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  1. Abstract Highlights

    CG modeling is performed to explore the thermomechanical behavior of PCN.

    Effects of nanoclay weight percentage and size on modulus are studied.

    Interface leads to nanoconfinement effect onTgand molecular stiffness.

    Correlations between molecular stiffness and modulus are identified.

    Simulations show spatial variation of dynamical heterogeneity.

     
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  2. Although the natural gas pipeline network is the most efficient and secure transportation mode for natural gas, it remains susceptible to external and internal risk factors. It is vital to address the associated risk factors such as corrosion, third-party interference, natural disasters, and equipment faults, which may lead to pipeline leakage or failure. The conventional quantitative risk assessment techniques require massive historical failure data that are sometimes unavailable or vague. Experts or researchers in the same field can always provide insights into the latest failure assessment picture. In this paper, fuzzy set theory is employed by obtaining expert elicitation through linguistic variables to obtain the failure probability of the top event (pipeline failure). By applying a combination of T- and S-Norms, the fuzzy aggregation approach can enable the most conservative risk failure assessment. The findings from this study showed that internal factors, including material faults and operational errors, significantly impact the pipeline failure integrity. Future directions should include sensitivity analyses to address the uncertainty in data to ensure the reliability of assessment results. 
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    Free, publicly-accessible full text available November 1, 2025
  3. This study provides new insights into the development of high-performance MXene-reinforced coatings to strengthen polymeric nanocomposites by enhancing microstructure, anti-aging properties, corrosion resistance, and robustness. MXene nanoparticles, labeled 25C and 80C, were synthesized using two different methods and incorporated at concentrations ranging from 0.1 to 2.0 wt.% into epoxy composites. The results demonstrated that 80C MXene, characterized by its finer morphology and superior dispersion, significantly improved the composite's performance compared to 25C. Electrochemical Impedance Spectroscopy (EIS) tests, along with long-term exposure assessments, suggested that incorporating both types of MXene nanoparticles enhances the corrosion protection performance of epoxy coatings over time. Micro-CT analysis revealed that both types of MXene substantially reduced defects and voids in the polymeric matrix, resulting in enhanced protective performance. This void reduction confirms that the incorporation of both 25C and 80C MXene improves microstructural integrity by filling voids and creating a more continuous, uniform structure, particularly in samples with 0.1% to 1.0% MXene flakes. The findings also highlighted MXene's potential in modifying the anti-aging properties of epoxy by inhibiting free radical generation and enhancing the composite's resistance against corrosion. Both 25C and 80C MXene-epoxy groups exhibited a clear trend of diminishing free radical intensity with increasing MXene concentration up to 1.0%, with free radical intensity reduced by over 40% compared to neat epoxy. The relationship between MXene concentration and reinforcement was also investigated, revealing superior corrosion protection properties at concentrations of 0.5-1.0 wt.%. This research offers a profound understanding of MXene's potential in polymer-based composites, laying a foundation for future investigations aimed at utilizing MXene to achieve superior material properties for a wide range of applications, particularly in the realm of metallic surface protection. 
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    Free, publicly-accessible full text available September 1, 2025
  4. Structural integrity can be compromised by the simultaneous presence of mechanical loads and corrosive agents. This study investigates the complex interplay between corrosion and impact loads in steel plates, utilizing discrete Fiber Bragg Grating (FBG) and distributed Optical Frequency Domain Reflectometry (OFDR) sensing technology. Generalized fiber optic-based sensing models are developed to quantify corrosion severity and rate. The experimental study was conducted using twelve epoxy-coated steel plates equipped with FBG and OFDR sensors, covering scenarios of individual exposure to corrosion, impact loads, as well as their combination. Test results reveal that specimens subjected to combined conditioning exhibit more corrosion damage than those subjected to individual corrosion. Both pit depth and its growth rate were exacerbated due to the impact loads. The study demonstrates the potential of fiber optic sensors (FOSs) for real-time monitoring and assessment of structural health under different simultaneous multiple factors in challenging conditions. 
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    Free, publicly-accessible full text available July 1, 2025
  5. The occurrence of local buckling, an external anomaly in pipelines, significantly contributes to pipeline incidents, posing challenges in monitoring such localized anomalies, particularly during pipeline operations. This paper introduces an approach aimed at monitoring local buckling occurring in the compression bending area of pipeline sections. The proposed approach utilizes fiber Bragg gratings (FBGs) to facilitate real-time measurement of strain changes. Experimental tests were conducted on the steel pipe equipped with FBGs positioned near the top and bottom of the pipe, subjected to four-point loading test to generate bending and local buckling. The strain data obtained from FBGs enable effective detection and localization of bending and buckling deformations during the loading process. This research contributes to enhancing the capability to monitor external threats to pipelines, thereby fostering improved condition assessments and bolstering infrastructure resilience. 
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    Free, publicly-accessible full text available June 1, 2025
  6. Limongelli, Maria Pina ; Ng, Ching Tai ; Glisic, Branko (Ed.)
    Civil engineering structures are routinely exposed to corrosive environments, posing threats to their structural integrity. Traditional corrosion control methods often involve employing physical barriers, such as various coatings, to isolate the steel substrate from surrounding electrolytes. Among these methods, thermal spraying of alloy coatings has emerged as a prominent technique in safeguarding steel matrices against corrosion, particularly in industrial and marine settings. However, the inherent porosity of thermal spraying coatings compromises their corrosion resistance. Incorporating a polymer top layer offers a promising solution by sealing pores and augmenting overall performance. This study investigates corrosion on duplex-coated steel utilizing distributed fiber optic sensors based on optical frequency domain reflectometry. Experimental analyses involve embedding serpentine-arranged distributed fiber optic strain sensors within both thermal spraying layers and epoxy layers. Results demonstrate the efficiency of distributed sensors in identifying corrosion propagation paths by measuring the induced strain changes. Furthermore, the duplex coating exhibits significant enhancements in corrosion resistance for steel structures. 
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    Free, publicly-accessible full text available May 9, 2025
  7. Natural gas pipelines are susceptible to external and internal risk factors, such as corrosion, environmental conditions, external interferences, construction and design faults, and equipment failures. Bayesian Networks (BN) is a promising risk assessment approach widely used to evaluate these risk factors. One of BN's inherent limitations is its inability to accurately capture statistical dependencies and causal relationships, which can be overcome by incorporating expert elicitation into BN. To account for uncertainty and vagueness in assessing pipeline failure risks, fuzzy set theory (FST) can be combined with BN, commonly known as Fuzzy Bayesian Networks (FBN). This study developed an FBN framework that uses linguistic variables to calculate fuzzy probability (FPr) through domain expert elicitation, and crisp probabilities (CPr) are computed using historical incident data from the Pipeline and Hazardous Materials Safety Administration (PHMSA). Based on the findings from the case study of the Midwest region of the USA, external factors, i.e., third-party interference, outside force, and other incidents, significantly impact pipeline performance and reliability. Diagnosis inference indicates that in the Midwest region of the USA, pipeline material and age are critical factors leading to corrosion failure by threatening pipeline integrity. The findings from this study suggested that a targeted risk mitigation strategy is paramount for minimizing the risks associated with pipeline networks. 
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    Free, publicly-accessible full text available May 1, 2025
  8. This study explored the enhancement potential of MXene, a novel two-dimensional material, in epoxy-based nanocomposites; which comprehensively examined the influence of MXene on epoxy's viscosity, void formation, aging resistance, mechanical properties, and anti-wear properties. MXene nanofillers, labeled as 25C and 80C, fabricated via different acid-etching methods, were incorporated into epoxy resin at varying weight percentages (0.1-2.0 wt.%). Observations revealed that for both varieties of MXene, inclusion of 1.0 wt.% MXene led to the mitigation of void content, whereas the incorporation of 2.0 wt.% MXene yielded maximal enhancements in both tensile strength and abrasion resistance. Additionally, the integration of 1.0 and 2.0 wt.% MXene displayed superior aging resistance, with around 80% reduction in free radical formation compared to the unmodified epoxy, while maintaining its excellent mechanical properties after QUV exposure. Therefore, both MXene types significantly enhanced the performance of epoxy composites, with the 80C-MXene displaying marginally superior enhancement due to its smaller particle size and higher purity, as identified by SEM and TEM images. 
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    Free, publicly-accessible full text available March 1, 2025
  9. This study examined the influence of laboratory corrosion testing methods, specifically salt spray, and immersion tests, on the long-term performance assessment of wire-arc-sprayed Zn-Al coatings. Two Zn-Al alloyed systems, Zn-15Al and Zn-Al pseudo-alloy, were selected for investigation, subjecting them to 1000 h of immersion and salt spray conditions. Electrochemical impedance spectroscopy was used to monitor corrosion progression in both coating systems at 200-h intervals. Post-exposure, the coatings underwent microstructural and chemical characterization, along with potentiodynamic polarization tests. Furthermore, some specimens in both coating systems were intentionally damaged and exposed to 1000 h of salt spray and immersion testing and analyzed with scanning electron microscopy. Immersion testing yielded similar results for both coatings, while salt spray testing unveiled significant differences and highlighted the susceptibility of the Zn-15Al to salt spray in both undamaged and damaged states. The continuously refreshed salt spray electrolyte hindered stable corrosion product formation, allowing chloride penetration and increased corrosion in Zn-15Al. Conversely, the Zn-Al pseudo-alloy coating formed Al (OH)3, acting as a barrier against chloride penetration during salt spray and offering superior protection. In summary, salt spray testing proved more aggressive than immersion when evaluating Zn-Al coatings with high zinc content primarily relying on active dissolution for corrosion protection. 
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  10. Sanders, Glen A. ; Lieberman, Robert A. ; Udd Scheel, Ingrid (Ed.)
    Each year, the global cost that is accounted to corrosion was estimated at $2.5 trillion. Corrosion not only imposes an economic burden, when corroded structures are under various loading conditions, it may also lead to structurally brittle failure, posing a potential threat to structural reliability and service safety. Although considerable studies investigated the combined effect of external loads and structural steel corrosion, many of the current findings on synergetic interaction between stress and corrosion are contrary. In this study, the combined effects of dynamic mechanical loads and corrosion on epoxy coated steel are investigated using the distributed fiber optic sensors based on optical frequency domain reflectometry. Experimental studies were performed using the serpentine-arranged distributed fiber optic strain sensors embedded inside the epoxy with three different scenarios including the impact loading-only, corrosion-only, and combined impact loading-corrosion tests. Test results demonstrated that the distributed fiber optic sensors can locate and detect the corrosion processing paths by measuring the induced strain changes. The combined impact loading-corrosion condition showed significantly accelerated corrosion progression caused by mechanical loads, indicating the significant interaction between dynamic mechanical loading and corrosion on epoxy coated steel. 
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