Cure dependent thermal conductivity of carbon fiber/epoxy composite - experiments and analysis
Date
2018-12Author
Legesse, Ephriem T.
Advisor
Keshavanarayana, Suresh R.Metadata
Show full item recordAbstract
Knowledge of thermal conductivity of fiber reinforced composites is important to
understand the thermal gradients and heat build-up during cure. Thermal conductivity of composite
materials depends on temperature, direction of heat flow, orientation of fibers, stacking sequence
of the laminate and state of cure.
The purpose of this study was to study thermal conductivity of carbon/epoxy composites
as a function of temperature, state of cure, and direction of heat flow and finally to determine semiempirical
parameters of the Halpin-Tsai model. Determination of Halpin-Tsai's reinforcement
efficiency parameter, ‘ζ’ is essential to predict thermal conductivities of fiber-reinforced
composites and its constituent materials without actually testing specimens.
The test specimens were manufactured from Cycom 5320-8HS prepreg and 5320-1 epoxy
resin. 5320-8HS is toughened out-of-autoclave (OOA) prepreg which is reinforced by T650 3K
carbon fiber in 5320-1 epoxy resin. The test specimens manufactured from these materials had
different degrees of cure (DOC). The thermal conductivity, specific heat and diffusivity tests were
performed by Laser Flash technique. Differential Scanning Calorimeter was employed to verify
the specific heat and to determine DOC of the samples.
Results show that, ‘ζ’, increased by about 36 % when DOC increases from 39% to 95%
along 0° direction. Along the TT direction, ‘ζ’, increased by about 200% when DOC increases
from 39% to 95%. The thermal conductivity and thermal diffusivity in 0° direction increased by
8.7% and 9.5 % respectively when DOC increases from 39% to 95%. The thermal conductivity
and diffusivity in the TT direction increased by 11.1 % and 15.0 % respectively when DOC
increases from 39 % to 95 %.
Description
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering