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Open AccessArticle

A Comparison of Three Simulation Techniques for Modeling the Fan Blade–Composite Abradable Rub Strip Interaction in Turbofan Engines

by

Aleksandr Cherniaev

J. Compos. Sci. 2023, 7(9), 389; https://doi.org/10.3390/jcs7090389 - 14 Sep 2023

Viewed by 333

Abstract

Turbofan engine models for foreign object impact simulations must include a representation of fan blade interactions with surrounding components of the engine, including rubbing against the abradable lining. In this study, three numerical techniques, namely, the finite element method (FEM), smoothed particles hydrodynamics [...] Read more.

Turbofan engine models for foreign object impact simulations must include a representation of fan blade interactions with surrounding components of the engine, including rubbing against the abradable lining. In this study, three numerical techniques, namely, the finite element method (FEM), smoothed particles hydrodynamics (SPH), and the adaptive (hybrid) FEM/SPH approach (ADT), were evaluated for their applicability to modeling of the blade–abradable rub strip (ARS) interaction. Models developed using these methods in the commercial code LS-DYNA were compared in terms of their computational cost, robustness, sensitivity to mesh density, and certain physical and non-physical parameters. As a result, the applicability of the models to represent the blade-ARS interaction was ranked as follows (1—most applicable, 3—least applicable): 1—SPH, 2—FEM, and 3—ADT. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Mechanical Properties of Uncured Thermoset Tow Prepreg: Experiment and Finite Element Analysis

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Mina Derakhshani Dastjerdi

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Massimo Carboni

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Mehdi Hojjati

J. Compos. Sci. 2023, 7(8), 312; https://doi.org/10.3390/jcs7080312 - 29 Jul 2023

Viewed by 607

Abstract

This paper presents an experimental analysis of the tensile behavior of unidirectional carbon/epoxy prepreg, focusing on the nonlinearity observed at the beginning of the stress–strain curve. Due to the material’s high viscosity, securely holding specimens during testing was challenging, prompting modifications in the [...] Read more.

This paper presents an experimental analysis of the tensile behavior of unidirectional carbon/epoxy prepreg, focusing on the nonlinearity observed at the beginning of the stress–strain curve. Due to the material’s high viscosity, securely holding specimens during testing was challenging, prompting modifications in the gripping method to ensure reliable data. By using a longer gauge length, the slippage impact on elastic modulus measurement was minimized, resulting in good repeatability among the test samples. Experimental findings highlighted the significant interaction between fiber waviness and the viscous matrix, leading to stiffness reduction. The linear stiffness of the samples closely matched that of the fibers and remained unaffected by temperature variations. However, at higher temperatures, the epoxy matrix’s decreased viscosity caused an upward shift in the stiffness plot within the non-linear region. To support the experimental findings, a micromechanical model of prepreg tow with fiber waviness was proposed. An RVE model of periodically distributed unidirectional waved cylindrical fibers embedded within the matrix was developed to predict effective material stiffness parameters. The simulation outcomes aligned well with the uniaxial tensile test of the prepreg tow, demonstrating the proposed RVE model’s capability to accurately predict elastic properties, considering factors like fiber arrangement, waviness, and temperature. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

An Efficient Method for Simulating the Temperature Distribution in Regions Containing YAG:Ce³⁺ Luminescence Composites of White LED

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Quang-Khoi Nguyen

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Thi-Hanh-Thu Vu

J. Compos. Sci. 2023, 7(7), 301; https://doi.org/10.3390/jcs7070301 - 22 Jul 2023

Viewed by 582

Abstract

A thermal model was built to estimate the temperature distribution in the hemispherical packaging volume of a white LED at a steady state. Inherent heat sources appeared in the white LED when its power was measured. A simplified 3D to 2D space process [...] Read more.

A thermal model was built to estimate the temperature distribution in the hemispherical packaging volume of a white LED at a steady state. Inherent heat sources appeared in the white LED when its power was measured. A simplified 3D to 2D space process that improves the model and solves the heat diffusion equation in a simpler and faster manner is presented. The finite element method was employed using MATLAB software (version R2017b) to identify the temperature distribution. The model was applied for different values of injection current, including 50 mA, 200 mA, 350 mA, and 500 mA. The influence of the injection current and thermal conductivity difference on the temperature distribution of the encapsulant, blue LED die, and substrate region was clearly observed. The results indicate that white light packaging technology should locate phosphor far from the LED die, that the thermal conductivity of the silicone–phosphor region should be improved, that heat should be dissipated for pc-WLEDs when using a high operating power, and that the injection current should be kept as moderate as possible. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Statistical Analysis and Optimization of the Experimental Results on Performance of Green Aluminum-7075 Hybrid Composites

by

Olanrewaju Seun Adesina

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Abayomi Adewale Akinwande

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Oluwatosin Abiodun Balogun

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Adeolu Adesoji Adediran

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Olufemi Oluseun Sanyaolu

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Valentin Romanovski

J. Compos. Sci. 2023, 7(3), 115; https://doi.org/10.3390/jcs7030115 - 13 Mar 2023

Cited by 4 | Viewed by 895

Abstract

The present study assessed the potential of engaging response surface analysis in the experimental design, modeling, and optimization of the strength performance of aluminum-7075 green composite. The design of the experiment was carried out via the Box–Behnken method and the independent variables are [...] Read more.

The present study assessed the potential of engaging response surface analysis in the experimental design, modeling, and optimization of the strength performance of aluminum-7075 green composite. The design of the experiment was carried out via the Box–Behnken method and the independent variables are rice husk ash (RHA) at 3–12 wt.%, glass powder (GP) at 2–10 wt.%, and stirring temperature (ST) at 600–800 °C. Responses examined are yield, ultimate tensile, flexural, and impact strengths, as well as microhardness and compressive strength. ANOVA analysis revealed that the input factors had consequential contributions to each response, eventually presenting regression models statistically fit to represent the experimental data, further affirmed by the diagnostic plots. The result of the optimization envisaged an optimal combination at 7.2% RHA, 6.2 GP, and 695 °C with a desirability of 0.910. A comparison between the predicted values for the responses and the values of the validation experiment revealed an error of <5% for each response. Consequently, the models are certified adequate for response predictions at 95% confidence, and the optimum combination is adequate for the design of the composite. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

A Mathematical Approach for Sound Insulation Characteristics and Cost Optimization of Double-Layer Composite Structures

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J. Compos. Sci. 2023, 7(3), 110; https://doi.org/10.3390/jcs7030110 - 09 Mar 2023

Viewed by 976

Abstract

The compressor is the primary source of noise in a refrigeration system. Most compressors are wrapped with multi-layer sound insulation cotton for noise reduction and sound insulation. We explore the sound insulation law of different polyvinyl chloride thicknesses and non-woven fibers. Polyvinyl chloride [...] Read more.

The compressor is the primary source of noise in a refrigeration system. Most compressors are wrapped with multi-layer sound insulation cotton for noise reduction and sound insulation. We explore the sound insulation law of different polyvinyl chloride thicknesses and non-woven fibers. Polyvinyl chloride with varying thicknesses and non-woven fibers are then combined by bonding to study the sound insulation characteristics of a two-layer composite structure. A sound insulation prediction model is established using the multi-parameter nonlinear regression method. An optimal cost mathematical model is established based on experimental and mathematical methods that can quickly determine the optimal cost scheme for different designs with the same effect. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Characterization of UV Light Curable Piezoelectric 0-0-3 Composites Filled with Lead-Free Ceramics and Conductive Nanoparticles

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Rytis Mitkus

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Lena Piechowiak

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Michael Sinapius

J. Compos. Sci. 2023, 7(2), 89; https://doi.org/10.3390/jcs7020089 - 20 Feb 2023

Cited by 1 | Viewed by 1195

Abstract

Lead-free piezoelectric materials are essential for our healthy future but offer lower performance than lead-based materials. Different material combinations are explored to improve the performance of lead-free materials. By filling the UV light curable photopolymer resin with 30 vol.% lead-free piezoelectric ceramics and [...] Read more.

Lead-free piezoelectric materials are essential for our healthy future but offer lower performance than lead-based materials. Different material combinations are explored to improve the performance of lead-free materials. By filling the UV light curable photopolymer resin with 30 vol.% lead-free piezoelectric ceramics and with up to 0.4 wt.% conductive nanofillers, thin and flexible piezoelectric 0-0-3 composites are formed. Two particle sizes of Potassium Sodium Niobate (KNN) and Barium Titanate (BTO) ceramics were used with four conductive nanofillers: Graphene Nanoplatelets (GNPs), Multi-Walled Carbon Nanotubes (MWCNTs), and two types of Graphene Oxide (GO). Resulting high viscosity suspensions are tape-cast in a mold as thin layers and subsequently exposing them to UV light, piezoelectric composite sensors are formed in 80 s. Even low nanofiller concentrations increase relative permittivities, however, they strongly reduce curing depth and increase undesirable dielectric losses. Non-homogeneous dispersion of nanofillers is observed. In total, 36 different compositions were mixed and characterized. Only six selected material compositions were investigated further by measuring mechanical, dielectric, and piezoelectric properties. Results show KNN composite performance as piezoelectric sensors is almost six times higher than BTO composite performance. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Micro-Scale Model of rCF/PA6 Spun Yarn Composite

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Tobias Georg Lang

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Mir Mohammad Badrul Hasan

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Anwar Abdkader

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Chokri Cherif

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Thomas Gereke

J. Compos. Sci. 2023, 7(2), 66; https://doi.org/10.3390/jcs7020066 - 06 Feb 2023

Viewed by 837

Abstract

Recycling carbon fibers (rCF) for reuse is one approach to improve the sustainability of CFRP. However, until now, recycled carbon fiber plastics (rCFRP) had limited composite properties due to the microgeometry of the fibers, which made it difficult to use in load-bearing components. [...] Read more.

Recycling carbon fibers (rCF) for reuse is one approach to improve the sustainability of CFRP. However, until now, recycled carbon fiber plastics (rCFRP) had limited composite properties due to the microgeometry of the fibers, which made it difficult to use in load-bearing components. The production of hybrid yarns from rCF and PA6 fibers allows the fibers to be aligned. The geometric properties of the yarn and the individual fibers influence the mechanical properties of the composite. An approach for the modeling and simulation of hybrid yarns consisting of recycled carbon fibers and thermoplastic fibers is presented. The yarn unit cell geometry is modeled in the form of a stochastic fiber network. The fiber trajectory is modeled in form of helical curves using the idealized yarn model of Hearle et al. The variability in the fiber geometry (e.g., length) is included in form of statistical distributions. An additional compaction step ensures a realistic composite geometry. The created model is validated geometrically and by comparison with tensile tests of manufactured composites. With the validated model, multiple parameter studies investigating the influence of fiber and yarn geometry are carried out. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Comparative Analysis of ANN-MLP, ANFIS-ACO_R and MLR Modeling Approaches for Estimation of Bending Strength of Glulam

by

Morteza Nazerian

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Masood Akbarzadeh

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Antonios N. Papadopoulos

J. Compos. Sci. 2023, 7(2), 57; https://doi.org/10.3390/jcs7020057 - 04 Feb 2023

Cited by 2 | Viewed by 878

Abstract

Multiple linear regression (MLR), adaptive network-based fuzzy inference system–ant colony optimization algorithm hybrid (ANFIS-ACO_R) and artificial neural network–multilayer perceptron (ANN-MLP) were tested to model the bending strength of Glulam (glue-laminated timber) manufactured with a plane tree (Platanus orientalis L.) wood [...] Read more.

Multiple linear regression (MLR), adaptive network-based fuzzy inference system–ant colony optimization algorithm hybrid (ANFIS-ACO_R) and artificial neural network–multilayer perceptron (ANN-MLP) were tested to model the bending strength of Glulam (glue-laminated timber) manufactured with a plane tree (Platanus orientalis L.) wood layer adhered with different weight ratios (WR) of modified starch/urea formaldehyde (UF) adhesive containing different levels of nano-ZnO (NC) used at different levels of the press temperature (Tem) and time (Tim). According to X-ray diffraction (XRD) and stress–strain curves, some changes in the behavior of the product were seen. After selecting the best model through determining statistics such as the determination coefficient (R2) and root mean square error (RMSE), mean absolute error (MAE) and sum of squares error (SSE), the production process was optimized to obtain the highest modulus of rupture (MOR) using the Genetic Algorithm (GA) combined with MLP. It was determined that the MLP had the best accuracy in estimating the response. According to the MLP-GA hybrid, the optimum input values for obtaining the best response include: WR—49.1%, NC—3.385%, Tem—199.4 °C and Tim—19.974 min. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

On the Influence of Fatigue Damage in Short-Fibre Reinforced Thermoplastic PBT GF30 on Its Residual Strength under High Strain Rates: An Approach towards Simulative Prediction

by

Christian Witzgall

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Patrick Steck

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Sandro Wartzack

J. Compos. Sci. 2023, 7(1), 23; https://doi.org/10.3390/jcs7010023 - 10 Jan 2023

Cited by 2 | Viewed by 1160

Abstract

Only by using accurate material data can precise simulation results be achieved. This principle also and especially applies in the field of crash simulation. However, in the simulation of short-fibre reinforced thermoplastics, material parameters are usually used that originate from the material testing [...] Read more.

Only by using accurate material data can precise simulation results be achieved. This principle also and especially applies in the field of crash simulation. However, in the simulation of short-fibre reinforced thermoplastics, material parameters are usually used that originate from the material testing of as-new samples. In order to get closer to the condition on the roads, where not only new vehicles are driving, the influence of service loads on the crashworthiness has to be investigated. This paper reports on studies of PBT GF30, a polybutylene terephthalate reinforced with 30% glass fibres, in which fatigue damage was induced in the material by cyclic loading. The residual strength was then determined in a high-speed experiment and compared with the strength of virgin samples. In order to enable the usability of the findings in the simulation, a modified failure criterion was implemented that takes the previous fatigue damage into account. The prediction quality of the simulation model was compared with the experimental findings and it can be concluded that there is good agreement. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Development of Prediction Models for the Torsion Capacity of Reinforced Concrete Beams Using M5P and Nonlinear Regression Models

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J. Compos. Sci. 2022, 6(12), 366; https://doi.org/10.3390/jcs6120366 - 02 Dec 2022

Cited by 5 | Viewed by 885

Abstract

Torsional strength is related with one of the most critical failure types for the design and assessment of reinforced concrete (RC) members due to the complexity of the associated stress state and low ductility. Previous studies have shown that reliable methods to predict [...] Read more.

Torsional strength is related with one of the most critical failure types for the design and assessment of reinforced concrete (RC) members due to the complexity of the associated stress state and low ductility. Previous studies have shown that reliable methods to predict the torsional strength of RC beams are still needed, namely for over-reinforced and high-strength RC beams. This research aims to offer a novel set of models to predict the torsional strength of RC beams with a wide range of design attributes and geometries by using advanced M5P tree and nonlinear regression models. For this, a broad database with 202 experimental tests is used to generate highly reliable and resilient models. To build the models, three independent variables related with the properties of the RC beams are considered: concrete cross-section area (area enclosed within the outer perimeter of the cross-section), concrete compressive strength, and torsional reinforcement factor (which accounts for the type—longitudinal or transverse—amount, and yielding strength of the torsional reinforcement). In contrast to multiple nonlinear regression approaches, the findings show that the M5P tree approach has the best estimation in terms of both accuracy and safety. Furthermore, M5P model predictions are far more accurate and safer than the most prevalent design equations. Finally, sensitivity and parametric studies are used to confirm the robustness of the presented models. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Micromechanical Approach to Predict Mechanical Properties of Particulate-Dispersed Composites with Dissimilar Interfacial Phases

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J. Compos. Sci. 2022, 6(12), 356; https://doi.org/10.3390/jcs6120356 - 22 Nov 2022

Viewed by 739

Abstract

The mechanical properties of composites are affected by their constituents. For the development of high-performance composites, it is expected that a technique will be developed which can predict the mechanical properties of composites based on the mechanical properties of their constituents. This study [...] Read more.

The mechanical properties of composites are affected by their constituents. For the development of high-performance composites, it is expected that a technique will be developed which can predict the mechanical properties of composites based on the mechanical properties of their constituents. This study developed a technique based on a micromechanical approach to predict the mechanical properties of composites with interfacial phases between reinforcements and matrix. A double-inclusion model (Hori and Nemat-Nasser, 1993) is effective for the solution of such problems, of which the validity remains unclear. Problems with a particle surrounded by an interfacial phase embedded in an infinite body were calculated via the model and finite element analysis to verify the model. It was found that the macroscopic average stress of the double inclusion could be accurately solved by the model, although the microscopic stress of each phase could not be calculated with high accuracy. Therefore, a micromechanical approach based on the model was formulated and applied to particulate-dispersed composites consisting of zirconia and titanium, and fabricated by spark plasma sintering, in which Ti oxides were created along the interface between zirconia and titanium. As a result, the elastic-plastic stress–strain curves of the composites could be predicted. The approach can investigate the mechanical properties of composites with various shapes of reinforcement surrounded by dissimilar materials in a matrix. It can be concluded that the approach is promising for the development of composites with an excellent mechanical performance. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Investigation of Mechanical Properties of Coffee Husk-HDPE-ABS Polymer Composite Using Injection-Molding Method

by

Berhanu Tolessa Amena

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Holm Altenbach

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Getechew Shunki Tibba

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Nazia Hossain

J. Compos. Sci. 2022, 6(12), 354; https://doi.org/10.3390/jcs6120354 - 22 Nov 2022

Cited by 1 | Viewed by 1276

Abstract

Waste biomass-based natural fibers are being extensively researched nowadays as a composite material with various waste-based high-density polyethylene (HDPE) to utilize the waste biomass and recycle the plastic waste in an effective approach. In this study, chemically modified spent coffee husk (CH) has [...] Read more.

Waste biomass-based natural fibers are being extensively researched nowadays as a composite material with various waste-based high-density polyethylene (HDPE) to utilize the waste biomass and recycle the plastic waste in an effective approach. In this study, chemically modified spent coffee husk (CH) has been applied with different ratios of HDPE to produce composite material and characterized comprehensively to determine the mechanical stability of the products. The injection molding method was used for composite development containing HDPE with untreated and 10 wt% NaOH-treated CH weight ratios of 0%, 15%, 20%, and 25% together with 10 wt% coupling agent and filler materials of acrylonitrile butadiene styrene (ABS) and kaolin clay, respectively. Physicochemical characteristics of untreated CH, 10 wt% NaOH treated CH, pristine HDPE and HDPE-CH composites have been analyzed comprehensively in this study. Adding 25 wt% fiber with 65 wt% HDPE and 10 wt% of ABS (7 wt%)-kaolin clay (3 wt%) increased the tensile and bending properties significantly. This composite presented the maximum tensile, flexural, and impact strengths, which were 36 MPa, 7.5 MPa, and 2.8 KJ/m², respectively. The tensile strength and bending strength of NaOH-treated coffee husk fibers (CHF) were enhanced by 32% and 29%, respectively. The microstructural characteristics of HDPE with treated and untreated CHF composites analyzed by scanning electron microscopy (SEM) demonstrated the fibers’ and matrix’s excellent adhesion and compatibility. Thus, HDPE polymer-treated CH composite presented excellent stability, which can be expected as a new addition for construction, food packaging, and other industrial applications. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Influence of Spatially Distributed Out-of-Plane CFRP Fiber Waviness on the Estimation of Knock-Down Factors Based on Stochastic Numerical Analysis

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J. Compos. Sci. 2022, 6(12), 353; https://doi.org/10.3390/jcs6120353 - 22 Nov 2022

Viewed by 839

Abstract

The presence of waviness defects in CFRP materials due to fiber undulation affects the structural performance of composite structures. Hence, without a reliable assessment of the resulting material properties, the full weight-saving potential cannot be exploited. Within the paper, a probabilistic numerical approach [...] Read more.

The presence of waviness defects in CFRP materials due to fiber undulation affects the structural performance of composite structures. Hence, without a reliable assessment of the resulting material properties, the full weight-saving potential cannot be exploited. Within the paper, a probabilistic numerical approach for improved estimation of material properties based on spatially distributed fiber waviness is presented. It makes use of a homogenization approach to derive viable knock-down factors for the different plies on the laminate level for reference material and is demonstrated for a representative tension loadcase. For the stochastic analysis, a random field is selected which describes the complex inner geometry of the plies in the laminate model and is numerically discretized by the Karhunen–Loeve expansion methods to fit into an FE model for the strength analysis. Conducted analysis studies reveal a substantial influence of randomly distributed waviness defects on the derived knock-down factors. Based on a topological analysis of the waviness fields, the reduction of the material properties was found to be weakly negatively correlated related to simple geometrical properties such as maximum amplitudes of the waviness field, which justifies the need for further subsequent sensitivity studies. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Utilizing of Magnetized Water in Enhancing of Volcanic Concrete Characteristics

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Mostafa M. Keshta

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Mohamed M. Yousry Elshikh

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Mohamed Abd Elrahman

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Osama Youssf

J. Compos. Sci. 2022, 6(10), 320; https://doi.org/10.3390/jcs6100320 - 19 Oct 2022

Cited by 5 | Viewed by 1437

Abstract

Volcanic concrete is an eco-friendly concrete type in that it contains coarse and fine aggregates that all extracted from the igneous volcanic rock. However, utilizing of volcanic ash (VA) as partial/full replacement of concrete cement significantly affects the concrete workability, especially at high [...] Read more.

Volcanic concrete is an eco-friendly concrete type in that it contains coarse and fine aggregates that all extracted from the igneous volcanic rock. However, utilizing of volcanic ash (VA) as partial/full replacement of concrete cement significantly affects the concrete workability, especially at high cement replacement ratios. This has also some adverse effects on concrete strength. Utilizing magnetized water (MW) in concrete as a partial/full replacement of ordinary tap water (TW) has a notable effect on enhancing the fresh and hardened concrete properties. This research aims to study the effect of using MW prepared in a magnetic field of 1.4 Tesla on the workability and hardened properties (compressive, tensile, and flexural strengths) of volcanic concrete. In this study, VA partially replaced volcanic concrete cement with ratios of 5%, 10%, 15%, and 20%. Ten volcanic concrete mixes were prepared in two groups. The first one was prepared with VA (0–20%) and mixed with TW. The other group was prepared with the same VA contents like group one, but mixed with MW. Microstructure imaging for volcanic concrete was also conducted in this study. Results of water tests showed 17% and 15% increase in total dissolved solids (TDS) and pH, respectively, of MW compared with those of TW. In addition, the water magnetization decreased the water surface tension by 7% compared with that of TW. Results of hardened concrete tests showed that the best ratio of VA in volcanic concrete was 5% with and without using magnetized water. The volcanic concrete slump decreased when using TW; however, using MW enhanced the volcanic concrete slump by up to 8%. The compressive strength was improved by 35%, 23%, and 20% at 7 days, 28 days, and 120 days, respectively, with no VA and with the presence of MW. The compressive strength was improved by 11%, 12%, and 11% after 7 days, 28 days, and 120 days, respectively, with using 5% VA and with the presence of MW. Both splitting tensile strength and flexural strength of volcanic concrete with and without VA or MW behaved similar to that of the corresponding compressive strength. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Mixed-Mode I/II Testing of Composite Materials—A Refined Data Reduction Scheme for the Wedge-Loaded Asymmetric Double Cantilever Beam Test

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J. Compos. Sci. 2022, 6(10), 319; https://doi.org/10.3390/jcs6100319 - 18 Oct 2022

Viewed by 1241

Abstract

The wedge-loaded asymmetric double cantilever beam (WADCB) test is an experimental method to determine the mixed-mode I/II fracture toughness of composite materials by inserting a wedge into the specimen along a potential delamination path. Whilst the current closed-form solution for the ADCB test [...] Read more.

The wedge-loaded asymmetric double cantilever beam (WADCB) test is an experimental method to determine the mixed-mode I/II fracture toughness of composite materials by inserting a wedge into the specimen along a potential delamination path. Whilst the current closed-form solution for the ADCB test assumes identical forces acting in both specimen arms, this manuscript proposes a refined closed-form solution allowing for different forces acting on both specimen arms, which is thought to be more general and more rigorous. WADCB tests were carried out on composites made from Torayca T700SC/2592 unidirectional prepreg. Both the current and the refined closed-form solution were used to analyze the data, and some differences were found in the predictions, indicating that the forces in the two specimen arms are indeed not identical. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Threshold Identification and Damage Characterization of Woven GF/CF Composites under Low-Velocity Impact

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Marzio Grasso

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Yigeng Xu

J. Compos. Sci. 2022, 6(10), 305; https://doi.org/10.3390/jcs6100305 - 11 Oct 2022

Viewed by 830

Abstract

The Delamination Threshold Load (DTL) is a key parameter representing damage resistance of a laminate and is normally identified by locating a sudden drop in the impact force-time history for the laminate made of unidirectional layers. For the woven composite, however, their failure [...] Read more.

The Delamination Threshold Load (DTL) is a key parameter representing damage resistance of a laminate and is normally identified by locating a sudden drop in the impact force-time history for the laminate made of unidirectional layers. For the woven composite, however, their failure mechanisms appear different and the current literature is not providing any clear procedure regarding the identification of the delamination initiation, as well as the evolution of the failure mechanisms associated with it. In this paper, experimental data have been collected using woven glass and carbon fiber composites. The results are analyzed in terms of force-time and force-displacement curves. While delamination and other damages were clearly observed using ultrasonic scans, the analysis of the results does not reveal any trend changes of the curves that can be associated with the incipient nucleation of delamination. A preliminary discussion regarding the nature of the mechanisms through which the delamination propagates in woven composite and a justification for the absence of a sudden change of the stiffness have been presented. It raises a question on the existence of DTL for woven composites under low velocity impact. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Mitigation of Heat Propagation in a Battery Pack by Interstitial Graphite Nanoplatelet Layer: Coupled Electrochemical-Heat Transfer Model

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J. Compos. Sci. 2022, 6(10), 296; https://doi.org/10.3390/jcs6100296 - 09 Oct 2022

Cited by 4 | Viewed by 1276

Abstract

The use of high thermal conductive materials for heat transfer is gaining attention as a suitable treatment for improving battery performance. Thermal runaway is a relevant issue for maintaining safety and for proficient employment of accumulators; therefore, new solutions for thermal management are [...] Read more.

The use of high thermal conductive materials for heat transfer is gaining attention as a suitable treatment for improving battery performance. Thermal runaway is a relevant issue for maintaining safety and for proficient employment of accumulators; therefore, new solutions for thermal management are mandatory. For this purpose, a hierarchical nanomaterial made of graphite nanoplatelet has been considered as an interface material. High-content graphite nanoplatelet films have very high thermal conductivity and might improve heat dissipation. This study investigates the effect of a thermally conductive material as a method for safety enhancement for a battery module. A numerical model based on the finite element method has been developed to predict the heat generation during a battery pack’s charge and discharge cycle, using the Multiphysics software Comsol. The lumped battery interface generates appropriate heat sources coupled to the Heat Transfer Interface in 3D geometry. Simulation results show that the protection of neighbouring cells from the interleaved layer is fundamental for avoiding heat propagation and an uncontrollable heating rise of the entire battery pack. The use of graphite nanocomposite sheets could effectively help to uniform the temperature and delay the TR propagation. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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A Study on the Structural Features of Amorphous Nanoparticles of Ni by Molecular Dynamics Simulation

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J. Compos. Sci. 2022, 6(9), 278; https://doi.org/10.3390/jcs6090278 - 19 Sep 2022

Cited by 2 | Viewed by 1067

Abstract

This study deals with the impact of the heating rate (HR), temperature (T), and the number of atoms (N) on the structural features of amorphous nanoparticles (ANPs) of Ni by molecular dynamics simulation (MDS) with the Pak–Doyama pair interaction potential field (PD). The [...] Read more.

This study deals with the impact of the heating rate (HR), temperature (T), and the number of atoms (N) on the structural features of amorphous nanoparticles (ANPs) of Ni by molecular dynamics simulation (MDS) with the Pak–Doyama pair interaction potential field (PD). The obtained results showed that the structural features of ANPs of Ni are significantly affected by the studied factors. The correlation between the size (D) and the N was determined to be D~N^−1/3. The energy (E) was proportional to N⁻¹, and the Ni-Ni link length was 2.55 Å. The glass transition temperature (T_g) derived from the E-T graph was estimated to be 630 K. An increase in the HR induced a change in the shape of the ANPs of Ni. Furthermore, raising the HR caused an enhancement in the D and a decrement in the density of atoms. The obtained results are expected to contribute to future empirical studies. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Finite Element Simulation of FRP-Strengthened Thin RC Slabs

by

Maha Assad

,

Rami Hawileh

and

Jamal Abdalla

J. Compos. Sci. 2022, 6(9), 263; https://doi.org/10.3390/jcs6090263 - 08 Sep 2022

Cited by 3 | Viewed by 1143

Abstract

This study aims to investigate the flexural behavior of high-strength thin slabs externally strengthened with fiber-reinforced polymer (FRP) laminates through a numerical simulation. A three-dimensional (3D) finite element (FE) model is created to simulate the response of strengthened reinforced concrete (RC) slabs under [...] Read more.

This study aims to investigate the flexural behavior of high-strength thin slabs externally strengthened with fiber-reinforced polymer (FRP) laminates through a numerical simulation. A three-dimensional (3D) finite element (FE) model is created to simulate the response of strengthened reinforced concrete (RC) slabs under a four-point bending test. The numerical model results in terms of load-deflection behavior, and ultimate loads are verified using previously published experimental data in the literature. The numerical results show a good agreement with the experimental results. The FE model is then employed in a parametric study to inspect the effect of concrete compressive strength on the performance of RC thin slabs strengthened with different FRP types, namely carbon fiber-reinforced polymers (CFRP), polyethylene terephthalate fiber-reinforced polymers (PET-FRP), basalt fiber-reinforced polymers (BFRP) and glass fiber-reinforced polymers (GFRP). The results showed that the highest strength enhancement was obtained by the slab that was strengthened by CFRP sheets. Slabs that were strengthened with other types of FRP sheets showed an almost similar flexural capacity. The effect of concrete compressive strength on the flexural behavior of the strengthened slabs was moderate, with the highest effect being a 15% increase in the ultimate load between two consecutive values of compressive strength, occurring in the CFRP-strengthened slabs. It can thus be concluded that the developed FE model could be used as a platform to predict the behavior of reinforced concrete slabs when strengthened with different types of FRP composites. It can also be concluded that the modulus of elasticity of the composite plays a major role in determining the flexural capacity of the strengthened slabs. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Experimental and Finite Element Study of a Novel Two-Way Corrugated Steel Deck System for Composite Slabs

by

,

,

and

J. Compos. Sci. 2022, 6(9), 261; https://doi.org/10.3390/jcs6090261 - 08 Sep 2022

Cited by 2 | Viewed by 1154

Abstract

This paper investigates the structural performance of a new two-way profiled steel decking system for steel-concrete composite slabs. Several studies have investigated steel decking for steel-concrete composite slabs and focused on utilising the conventional deck as a one-way floor system. The newly developed [...] Read more.

This paper investigates the structural performance of a new two-way profiled steel decking system for steel-concrete composite slabs. Several studies have investigated steel decking for steel-concrete composite slabs and focused on utilising the conventional deck as a one-way floor system. The newly developed deck consists of top-hat sections formed by bending corrugated sheets at 90°, which are attached to a corrugated base sheet. The deck is designed for improved composite and two-way action contributed by its unique geometry due to corrugations in the transverse and longitudinal directions. This paper experimentally tested a novel steel decking geometry under construction stage loading. It was in the absence of concrete to establish the deck’s suitability for construction and contribution towards loading capacity and performance for future use as a two-way composite slab. Ultimate load, two-way action, and failure modes were identified. A finite element model was also developed, and parameters assessed that could influence the performance when the deck is potentially used in the composite stage. It was concluded that, while increasing the thickness of the corrugated base sheet significantly affects the load-carrying capacity, the thickness of the top hats has no significant impact. Improved load transfer with two-way behaviour is observed when the bottom flanges of the top hats are continuously connected to the bottom flanges of the adjacent top hats to form a deck. This contrasts with the concept deck, where individual top hats are attached to a corrugated base sheet. In this case, decks with a corrugated base sheet perform 54% better in ultimate load capacity than decks without a corrugated base sheet. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Development and Characterization of PHB-PLA/Corncob Composite for Fused Filament Fabrication

by

Okezie Ohaeri

and

Duncan Cree

J. Compos. Sci. 2022, 6(9), 249; https://doi.org/10.3390/jcs6090249 - 26 Aug 2022

Cited by 3 | Viewed by 1347

Abstract

The development of environmentally friendly polymeric composites holds great potential for agricultural leftovers. This study explores the effects of lignocellulosic corncob powder as a filler in a polyhydroxybutyrate (PHB)/polylactic acid (PLA) biopolymer matrix. The PHB-PLA matrix consists of a 55% to 45% blend, [...] Read more.

The development of environmentally friendly polymeric composites holds great potential for agricultural leftovers. This study explores the effects of lignocellulosic corncob powder as a filler in a polyhydroxybutyrate (PHB)/polylactic acid (PLA) biopolymer matrix. The PHB-PLA matrix consists of a 55% to 45% blend, respectively, while the filler loadings range from 0 wt.% to 8 wt.%. The components are combined and directly extruded into fused filaments for three-dimensional (3D) printing. The tensile strength of both the filament and dog-bone samples, flexural strength, and Charpy impact toughness of the composites, all decreased as filler loading increased. The tensile and flexural modulus of all samples examined improved noticeably with increasing filler loading. The filler particles had dense, mildly elongated sheet-like shapes, whereas the fractured surfaces of the composite samples had flat features for the pure polymer blend, but became rougher and jagged as filler loading increased. The fractured surface of Charpy impact test samples had smoother morphology when tested at cryogenic temperatures, compared to room temperature testing. All attributes showed a fourth-degree polynomial relationship to filler loading and all improved as filler loading increased, with the best results obtained at 6 wt.% loading. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Open AccessArticle

Prediction of Damage in Non-Crimp Fabric Composites Subjected to Transverse Crushing: A Comparison of Two Constitutive Models

by

Milad Kazemian

and

Aleksandr Cherniaev

J. Compos. Sci. 2022, 6(8), 224; https://doi.org/10.3390/jcs6080224 - 04 Aug 2022

Viewed by 1468

Abstract

Non-crimp fabrics (NCFs) are increasingly used in industry for manufacturing of composite structures due to a combination of high mechanical properties and excellent manufacturability. As with other composites, in-service damage can be a cause for severe reduction in load-carrying capacity of NCF-reinforced plastics. [...] Read more.

Non-crimp fabrics (NCFs) are increasingly used in industry for manufacturing of composite structures due to a combination of high mechanical properties and excellent manufacturability. As with other composites, in-service damage can be a cause for severe reduction in load-carrying capacity of NCF-reinforced plastics. In this experimental and numerical study, two constitutive material models previously used only for damage prediction in unidirectional (UD) tape and woven fabric-reinforced materials (LS-DYNA’s *MAT_ENHANCED_COMPOSITE_DAMAGE—MAT54 and *MAT_LAMINATED_COMPOSITE_FABRIC—MAT58) were evaluated for simulating transverse crushing of composite parts processed from a non-crimp carbon fabric. For this purpose, UD NCF components of tubular shape were subjected to transverse crushing through a controlled indentation of a metallic cylinder, and results of the experiment were compared with numerical modeling. Considered verification metrics included the observed and the predicted patterns of interlaminar damage, the extent of delamination, as well as the ability of the models to replicate force-displacement response exhibited by the tested specimens. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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Review

Jump to: Research

Open AccessReview

Review on Characterization of Biochar Derived from Biomass Pyrolysis via Reactive Molecular Dynamics Simulations

by

Zhong Hu

and

Lin Wei

J. Compos. Sci. 2023, 7(9), 354; https://doi.org/10.3390/jcs7090354 - 25 Aug 2023

Viewed by 410

Abstract

Biochar is a carbon-rich solid produced during the thermochemical processes of various biomass feedstocks. As a low-cost and environmentally friendly material, biochar has multiple significant advantages and potentials, and it can replace more expensive synthetic carbon materials for many applications in nanocomposites, energy [...] Read more.

Biochar is a carbon-rich solid produced during the thermochemical processes of various biomass feedstocks. As a low-cost and environmentally friendly material, biochar has multiple significant advantages and potentials, and it can replace more expensive synthetic carbon materials for many applications in nanocomposites, energy storage, sensors, and biosensors. Due to biomass feedstock species, reactor types, operating conditions, and the interaction between different factors, the compositions, structure and function, and physicochemical properties of the biochar may vary greatly, traditional trial-and-error experimental approaches are time consuming, expensive, and sometimes impossible. Computer simulations, such as molecular dynamics (MD) simulations, are an alternative and powerful method for characterizing materials. Biomass pyrolysis is one of the most common processes to produce biochar. Since pyrolysis of decomposing biomass into biochar is based on the bond-order chemical reactions (the breakage and formation of bonds during carbonization reactions), an advanced reactive force field (ReaxFF)-based MD method is especially effective in simulating and/or analyzing the biomass pyrolysis process. This paper reviewed the fundamentals of the ReaxFF method and previous research on the characterization of biochar physicochemical properties and the biomass pyrolysis process via MD simulations based on ReaxFF. ReaxFF implicitly describes chemical bonds without requiring quantum mechanics calculations to disclose the complex reaction mechanisms at the nano/micro scale, thereby gaining insight into the carbonization reactions during the biomass pyrolysis process. The biomass pyrolysis and its carbonization reactions, including the reactivity of the major components of biomass, such as cellulose, lignin, and hemicellulose, were discussed. Potential applications of ReaxFF MD were also briefly discussed. MD simulations based on ReaxFF can be an effective method to understand the mechanisms of chemical reactions and to predict and/or improve the structure, functionality, and physicochemical properties of the products. Full article

(This article belongs to the Special Issue Characterization and Modelling of Composites, Volume III)

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