Jason Patrick

Internal delamination damage in fiber-reinforced composites is difficult to detect and nearly impossible to repair by conventional methods. To date, this failure mechanism remains one of the most significant factors limiting the reliability and leads to wasteful design of composites for lightweight structures [1]. Drawing upon inspiration from biology, self-healing polymers and composites have emerged to combat inevitable degradation from in-service operation and/or unavoidable damage from unexpected overload [2,3]. We propose to develop a sustainable self-healing composite system capable of complete restoration in interlaminar fracture resistance without compromising in-plane mechanical properties. Our project takes a collaborative, interdisciplinary approach by combining polymer mechanics/chemistry, emergent manufacturing, advanced computing and deep learning to accelerate the development of such self-repairing structural composites. This synergistic experimental-computational strategy relies on: (1) a newly realized in situ self-healing platform in thermoset composites via thermal remending of an environmentally inert 3D printed thermoplastic interlayer; and (2) novel microstructural material optimization using automated finite element (FE) simulations and deep learning. The envisioned self-repairing composite and complementary computational design platform will eliminate the need for costly inspection, reduce overall maintenance/replacement, and provide enhanced safety, resilience, and reliability in order to preserve DoD competitive advantage.

Abstract: The NSF IUCRC for Integration of Composites into Infrastructure (CICI) is specialized at innovating advanced fiber-reinforced polymer (FRP) composites and techniques for the rapid repair, strengthening or replacement of highway, railway, waterway, bridge, building, pipeline and other critical civil infrastructure. The Center consists of West Virginia University (WVU) as the lead institution in the current Phase II, with North Carolina State University (NCSU), the University of Miami (UM), and the University of Texas at Arlington (UTA) as partner university sites. CICI is currently establishing an international site at the Center for Engineering and Industrial Development (CIDESI) in Queretaro, Mexico, through a collaboration between NSF and the National Council of Science and Technology (CONACYT) in Mexico. The primary objective of the Center is to accelerate the adoption of polymer composites and innovative construction materials into infrastructure through joint research programs between the university sites in collaboration with the composites and construction industries. In Phase III, CICI aims to broaden its scope of research in composites to include: 1) nondestructive testing methods; 2) manufacturing techniques, such as 3D printing; 3) inspection techniques, such as the use of drones with high resolution cameras; 4) in-situ modifications of infrastructure systems, resulting in enhanced durability and thermo-mechanical properties; and 5) cost-effective recycling of high value composites, enabled by the addition of CIDESI.

Fiber-reinforced composites (FRCs) are ubiquitous structural materials, particularly in lightweight applications (e.g., aerospace), owing to their high specific strength/stiffness. However, the lack of through-thickness reinforcement in laminated composites creates inherent susceptibility to fiber-matrix debonding (i.e., delamination). This multiscale damage is difficult to detect and nearly impossible to repair via conventional methods, and thus remains a significant factor limiting the reliability of FRC structures. Self-healing strategies have emerged to combat material degradation through a bioinspired process of self-repair, thus offering transformative solutions. While technologies that resolve smallscale defects (e.g., scratches) have recently come to market, self-healing of structural-level damage (i.e., interlaminar delamination) remains challenging. The major hurdles are: inability for repeated repair, lack of environmental versatility, and difficulty achieving in situ mechanical recovery under service loads. Hence, there is a pressing need to develop, understand, and deploy a robust self-healing strategy in FRCs that can overcome such obstacles for real-world translation. The proposed I-Corps project aims to close existing self-healing knowledge gaps and address industry needs by building upon a recent laboratory demonstration. The platform features thermoplastic 3D-printed on fibrous reinforcement that is co-laminated with resistive heaters to enable polymer melting and reentanglement for repeated in-service self-healing of interfacial fracture.

Due to the nature of Civil Engineering problems, students have had limited hands-on experiences in classrooms (e.g., learning concepts of structural behaviors of a bridge on a piece of paper if not on a computer screen). The proposed work aims to bring real-world problems in Civil Engineering into classrooms. The main goal of this proposal is to validate the proposed interactive learning tools that promote physical interaction among students and instructors can improve students������������������ understanding of Civil Engineering concepts. Moreover, there are no traditional courses in Civil Engineering that introduces emerging technologies to undergraduate students and students simply have limited chances to learn about them, according to the research team������������������s observation at their three institutions ������������������ North Carolina State University (NCSU) and Texas A&M. Increasing engagement and interaction through emerging technologies in classes has a significant potential to address such educational challenges and prepare our future Civil Engineers for the emerging and non-traditional Civil Engineering career opportunities, in addition to the traditional opportunities. The proposed work is driven by the hypotheses that 1) undergraduate students will better understand Civil Engineering concepts through physical interactions that provide engaged student learning, and 2) they will be better prepared for leveraging advanced technologies that will shape their field of Civil Engineering in their near future. The research team foresees the potential for increasing awareness and interest in Civil Engineering among freshman engineering students before declaring their majors, which will help them make informed career decisions. The proposed work focuses on developing and evaluating two Student-centric Cyber-Physical Systems (SCPS) research prototypes and implementing them in one Engineering and four Civil Engineering undergraduate courses at various levels ������������������ freshmen to senior. Two Civil Engineering concepts of structural engineering and building science will be taught in these five undergraduate courses.

This proposal describes an interdisciplinary research effort to develop multifunctional fiber-composites with integrated self-healing and self-sensing capabilities. The new platform of bioinspired materials will employ microvascular networks for functional fluid transport combined with fiber-optic waveguides for light-activated healing and in situ structural health monitoring. Self-sensing of both damage and the transient healing response will provide real-time, remote feedback of mechanical stasis. In pursuing this ambitious goal, the proposal builds upon recent progress in self-healing composites, microvascular fabrication, in situ fiber-optic interrogation, and dynamic photo-chemistries. This project moves beyond two-part liquid reagents that require adequate vascular density and/or active pumping protocols to achieve sufficient in situ mixing for fracture healing. By employing the latest in sacrificial material advancements and multidimensional vascular templating techniques (e.g. 3D printing), single-liquid photo-reactive chemistries will be sequestered in evolutionary-optimized, biomimetic microvasculature. Through strategic integration of fiber-optics with vascular networks, a novel photonic pathway will be established for autonomous, luminous energy delivery after fracture to accomplish in situ healing and locally probe polymer formation. Self-sensing via in situ spectroscopy will relate internal polymerization with mechanical self-recovery in a remotely accessible, non-destructive manner. Hierarchically patterned fiber-optics around central vasculature will provide an unprecedented mechanism to repair fluidic conduits and restore circulation for repeated heal cycles. Moreover, intrinsic self-recovery of the self-sensing function via translucent healed polymer light transmission will afford repeated sensing cycles. Fiber-composites with synergistic self-healing/sensing capabilities have immediate application in aerospace structures. The multifunctional packaging has the potential to significantly reduce weight, size, and other overdesign costs while improving material performance, reliability, and extending useful lifetime. This breakthrough technology will provide radically enhanced tactical capabilities for competitive advantage in Department of Defense (DOD) operations

The proposed project has an information technology (IT) component that will be coordinated with CICI university partners (UM and NCSU). The following sections highlight the nature of the project������������������s data generation, storage, retention, and sharing components as per NCSU. Expected data This research is expected generate datasets similar to those produced by a typical materials/structures laboratory. The types of data include: ������������������� Experimental measurements from voltage or current measurement devices. These measurements will be converted to useful units through calibration scales. Data will be collected by instruments and sensors such as: strain gauges, load cells, linear variable differential transformers (LVDTs), and displacement transducers. ������������������� Quantitative information in the form of human or machine readouts from measurement devices such as rulers, meter tapes, volume measurement containers, scales, and environmental gauges. ������������������� Qualitative information such as experimental behavior, test conditions, or other significant observations. ������������������� Multimedia data such as photographs, videos, screen captures, audio/video logs captured by cameras, camcorders, or audio recorders, or other multimedia devices. ������������������� Written documents such as progress logs, journal articles, periodic reports, presentations, or any other document detailing progress, results, or outcomes. Data will be collected for the entire duration of this project. In particular, data is expected to be collected during testing preparation, equipment calibration, testing, personnel training, and demonstrations. Data related to the dissemination of information such as written documents or multimedia data, as it relates to publication or sharing of results, creation of manuscripts for archival publication, presentations, and reports, is expected to be generated following significant milestones in the project, and can be expected on a monthly or longer frequency. The project will result in the creation of a software framework for data management, sharing, analysis, and visualization. The code will be managed by graduate students and will be supervised by the PI. The majority of the code will be uploaded to a code repository such as GITHUB, where the code will be made open source under a GNU license.