Influence Of Moisture Research Articles

Operational risk management – Measurement and evaluation of friction coefficients for geotextile sandbags for flood protection

AbstractThe present work focuses on the friction coefficient for various geotextile sandbag structures especially dikes under different conditions. Based on the review of existing investigations there are several gaps to close. Former investigations do not include the whole scope of needed surfaces and conditions. Especially the friction coefficients for polypropylene and even for jute as material mainly used for small geotextile sandbags are not fully available. Additionally, the influence of the surface moisture is not consequently investigated, particularly for jute. Due to this, eleven test series (three with sandbag on sandbag configuration and eight with sandbag on ground surface) with 780 single readings are finalized. In comparison to former studies there are results for surface combinations of good harmonization and those with differences. A comparison of the earlier studies already shows different results Summarized it can be stated that the presented results are representative friction coefficients for calculation of realistic sandbag structures e. g., sandbag dikes or spring cascades.

Data-driven modeling of equatorial atmospheric waves: The role of moisture and nonlinearity on global-scale instabilities and propagation speeds.

The equatorial region of the Earth's atmosphere serves as both a significant locus for phenomena, including the Madden-Julian Oscillation (MJO), and a source of formidable complexity. This complexity arises from the intricate interplay between nonlinearity and thermodynamic processes, particularly those involving moisture. In this study, we employ a normal mode decomposition of atmospheric reanalysis ERA-5 datasets to investigate the influence of nonlinearity and moisture on amplitude growth, propagation speed, and mode coupling associated with equatorially trapped waves. We focus our analysis on global-scale baroclinic Kelvin and Rossby waves, recognized as crucial components contributing to the variability of the MJO. We examine the dependence of wave amplitudes on the background moisture field in the equatorial region, as measured by total column water vapor. Our analysis demonstrates the crucial role of moisture in exciting these waves. We further investigate the dependence of the propagation speed of the waves on their amplitudes and the background moisture field. Our analysis reveals a robust correlation between the phase speed of the normal modes and their corresponding amplitude, whereas a weaker correlation is found between the eigenmodes' phase speed and the moisture field. Hence, our findings suggest that moisture plays a role in exciting the global-scale Rossby-Kelvin structure of the MJO. In this context, the propagation speed of the eigenmodes is mainly influenced by their amplitudes, underscoring the significant role of nonlinearity in wave propagation.

Influence of Lake Breezes on the Triggering of Moist Convection on the Tibetan Plateau: A Large-Eddy Simulation Study

Abstract Applying 1D surface heterogeneity and observed atmospheric vertical profiles as initial conditions, two sets of large-eddy simulation experiments provided insight into the influence of lake size and soil moisture (SM) on the development of lake breezes and moist convection over land beside the lake. When the lake diameter increased from 20 km to 50 and 70 km, the maximum precipitation increased by 71.4% and 1.29 times, respectively. There are two reasons for larger precipitation over land in large-lake simulations: 1) Stronger and broader updrafts were found near the lake-breeze front (LBF); 2) the air at 2–4 km was moister, probably because more water vapor below 2 km was advected by the lake breezes and transported upward through turbulent exchange. Moreover, when the lake diameter increased from 20 km to more than 50 km, the deep moist convection (DMC) occurred 20 min earlier. This may be related to broader shallow convective cloud and larger vertical velocity of cloud-initiating parcels in large-lake simulations. Shallow moist convection transitioned to DMC earlier with broader clouds under moderate and high soil moisture conditions. Notably, stronger and broader updrafts near the LBFs, along with the advection of moisture induced by the lake breezes, caused the shallow moist convection to reach its peak 1 h earlier in the driest soil moisture case. However, smaller evapotranspiration could not provide sufficient moisture for the development of DMC. Our simulation results show that lake-breeze circulations are essential for the development of moist convections in the lake region.

A low-cost simple lysimeter soil retriever design for retrieving soil from small lysimeters

A lysimeter-soil retriever (LSR) is a device used to retrieve the soil with minimum disturbance from lysimeters. This device makes the process of sampling intact soil layers from lysimeters easier and faster, especially when a large number of lysimeters are being sampled. In this study, mini lysimeters (200 mm diameter and 25 kg weight) were used to test fertilizers. A low-cost LSR was designed to aid the accurate removal of the soil from these lysimeters. This paper describes the design and testing of the suitability of a linear actuator for this application. This study investigates the influence of soil moisture on the retrieval and structural stability of lysimeter and LSR. The results revealed that soil with a high moisture level was more suitable as it showed lower disturbance for the retrieved block, lower soil losses, minimal disturbance for roots and lower variation of soil block height and weight. The retrieval time was influenced by soil moisture level and were 48 and 52 s for low and high-moisture soils, respectively. The finite element model showed that the stress applied by the linear actuator on the lysimeter body and top-wood plate were 2.18 and 0.32 MPa, respectively. These stress values were within the safe limit of the corresponding materials. It was found that the selected linear actuator is suitable for soil retrieving from lysimeters packed with sandy-clay loam and sand. It showed consistent performance (stroke time and maximum force) after retrieval of 400 soil blocks. The suitability of this design for various soil types needs to be tested to determine its applicability in a broader range of scenarios.

Understanding the influence of soil moisture on heatwave characteristics in the contiguous United States

In the context of global climate change, heatwaves are becoming increasingly significant because of the adverse impacts on human health and ecosystems. However, the quantification of heatwaves relies on different temperature metrics, and little is known about how the different types of heatwaves are affected by soil moisture. Using a set of observational datasets during the period 1981–2020, this study investigates the characteristics of warm-season heatwaves over the contiguous United States (CONUS) derived from three different temperature metrics (temperature, wet-bulb temperature, and equivalent temperature), and examines how different types of heatwaves are associated with soil moisture. Increasing trends of all types of heatwaves are observed in most parts of CONUS except for the central US, posing potential risks to human health. Due to limited evaporative cooling over dry soil, there is a substantial negative relationship between soil moisture and temperature-only heatwaves across the CONUS. Meanwhile, in some regions of the western and central CONUS, there is an evident positive relationship between soil moisture and humidity-included heatwaves, which represent the combined effects of temperature and humidity. The event-based analysis in Nebraska emphasizes that temperature-only heatwaves occur over relatively dry soil conditions, while humid heatwaves tend to occur over somewhat wet soil. Our results highlight the importance of considering different types of heatwaves and their relationship with soil moisture from the land-atmosphere coupling perspective, offering valuable insights for local and regional climate planning and mitigation.

Interannual Variability of Water and Heat Fluxes in a Woodland Savanna (Cerrado) in Southeastern Brazil: Effects of Severe Drought and Soil Moisture

The Brazilian Cerrado biome is known for its high biodiversity, and the role of groundwater recharge and climate regulation. Anthropogenic influence has harmed the biome, emphasizing the need for science to understand its response to climate and reconcile economic exploration with preservation. Our work aimed to evaluate the seasonal and interannual variability of the surface energy balance in a woodland savanna (Cerrado) ecosystem in southeastern Brazil over a period of 19 years, from 2001 to 2019. Using field micrometeorological measurements, we examined the variation in soil moisture and studied its impact on the temporal pattern of energy fluxes to distinguish the effects during rainy years compared to a severe drought spell. The soil moisture measures used two independent instruments, cosmic ray neutron sensor CRNS, and FDR at different depths. The measures were taken at the Pé de Gigante (PEG) site, in a region of well-defined seasonality with the dry season in winter and a hot/humid season in summer. We gap-filled the energy flux measurements with a calibrated biophysical model (SiB2). The long-term averages for air temperature and precipitation were 22.5 °C and 1309 mm/year, respectively. The net radiation (Rn) was 142 W/m2, the evapotranspiration (ET) and sensible heat flux (H) were 3.4 mm/d and 52 W/m2, respectively. Soil moisture was marked by a pronounced negative anomaly in the 2014 year, which caused an increase in the Bowen ratio and a decrease in Evaporative fraction, that lasted until the following year 2015 during the dry season, despite the severe meteorological drought of 2013/2014 already ending, which was corroborated by the two independent measurements. The results showed the remarkable influence of precipitation and soil moisture on the interannual variability of the energy balance in this Cerrado ecosystem, aiding in understanding how it responds to strong climate disturbances.

Moisture effect on tensile and low‐velocity impact tests of flax fabric‐reinforced PLA biocomposite

AbstractThis study investigates the hygrothermal aging effect on the tensile and impact behavior of flax/PLA biocomposites. Specimens underwent up to four weeks of conditioning at 40°C in a climate chamber with water. Analysis covered porosity, moisture diffusibility, and transversal microstructure, enabling assessment of tensile strength, tensile modulus, and impact performance in relation to moisture uptake and fiber orientation. The study of tensile properties revealed that at approximately 12% moisture content, stiffness and yield stress decrease, while strength remains constant. Moisture diffusivity is higher in warp and weft yarn directions than the out‐of‐plane direction. Tensile testing at environmental equilibrium moisture reveals greater stiffness in the weft direction, correlated with lower crimp percentage and yarn angle. The main contribution of the paper is the study of the influence of moisture on the impact behavior, the results show that energy absorption capability of flax/PLA biocomposite increases with moisture content.Highlights Fully biodegradable composite material by heat‐compression molding subjected to hygrothermal aging conditions for up to four weeks. The moisture diffusivity in both the warp and weft yarn directions registered higher values in comparison to the out‐of‐plane direction. Tensile testing at environmental equilibrium moisture revealed that the stiffness in the weft direction presented higher values. At 12% of moisture uptake, the stiffness and yield stress reached their lowest values, while strength remained constant. However, the low‐velocity impact properties of the composites exhibited improvement with moisture.

Influence of moisture on the sound absorption properties of wood-based pulp fibre foams

The use of wood fibres, and other biofibres in general, as raw materials to produce sound absorbers has gradually increased lately. The main reason for their increased use is their contribution to reducing CO2 from the atmosphere by binding CO2 into the building structure for decades. Understanding of the ultrastructure of wood fibres is essential as it has a strong influence on the fibre properties, and thus, on the final material properties. In this work, the effect of moisture on the sound absorption properties of wood-based pulp fibre foams has been studied. It is shown that increasing moisture content (> 9%) in pulp fibres leads to greater sound absorption at low-mid frequencies. Fibre swelling, increasing fibre flexibility, and increasing foam bulk density with increasing fibre moisture content are hypothesized as the causes for the increase in sound absorption. Hygroexpansion, mechanical properties as well as moisture absorption capability of different types of pulp fibres are studied and related to their sound absorption properties. It is concluded that, in addition to fibre diameter and bulk density of foams, the elastic properties of the pulp fibres are partially responsible for the improved sound absorption of the foams exposed to greater relative humidity conditions.

Effect of electric field on bubble generation and dissolution characteristics in oil–paper insulation

AbstractThe interturn paper insulation of oil‐immersed power transformer windings, under the combined influence of electric fields, moisture, and conductor heating, will produce bubbles, which pose a significant threat to the insulation system. However, there is limited research on the characteristics of bubble evolution in oil–paper insulation under the influence of electric fields and the subsequent dissolution process. Based on the continuous observation of bubble size using electron microscopes, experimental and theoretical investigations into the formation and dissolution of bubbles under electric field conditions are presented. The effects of different field strengths on bubble evolution and dissolution characteristics were studied. The results showed that the electric field promoted both the generation and dissolution of bubbles, with a more pronounced effect observed at higher field strengths (below partial discharge (PD) inception electric field, hereafter referred to as PDIE). However, when the field strength exceeded PDIE, the bubbles tended to shrink and gradually increase in size. The changes in bubble volume were related to not only gas diffusion but also oxygen consumption and fault gases generation due to PD. A better understanding of the formation and dissolution characteristics of bubbles under varying field strengths is achieved. Furthermore, it also provides a reference for assessing the risk of bubble generation and conducting bubble‐related fault diagnosis during the overload operation of oil‐immersed power equipment.

Clinical performance of posterior restorations using a universal adhesive over moist and dry dentin: A 36-month double-blind split-mouth randomized clinical trial

ObjectivesTo evaluate the influence of dentin moisture on the clinical behavior of a universal adhesive on posterior teeth after 36 months of follow-up. MethodsForty-five patients participated in this study. Following a split-mouth design, three operators placed 90 Class I/Class II restorations over moist dentin (MD) or dry (DD) (n = 45) with resin composite (Filtek Bulk Fill) and a universal adhesive used in the etch-and-rinse mode (Single Bond Universal). Each restoration was evaluated according to the FDI and USPHS criteria (postoperative sensitivity, fracture and retention, marginal staining, marginal adaptation, and recurrence of caries) at baseline and after 6-, 12-, and 36 months. For statistical analysis, Kruskal Wallis analysis of variance rank (α = 0.05) and Kaplan-Meier survival analysis were used. ResultsNo significant difference between groups was observed in each FDI criterion after 36 months of clinical evaluation (p > 0.05). The retention rates (confidence interval 95 %) were 97.37 % (86.5 - 99.5) for both MD and DD without significant difference between them (p > 0.05). Eight restorations (MD = 4; DD = 4) showed minimal marginal staining defects (p > 0.05). Two restorations were lost (MD = 1; DD = 1). Fifteen restorations (MD = 8; DD = 7) presented minor marginal discrepancies according to the FDI criteria (p > 0.05). ConclusionThe clinical performance of the universal adhesive when applied in etch-and-rinse mode was not influenced by dentin moisture in posterior bulk-fill composite restorations. Clinical significanceThe level of dentin moisture appears not to influence the clinical efficacy of a universal adhesive when applied using the etch-and-rinse technique in posterior composite resin restorations.

Origin identification and accuracy control of electrode interface-related asymmetrical hysteresis in light-controlled resistive switching of single CH3NH3PbI3 micro/nanowire

Remarkable photoresponse and resistive switching (RS) performance of CH3NH3PbI3 has garnered significant attention. However, precise control over the emergence and polarity of hysteresis loops in bipolar RS remains challenging. Herein, we constructed an individual CH3NH3PbI3 micro/nanowire device configured with two symmetrical Ag electrodes and asymmetrically modulated their electrode interface states by encapsulating only one electrode. We propose an electrode interface-related RS mechanism to modulate the hysteresis features and achieve different types of high-performance light-controlled RS. In an unpacked electrode interface, large potential induces oxidation of Ag to AgI with high resistivity under light and trace moisture, resulting in a high-resistance state. On the other hand, in a packed electrode interface, large potential triggers hole injection into interface traps with the assistance of light, resulting in a low-resistance state. Additionally, reversible Ag/AgI oxidation/reduction-related negative RS and hole injection/ejection-associated positive RS lead to bipolar RS, accompanied by clockwise and counterclockwise hysteresis loops in two directions. Furthermore, performance is entirely determined by illumination intensity and bias amplitude, achieving photomemory. This work unveils the influence of moisture and illumination on electrode interface and the actual origin of hysteresis, while also precisely controlling photomemory performance. Therefore, it provides a specific strategy for designing high-performance light-controlled RS with nonvolatile photomemory.

Frictional Behavior of Chestnut (Castanea sativa Mill.) Sawn Timber for Carpentry and Mechanical Joints in Service Class 2

Wood is poised to become a material of choice for future construction. When appropriately managed, it is a renewable material with unique mechanical properties. Thus, there has been a growing demand for hardwoods, including Castanea sativa Mill., the focal point of this investigation, for structural applications. Albeit in a limited capacity, Eurocode 5-2 offers friction coefficients for softwoods, but it falls short for hardwoods. These coefficients play a critical role in numerical simulations involving friction, enabling the optimization of joints and, by extension, the overall structural integrity. Test samples were evaluated at 15% and 18% moisture content (Service Class 2) for various orientations of timber-to-timber and timber-to-steel friction. The results provide an experimental database for numerical simulations and highlight the influence of moisture on the stick–slip phenomenon, which was absent for the timber-to-timber tests, as well as on the rising friction values. At 18%, the static and kinetic coefficients were 0.70 and 0.48 for timber-to-timber and 0.5 and 0.50 for timber-to-steel. The increase was around 50% for timber-to-timber friction and over 170% for timber-to-steel pairs. Moreover, the findings proved a relationship between both coefficients and the validity of the linear estimation approach within the 12–18% moisture commonly applied to softwoods.

Coupled Influence of Compaction and Moisture on Unsaturated Soil Response in Triaxial Tests

Coupled Influence of Compaction and Moisture on Unsaturated Soil Response in Triaxial Tests

Influence of root canal moisture on the penetration of TotalFill bioceramic sealer into the dentinal tubules: A confocal laser scanning microscopy study

Abstract Introduction: Bioceramic (BC) sealers exhibit multiple desirable biologic and physical properties. The aim of this study was to evaluate the effect of root canal moisture on the depth of TotalFill BC sealer penetration into dentinal tubules at different levels using a confocal laser scanning microscope (CLSM). Materials and Methods: The manuscript of this laboratory study has been written according to preferred reporting items for laboratory studies in endodontology 2021 guidelines. Forty single-rooted extracted human premolars were decoronated using a low-speed diamond disc, followed by root canal preparation using nickel–titanium files under copious irrigation. The samples were randomly allocated for obturation into four groups n = 10 based on the sealer and root canal moisture status. Group A: TotalFill BC sealer in wet canal, Group B: TotalFill BC sealer in dry canal, Group C: AH Plus sealer in wet canal, and Group D: AH Plus sealer in dry canal. The roots were sectioned at three different distances from the apex. The root segments were examined using CLSM to measure the extent of sealer penetration into the dentinal tubules. The data underwent analysis through a three-way mixed ANOVA test, followed by post hoc assessments (P < 0.05). Results: In wet canals, the tubular penetration of TotalFill BC sealer was notably greater than that of AH plus, with a statistically significant difference. However, AH Plus sealer had a statistically significant tubular penetration in the dry canals compared to the wet. Greater sealer penetration was observed at 5 mm from the apex, followed by 3 mm, and the least penetration depth was found at 1 mm from the apex. Conclusions: The presence of root canal moisture and distance from the apex had a significant impact on the penetration of TotalFill BC sealer into the dentinal tubules.

Increased global cropland greening as a response to the unusual reduction in atmospheric PM₂.₅ concentrations during the COVID-19 lockdown period

The devastating effects of COVID-19 pandemic have widely affected human lives and economy across the globe. There were significant changes in the global environmental conditions in response to the lockdown (LD) restrictions made due to COVID-19. The direct impact of LD on environment is analysed widely across the latitudes, but its secondary effect remains largely unexplored. Therefore, we examine the changes in particulate matter (PM₂.₅) during LD, and its impact on the global croplands. Our analysis finds that there is a substantial decline in the global PM₂.₅ concentrations during LD (2020) compared to pre-lockdown (PreLD: 2017–2019) in India (10–20%), East China (EC, 10%), Western Europe (WE, 10%) and Nigeria (10%), which are also the cropland dominated regions. Partial correlation analysis reveals that the decline in PM₂.₅ positively affects the cropland greening when the influence of temperature, precipitation and soil moisture are limited. Croplands in India, EC, Nigeria and WE became more greener as a result of the improvement in air quality by the reduction in particulates such as PM₂.₅ during LD, with an increase in the Enhanced Vegetation Index (EVI) of about 0.05–0.1, 0.05, 0.05 and 0.05–0.1, respectively. As a result of cropland greening, increase in the total above ground biomass production (TAGP) and crop yield (TWSO) is also found in EC, India and Europe. In addition, the improvement in PM₂.₅ pollution and associated changes in meteorology also influenced the cropland phenology, where the crop development stage has prolonged in India for wet-rice (1–20%) and maize (1–10%). Therefore, this study sheds light on the response of global croplands to LD-induced improvements in PM₂.₅ pollution. These finding have implications for addressing issues of air pollution, global warming, climate change, environmental conservation and food security to achieve the Sustainable Development Goals (SDGs).

A soil mechanics model to determine the onset of wind erosion

Determining the friction threshold velocity (FTV) of wind-induced erosion is crucial to understanding and predicting the morphodynamics and management of foreshores and dunes. However, the FTV is influenced by multiple factors, including particle size, mineralogy, surface roughness, and moisture content. Although existing models account for these parameters, they suffer from limited precision, are not generalized and developed for specific sediment types, and rely on expensive and time-consuming testing procedures. Furthermore, no predictive equations for FTV currently consider the combined effects of bed inclination and moisture common to coastal dunes. This study presents a comprehensive closed-form model for predicting the FTV in the onset of wind erosion for different types of sands. The model considers various geometric and material properties, including cohesion, moisture, soil packing, slope, and grain size distribution. A soil water retention curve (SWRC) is incorporated into the formulation to establish a relationship between water content and sediment shear strength. This simple SWRC approach enables simplified calculations of the onset of wind erosion under various conditions, requiring only a few inexpensive inputs. Extensive parametric wind tunnel experiments were conducted to measure the FTV in combinations of bed slope, sand particle size, moisture, and density. The findings indicate that the combined influence of slope and moisture increases the FTV. Furthermore, compared to the FTV for dry sediments on a horizontal bed, the amplification factor exhibits a nonlinear combination of the effects of inclination and moisture. The proposed FTV predictive model demonstrates adequate agreement with published results when applied to scenarios such as dry sand on a horizontal surface, dry sand on an inclined bed, and moist sand on a horizontal surface.

Exploring the Effect of Moisture on CO2 Diffusion and Particle Cementation in Carbonated Steel Slag

The study of the mechanisms affecting the preparation parameters of carbonated steel slag is of great significance for the development of carbon sequestration materials. In order to elucidate the mechanism of the influence of moisture on CO2 diffusion and particle cementation in steel slag, the effects of different water–solid ratios and water contents on the mechanical properties, carbonation products, and pore structure of steel slag after carbonation were investigated. The results show that increasing the water–solid ratio of steel slag can control the larger initial porosity and improve the carbon sequestration capacity of steel slag, but it will reduce the mechanical properties. The carbonation process relies on pores for CO2 diffusion and also requires a certain level of moisture for Ca2+ dissolution and diffusion. Increasing the water content enhances particle cementation and carbonation capacity in steel slag specimens; however, excessive water hinders CO2 diffusion. Reducing the water content can increase the carbonation depth but may compromise gelling and carbon sequestration ability. Therefore, achieving a balance is crucial in controlling the water content. The compressive strength of the steel slag with suitable moisture and initial porosity can reach 118.7 MPa, and 217.2 kg CO2 eq./t steel slag can be sequestered.

Simultaneous influence of strain rate and moisture on the anisotropic mechanical behavior of direct compounded compression molded PA6/Glass LFTs

Fibre-reinforced polymer composites are an increasingly critical long-term solution for lightweighting the transportation sector, therefore, a comprehensive understanding of their mechanical behavior under varying environmental conditions and loading rates is critical. This study investigated the tensile properties and behavior of a direct-compounded compression-molded Polyamide6 (PA6)/glass long fibre thermoplastic (LFT-D) material, specifically examining the influence of moisture content and intermediate tensile loading rates, up to 150 s−1. This range is of significance to the transportation industry and is highly desirable for engineering design since data in the current literature is limited. Dried and undried samples were also examined at four distinct material orientations: 0°, +45°, ˗45°, and 90°. The results confirmed that moisture presence significantly altered the mechanical properties of PA6/Glass LFT material under quasi-static loading rates; in contrast, its effects were negligible under dynamic loadings. Notably, the material exhibited significant strain rate sensitivity within the range of 0.0001 s−1 to 150 s−1. In the 0° material direction, with higher fibre orientation distribution, the undried materials demonstrated a substantial increase of 93% in Young's modulus and 172% in ultimate tensile strength while the complementary dried samples displayed increases of 76% and 97%, respectively. Tensile strength reached 293.8 MPa and 276.7 MPa for undried and dried samples, respectively, in this particular material direction. However, the strain at failure remained consistent at approximately 4% for undried samples and 3% for dried samples, resulting in an increase in tensile toughness by 292% (up to 6.9 MPa) for undried samples and 114% (up to 4.7 MPa) for dried samples.

Soil Moisture Profiles of Ecosystem Water Use Revealed With ECOSTRESS

AbstractWhile remote sensing has provided extensive insights into the global terrestrial water, carbon, and energy cycles, space‐based retrievals remain limited in observing the belowground influence of the full soil moisture (SM) profile on ecosystem function. We show that this gap can be addressed when coupling 70 m resolution ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station retrievals of land surface temperature (LST) with in‐situ SM profile measurements. These data sets together reveal that ecosystem water use decreases with depth with 93% of sites showing significant LST coupling with SM shallower than 20 cm while 34% of sites have interactions with SM deeper than 50 cm. Furthermore, the median depth of peak ecosystem water use is estimated to be 10 cm, though forests have more common peak interactions with deeper soil layers (50–100 cm) in 37% of cases. High spatial resolution remote sensing coupled with field‐level data can thus elucidate the role of belowground processes on land surface behavior.

Influence of moisture and salinity on property degradation of nano-engineered epoxy polymers for offshore applications

This study has attempted to investigate the influence of major environmental degradation factors for offshore and coastal structures, such as moisture and salinity, on epoxy-based bonded composite systems and to identify the means of degradation of the same. Exhaustive experimental investigations have been carried out with different salinity levels (0%, 2.5% and 5%) and exposure periods (45 days to longer time periods (>1 year)) to determine the influence of the same on the mechanical property degradation of epoxy polymers. The effect of degraded properties on the performance degradation of bonded epoxy composite systems in terms of damage pattern and load-carrying capacity has been investigated using numerical simulations with non-linear material models and traction-separation interface behaviour. Further, it is also attempted to fundamentally engineer the epoxy polymers using nanosilica to improve their mechanical properties and environmental resistance. Finally, diffusion tests have been performed on the plain and nanoengineered epoxy polymers to understand the change in diffusion mechanisms due to nanoengineering, and a correlation has been established between the diffusion behaviour and the mechanical property degradation. The findings of this study will lead towards the development of stronger and more durable epoxy-bonded composite systems for marine applications.