@article{zhang_pai_turicek_snyder_patrick_soghrati_2024, title={An integrated microstructure reconstruction and meshing framework for finite element modeling of woven fiber-composites}, volume={422}, ISSN={["1879-2138"]}, url={https://doi.org/10.1016/j.cma.2024.116797}, DOI={10.1016/j.cma.2024.116797}, abstractNote={Critical to finite element (FE) analysis of fiber-reinforced composites is accurately reproducing microstructural features via high-quality meshes such that the material heterogeneity and anisotropy are properly captured. Here we present an integrated computational framework for generating realistic FE models of woven composites with high fiber volume fractions (>50%). This framework relies on a virtual microstructure reconstruction algorithm that first generates a geometric model of loosely-woven yarns (i.e., bundles of fibers), followed by performing an FE compaction simulation to create the final textile composite microstructure. A non-iterative meshing algorithm, i.e., conforming to interface structured adaptive mesh refinement (CISAMR), has been adapted to automatically transform synthesized microstructures into conforming FE meshes. CISAMR can handle challenging geometrical features such as thin resin interstices and yarn interpenetrations (an artifact of the FE compaction) without the need to reprocess the digital geometry before mesh generation. We show that the homogenized elastic moduli obtained from FE simulations of an 8-harness satin woven composite laminate agree well with experimental measurements (within 3%), thereby validating the accuracy of the framework. We also present several other mechanical analysis examples, including a nonlinear damage simulation, that further demonstrate the ability of this framework to construct high-fidelity FE models of intricate woven composites with varying 2D and 3D woven architectures.}, journal={COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING}, author={Zhang, Pengfei and Pai, Salil and Turicek, Jack S. and Snyder, Alexander D. and Patrick, Jason F. and Soghrati, Soheil}, year={2024}, month={Mar} }
 @article{snyder_turicek_diesendruck_varley_patrick_2024, title={Unraveling chemical and rheological mechanisms of self-healing with EMAA thermoplastics in fiber-reinforced epoxy composites}, volume={185}, ISSN={["1878-5840"]}, url={https://doi.org/10.1016/j.compositesa.2024.108271}, DOI={10.1016/j.compositesa.2024.108271}, abstractNote={Interlaminar delamination is a prevalent and insidious damage mode limiting the mechanical integrity and lifetime of fiber-reinforced composites. Conventional resolution involves over-design, laborious inspection, and repair/replacement at cost to the economy and environment. Self-healing via in situ thermal remending of thermoplastic interlayers offers a promising solution. However, better understanding of the healing agent and related mechanisms is necessary to tailor healing performance. Here, we compare non-neutralized (copolymer) and metallic-ion neutralized (ionomer) poly(ethylene-co-methacrylic acid) (EMAA) thermoplastics for healing interlaminar fracture. We reveal (i) how EMAA chemistry affects the interfacial reactions driving healing and (ii) the influence of molten viscosity on repair efficiency. At fixed viscosity, higher methacrylic acid content, chain mobility, and lower neutralization positively influence healing, where lower melt viscosity at fixed temperature improves delamination recovery. Thus, this study deepens scientific understanding of key variables for healing interlaminar fracture with EMAA, providing new insight for the design of multifunctional composites.}, journal={COMPOSITES PART A-APPLIED SCIENCE AND MANUFACTURING}, author={Snyder, Alexander D. and Turicek, Jack S. and Diesendruck, Charles E. and Varley, Russell J. and Patrick, Jason F.}, year={2024}, month={Oct} }
 @article{turicek_snyder_nakshatrala_patrick_2023, title={Topological effects of 3D-printed copolymer interlayers on toughening and in situ self-healing in laminated fiber-composites}, volume={240}, ISSN={["1879-1050"]}, url={https://doi.org/10.1016/j.compscitech.2023.110073}, DOI={10.1016/j.compscitech.2023.110073}, abstractNote={Interlaminar delamination in fiber-reinforced composites limits structural capacity and service life. Delaminations, which occur subsurface and can lead to catastrophic failures, are hard to detect and repair. Contrasting traditional mitigation strategies (e.g., inspection, over-design), proactive toughening and responsive self-healing of damaged interfaces offer practical, cost-effective solutions. Our recently developed strategy to address interlaminar damage—3D-printed thermoplastic interlayers and structurally integrated heaters—has been shown to achieve composite toughening and in situ self-healing via thermal remending, abetting repeated repair and improved delamination resistance. Here, we leverage this latest thermal remending strategy to investigate the effects of 3D-printed pattern topology on damage resistance and self-healing response. The chief attributes are: (i) realizing up to 450% increase in mode-I fracture resistance, (ii) restoring up to 100% of the increased fracture resistance for ten consecutive healing cycles, and (iii) achieving in situ self-healing below the thermoset-matrix glass transition temperature, thereby preserving structural integrity during repair. The proposed damage mitigation strategy fosters structural reliability, reduces failure risk, and increases service lifetime—three essential attributes in meeting the multifaceted demands of modern composite infrastructure.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Turicek, Jack S. and Snyder, Alexander D. and Nakshatrala, Kalyana B. and Patrick, Jason F.}, year={2023}, month={Jul} }
 @article{hia_snyder_turicek_blanc_patrick_therriault_2023, title={Electrically conductive and 3D-printable copolymer/MWCNT nanocomposites for strain sensing}, volume={232}, ISSN={["1879-1050"]}, url={https://doi.org/10.1016/j.compscitech.2022.109850}, DOI={10.1016/j.compscitech.2022.109850}, abstractNote={Structural health monitoring (SHM) of safety-critical composite components is essential to ensure mechanical stasis and detect local damage before it can produce global failure. SHM technologies must also adapt to ever-evolving materials and geometries, but traditional piezoresistive strain sensors lack the ability for end-user customization and modifications throughout service-life. Additive manufacturing via fused filament fabrication (FFF) provides a practical pathway to overcome such sensor shortcomings. However, the electrical conductivity of conventional polymer feedstock is not sufficient for accurate strain measurements without compromise to melt viscosity and thus printability. Here we report the development of a new 3D-printable and electrically responsive nanocomposite by melt-mixing poly(ethylene-co-methacrylic acid) (EMAA) with multi-walled carbon nanotubes (MWCNT). Bulk electrical conductivity of 43.9 S m−1 is achieved at only 5 wt% loading – higher than comparable materials – where the nano-dispersion heterogeneity of MWCNT in EMAA is linked to the favorable conductivity while retaining molten flowability. FFF is employed to print thin (150μm) serpentine strain sensors onto the surface of a glass fiber-reinforced polymer composite, which exhibit strong adhesion and accurate piezoresistive sensing under cyclic flexural loading. Twenty consecutive cycles with converged sensor readings (i.e., < 1% variation in measured resistance) demonstrates reliable performance across a relevant service strain range (0.4 – 0.8 %) for such fiber-composites. This rapid fabrication and transferable sensing strategy, suitable for new and existing structures, thus provides a crosscutting SHM solution.}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Hia, Iee Lee and Snyder, Alexander D. and Turicek, Jack S. and Blanc, Fernanda and Patrick, Jason F. and Therriault, Daniel}, year={2023}, month={Feb} }
 @article{turicek_kowal_holland_kalchik_stowe_hart_2022, title={Evaluation of a vascularized, self-healing structure fabricated via material extrusion}, volume={31}, ISSN={["1361-665X"]}, url={https://doi.org/10.1088/1361-665X/ac9adc}, DOI={10.1088/1361-665X/ac9adc}, abstractNote={Abstract
               Material extrusion is a versatile 3D-printing platform for building complex one-off designs. However, the mechanical properties of parts printed using material extrusion are limited by the weak bonding between successive layers of the print, causing premature failure at these critical locations. In this work, an additively manufactured component is crafted which incorporates internal vascular channels capable of autonomously delivering a one-part healing agent to the site of interlaminar damage, when and where it occurs thereby restoring the base structure. The effectiveness of fracture toughness restoration was investigated for various healing times and healing agents. Healing efficiencies of greater than 100% are reported for experimental-type samples using acetone as the healing agent while control specimens using a non-solvent agent demonstrated no recovery. Fractography of damaged surfaces via optical imaging and scanning electron microscopy revealed multiple healing mechanisms that are discussed herein. Lastly, biological analogies and the viability of our design in application are discussed.}, number={11}, journal={SMART MATERIALS AND STRUCTURES}, author={Turicek, Jack and Kowal, Eirene and Holland, Kyle and Kalchik, Dylan and Stowe, Jonathan and Hart, Kevin}, year={2022}, month={Nov} }
 @article{snyder_phillips_turicek_diesendruck_nakshatrala_patrick_2022, title={Prolonged in situ self-healing in structural composites via thermo-reversible entanglement}, volume={13}, ISSN={["2041-1723"]}, url={http://dx.doi.org/10.1038/s41467-022-33936-z}, DOI={10.1038/s41467-022-33936-z}, abstractNote={AbstractNatural processes continuously degrade a material’s performance throughout its life cycle. An emerging class of synthetic self-healing polymers and composites possess property-retaining functions with the promise of longer lifetimes. But sustained in-service repair of structural fiber-reinforced composites remains unfulfilled due to material heterogeneity and thermodynamic barriers in commonly cross-linked polymer-matrix constituents. Overcoming these inherent challenges for mechanical self-recovery is vital to extend in-service operation and attain widespread adoption of such bioinspired structural materials. Here we transcend existing obstacles and report a fiber-composite capable of minute-scale and prolonged in situ healing — 100 cycles: an order of magnitude higher than prior studies. By 3D printing a mendable thermoplastic onto woven glass/carbon fiber reinforcement and co-laminating with electrically resistive heater interlayers, we achieve in situ thermal remending of internal delamination via dynamic bond re-association. Full fracture recovery occurs below the glass-transition temperature of the thermoset epoxy-matrix composite, thus preserving stiffness during and after repair. A discovery of chemically driven improvement in thermal remending of glass- over carbon-fiber composites is also revealed. The marked lifetime extension offered by this self-healing strategy mitigates costly maintenance, facilitates repair of difficult-to-access structures (e.g., wind-turbine blades), and reduces part replacement, thereby benefiting economy and environment.}, number={1}, journal={NATURE COMMUNICATIONS}, publisher={Springer Science and Business Media LLC}, author={Snyder, Alexander D. and Phillips, Zachary J. and Turicek, Jack S. and Diesendruck, Charles E. and Nakshatrala, Kalyana B. and Patrick, Jason F.}, editor={Turicek, Jack S.Editor}, year={2022}, month={Oct} }
 @article{turicek_ratts_kaltchev_masoud_2021, title={Investigation of a helium tubular cold atmospheric pressure plasma source and polymer surface treatment application}, volume={30}, url={http://dx.doi.org/10.1088/1361-6595/abda9f}, DOI={10.1088/1361-6595/abda9f}, abstractNote={Abstract Cold atmospheric plasma (CAP) is a simple and inexpensive method to produce plasma in ambient air. In this study, CAP was generated by flowing helium gas through a glass tube with a copper electrode rounded externally around it to provide an electric field for gas excitation. The plasma extended for up to a few centimeters from the opening of the tube forming a plume. Optical emission spectroscopy (OES) was used to identify the composition of the plasma along the length of the plume. Four positions along the plume were investigated at flow rates of 1, 1.5, and 2.5 L min −1 . Results revealed that the plume consisted of a varying composition of excited state species dependent on the location in the plume and gas flow rate. Identified in the emission spectra were the nitrogen second positive and first negative system along with OH * emissions at 282 and 308 nm. The OH * emissions, found at the opening of the tube, had a higher intensity as the flow rate increased and were attributed to impurities from the ambient air in the source tubing, while the N 2 and N 2 + emissions came from the nitrogen of the ambient air and dominated the rest of the measured spectra. Identifying the species and their intensities at different locations of the plume with different flow rates helped in determining the appropriate location and flow rate needed for a specific application of the surface treatment of ultra-high-molecular-weight-polyethylene (UHMWPE) to change its roughness. Additional spectra were taken in situ with an UHMWPE sample present to compare the reactive species of a free jet with those when a target was present. Finally, preliminary roughness tests showed increases of as low as three and as much as over ten times the pristine value depending on the position of the polymer in the plume and the source flow rate.}, number={2}, journal={Plasma Sources Science and Technology}, publisher={IOP Publishing}, author={Turicek, J and Ratts, N and Kaltchev, M and Masoud, N}, year={2021}, month={Feb}, pages={025005} }
 @article{turicek_ratts_kaltchev_masoud_2021, title={Surface Treatment of Ultra-High Molecular Weight Polyethylene (UHMWPE) by Cold Atmospheric Plasma (CAP) for Biocompatibility Enhancement}, volume={11}, url={https://www.mdpi.com/2076-3417/11/4/1703}, DOI={10.3390/app11041703}, abstractNote={Ultra-high molecular weight polyethylene (UHMWPE) is one of the most commonly used polymers in joint replacements because of its biologically inert properties and low friction coefficient. However, it has downfalls relating to its wear, adhesion, and lubrication. In this study, UHMWPE samples were treated with a tubular helium cold atmospheric pressure (CAP) plasma source in order to improve three properties of the polymer: (1) its wear resistance, which was characterized by durometer hardness, (2) its lubrication characterized by water contact angle, and (3) its adhesion characterized by both root mean square surface roughness (Rq) and water contact angle. The polymer was treated by two different parts of the plasma plume (the base and the tip) at two different helium flow rates (1 L/min and 2.5 L/min), for different treatment times. Results of the plasma treatment showed a decrease in the contact angle of between 32 and 54 degrees, a significant increase in the roughness by up to 10 times the pristine surface, and no substantial change in the hardness. These improvements to the adhesion and lubrication properties of the polymer examined suggest that the treated surface could be more suitable for use in artificial joints.}, number={4}, journal={Applied Sciences}, publisher={MDPI AG}, author={Turicek, Jack S. and Ratts, Nicole and Kaltchev, Matey and Masoud, Nazieh}, year={2021}, month={Feb}, pages={1703} }