Effect Of Fiber Arrangement Research Articles

Numerical and experimental study on anisotropic heat transfer behaviors of quartz fabric composite preforms: Multiple micro‐scale models method

AbstractThis paper presents a comprehensive study on anisotropic heat transmission behaviors in quartz fiber fabrics. Considering the random distribution characteristic of fibers within the yarn, an innovative two‐scale finite element method (tFEM) is introduced, incorporating multiple micro‐scale fiber models (MMFM) based on scanning electron microscope (SEM) observations. MMFM are divided into 8 distinct models to capture intricate fiber arrangements. The macro‐scale fabric model is constructed based on the geometric structure analysis by Micro‐CT technology. Both micro‐ and macro‐scale models are assembled with the air matrix to form the two‐phase composite model. The Hot‐Disk thermal analysis instrument is applied to measure the anisotropic thermal conductivity (ATC). Numerical results from MMFM shows more excellent agreements with the experimental ones at 3D orthogonal directions of fabrics, i.e., the error rates of the thermal conductivity in the warp, weft and thickness directions between numerical and experimental methods are all less than 3%, which indicates the tFEM including MMFM in this paper is more accurate than the tFEM including OSMFM. In addition, the temperature distribution and heat transmission differences due to fiber arrangements are simulated and illustrated through the MMFM. Afterwards, temperature drop and isothermal characteristics are demonstrated in this study.Highlights Effects of fiber arrangements on steady heat transfer behaviors at micro‐scale are illustrated. Isothermal and temperature‐drop characteristics at micro‐ and macro‐scale are simulated and studied. The transverse isotropy of thermal conductivity at micro‐scale and the anisotropy of that at macro‐scale are revealed.

Structural properties and barrier performance of low-cost aerogel composites for building insulation

The high cost and weak mechanical properties of silica-based aerogel seriously affect its wide application in the field of building insulation. In this paper, low-cost SiO2 aerogel (WSA) was prepared based on water glass/water system, and the modulation of aerogel network structure was achieved under the dual effect of sodium methylsilicate (SMS) and pH. WSA exhibits extremely low density (∼88.5 kg/m3) and thermal conductivity (0.02114 W/(m·K)) as well as high hydrophobicity (150°). The cost of WSA is 53 % lower compared to atmospheric pressure drying and 21.5 % lower than commercial aerogel. On this basis, rock wool fiber felt (RWF) and ultrafine glass fiber wool felt (UGFW) were modified with WSA. The effect of fiber arrangement on the force-thermal coupling property of WSA@RWF was investigated. Meanwhile, the addition of WSA reduced the volumetric water absorption of RWF by 85.1 % and 91.4 %. Since the sandwich structure, the thermal conductivity of WSA@UGFW can be as low as 0.01168 W/(m·W), which is 44.7 % and 44.4 % lower than that of UGFW and WSA. It features a low density of 45.7 kg/m3 and a high hydrophobicity angle of 155.87°. In addition, the compressive strength of WSA@UGFW is increased by 16.5 times. Therefore, the aerogel materials prepared in this paper have great application potential as fire-proof building insulation materials.

Strengthening of deep RC coupling beams with FRP composites: A numerical study

Currently, most buildings have earthquake-resistant systems such as coupled shear walls and couple beams, designed based on previous code specifications. Also, due to specifications of new codes, diagonal reinforcement details in coupled beams are introduced, which due to the high reinforcement congestion, creates problems in fabrication and pouring. The main goal of this paper is to numerically study retrofitting with polymer composites reinforced with carbon fiber with external bonding for reinforced concrete coupling beams. The previous studies are divided into three categories. The first part concerns using externally bonded composite FRPs and the effect of fiber arrangement and thickness on the coupled beam behavior. The maximum displacement ductility in shear reinforcement patterns belonged to I and 2I patterns, which had the maximum ductility coefficients of 7.04 and 8.87. By comparing 7 CFRP reinforcement patterns, results showed that due to the mixed failure mode (flexural-shear) of the coupling beam, the U-X reinforcement pattern increased the load-bearing capacity by 18% compared with the base sample. By using suitable anchorage and preventing premature debonding, this method could be introduced as an effective method for improving the coupling beam’s behavior. In the second category, reinforcement with composite FRPs was compared with diagonal reinforcement and strengthening by installing steel plates and the accompanying behavior diagrams were given. Compared with other reinforcement methods in terms of load-bearing capacity and ductility, the specimen reinforced with CFRP and steel plates had a 49% and 70.4% increased load-bearing capacity of the control specimen. Among the studied specimens, the best performance belonged to the specimen with diagonal reinforcements, which had an increased load-bearing capacity and ductility of 124% and 4.2% compared with the base specimen. Finally, the third part is about the effective parameters of the coupling beam such as span length to height ratio and longitudinal reinforcement value regarding coupling beam behavior.

The Effect of Fiber Arrangement in the Bio-Laminate and Geometric Parameters on the Stability of Thin-Walled Angle Column Under Axial Compression

The Effect of Fiber Arrangement in the Bio-Laminate and Geometric Parameters on the Stability of Thin-Walled Angle Column Under Axial Compression

Effect of fibre arrangement on temperature field of CFRP induction heating

Because the characteristics of carbon fibre composites (CFRP) are directly related to the arrangement of fibre bundles, changing the orientation of fibres generates a shift in temperature field distribution during material heating. As a result, a finite element meso analysis model of CFRP induction heating is developed based on the actual laying mode and equivalent electro-magnetic thermal characteristics, and the variation laws of vortex current, calorific value, and temperature field distribution in CFRP with various fibre arrangements are simulated to investigate the role of fibre laying mode in the induction heating process. Simultaneously, the induction heating experiment shows that the finite element model developed in this paper can accurately calculate the distribution of temperature field of various types of CFRP.

Experimental investigations on thermal, flame retardant, and impact properties of additively manufactured continuous FRPC

AbstractAs an additive manufacturing (AM) technology, fused deposition modeling (FDM) is widely used to fabricate highly complex components. Polymer components fabricated by FDM technique have weak mechanical properties. To enhance the mechanical properties, 3D printing of polymer composites is done by reinforcing particles, nanomaterials, short and continuous fibers into thermoplastic polymers. The thermal, flame retardant, and impact properties of a continuous kevlar fiber‐reinforced onyx 3D‐printed composite are investigated in this study. Additionally, the effect of fiber arrangement and orientation (0°, 90°, 0°/90°, and +45°/−45°) on the impact strength of 3D‐printed composites have been investigated. The impact strength of the 3D‐printed composite specimens was determined using izod impact testing. It was found that specimens with fiber arrangement having fiber and matrix layer configuration as 21O|20K|20O|20K|21O have a higher impact strength and specimens with fiber arrangement as 31O|40K|31O have lower impact strength. Furthermore, specimen 3D printed with a unidirectional 0° fiber angle had the highest impact strength, while specimen 3D printed with a unidirectional 90° fiber angle had the lowest impact strength. Furthermore, flammability tests and thermogravimetric analysis were performed to investigate the flame retardant and thermal properties of 3D‐printed composites. Morphological study of onyx and kevlar fiber filament was also done using scanning electron microscope (SEM).

Prediction of permeability of five-harness satin fabric by a modified Kozeny constant determined from experiments

Permeability is a critical parameter not only in flow simulation analysis but also in liquid composite molding process. When a liquid resin is infused into a dry preform, the impregnation is mainly characterized by the permeability. The permeability of a dry preform can be obtained through theoretical and experimental methods. In the theoretical estimation of permeability, the effects of fiber arrangement as well as fabric type and form for various types of preforms are not sufficiently reflected in the calculation. Thus, there is a gap between the theoretical and experimental permeability. Recently, experimental determination has been gaining considerable attention as a mean to obtain accurate permeability values; however, it requires a number of trials. In this study, the permeability of the Hexforce G0926 5HS (five-harness satin) carbon fabric preform is estimated using representative theoretical prediction models, the Gebart and Kozeny–Carman equations. In addition to the Kozeny–Carman permeability (using the Kozeny constant values from literature), the Kozeny constant obtained through experiments was used to obtain a modified Kozeny–Carman permeability. All three calculated permeabilities were compared and verified with the fabric manufacturer’s reference value. The results showed that the modified Kozeny–Carman permeability using the experimentally determined Kozeny constant was closest to the reference value at 57% fiber volume fraction. Further, the predicted permeability was compared with other experimental permeability values from literature over the 40%–65% range of fiber volume fraction. We found that the modified Kozeny–Carman permeability once again came closest to the literature values. Finally, an optimized fitting equation was proposed to replace the Kozeny–Carman equation for predicting the permeability of Hexforce G0926 5HS carbon fabric over the 40%–65% fiber volume fraction range.

Woven and Unidirectional Glass-Aluminium Fibre Metal Laminates (FML): Quasi-Static Indentation Properties

In this study, the effect of fibre arrangement and aluminium thin sheet on quasi-static indentation properties of fibre metal laminates (FML) based on glass fibre reinforced polymer composite (GFRP) and Aluminium (Al) was investigated. The woven and unidirectional types of glass fibre prepreg and 0.5mm, 1mm and 2 mm of Al sheet thickness were used in the fabrication of Glass fibre-Al FML systems. The GFRP and FML samples were fabricated using a combination of hand lay–up and hot press methods. Quasi-static indentation test was performed according to ASTM D6264. The results showed that the woven type of GFRP and FMLs exhibited the highest energy absorption as compared to those of unidirectional of GFRP and FMLs. It was observed that for the woven type specimens of GFRP and FMLs, the matrix cracking and fibre breakage/delamination triggered in weft and wrap direction, which showed diamond-shaped damage. While the damage surface of unidirectional GFRP and FMLs showed single axis orientation damage type that lateral with the direction of the fibre namely fibre splitting mechanism. The FML2 systems for both woven and unidirectional, that used 2mm thickness of Al, demonstrated the highest energy absorption when compared to the other FML systems. This shows that FMLs absorbed more energy when thicker Al sheet was used.

The effect of electrospun polycaprolactone scaffold morphology on human kidney epithelial cells

There is a pressing need for further advancement in tissue engineering of functional organs with a view to providing a more clinically relevant model for drug development and reduce the dependence on organ donation. Polymer-based scaffolds, such as polycaprolactone (PCL), have been highlighted as a potential avenue for tissue engineered kidneys, but there is little investigation down this stream. Focus within kidney tissue engineering has been on two-dimensional cell culture and decellularised tissue. Electrospun polymer scaffolds can be created with a variety of fibre diameters and have shown a great potential in many areas. The variation in morphology of tissue engineering scaffold has been shown to effect the way cells behave and integrate. In this study we examined the cellular response to scaffold architecture of novel electrospun scaffold for kidney tissue engineering. Fibre diameters of 1.10 ± 0.16 μm and 4.49 ± 0.47 μm were used with three distinct scaffold architectures. Traditional random fibres were spun onto a mandrel rotating at 250 rpm, aligned at 1800 rpm with novel cryogenic fibres spun onto a mandrel loaded with dry ice rotating at 250 rpm. Human kidney epithelial cells were grown for 1 and 2 weeks. Fibre morphology had no effect of cell viability in scaffolds with a large fibre diameter but significant differences were seen in smaller fibres. Fibre diameter had a significant effect in aligned and cryogenic scaffold. Imaging detailed the differences in cell attachment due to scaffold differences. These results show that architecture of the scaffold has a profound effect on kidney cells; whether that is effects of fibre diameter on the cell attachment and viability or the effect of fibre arrangement on the distribution of cells and their alignment with fibres. Results demonstrate that PCL scaffolds have the capability to maintain kidney cells life and should be investigated further as a potential scaffold in kidney tissue engineering.

Thermo-oxidative induced shrinkage in Organic Matrix Composites for High Temperature Applications: Effect of fibre arrangement and oxygen pressure

The present paper focuses on thermo-oxidative induced chemical shrinkage in HTS/TACTIX carbon/epoxy Organic Matrix Composites for High Temperature Applications, providing an insight on the effect of the fibre arrangement and of the oxygen pressure as an accelerating parameter. In particular, measurement of matrix shrinkage in composites surface is carried out by Interferometric Microscopy for virgin samples (initial state) and for samples aged under oxygen pressure and air at atmospheric pressure: some discussion about the “structural” effect (arrangement of fibres, fibre volume fraction) on matrix shrinkage development of unidirectional composites is provided; a link between the measured surface matrix shrinkage and the evolution of the surface elastic indentation modulus measured in pure resin samples can be clearly established: moreover, it is shown that matrix shrinkage development in composites can be conveniently accelerated by the employment of oxygen pressure, as in pure resin systems.

A Monte Carlo simulation and effective thermal conductivity calculation for unidirectional fiber reinforced CMC

Due to the high thermal-mechanical performance, ceramic matrix composite (CMC) is regarded as an alternate material for high temperature components of aircrafts. The thermal conductivity of unidirectional CMC is sensitive to its microstructural characteristics. Herein, the Monte Carlo method is introduced to simulate the real distribution of fibers and air pores. The complete procedure is programmed by ANSYS Parametric Design Language and executed automatically. The effective thermal conductivity of this composite at room temperature is calculated. The effect of fiber arrangement as well as matrix porosity with different fiber fractions is studied. The statistic results are gotten and both longitudinal and transverse thermal conductivity are computed. The random arrangement of fibers can result in a deviation of transverse thermal conductivity in different calculation times. The amount of air pores in matrix can also affect thermal conductivity of this material. This method is proved to be valid and accurate by comparison of numeric and experimental data; the relative error is less than 2%. The method can be used as an effective supplement of theoretical analysis and general FEM calculation for thermal conductivity.

Effect of fibre arrangement on the multiaxial fatigue of fibrous composites: a micromechanical computational model

Structural components made of fibre-reinforced materials are frequently used in engineering applications. Fibre-reinforced composites are multiphase materials, and complex mechanical phenomena take place at limit conditions but also during normal service situations, especially under fatigue loading, causing a progressive deterioration and damage. Under repeated loading, the degradation mainly occurs in the matrix material and at the fibre-matrix interface, and such a degradation has to be quantified for design structural assessment purposes. To this end, damage mechanics and fracture mechanics theories can be suitably applied to examine such a problem. Damage concepts can be applied to the matrix mechanical characteristics and, by adopting a 3-D mixed mode fracture description of the fibre-matrix detachment, fatigue fracture mechanics concepts can be used to determine the progressive fibre debonding responsible for the loss of load bearing capacity of the reinforcing phase. In the present paper, a micromechanical model is used to evaluate the unixial or multiaxial fatigue behaviour of structures with equi-oriented or randomly distributed fibres. The spatial fibre arrangement is taken into account through a statistical description of their orientation angles for which a Gaussian-like distribution is assumed, whereas the mechanical effect of the fibres on the composite is accounted for by a homogenization approach aimed at obtaining the macroscopic elastic constants of the material. The composite material behaves as an isotropic one for randomly distributed fibres, while it is transversally isotropic for unidirectional fibres. The fibre arrangement in the structural component influences the fatigue life with respect to the biaxiality ratio for multiaxial constant amplitude fatigue loading. One representative parametric example is discussed.

Electromechanical behavior of fiber-reinforced dielectric elastomer membrane

Based on its large deformation, light weight, and high energy density, dielectric elastomer (DE) has been used as driven muscle in many areas. We design the fiber-reinforced DE membrane by adding fibers in the membrane. The deformation and driven force direction of the membrane can be tuned by changing the fiber arrangements. The actuation in the perpendicular direction of the DE membrane with long fibers first increases and then decreases by the increasing of the fiber spacing in the perpendicular direction. The horizontal actuation of the membrane decreases by decreasing the spacing of short fibers. In the membrane-inflating structure, the radially arranged fibers will break the axisymmetric behavior of the structure. The top area of the inflated balloon without fiber will buckle up when the voltage reaches a certain level. Finite element simulations based on nonlinear field theory are conducted to investigate the effects of fiber arrangement and verify the experimental results. This work can guide the design of fiber-reinforced DE.

Numerical evaluation of the coefficients of thermal expansion of fibers in composite materials using a lamina-scale cost function with quasi-analytical gradients

In this work, the coefficients of thermal expansion (CTEs) of fibers in composite materials that contain microstructures are numerically evaluated using a lamina-scale cost function with quasi-analytical gradients. To consider the effects of fiber arrangements and local defects, such as interface debonding and voids, a variety of representative volume elements are modeled with a number of finite element meshes. Then, the CTEs of fibers are evaluated by minimizing a lamina-scale cost function that represents the difference between the measured CTEs and the computed CTEs by means of a computational homogenization scheme for the composite lamina. The descent direction of the cost function is obtained using quasi-analytical gradients that take partial derivatives from prediction models, such as the Schapery model and Hashin model defined in an explicit manner, which accelerates the minimization procedure. To verify the performance of the proposed scheme in terms of accuracy and efficiency, the CTEs of constituents calculated using the proposed scheme in a unidirectional composite lamina are compared with experimental values reported in the literature. Furthermore, the convergence behavior of the proposed scheme with quasi-analytical gradients is also investigated and compared with other minimization methods.

Prediction by a Genetic Algorithm of the Fiber–Matrix Interface Damage for Composite Material. Part 1. Study of Shear Damage in Two Composites T300/914 and PEEK/APC2

We have conducted research on the effect of fiber arrangement on the optimization of the damage to the interface, recently published. We develop in this paper the evolution of the damage in the shearing direction by genetic algorithm. The results obtained by varying the shear rate of the interface of the two materials studied T300 and PEEK, show a good agreement between our genetic approach and the mathematical models presented by Cox and Weibull.

Upscaling and microstructural analysis of the flow-structure relation perpendicular to random, parallel fiber arrays

Owing largely to multiscale heterogeneity in the underlying fibrous structure, the physics of fluid flow in and through fibrous media is incredibly complex. Using fully resolved finite element (FE) simulations of Newtonian, incompressible fluid flow perpendicular to the fibers, the macroscopic permeability is calculated in the creeping flow regime for arrays of random, ideal, perfectly parallel fibers.On the micro-scale, several order parameters, based on Voronoi and Delaunay tessellations, are introduced to characterize the structure of the randomly distributed, parallel, non-overlapping fiber arrays. In particular, by analyzing the mean and the distribution of the topological and metrical properties of Voronoi polygons, we observe a smooth transition from disorder to (partial) order with decreasing porosity, i.e., increasing packing fraction.On the macro-scale, the effect of fiber arrangement and local crystalline regions on the macroscopic permeability is discussed. For both permeability and local bond orientation order parameter, the deviation from a fully random configuration can be well represented by an exponential term as function of the mean gap width, which links the macro- and the micro-scales.Finally, we verify the validity of the, originally, macroscopic Darcy's law at various smaller length scales, using local Voronoi/Delaunay cells as well as uniform square cells, for a wide range of porosities. At various cell sizes, the average value and probability distributions of macroscopic quantities, such as superficial fluid velocity, pressure gradient or permeability, are obtained. These values are compared with the macroscopic permeability in Darcy's law, as the basis for a hierarchical upscaling methodology.

Effect of fiber arrangement on mechanical properties of short fiber reinforced composites

The present paper developed a three-dimensional (3D) “tension–shear chain” theoretical model to predict the mechanical properties of unidirectional short fiber reinforced composites, and especially to investigate the distribution effect of short fibers. The accuracy of its predictions on effective modulus, strength, failure strain and energy storage capacity of composites with different distributions of fibers are validated by simulations of finite element method (FEM). It is found that besides the volume fraction, shape, and orientation of the reinforcements, the distribution of fibers also plays a significant role in the mechanical properties of unidirectional composites. Two stiffness distribution factors and two strength distribution factors are identified to completely characterize this influence. It is also noted that stairwise staggering (including regular staggering), which is adopted by the nature, could achieve overall excellent performance. The proposed 3D tension–shear chain model may provide guidance to the design of short fiber reinforced composites.

Effect of fiber arrangement on shape fixity and shape recovery in thermally activated shape memory polymer-based composites

In the present study, we conducted periodic-cell simulations of the thermomechanical cycle of thermally activated shape memory polymer (SMP)-based composites. The present simulation utilizes a micromechanical model for reproducing the discontinuous fibers and SMP. We analyzed the effect of fiber volume fraction, fiber aspect ratio, and fiber end position on the shape fixity and shape recovery of the composite. The simulated results revealed that fiber elasticity is a key factor for the shape fixity of the composite, while both strain concentration near the fiber ends and fiber elasticity play important roles in the shape recovery properties of the composite.

A periodic unit-cell simulation of fiber arrangement dependence on the transverse tensile failure in unidirectional carbon fiber reinforced composites

The effect of fiber arrangement on transverse tensile failure in unidirectional carbon fiber reinforced composites with a strong fiber-matrix interface was studied using a unit-cell model that includes a continuum damage mechanics model. The simulated results indicated that tensile strength is lower when neighboring fibers are arrayed parallel to the loading direction than with other fiber arrangements. A shear band occurs between neighboring fibers, and the damage in the matrix propagates around the shear band when the interfacial normal stress (INS) is sufficiently high. Moreover, based on the observation of Hobbiebrunken et al., we reproduced the damage process in actual composites with a nonuniform fiber arrangement. The simulated results clarified that the region where neighboring fibers are arrayed parallel to the loading direction becomes the origin of the transverse failure in the composites. The cracking sites observed in the simulation are consistent with experimental results. Therefore, the matrix damage in the region where the fiber is arrayed parallel to the loading direction is a key factor in understanding transverse failure in unidirectional carbon fiber reinforced composites with a strong fiber/matrix interface.

Effects of Fiber Arrangement on Mechanical Behavior of Unidirectional Composites

Micromechanical approaches are employed to investigate the influence of different fiber arrangement on the mechanical behavior of unidirectional composites (UD) under various loading conditions. A micromechanical model with a random fiber array is generated and used in a finite element analysis together with two frequently used representative volume elements (RVE), or unit cell models of square and hexagonal arrays. The algorithm for generating the random fiber array is verified by comparing the comprehensive performance of a unit cell based on our random array and that of a unit cell based on a real fiber distribution in the UD cross-section. Performance of the random and regular fiber arrays is also evaluated through frequency distributions of stress invariants in matrix and tractions at the fiber—matrix interface due to various loading types. The effects of different loading angles on the overall response of regular arrays to various loading conditions are investigated thoroughly. Finally, the Weibull distribution of the maximum normal interfacial traction in random array is compared with the cumulative probability distribution of transverse strength data acquired from experiment, and good agreement is achieved.