Fuzzy Fiber Research Articles

On Structure Fuzzy Fibration

In this paper, we introduced concept of fuzzy homotopy lifting property, fuzzy fiber structure is introduced. Also, the definition of the fuzzy lifting function and some theorems in a fuzzy topological space are discussed.

Development and Application of an Interval-Valued Pythagorean Fuzzy Set-Based Grade Evaluation Method to Foreign Fiber Content

ABSTRACT To solve the problem of the grade evaluation of foreign fiber content in cotton, this paper divided the problem into multi-criteria decision-making field and proposed an interval-valued Pythagorean fuzzy set foreign fiber content grade evaluation method. Taking into account the various properties of foreign fibers, the multi-criteria evaluation of single foreign fiber content and comprehensive foreign fiber content is carried out to improve the quality of cotton textiles. Based on the Pythagorean fuzzy set, we used AHP and TOPSIS methods to determine the relevant weight information, combined with the grade evaluation index of foreign fiber content and the interval-valued Pythagorean fuzzy weighted average or geometric operators to construct a fiber multi-criteria decision model. Then, the evaluation index function is improved to make the score function more consistent with the facts, and the digitization and intelligence methods required for foreign fiber content detection and grade evaluation are developed. Further, an example is given to verify the feasibility and effectiveness of the model. In addition, the multi-criteria decision-making method adopted has high theoretical innovation and application value for the textile industry.

Effect of Fiber Anisotropy and Interphase on the Stress Jumps Across the Fiber/Matrix Interface in Fuzzy Fiber Composites

Effect of Fiber Anisotropy and Interphase on the Stress Jumps Across the Fiber/Matrix Interface in Fuzzy Fiber Composites

Recursive multiscale homogenization of multiphysics behavior of fuzzy fiber composites reinforced by hollow carbon nanotubes

Fuzzy fibers are fibers enhanced in terms of multiphysics properties with radially oriented carbon nanotubes grown on their surface through the chemical deposition process. For the first time, this paper attempts to present two generalized zeroth-order asymptotic homogenization schemes aimed at identifying the homogenized and local response of fuzzy fiber-reinforced composites, accounting for both multiphysics piezoelectric effect and cylindrically orthotropic material behavior. The unit cell problems are solved using the multiphysics finite-volume and the multiphysics finite-element techniques, respectively. While the former approach is based on the strong form solution of the equilibrium and conservation equations in an averaged sense in the discretized domain, the latter is based on the minimization of the total potential energy over the entire unit cell. A recursive multiscale analysis algorithm is developed wherein homogenized moduli (or local fields) obtained from the homogenization (or localization) analysis at one scale are utilized in the calculation of homogenized moduli (or local fields) at the next scale. Numerical examples indicate that good agreement of the homogenized properties and local field distributions generated by the two approaches is observed hence confirming the accuracy of the new homogenization methods for fuzzy fiber composites with multiphysics behaviors.

Energy dissipation of CFRP composites coated by wavy CNT with focus on the CNT maximum reachable volume fraction

Dynamic moduli and energy dissipation capability of polymer hybrid nanocomposite reinforced with carbon fiber (CF) coated by carbon nanotube (CNT) which makes a fuzzy fiber nanocomposite (FFNC) are estimated through a micromechanical model. An analytical expression is derived to extract the damping properties in the frequency domain. Then, a separate phase known as interphase whose properties vary gradually is taken into account to model the CNT/polymer interactions. The CNT waviness and random orientation are also included. Acceptable agreements in comparison with the molecular dynamics simulations and experiments prove the accuracy of the proposed model. Moreover, the maximum reachable volume fraction of CNTs is studied considering the radius of gyration of polymer chain, the CNT aspect ratio (CNTAR), radius, and waviness amplitude. The effects of the CNT inter-tube distance (CNTID), waviness, CNTAR, and the loading frequency are examined on the energy dissipation and storage capability, and hysteresis loop of FFNC. It is found that the FFNC effective dynamic moduli enhance by increasing the CNTAR, while the CNTAR becomes less influential as the CNTID increases. Furthermore, as the frequency increases, the area of the hysteresis loop is decreased. Whereas the hysteresis loop is converted to a straight line beyond the frequency of about 1e17 Hz.

An effective growth of hierarchical BNNTs/SiC fibers with enhanced interfacial properties

Tailoring the SiC fiber-matrix interface in micron-sized fibers is crucial to attaining enhanced mechanical properties in ceramic reinforced composites. Herein, the authors report the growth of boron nitride nanotubes (BNNT) onto SiC fibers (SiCf), creating a fuzzy fiber architecture to promote the surface area for a defined load path of fiber to the matrix and improve the mechanical properties of these structures. Successful BNNT-growth is achieved by a boron oxide chemical vapor deposition method combined with growth vapor trapping with optimum parameters of 1200 °C and 1 h, comparatively low temperature to those reported in the literature. The strength loss of SiCf after exposure to 1200 °C was attributed to high process temperature, similar to what has been observed in the literature. Hence, BNNT growth does not lead to additional strength loss on these fibers measured by a single fiber tensile test. Moreover, through this direct growth method, grown BNNTs utilize a surface-anchored BNNTs/SiCf, creating a good matrix adhesion to prevent fiber-fiber sliding and pullout and increasing the interfacial shear strength (IFSS) with epoxy. Furthermore, microbond tests show that fuzzy BNNTs/SiCf architecture increased IFSS by at least 87.8% compared to as-received SiCf.

Hybrid hierarchical homogenization theory for unidirectional CNTs-coated fuzzy fiber composites undergoing inelastic deformations

A new hybrid homogenization approach is proposed for simulating the homogenized and local response of unidirectional fuzzy fiber nanocomposites undergoing inelastic deformations. Fuzzy fiber composites are hierarchical reinforcing structures where the fibers coated with radially aligned carbon nanotubes (CNTs) are embedded in the matrix. In this spirit, the fuzzy fiber composites are modeled as a three-scale medium. At the microscale, the CNTs-reinforced matrix is homogenized as nanocomposite interphase (NCP) attached to the main fiber via the asymptotic expansion homogenization (AEH). At the mesoscale, an intermediate equivalent fiber that substitutes for the NCP and the main fiber is constructed using the composite cylinder assemblage (CCA) and the transformation field analysis (TFA) techniques. At the macroscale, homogenization of the equivalent fiber and the surrounding matrix is handled by AEH which yields the effective response of the whole fuzzy fiber composites. The new technique facilitates accurate and efficient studies of the inelastic deformation mechanisms of periodic fuzzy fiber arrays with single or multiple inclusions under biaxial and triaxial loading conditions, eliminating exhausting interphase mesh discretizations encountered in the classical full-field homogenization. An added advantage is that the proposed theory captures the fiber-fiber interaction neglected in the classical CCA-TFA, an issue that leads to the exceptionally stiff post-yielding stress-strain response common in the mean-field micromechanics approaches.

EFFECTIVE DISSIPATIVE PROPERTIES OF A WHISKERED LAYER IN MODIFIED FIBROUS COMPOSITES WITH WHISKERED FIBRES

It is known that the mechanical properties of fiber-reinforced composites are controlled by the conditions of contact between the fiber and the matrix. In this regard, great efforts of mechanics are directed to developing various techniques to improve the quality of the interface. The most common are: modification of the fiber surface, improvement of chemical interactions, or the addition of a third phase (interfacial layer) between the fiber and the matrix. The most common are: modification of the fiber surface, improvement of chemical interactions, or a third phase (interfacial layer) between the fiber and the matrix. In this study, the authors aim to examine the effective dynamic properties of a whiskered layer of fibers in modified composites, taking into account the structural characteristics of the interfacial layer – its thickness – length of whiskers, volumetric content of whiskers, and their mechanical properties. The dynamic performance of the whiskered layer surrounding the base fiber in modified composites was estimated. The whiskered layer is considered a fibrous composite formed by nanoscale whiskers grown on the surface and a matrix. An epoxy binder or a viscoelastic polymer is considered as a matrix. An approximate model was used. The effective characteristics of the whiskered layer were modeled and determined as the properties of a transversally isotropic fibrous system with the isotropy axis coinciding with nanowhiskers in the whiskered layer. A feature of the whiskered layer is that the density of whiskers varies with distance from the fiber surface. Therefore, it depends on the length of the nanowhiskers (the thickness of the interfacial layer). In this case, it turns out that the bulk for the matrix in the whiskered layer, even at the maximum density of nanowhiskers grown on the fiber surface and for sufficiently thin interfacial layers, is very significant. Fuzzy fiber composite, nanofibers, epoxy binder, damping properties.

Experimental and numerical simulation of lightning damage development on composites with/without a carbon-based protection layer

We analyzed a three-dimensional thermal-electrical coupled model based on COMSOL to characterize the thermal damage response of a woven carbon fiber reinforced polymer (CFRP) composite with and without a lightning strike protection (LSP) system. Fuzzy fiber (FF) fabric serving as a carbon-based protection layer was attached to the outermost ply of the CFRP composite to fabricate a fuzzy fiber reinforced polymer (FFRP) composite. CFRP and FFRP composites with temperature-dependent properties were inspected to predict lightning-induced damage resulting from a 20- and 40-kA peak current for 100 μs. The predicted area of thermal damage and the appearance of the composite surface agreed fairly well with post-lightning damage observed from experiments, thus demonstrating the credibility of the numerical model. LSP characteristics were evaluated for a range of CFRP composite properties in the outermost layer by enhancing the functional conductivity of the top layer in the in-plane and out-of-plane directions. The irreversible thermal damage region in the in-plane and thickness directions was dramatically mitigated by enhanced electrical conductivity, whereas a slight matrix decomposition damage change was observed by varying the thermal conductivity. Due to the increased electrical conductivity and integration of the lightweight FF carbon-based protection layer into the uppermost composite layer, the depth and area of damage can be limited by decreasing the thermal damage penetration through the underlying composites. These results reveal that a highly conductive FF layer may serve as a lightweight and effective anti-lightning strike layer for protecting the underlying composite.

A hierarchical prediction scheme for effective properties of fuzzy fiber reinforced composites with two-scale interphases: Based on three-phase bridging model

In this paper, based on Huang's bridging model (Huang Z-M, 2001), an effective and concise analytical prediction scheme for effective elastic properties of fuzzy fiber reinforced composites' (FFRCs), is presented. The distinctive constructional feature of the FFRCs, herein, is that the fuzzy fibers are continuous, aligned, and having wavy nanofillers (like CNTs) grown radially on the circumferential surfaces. By means of the proposed approach, two-scale interphase effects on the overall properties of FFRCs are investigated, including the CNTs/matrix interphase and the fuzzy interphase surrounding the micro-fibers. Meanwhile, the size effect and the waviness effect of nanofillers are evaluated. The accuracy and effectiveness of this prediction scheme is validated by comparisons with the existing experimental data and analytical results. A thorough parametric study indicates that the introduction of slender nanofillers into the micro-fiber/matrix interfacial zone, indeed, leads to significant enhancement to the transverse and shear performance of the composite. Moreover, such enhancement depends on some major parameters, including the contents of the two-scale reinforcements, the stiffness of the two-scale interphase, CNT waviness, as well as the radius and length of CNTs. Those findings may have important implications in the future design of FFRCs.

Fracture toughness enhancement of fuzzy CNT-glass fiber reinforced composites with a combined reinforcing strategy

Low interlaminar mechanical properties is the foremost drawback of glass fiber reinforced composites (GFRPs). Hierarchical nanoparticles on fibers (e.g. carbon nanotubes (CNTs)) can improve interlaminar properties of composites with negligible weight increase because of excellent mechanical properties, and low density. Interlaminar properties of composites can be enhanced with the well-dispersed CNTs in polymer matrices as it facilitates load transfer from matrix to fibers. This paper investigates the mechanical properties of CNT-reinforced GFRPs. Two reinforcing strategies were studied as dispersion of CNTs in epoxy matrix and direct growth of CNTs onto glass fibers (GFs), simultaneously. The former is referred to as nanotube-reinforced composites (NRCs) while the latter is known as fuzzy architectures. Furthermore, the combination of NRCs and fuzzy glass fibers (F-GFs), also known as fuzzy nano-reinforced composites (F-NRCs), is used to fabricate composites and identify the reinforcing capabilities through both methods. Mechanical properties are investigated by Mode-I fracture toughness and unidirectional (UD) composite tensile tests. Even though NRCs and F-NRCs yield similar enhancements in the propagation fracture toughness as 113% and 119%, respectively, the tensile strength of F-NRCs is decreased by 24% due to heat treatment during the CNT synthesis.

A multiscale analysis for free vibration of fuzzy fiber-reinforced nanocomposite conical shells

Abstract In this paper, the free vibration analysis of fuzzy fiber reinforced (FFRC) nanocomposite truncated conical shell is investigated. The FFRC constructional feature is that the uniformly aligned carbon nanotubes (CNTs) are radially grown on the circumferential surfaces of unidirectional carbon fibers. Using a micromechanical model based on the simplified unit cell (SUC) method, the effective material properties of the FFRC conical shells are evaluated. The thin-walled classical shell theory and Hamilton's principle are used to extract the governing equations, and the Ritz method is used to solve the problem. The model predictions are compared with other numerical results available in the literature and the correctness of the proposed theoretical method is attested. Some novel results, including the vibration results of FFRC conical shell accompanied with different combinations of boundary conditions and different material and geometrical properties are presented. The results reveal that the FFRC conical shell vibration behavior is strongly dependent on the material properties, volume fractions of two reinforcements, geometrical characteristics and boundary conditions.

Multiscale modeling accounting for inelastic mechanisms of fuzzy fiber composites with straight or wavy carbon nanotubes

This paper proposes a micromechanical approach aimed at identifying the response of unidirectional fuzzy fiber composites undergoing inelastic fields. Fuzzy fibers are reinforcement fibers coated with radially aligned straight or wavy carbon nanotubes grown through chemical deposition process (PVD or CVD). Due to this nature, the composite with fuzzy fibers is described by three scales: i) the microscale consisting of carbon nanotubes and their surrounding matrix, ii) the mesoscale containing the fiber, the nanocomposite and the matrix, and iii) the macroscale related to the overall fuzzy fiber composite. The developed framework considers for the mesoscopic scale an analytical formulation, based on the composite cylinders assemblage (CCA) method, combining the principles of the Transformation Field Analysis (TFA) technique. A numerical example that includes comparisons with full field homogenization strategies confirms the accuracy of the framework to predict the overall response, as well as the average local fields of the constituents.

Electrical conductivity and mechanical property improvement by low-temperature carbon nanotube growth on carbon fiber fabric with nanofiller incorporation

Carbon fiber reinforced polymer composites offer many advantages due to their great combination of high strength and modulus combined with low density and light-weight; however, they typically feature low electrical conductivity. These advanced composites are often unsatisfactory compared to conventional conductive metals that are vulnerable to lightning strike damage. To develop a new generation of highly conductive carbon fiber composites that address these shortcomings, carbon nanotubes (CNTs) were grown on nickel-coated carbon fiber using low-temperature growth to create a fuzzy fiber surface. An additional conductive filler, graphene nanoplatelets (GNPs), was then dispersed on the fuzzy fiber surface to form synergistic physical interactions between two different low-dimensional carbon-based nanostructures. The results reveal a synergistic enhancement in both functional conductivity and mechanical properties. The electrical conductivity of composites with the inclusion of GNPs resulted in approximately 40%, 300%, and 190% enhancement in the fiber, surface, and through-thickness direction compared to the fuzzy fiber composites. Mechanical properties, including flexural, work of fracture, impact, and interlaminar shear stress properties were further enhanced. These results reveal that the presence of GNPs creates more electron transfer pathways, and also promotes a synergistic effect in physical interactions. Altogether, these enhancements provide avenues for future high-performance conductive carbon fiber composites in aircraft structures.

Modeling the effective mechanical properties of “fuzzy fiber” composites across scales length

Abstract We employ a variant of generalized Eshelby's homogenization method to deduce effective properties of multilayered nanostructured fiber composites where one layer is highly heterogeneous with respect to its mechanical response strain gradients. We focus on carbon (C) fibers coated by carbon nanotubes (CNT) embedded in polymeric matrix with the aid of CNT “blistered” interphase layer developed between the coating and the matrix during processing and/or use. Each of the three phases is treated for simplicity by classical elasticity, while the interphase layer around the coated fibers (“fuzzy fibers”) to provide adhesion, and is treated by the simple gradient elasticity (GradELa) model. The novelty of the work lies on the fact of treating the CNT “fuzzy” layer by the GradEla model, that consequently allows to consider the extra gradient coefficient or internal length (characterizing this model) in relation to other constitutive and geometric parameters of the composite to optimize its overall mechanical properties and functionality. The method is general and can apply to treat other types of “fuzzy fiber” composites.

Field Emission From Metal Surfaces Irradiated With Helium Plasmas

Field electron emission from metal (tungsten, molybdenum, and tantalum) surfaces with different surface morphology was measured. Fuzz and loop samples had small increment in the emission current, whereas bubble samples marked huge increment in the current, accompanied by breakdown. The emission current became greater on the fuzzy samples than the loop samples probably because of more elongated morphology of fuzzy fiber. Among the materials, molybdenum had the lowest current. From Fowler–Nordheim plot analysis, it was revealed that fuzz samples had higher field enhancement factor than loop samples. Bubble samples marked the highest value in the field enhancement factor among the three types of morphology, likely due to the continuous emission from the craters formed after the breakdown. Molybdenum showed favorable properties in terms of suppressing the field emission and preventing the breakdown and the arcing in fusion reactor. From the scanning electron microscope observation, the size of the crater increases with the emission current on the bubble samples. Fuzzy structure was observed at the crater on the tantalum bubble surface after breakdown even without stationary plasma irradiation or stationary incidence of ion flux.

Control of large amplitude vibrations of doubly curved sandwich shells composed of fuzzy fiber reinforced composite facings

This paper is concerned with the analysis of active constrained layer damping (ACLD) of geometrically nonlinear vibrations of doubly curved sandwich shells with facings composed of fuzzy fiber reinforced composite (FFRC). FFRC is a novel composite where the short carbon nanotubes (CNTs) which are either straight or wavy are radially grown on the periphery of the long continuous carbon fiber reinforcements. The plane of waviness of the CNTs is coplanar with the plane of carbon fiber. The constraining layer of the ACLD treatment is composed of the vertically/obliquely reinforced 1–3 piezoelectric composites (PZCs) while the constrained viscoelastic layer has been sandwiched between the substrate and the PZC layer. The Golla–Hughes–McTavish (GHM) method has been implemented to model the constrained viscoelastic layer of the ACLD treatment in time domain. A three dimensional finite element (FE) model of smart doubly curved FFRC sandwich shells integrated with ACLD patches has been developed to investigate the performance of these patches for controlling the geometrically nonlinear vibrations of these shells. This study reveals that the performance of the ACLD patches for controlling the geometrically nonlinear vibrations of the doubly curved sandwich shells is better in the case of the facings composed of laminated FFRC than that in the case of the facings made of conventional orthotropic laminated composite. The research carried out in this paper brings to light that even the wavy CNTs can be properly utilized for attaining structural benefits from the exceptional elastic properties of CNTs.

Modeling of thermomechanical properties of polymeric hybrid nanocomposites

This article reports modeling of effective thermomechanical properties of multifunctional carbon nanotube (CNT)‐reinforced hybrid polymeric composites (hereafter, it is referred as “fuzzy fiber composite”). The novel constructional feature of fuzzy fiber composite (FFC) is that nanoscale CNTs are radially grown on the circumferential surfaces of microscale carbon fibers. Several micromechanical models were developed to predict the effective thermomechanical properties of FFC. The waviness of CNTs is intrinsic to many manufacturing processes and it influences thermomechanical behavior of two‐phase CNT‐reinforced composites. Therefore, an endeavor was also made to investigate the effect of wavy CNTs on the effective thermomechanical properties of FFC. The proposed modeling approach was applied to a heat exchanger made of FFC to determine its effective thermal conductivities. The findings of our study suggest that FFC containing nano‐ and micro‐scale fillers show improved thermomechanical properties and are promising next‐generation polymeric composites for advanced structural applications. POLYM. COMPOS., 39:4148–4164, 2018. © 2017 Society of Plastics Engineers

Stochastic multi-scale modeling of randomly grown CNTs on carbon fiber

The main objective of this article is to develop a stochastic multi-scale approach for predicting mechanical properties of a carbon fiber coated with randomly oriented carbon nanotubes (CNT) known as a fuzzy fiber. The core fiber and surrounding CNT/polymer nanocomposites can be considered as two constitutive phases of a fuzzy fiber. Firstly, effective properties of carbon nanotubes reinforced polymer are estimated while non-bonded van der Waals (vdW) interaction is assumed between carbon nanotubes and polymer. Then, effective properties of the fuzzy fiber are predicted. The curvature, volume fraction and orientation of CNTs are considered as random variables in the developed modeling procedure. For validation purpose, a comparison is done between the obtained results from developed computational modeling and published experimental data in literature for a single fuzzy fiber containing randomly oriented CNTs. an excellent conformity is realized between developed modeling procedure and experimental observations demonstrating the importance of taking into account random parameters. Finally, the influence of CNT contents on improving the transverse Young's modulus of investigated fiber is studied.

Predicting mechanical properties of fuzzy fiber reinforced composites: radially grown carbon nanotubes on the carbon fiber

It is intended to predict mechanical properties of fuzzy fiber reinforced polymer. An appropriate computational modeling is developed on the basis of bottom-up modeling covering all involved scales of nano, micro, meso and macro. The effective parameters of each scale are identified using top-down scanning approach and defining a representative volume element for each scale of analysis. At nano-scale, mechanical properties of isolated CNT are estimated. Then, at the upper scale of micro, the interaction between CNT and surrounding polymer is investigated considering non-bonded van der Waals interactions. Mechanical properties of the CNT/polymer nanocomposite with radial arrangement of CNT are derived at meso scale. Subsequently, mechanical properties of a single fuzzy fiber encompassing core carbon fiber and surrounding CNT/polymer are calculated. Finally, mechanical properties of the uni-directional and short fuzzy fiber reinforced composites are evaluated at the scale of macro. Treating CNT volume fraction and its arbitrary non-straight shapes as random parameters, developed modeling is conducted stochastically. The results imply on the importance of stochastic modeling, since deterministic modeling is led to a noticeable overestimation in predicted results. A very good agreement is reported between predicted results by stochastic modeling and published experimental data in literature.