Experimental and numerical investigation on the impact of vacuum level on effective thermal conductivity and microstructure of carbon fibre reinforced epoxy composites manufactured by vacuum bag method
Michał Kubiś , Mirosław Seredyński , Łukasz Cieślikiewicz , Tomasz Wiśniewski , Anna Boczkowska
AbstractThe physical properties of epoxy based carbon reinforced composites are highly anisotropic due to their directional structure. Properties are additionally influenced by the microstructure quality related to manufacturing process and its parameters. Thermal conductivity was found to be dependent on the void volume fractions, which appear as a result of the insufficient vacuum level. In the proposed paper the multi-scale computational model of heat transfer across the carbon fiber-epoxy resin composite is proposed. The meso-scale effective thermal conductivities are determined with analytical formulae for isotropic and anisotropic media, the latter takes into account thermal resistance at the interface of fibers and epoxy resin. In the meso-scale the morphology of bunches of fibers immersed in epoxy is reflected. Proposed model is utilized to determine the effective thermal conductivity in the direction perpendicular to plies of composite. The analysis is performed to estimate the thermal resistance and subsequently the analysis of influence of void fractions on the effective thermal conductivity of the composite is done. The numerical outcomes underestimate the real variation in conductivity, which can be caused by change in carbon volume fraction of samples manufactured at different vacuum levels which was not considered in numerical computation. However, representative volume element geometry was based on the structure of composite manufactured at the higher vacuum - 90 kPa below atmospheric pressure. In this case a discrepancy of results obtained in both experimental and modeling approach is rather minor.
|Publication size in sheets||0.3|
|Book||Węglowski Bohdan (eds.): XIth International Conference on Computational Heat, Mass and Momentum Transfer. May 21-24 2018, Cracow, Poland. Book of Abstract Volume 1, 2018, ISBN 0000000000000, 336 p.|
|Keywords in English||carbon fiber-epoxy composites, effective thermal conductivity, heat transfer, REV, modeling|
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