Comparisons of thermal conductive behaviors of epoxy resin in unidirectional composite materials

Abstract

This paper reports thermal conductive behaviors of three kinds of materials, i.e., epoxy resin bar, carbon fiber bundles/epoxy system, and unidirectional carbon fiber/epoxy lamina along 0°and 90°directions. The apparatus for thermal conduction measurement was manufactured and calibrated with an aluminum bar with known thermal conductivity. The thermal conductive behaviors, including the thermal conductive rate and thermal equilibrium time, were tested and numerically simulated with finite element method. It is found that these materials have similar thermal conductive characteristics with same trends of temperature-time curves and thermal gradient-time curves. In addition, with the increase in fiber volume content or decrease in fiber orientation angle, the thermal conductive rate will be speeded up and thermal equilibrium time will be reduced. The temperature of epoxy resin in composite will increase with the increment of fiber volume content. Due to the existence of interface between fiber and resin, the overall thermal conductive ability of composite will be weakened. Owing to the epoxy resin, carbon fiber bundles/epoxy system and unidirectional carbon fiber/ epoxy lamina are the basic materials for the laminates or complex preform reinforced composites, and the thermal conductive behaviors of these basic materials could be extended to design the thermal conductive behaviors of laminates and complex reinforcement composite materials.

A Novel Methodology for Macroscale, Thermal Characterization of Carbon Fiber-Reinforced Polymer for Integrated Aircraft Electrical Power Systems

“…This paper will focus on UD [0°] CFRP, where fibres of CFRP lie parallel within each ply, held in place by the resin Thermally, CFRP is a complex material due to thermal resistance and localised heating at the interface between the carbon fibre and the resin matrix [21], [33]. In addition the thermal conductivity of carbon fibre is much higher than resin, leading to a strong interdependency between lay-up and thermal properties [23], [29]. The localised fibre fraction volume content can be highly varied across a given sample on the micro-scale (10s of µm [15]) due to variation in the curing process, resulting in imperfections through the CFRP [34].…”

“…Results from homogenised macro-scale models based on numerical modelling methods such as finite element modelling, have been demonstrated in the literature to give a good representation of the thermal behaviour of UD CFRP materials with high fibre content [20], [23], [37], [43], [44]. The methods presented develop a thermal micro-mechanical model of a unit of the CFRP at a micro scale, and then directly use this to model the CFRP as a homogenous material at a macro-scale e.g.…”

“…The methods presented develop a thermal micro-mechanical model of a unit of the CFRP at a micro scale, and then directly use this to model the CFRP as a homogenous material at a macro-scale e.g. [23], or create an intermediary meso-scale model (a few mm [15]) which is then used to develop a macro-scale model e.g. [37].…”

“…The results presented in the literature, for UD CFRP, have utilised the numerical modelling method to develop macroscale models, from which the transient thermal response e.g. [20], [23], [37] for a predetermined size of CFRP panel can be estimated. Hence, in order to compare the thermal response of different sizes of structures, the numerical model must be rerun.…”

“…Critical to this is that the level of complexity of the thermal characterisation of the CFRP is such that it maps the appropriate complexity level of the modelling paradigm for modelling aircraft EPS, as set out in SAE AIR 6326 [19], thus enabling systems level transient studies to take place. Thermal models of carbon fibre composites are typically based on numerical modelling methods [20]- [23], which are too complex (require too small a simulation time-step) for transient, systems studies according to [19]. Numerical models can be used to identify thermal response of a CFRP component, the response is for a particular component geometry.…”