scholarly journals An Extended Thickness-Dependent Moisture Absorption Model for Unidirectional Carbon/Epoxy Composites

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 440
Author(s):  
Azisyahirah Azizan ◽  
Mahzan Johar ◽  
Salvinder Singh Karam Singh ◽  
Shahrum Abdullah ◽  
Seyed Saeid Rahimian Koloor ◽  
...  
Keyword(s):  
Moisture Content ◽  
Weibull Distribution ◽  
Moisture Absorption ◽  
Epoxy Composites ◽  
Long Period ◽  
Content Ratio ◽  
Dependent Model ◽  
The Relationship ◽  
Maximum Moisture Content ◽  
Upper Boundary

Moisture absorption tests for materials that exhibit non-Fickian behavior generally require a relatively long period to reach saturation. Therefore, it would be beneficial to establish a relationship between the moisture content and the thickness to minimize the experimental time and cost. This research characterizes the moisture absorption behavior of AS4/8552 carbon/epoxy composites. Specimens were prepared at 4, 8, and 16 plies and immersed in distilled water at 60 °C. The relationship between the non-Fickian parameters (Fickian to non-Fickian maximum moisture content ratio ϕ, non-Fickian diffusivity per square thickness α, and non-Fickian initiation time to) and thickness was characterized using a thickness-dependent model. A comparison with other materials revealed that all three non-Fickian parameters are able to be fitted using a power law. Nevertheless, the upper boundary for the applicability of this model was not determined in this study. The Weibull distribution plots indicate that the probability of non-Fickian moisture absorption is influenced by ϕ and α at approximately 62% within a normalized thickness range of 2–3. In regards to to, it is 82% at a normalized thickness of 6. Therefore, the Weibull distribution is proposed for the assessment of non-Fickian moisture absorption based on the material’s thickness.

Assessing Freeze-Thaw Damage in Segmental Retaining Walls Units by Mass Loss, Moisture Gain, and Relative Dynamic Modulus

2019 ◽  
Vol 2673 (11) ◽  
pp. 309-318
Author(s):  
Cesar T. Chan ◽  
Kenneth C. Hover
Keyword(s):  
Moisture Content ◽  
Mass Loss ◽  
Dynamic Modulus ◽  
Moisture Absorption ◽  
Surface Damage ◽  
Mass Gain ◽  
Retaining Walls ◽  
Freeze Thaw ◽  
Cast Concrete ◽  
The Relationship

Segmental retaining walls (SRWs) constructed of dry-cast concrete masonry units are used in transportation-related applications for which freeze-thaw (FT) durability is evaluated on the basis of percent mass-loss accumulated after multiple FT cycles as per ASTM C1262. This study compared mass loss, mass gain owing to absorption during (FT) exposure, and relative dynamic modulus (RDM) as per ASTM C215. Application of RDM required accounting for the influence of the shape and moisture content of SRW coupons on resonant frequency, with corrections that are likewise applicable to ASTM C666 for ordinary concrete. It was demonstrated that mass loss does not exclusively indicate surface damage, and the relationship between mass loss and RDM is unique to each specimen. Mass gain (as moisture absorption) during testing emerged as a key index of damage, with rapid escalation of mass loss and reduction in RDM at the number of FT cycles required to increase the moisture content of the residual coupon by about 1%.

scholarly journals Moisture Absorption Effects on Mode II Delamination of Carbon/Epoxy Composites

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2162
Author(s):  
King Jye Wong ◽  
Mahzan Johar ◽  
Seyed Saeid Rahimian Koloor ◽  
Michal Petrů ◽  
Mohd Nasir Tamin
Keyword(s):  
Fracture Toughness ◽  
Moisture Content ◽  
Composite Structures ◽  
Moisture Absorption ◽  
Peak Load ◽  
Epoxy Composites ◽  
Mode Ii ◽  
Damage Initiation ◽  
Residual Properties ◽  
Mode Ii Fracture Toughness

It is necessary to consider the influence of moisture damage on the interlaminar fracture toughness for composite structures that are used for outdoor applications. However, the studies on the progressive variation of the fracture toughness as a function of moisture content M (%) is rather limited. In this regard, this study focuses on the characterization of mode II delamination of carbon/epoxy composites conditioned at 70 °C/85% relative humidity (RH). End-notched flexure test is conducted for specimens aged at various moisture absorption levels. Experimental results reveal that mode II fracture toughness degrades with the moisture content, with a maximum of 23% decrement. A residual property model is used to predict the variation of the fracture toughness with the moisture content. Through numerical simulations, it is found that the approaches used to estimate the lamina and cohesive properties are suitable to obtain reliable simulation results. In addition, the damage initiation is noticed during the early loading stage; however, the complete damage is only observed when the numerical peak load is achieved. Results from the present research could serve as guidelines to predict the residual properties and simulate the mode II delamination behavior under moisture attack.

Effect of Moisture Absorption on the Bending Strength of Carbon/Epoxy Composites with Voids

2011 ◽  
Vol 311-313 ◽  
pp. 165-168
Author(s):  
A Ying Zhang ◽  
Jian She Zhang ◽  
Jia Zhi Wang ◽  
Di Hong Li ◽  
Dong Xing Zhang ◽  
...  
Keyword(s):  
Moisture Content ◽  
Water Uptake ◽  
Immersion Time ◽  
Room Temperature ◽  
Moisture Absorption ◽  
Bending Strength ◽  
Experimental Results ◽  
Epoxy Composites ◽  
Effect Of Moisture

The effects of voids on the bending strength of T300/914 laminates that exposed to room temperature, hygrothermal and drying environment was discussed in this paper. The experimental results revealed that the saturated moisture content and the rate of water uptake increased with porosity increasing from 0.71% to 1.50%, which proved that voids facilitate moisture absorption. The bending strength of the unaged, aged and dried specimens were characterized and analyzed. The results revealed that the bending strength of the aged specimens decreased with the increasing void contents and immersion time. Compared to the unaged specimens, the bending strength of the aged specimens decreased 13.33% and 18.78% with porosity of 0.71% and 1.50%, respectively. The bending strength of the dried specimens was higher than that of the aged specimens and lower than that of the unaged specimens in the case of similar porosity.

Moisture absorption effects on the mechanical properties of carbon/epoxy composites

2020 ◽  
Vol 11 (4) ◽  
pp. 605-614 ◽  
Author(s):  
Siti Faizah Mad Asasaari ◽  
King Jye Wong ◽  
Mohd Nasir Tamin ◽  
Mahzan Johar
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Moisture Content ◽  
Moisture Absorption ◽  
Epoxy Composites ◽  
Content Type ◽  
Longitudinal Tensile Strength ◽  
Ageing Period ◽  
Longitudinal Modulus ◽  
Transverse Modulus

PurposeThis paper investigates the influence of moisture absorption on the mechanical properties of carbon/epoxy composites.Design/methodology/approachThree types of specimens are prepared, which are for longitudinal, transverse and shear tests. Specimens are immersed in distilled water at 70°C for 1, 3 and 9 months. These correspond to the moisture content of 2.2, 3.8 and 5.3%.FindingsCompared to the values at dry condition, the longitudinal modulus, shear modulus and Poisson's ratio are invariant with the moisture content. However, the transverse modulus, transverse strength and shear strength are sensitive to moisture attack. The maximum degradation is 33%, 76 and 33% for the three properties, respectively. It is also worth to note that the longitudinal tensile strength is stable at 1 and 9 months of immersion. However, at 3-months ageing period, there is only 67% of the longitudinal tensile strength retained.Originality/valueThe experimental results are fitted with a residual property model. Results show comparatively good fit, with a difference within 16% except the longitudinal tensile strength at 9-months immersion. This highlights that the model is not suitable to fit the experimental data with a fluctuated trend.

scholarly journals Jackfruit as an Object of Drying: A Hygroscopic Study

2019 ◽  
pp. 612-620
Author(s):  
Thi Sen Nguyen ◽  
Igor Aleksanyan ◽  
Albert Nugmanov ◽  
Lyubov Titova
Keyword(s):  
Moisture Content ◽  
Moisture Absorption ◽  
Moisture Transfer ◽  
Sorption Process ◽  
Ambient Temperatures ◽  
Thermodynamically Equilibrium ◽  
Mathematical Approximation ◽  
Pre Treatment ◽  
Object Of Study ◽  
The Relationship

Statics of drying is based on the laws of interaction between the gas medium and the dehydration facility, which seek a thermodynamically equilibrium state. Jackfruit is a wet thermolabile material. With a static equilibrium between the product and the environment, the water content in a hygroscopic state depends on the type of the product, its energy, humidity, and a number of parameters, e.g. temperature and partial pressure of the vapor on the surface. The paper introduces graphical dependences of the activity of water of jackfruit slices on humidity at various ambient temperatures. The authors also give its analogy in semilogarithmic coordinates. It helped to define a range of humidity that determined the type of connection between the moisture of the object and the dry residue. The laws of the mechanism of heat and mass transfer are relevant in determining the dynamics of the dehydration process. Their study can help to intensify the process of moisture removal with rational operating parameters. The present study featured the equilibrium states in the system, which made it possible to find the driving force of moisture transfer and to evaluate the heat carrier potential, as well as to substantiate the values of the parameters and the environment during storage and transportation of the finished dry product. The value of relative moisture content in equilibrium was determined by isothermal sorption curves. The value depends on the pre-treatment of the drying object, the conditions of its contact with the external environment, as well as by the energy and type of relationship between the dry residue and the moisture. The empirical results were arranged in the form of graphical dependences, which made it possible to theoretically obtain their mathematical approximation. The equations of dependence between the equilibrium moisture content of the material and the relative humidity of the vapor-air medium included a lot of constants, which also needed to be determined empirically. The mathematical dependences approximate the isothermal sorption curves, i.e. the relationship between the product’s moisture and water activity indices. The dependences can be used to conduct a thermodynamic analysis of the sorption process and determine the free, bound, and internal energies of the process of moisture absorption by the capillary-porous object of study. The hygroscopic examination of jackfruit is also necessary when making design decisions for the rational implementation of technological operations, including the storage and transportation of dry jackfruit slices.

Energetic relationships for crushing of soil clods

2006 ◽  
Vol 2 (1) ◽  
pp. 51-72
Author(s):  
István Patay ◽  
Virág Sándor
Keyword(s):  
Moisture Content ◽  
Specific Energy ◽  
Soil Moisture Content ◽  
Energy Requirement ◽  
Clay Content ◽  
Clay Soils ◽  
Rigid Support ◽  
Soil Plasticity ◽  
Specific Energy Requirement ◽  
The Relationship

Clod crushing is a principal problem with soils of high clay content. Therefore, there is a need for determining the conditions for clod breaking and clod crushing. The objective of the work was to develop a special purpose tool for single clod breaking both by rigid support of the clod and by a single clod supported by soil and to develop a machine for clod crushing. Furthermore, the purpose was to determine the relationship between the specific energy requirement for clod crushing in the function of soil plasticity and the soil moisture content by the means of the developed tool and machine. The main result of the experiments is summarized in a 3D diagram where the specific energy requirement for soil clod crushing is given in the function of the moisture content and the plasticity index for different clay soils.

Barley seed storage under controlled conditions

2019 ◽  
pp. 140-150 ◽  
Author(s):  
O. A. Zadorozhna ◽  
T. P. Shyianova ◽  
M.Yu. Skorokhodov
Keyword(s):  
Hordeum Vulgare ◽  
Moisture Content ◽  
Spring Barley ◽  
Seed Storage ◽  
Growing Season ◽  
Storage Conditions ◽  
Meteorological Conditions ◽  
Hordeum Vulgare L ◽  
The Relationship ◽  
And Storage

Seed longevity of 76 spring barley gene pool samples (Hordeum vulgare L. subsp. distichon, convar. distichon: 56 nutans Schubl., two deficience (Steud.) Koern., two erectum Rode ex Shuebl., two medicum Koern.; convar. nudum (L.) A.Trof.: one nudum L. та subsp. vulgare: convar. vulgare: nine pallidum Ser., three rikotense Regel.; convar. coeleste (L.) A.Trof.: one coeleste (L.) A.Trof.) from 26 countries, 11 years and four places of reproduction was analyzed. Seeds with 5–8% moisture content were stored in chamber with unregulated and 4oC temperature. The possibility of seed storage under these conditions for at least 10 years without significant changes in germination has been established. The importance of meteorological conditions in the formation and ripening of seeds for their longevity is confirmed. The relationship between the decrease of barley seeds longevity and storage conditions, amount of rainfall, temperature regime during the growing season of plants is discussed.

scholarly journals Influence of moisture content on the contact angle and surface tension measured on birch wood surfaces

2021 ◽  
Author(s):  
Rami Benkreif ◽  
Fatima Zohra Brahmia ◽  
Csilla Csiha
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Moisture Content ◽  
Solid Wood ◽  
Contact Angles ◽  
Surface Moisture ◽  
Wood Coatings ◽  
The Relationship ◽  
Wood Surfaces

AbstractSurface tension of solid wood surfaces affects the wettability and thus the adhesion of various adhesives and wood coatings. By measuring the contact angle of the wood, the surface tension can be calculated based on the Young-Dupré equation. Several publications have reported on contact angle measured with different test liquids, under different conditions. Results can only be compared if the test conditions are similar. While the roles of the drop volume, image shooting time etc., are widely recognized, the role of the wood surface moisture content (MC) is not evaluated in detail. In this study, the effect of wood moisture content on contact angle values, measured with distilled water and diiodomethane, on sanded birch (Betula pendula) surfaces was investigated, in order to find the relationship between them. With increasing MC from approximately 6% to 30%, increasing contact angle (decreasing surface tension) values were measured according to a logarithmic function. The function makes possible the calculation of contact angles that correspond to different MCs.

Shear Strength Monitoring System Based on Measurement of Shear Wave Velocity and Moisture Content

2014 ◽  
Vol 635-637 ◽  
pp. 750-754
Author(s):  
Peng Hu ◽  
Qing Li ◽  
Yi Wei Xu ◽  
Nan Ying Shentu ◽  
Quan Yuan Peng
Keyword(s):  
Shear Strength ◽  
Moisture Content ◽  
Shear Wave ◽  
Monitoring System ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Bender Elements ◽  
Strength Measurement ◽  
Soil Shear Strength ◽  
The Relationship

Expound the importance of soil shear strength measurement at mudslide hidden point to release the loss caused by the disaster, explain the relationship between shear wave velocity, moisture content and shear strength, design the shear strength monitoring system combining the shear wave velocity measured by Piezoelectric bender elements and moisture content.

scholarly journals Study on the Moisture Absorption and Thermal Properties of Hygroscopic Exothermic Fibers and Related Interactions with Water Molecules

Polymers ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 98 ◽  
Author(s):  
Yi Cui ◽  
Shuyi Gao ◽  
Ruiyun Zhang ◽  
Longdi Cheng ◽  
Jianyong Yu
Keyword(s):  
Moisture Content ◽  
Thermal Performance ◽  
Water Sorption ◽  
Moisture Absorption ◽  
Bound Water ◽  
Absorption Process ◽  
Heating Performance ◽  
Hygroscopic Behavior ◽  
Water Sorption Capacity ◽  
Main Factor

The aim of this paper is to study the hygroscopic behavior of hygroscopic exothermic fiber-based materials and to obtain a better understanding of the thermal performance of these fibers during the moisture absorption process. The temperature distribution of different kinds of hygroscopic exothermic fibers in the process of moisture absorption, observed by infrared camera, demonstrated two types of heating performance of these fibers, which might be related to its hygroscopic behavior. Based on the sorption isotherms, a Guggenheim-Anderson-de Boer (GAB) multi-layer adsorption model was selected as the optimal moisture absorption fitting model to describe the moisture absorption process of these fibers, which illustrated that water sorption capacity and the water–fiber/water–water interaction had a significant influence on its heating performance. The net isosteric heats of sorption decreased with an increase of moisture content, which further explained the main factor affecting the heat dissipation of fibers under different moisture contents. The state of adsorbed water and water vapor interaction on the fiber surface were studied by simultaneous thermal analysis (TGA-DSC) measurement. The percentage of bound and unbound water formation at low and high humidity had a profound effect on the thermal performance of fibers. It can therefore be concluded that the content of tightly bound water a strong water–fiber interaction was the main factor affecting the heating performance of fibers at low moisture content, and the content of loosely bound water reflected that water sorption capacity was the main factor affecting the heating performance of fibers at high moisture content. This was further proven by the heat of desorption.

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