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

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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.