scholarly journals Influence of Fiber Volume Content on Thermal Conductivity in Transverse and Fiber Direction of Carbon Fiber-Reinforced Epoxy Laminates

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1084 ◽  
Author(s):  
Simon Bard ◽  
Florian Schönl ◽  
Martin Demleitner ◽  
Volker Altstädt
Keyword(s):  
Thermal Conductivity ◽  
Carbon Fiber ◽  
Volume Content ◽  
Transverse Direction ◽  
Strong Influence ◽  
Measurement Methods ◽  
Fiber Direction ◽  
Heat Distribution ◽  
Fiber Volume ◽  
Transverse Thermal Conductivity

Thermal conductivity is an important material property for thermo-mechanical calculations, as mechanical properties strongly depend on the temperature and heat distribution in the manufactured parts. Although several suggestions for approximation formulae have been made, existing experimental data are rare and are not comparable due to different measurement methods. In addition, scarcely has the thermal conductivity in both the fiber direction and transverse direction been studied. The aim of the current research is to show the influence of carbon fiber volume content on the thermal conductivity of laminates. The values are then used to verify the micromechanical models used in the literature. A strong influence on the thermal conductivity could be determined. For the transverse thermal conductivity, the correlation was exponential; for the conductivity in the fiber direction, a linear correlation was found.

scholarly journals Transverse Thermal Conductivity of Epoxy Carbon Fiber Prepreg Laminates with a Graphite Filled Matrix

2019 ◽  
Vol 3 (2) ◽  
pp. 44 ◽  
Author(s):  
Simon Bard ◽  
Martin Demleitner ◽  
Marius Radtke ◽  
Volker Altstädt
Keyword(s):  
Thermal Conductivity ◽  
Carbon Fiber ◽  
New Technologies ◽  
Fiber Reinforced Polymers ◽  
Fiber Volume ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
The Matrix ◽  
Thermally Conductive ◽  
Transverse Thermal Conductivity

The thermal conductivity of carbon fiber reinforced polymers is crucial for new technologies and is used in cutting-edge technologies such as sensors, heated rollers and anti-icing of airplane wings. Researchers so far focused on coating conventional prepregs with thermally conductive materials to enhance the transversal conductivity. Another strategy is followed in this study: Thermally conductive matrices filled with graphite platelets were processed by a laboratory prepreg line. Laminates produced from this type of prepregs show an enhancement in thermal conductivity by 3.3 times with a 20 vol% filler content relative to the matrix, and a 55 vol% fiber volume content in the laminate. The research shows that the incorporation of conductive particles in the matrix is more effective for increasing the conductivity than previous methods.

Carbon fiber reinforced tin-superconductor composites

1989 ◽  
Vol 4 (6) ◽  
pp. 1339-1346 ◽  
Author(s):  
C. T. Ho ◽  
D. D. L. Chung
Keyword(s):  
Thermal Conductivity ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Tensile Modulus ◽  
Tensile Load ◽  
Tensile Fracture ◽  
Fiber Direction ◽  
Continuous Carbon Fiber

Unidirectional and continuous carbon fiber tin-matrix composites were used for the packaging of the high-temperature superconductor YBa2Cu3O7–δ by diffusion bonding at 170 °C and 500 psi. Tin served as the adhesive and to increase the ductility, the normal-state electrical conductivity, and the thermal conductivity. Carbon fibers served to increase the strength and the modulus, both in tension along the fiber direction and in compression perpendicular to the fiber layers, though they decreased the strength in compression along the fiber direction. Carbon fibers also served to increase the thermal conductivity and the thermal fatigue resistance. At 24 vol. % fibers, the tensile strength was approximately equal to the compressive strength perpendicular to the fiber layers. With further increase of the fiber content, the tensile strength exceeded the compressive strength perpendicular to the fiber layers, reaching 134 MPa at 31 vol. % fibers. For fiber contents less than 30 vol. %, the compressive ductility perpendicular to the fiber layers exceeded that of the plain superconductor. At 30 vol. % fibers, the tensile modulus reached 15 GPa at room temperature and 27 GPa at 77 K. The tensile load was essentially sustained by the carbon fibers and the superconducting behavior was maintained after tension almost to the point of tensile fracture. Neither Tc nor Jc was affected by the composite processing.

Micromechanical analysis for transverse thermal conductivity of composites

2010 ◽  
Vol 45 (11) ◽  
pp. 1245-1255 ◽  
Author(s):  
Sangwook Sihn ◽  
Ajit K. Roy
Keyword(s):  
Thermal Conductivity ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Numerical Models ◽  
Matrix Material ◽  
Analytic Solutions ◽  
Fiber Distribution ◽  
Fiber Volume ◽  
Volume Fractions ◽  
Transverse Thermal Conductivity

Micromechanical analyses were conducted for the prediction of transverse thermal conductivity of laminated composites. We reproduced and reinvestigated both analytic and numerical models with regular and randomly distributed fibers in matrix material. A parametric study was conducted for wide ranges of fiber volume fractions and fiber-to-matrix thermal conductivity ratios. The numerical solutions using finite element (FE) analysis were compared with various analytic solutions from simple and enhanced rule or mixtures and an effective inclusion method (EIM). It was found that the EIM yields a reasonably agreeable solution with the FE solution using a hexagonal-array of regular fiber distribution for wide ranges of fiber volume fraction and fiber-to-matrix thermal conductivity ratios, which makes the EIM a useful method in predicting various multiphysical transverse properties of composites. Comparison of the results from the regular- and random-fiber models indicates that the transverse thermal conductivity of composites can significantly be affected by the random fiber distributions, especially at high fiber volume fractions. A similar conclusion was made for the foams with random pore distribution. It was shown that the predictions with the random fiber distribution agree well with the experimental data.

A Novel Model for Predicting the Thermal Conductivity of Fiber Reinforced Ceramic Materials

2014 ◽  
Vol 936 ◽  
pp. 154-163
Author(s):  
Rui Xu ◽  
Jun Kui Mao ◽  
Jing Yu Zhang ◽  
De Cang Lou ◽  
Wen Guo
Keyword(s):  
Thermal Conductivity ◽  
Volume Content ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Good Precision ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
High Fiber ◽  
Novel Model ◽  
Thermal Conductivities

The prediction of fiber reinforced ceramic is one of the most important procedure when investigating the application of ceramic composite. Numerical simulations were applied and a novel model was brought out in this paper. Firstly, four different models for predicting thermal conductivities of unidirectional fiber reinforced materials were compared, which include the Rayleigh,LN,ST and TE model,. It shows that Rayleigh model and LN model have good precision only in low fiber volume content cases. There existed big differences between the experimental and numerical results if predicted the high fiber volume content with either these four models. Then a novel model based on LN model was studied with the correction of the representative volume element method. Further comparison results indicate that the error can be reduced as 55.6% with this novel model. At the same time, the longitudinal (k11) and transverse (k22) thermal conductivities predicted by the novel model were also analyzed. It was found thatk11had a linear relationship with fiber volume fraction and thermal conductivity ratio (p). Butk22had a nonlinear relationship with fiber volume fraction, which increased much greatly when fiber volume fraction increasing at high fiber volume fraction andp>1.

scholarly journals Finite Element Analysis of Lightning Damage Factors Based on Carbon Fiber Reinforced Polymer

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5210
Author(s):  
Yansong Zhu ◽  
Yueke Ming ◽  
Ben Wang ◽  
Yugang Duan ◽  
Hong Xiao ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Carbon Fiber ◽  
Fiber Reinforced Polymers ◽  
Fiber Direction ◽  
Fiber Reinforced ◽  
Element Analysis ◽  
Carbon Fiber Reinforced

While carbon-fiber-reinforced polymers (CFRPs) are widely used in the aerospace industry, they are not able to disperse current from lightning strikes because their conductivity is relatively low compared to metallic materials. As such, the undispersed current can cause the vaporization or delamination of the composites, threatening aircraft safety. In this paper, finite element models of lightning damage to CFRPs were established using commercial finite element analysis software, Abaqus, with the user-defined subroutines USDFLD and HEAVEL. The influences of factors such as the structural geometry, laminate sequence, and intrinsic properties of CFRPs on the degree of damage to the composites are further discussed. The results showed that when a current from lightning is applied to the CFRP surface, it mainly disperses along the fiber direction in the outermost layer. As the length of the CFRP increases, the injected current has a longer residence time in the material due to the increased current exporting distance. Consequently, larger amounts of current accumulate on the surface, eventually leading to more severe damage to the CFRP. This damage can be alleviated by increasing the thickness of the CFRP, as the greater overall resistance makes the CFRP a better insulator against the imposed current. This study also found that the damaged area increased as the angle between the first two layers increased, whereas the depth of the damage decreased due to the current dispersion between the first two layers. The analysis of the electrical conductivity of the composite suggested that damage in the fiber direction will be markedly reduced if the conductivity in the vertical fiber direction increases approximately up to the conductivity of the fiber direction. Moreover, increasing the thermal conductivity along the fiber direction will accelerate the heat dissipation process after the lightning strike, but the influence of the improved thermal conductivity on the extent of the lightning damage is less significant than that of the electrical conductivity.

Evaluation of DOPO and Nano-Silica Modified Epoxy Resin Systems as Low Viscous, Flame Retardant Additives for Infusion and Injection Processing of Carbon Fiber Reinforced Plastics

2019 ◽  
Vol 809 ◽  
pp. 3-8
Author(s):  
Markus Häublein ◽  
Karin Peter ◽  
Alexander Brückner ◽  
Volker Altstädt
Keyword(s):  
Carbon Fiber ◽  
Flame Retardant ◽  
Epoxy Resin ◽  
Volume Content ◽  
Cone Calorimeter ◽  
Fiber Reinforced ◽  
Fiber Volume ◽  
Carbon Fiber Reinforced ◽  
Flame Retardant Properties ◽  
Modified Epoxy

In the present study, a low viscous (complex viscosity between 200 to 500 mPas at 60 °C), flame retardant epoxy resin formulation is prepared and transferred to the carbon fiber reinforced plastic (CFRP) laminate using resin transfer molding (RTM) method. For the laminate production, a 12k carbon fiber fabric with an areal weight of 400 g/m2 is used to achieve a fiber volume content of approximately 60 vol % carbon fibers. Subsequently the unmodified laminate is produced, varying carbon fiber volume content to study its effect on flame retardant properties. As additives, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) modified epoxy resin and nanosilica particles delivered in an epoxy novolac masterbatch are added to the neat novolac resin system. The mixture is cured with isophorone diamine (IPDA) and polyetheramine hardener blend, resulting in a glass transition temperature of 104 °C for the unmodified laminate. Flame retardant properties of the materials are tested using cone calorimeter and thermal gravimetrical analysis. In addition, the mechanical behavior of the systems is evaluated via three-point bending method in static and dynamical loadings. In order to get deeper information on the resulting flame retardant mechanisms of the additives, the residual cone calorimeter char is analyzed with scanning electron microscopy, indicating the different flame retardant mechanisms of phosphorous and silica as well as the combination of both additives.

scholarly journals Multi-scale Rule-of-Mixtures Model of Carbon Nanotube/Carbon Fiber/Epoxy Lamina

2005 ◽  
Vol 887 ◽  
Author(s):  
Sarah-Jane Frankland ◽  
J. C. Riddick ◽  
T. S. Gates
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Fiber ◽  
Volume Fraction ◽  
Scale Model ◽  
Fiber Direction ◽  
Fiber Volume ◽  
Multi Scale ◽  
Rule Of Mixtures ◽  
Constitutive Properties ◽  
Carbon Fiber Epoxy

ABSTRACTA unidirectional carbon fiber/epoxy lamina in which the carbon fibers are coated with single-walled carbon nanotubes is modeled with a multi-scale method, the atomistically informed rule-of-mixtures. This multi-scale model is designed to include the effect of the carbon nanotubes on the constitutive properties of the lamina. It included concepts from the molecular dynamics/equivalent continuum methods, micromechanics, and the strength of materials. Within the model both the nanotube volume fraction and nanotube distribution were varied. It was found that for a lamina with 60% carbon fiber volume fraction, the Young’s modulus in the fiber direction varied with changes in the nanotube distribution, from 138.8 to 140 GPa with nanotube volume fractions ranging from 0.0001 to 0.0125. The presence of nanotube near the surface of the carbon fiber is therefore expected to have a small, but positive, effect on the constitutive properties of the lamina.

Numerical Analysis of the Transverse Thermal Conductivity of Composites With Imperfect Interfaces

2003 ◽  
Vol 125 (3) ◽  
pp. 389-393 ◽  
Author(s):  
Samuel Graham ◽  
David L. McDowell
Keyword(s):  
Thermal Conductivity ◽  
Volume Fraction ◽  
Ceramic Composites ◽  
Reinforced Composites ◽  
Continuous Fiber ◽  
Fiber Volume ◽  
Element Analysis ◽  
Imperfect Interfaces ◽  
Transverse Thermal Conductivity ◽  
Johnson Model

Estimation of the transverse thermal conductivity of continuous fiber reinforced composites containing a random fiber distribution with imperfect interfaces was performed using finite element analysis. FEA results were compared with the classical solution of Hasselman and Johnson to determine limits of applicability. The results show that the Hasselman and Johnson model predicts the effective thermal conductivity within 3 percent of the numerical estimates for interfacial conductance values of 1×10−2−1×103W/m2K, fiber-matrix conductivity ratios between 1 and 100, and fiber volume fractions up to 50 percent which are properties typical of ceramic composites. The results show that the applicability of the classical dilute concentration model can not be determined by constituent volume fraction, but by the degree of interaction between the microstructural heterogeneities.

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