 本研究的结果将增进对异质材料的微结构行为的了解，这些微结构行为强烈影响复合材料结构的整体响应。 这将有利于民用和航空基础设施，如飞机结构部件、桥梁、隧道、流体输送管道等。 研究和教育计划相结合，以便教育举措利用研究成果。 职业计划的跨学科性质将超越和影响机械，民用，航空航天和石油工程部门的学生。 教育计划的重点是加强固体力学课程在得克萨斯州A M通过开发研究生课程计算非弹性和准备本科生和研究生谁可以有助于非线性力学的异质系统都作为工程师和研究人员。 为了加强学生在材料和结构行为方面的学习，将开发与使用DIC技术的真实的测试相关的可视化和动画。 将建立一个针对高中教师的暑期研究计划，向公众传播微观结构材料演变的研究。 此外，还将开始与工业界合作，将研究成果应用于石油钻探和飞机结构的分析。

CAREER: Time-dependent Multi-scale Frameworks for Mechano-thermo-hygro-visco and Damage Behaviors of Composite Materials and StructuresPI: Anastasia Muliana (Texas A&M University)Long-term mechanical performance and durability of fiber reinforced polymer (FRP) composite structures are strongly influenced by the evolution of their microstructure. A multi-scale analysis framework of composite structures that recognize microstructural deterioration due to coupled time-stress-temperature-moisture effects are needed in conjunction with experimental works for microstructural characterization to understand and predict material/structural behaviors. The proposed CAREER program aims to develop a method for linking the evolution of composite constituent (fiber-matrix-interphase) to the overall viscoelastic and damage behaviors of FRP structures and to effectively model and characterize the microstructural properties. The research plan consists of (1) An analytical/computational formulation phase to develop a multi-scale material and structural modeling framework. The framework is based on a synthesis of three major components: numerical algorithms of time-dependent constitutive models with hygrothermal, stress, and damage effects at the constituent (matrix-interphase) levels, hierarchical micromechanical constitutive models for several composite reinforcements, and layered structural elements that incorporate through-thickness material variability and transverse shear deformations. The framework is implemented in a general three-dimensional (3D) nonlinear finite element (FE) code. (2) Experimental phase to characterize in-situ microstructural properties and verify the proposed multi-scale framework. Macro scale testing includes axial and shear creep tests on FRP specimens with Digital image correlation (DIC) to record full field surface displacements. Micro scale testing includes creep indentation and scratch tests on fiber, matrix and interphase regions. While major progress has been made in multi-scale material constitutive modeling, the proposed research plan is significant and unique because it provides an overall microstructural-global material and structural framework that couples time, mechanical, hygrothermal, and damage behaviors from the micro-level (micron scale) to the nonlinear response at the structural level (meters scale). The outcome of this research will enhance understanding of microstructural behaviors of heterogeneous materials that strongly influence the global responses of composite structures. This will benefit both civil and aerospace infrastructures, such as aircraft structural components, bridges, tunnels, fluid conveying pipes, and many others. The research and education plans are integrated so that the education initiatives draw upon the research results. The interdisciplinary nature of the CAREER Plan will overreach and impact students in the mechanical, civil, aerospace, and petroleum engineering departments. The educational plan focuses on strengthening solid mechanics curriculum at Texas A&M by developing graduate course in Computational Inelasticity and preparing undergraduate and graduate students who can contribute to nonlinear mechanics of heterogeneous systems both as engineers and researchers. To enhance student learning in material and structural behaviors, visualization and animations that are correlated with real testing using DIC technique will be developed. A summer research program that targets high-school teachers will be established to disseminate research in the evolution of microstructural materials to public. In addition, collaborations with industry will be initiated to apply the research finding in the analyses of oil drilling and aircraft structures.