Transverse thermal conductance of thermosetting composite materials during their cure

Farmer, Jeffrey D.; Covert, Eugene E.

doi:10.2514/3.546

Cited by 17 publications

(15 citation statements)

References 19 publications

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“…In a previous paper, 8 the transversely anisotropic behavior of multiangled laminates was modeled using a variation of Rayleigh's 14 model for cylinders arranged in rectangular order. When the statistically averaged resin rectangle around a typical fiber within a laminate has a moderate aspect ratio (width/ height not much greater than 1.0), the approximate throughthickness conductivity K 33 for a laminate may be calculated …”

Section: Through-thickness Transverse Conductivity Vs the Ply Lay-up mentioning

confidence: 99%

Thermal conductivity of a thermosetting advanced composite during its cure

Farmer

Covert

1996

Journal of Thermophysics and Heat Transfer

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The thermal conductivity of a thermosetting advanced composite material during its cure was experimentally investigated and compared to analytical models. The thermal conductivity of graphite/epoxy was experimentally measured using a guarded hot plate apparatus. The through-thickness transverse thermal conductivity of composite laminates was measured at various resin degrees of cure and fiber volume fractions while using various ply lay-up angles. The in-plane thermal conductivity was measured using unidirectional laminates, as well as laminates with various ply lay-up angles. Techniques for manufacturing composite laminates with these various properties, as well as the guarded hot plate apparatus necessary for accurate measurements, are described. Finally, various analytical models were researched, and those that compare most favorably with the experimental data are presented. NomenclatureH c = thermal contact conductance of the experiment, W/m 2°C H r = resin heat of reaction for AS4/3501-6, J/g K = thermal conductivity, W/m°C L = laminate dimension in the x direction, m N = number of plies in a laminate p = function of the fiber volume fraction, Eq. (6) Q = total heat flux, W q = heat flux/area, W/m 2 q = resin energy generation rate per unit volume, W/m 3 q ln = heat flux/area applied by the guarded hot plate, W/m 2 T = temperature, °C t = laminate dimension in the z direction, m V = volume fraction of a constituent material W = laminate dimension in the y direction, m *, v, z = laminate coordinates defined in Fig. 1 a = resin degree of cure, scale of 0-1.0 y = function of material conductivities, Eq. (11) 8 = resin rectangle side parallel to measured K, fjun e = resin rectangle side J_ to measured K, /mi 0 = direction of ply alignment, Fig. 1, deg v' = function of material conductivities, Eq. (5) p = density, g/m 3 Subscripts act s= actual material property c = experimental setup contact region property comp = composite property

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Section: Through-thickness Transverse Conductivity Vs the Ply Lay-up mentioning

confidence: 99%

Thermal conductivity of a thermosetting advanced composite during its cure

Farmer

Covert

1996

Journal of Thermophysics and Heat Transfer

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“…They used a guarded hot plate to determine thermal conductivity over the temperature range of 313-450 K. Over that range, the conductivity varied in the range 0.17< e <0.20, somewhat below the values found here. A later paper [29] reports higher values of e of 0.255, 0.270 and 0.283 W/m K (AE 4.3%) at 368, 418 and 448 K respectively at d ¼ 0.98. These data agree with the present results within experimental error.…”

Section: Discussionmentioning

confidence: 91%

New Experimental Data for Enthalpy of Reaction and Temperature- and Degree-of-Cure-Dependent Specific Heat and Thermal Conductivity of the Hercules 3501-6 Epoxy System

Chern

Moon

Howell³

et al. 2002

Journal of Composite Materials

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Measurements of enthalpy of reaction and temperature-and degreeof-cure-dependent specific heat and thermal conductivity are reported for a commercial epoxy resin system (Hercules 3501-6 resin). A Differential Scanning Calorimeter (DSC) was used to determine heat of reaction and specific heat while the line source method was employed for thermal conductivity. The measured heat of reaction of 508 AE 19 J/g is compared with conflicting data previously reported by others. Specific heat is reported in the temperature range of 320-550 K and at degrees of cure 20, 40, 74 and 100%. Both raw data and polynomial curve fits are reported. Thermal conductivity is reported in the temperature range of 298-500 K and at degrees of cure 11.5, 51.2 and 100%. These data are found to be independent of degree of cure within experimental error over this range. The data are represented by e ¼ ð0:202 þ 6:122 Â 10 À3 T À 4:8107 Â 10 À5 T 2 þ 1:248 Â 10 À7 T 3 À 1:043 Â 10 À10 T 4 ÞðW=m KÞ The fractional uncertainty (based on two standard deviations) of the measured enthalpy of reaction, specific heat and thermal conductivity is estimated to be less than AE 3.7, AE 5 and AE 11.8%, respectively.

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“…Geometry and finite element mesh of a 3D models are represented in Figure 7 for case i & case ii and Figure 8 or case iii. Mesh for finite element models are refined and converged, then results obtained are validated with theoretical models of Hasselman-Johnson [9] and Farmer-Covert [10] for perfect bond and total debond cases.…”

Section: Geometric Modellingmentioning

confidence: 99%

“…[1] Prediction of through-thickness thermal conductivity is quite complex, yet this is important, since heat sources on one side of the laminate often creates through-thickness temperature gradient. Prediction of effective transverse thermal conductivity of fibrereinforced composites was made for several models, such as experimental determination of effective thermal conductivity of aligned fibre composite of Chamis, [2] effect of fibre orientation on the thermal conductivity of unidirectional aligned fibre composite of Hasselman et al [3] thermal conductivity of constituents of FRCL by backout method of Faleh et al [4] simple thermal resistance model of Springer and Tsai, [5] transverse thermal conductivity of a composite material with continuous unidirectional fibres packed in square array by finite element and statistical models of Grove, [6] theoretical conduction models of Lord Rayleigh, [7] filler size effects of Holotescu and Stoian, [8] interface resistance models of Hasselman-Johnson, Farmer-Covert, Mingqingzou et al and Benveniste, [9][10][11][12] 2-D Numerical model of Md. Islam and Pramila, [13] 2-D thermal contact resistance model of Ramani and Vaidyanathan, [14] and homogenized model for totally debonded composite of Mahesh et al [15].…”

Section: Introductionmentioning

confidence: 99%

Homogenization of partial debond effect on the effective thermal conductivities of FRP composite using finite element analysis

Mahesh¹,

Govindarajulu²,

Murthy³

2014

Composite Interfaces

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Accurate prediction of effective properties of composites prevents catastrophic failure of components designed, which depends on the non-similarities such as voids, debond, cracks and fibre orientation. Prediction of effective properties of composites with the inclusion of non-similarities in composites by micromechanics approach is prohibitively expensive; Homogenization (macro-mechanics) approach solves the problem by reducing computational capabilities. In this study, finite element models are presented for predicting effective thermal conductivities of a partially debonded unidirectional square-packed array composite. Partial debond angle effect and its location effect are studied. Also applicability of Homogenization approach is tested for three different cases and is found that maximum error between macro-and micro-mechanics approaches (homogenization) is 2.1 %. Effective longitudinal thermal conductivity of the composite is not affected by partial debond.

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Transverse thermal conductance of thermosetting composite materials during their cure

Cited by 17 publications

References 19 publications

Thermal conductivity of a thermosetting advanced composite during its cure

Thermal conductivity of a thermosetting advanced composite during its cure

New Experimental Data for Enthalpy of Reaction and Temperature- and Degree-of-Cure-Dependent Specific Heat and Thermal Conductivity of the Hercules 3501-6 Epoxy System

Homogenization of partial debond effect on the effective thermal conductivities of FRP composite using finite element analysis

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