Abstract
A 3D thermal response model is developed to evaluate the thermal behavior of glass fiber/phenolic composite exposed to heat flux on one side. The model is built upon heat transfer and energy conservation equations in which the heat transfer is in the form of anisotropic heat conduction, absorption by matrix decomposition, and diffusion of gas. Arrhenius equation is used to characterize the pyrolysis reaction of the materials. The diffusion equation for the decomposition gas is included for mass conservation. The temperature, density, decomposition degree, and rate are extracted to analyze the process of material decomposition, which is implemented by using the UMATHT (User subroutine to define a material’s thermal behavior) and USDFLD (User subroutine to redefine field variables) subroutines via ABAQUS code. By comparing the analysis results with experimental data, it is found that the model is valid to simulate the evolution of a glass fiber/phenolic composite exposed to heat flux from one side. The comparison also shows that longer time is taken to complete the pyrolysis reaction with increasing depth for materials from the numerical simulation, and the char region and the pyrolysis reaction region enlarge further with increasing time. Furthermore, the decomposition degree and temperature are correlated with depths, as well as the peak value of decomposition rate and the time to reach the peak value.
Highlights
Fiber reinforced polymer (FRP) composites have been significantly used to construct components of airplane, such as fuselage, wing, empennage, and other structures [1,2] because they have many excellent characteristics, for instance lightweight, high specific intensity, good corrosion and fatigue performance [3,4]
The FE model of cylindrical glass fiber/phenolic composite exposed to heat flux on one side was established using the thermophysical and geometrical parameters of material and boundary condition given in reference [8]
Taking into account heat conduction, matrix pyrolysis, and gas diffusion, a transient three-dimensional numerical model for glass fiber/phenolic composite under a one-sided heat flux has been established via ABAQUS code to predict and analyze the thermal response of material
Summary
Fiber reinforced polymer (FRP) composites have been significantly used to construct components of airplane, such as fuselage, wing, empennage, and other structures [1,2] because they have many excellent characteristics, for instance lightweight, high specific intensity, good corrosion and fatigue performance [3,4]. In the airworthiness by FAA, there is a requirement to ensure the safety of using composite materials in civil airframe. AC 20-107B [6] indicates that the flame retardant and fire-resistant requirements should be taken into account in the design of composite structures, especially exposure to flame exceeding maximum operating temperature. It is essential to Materials 2020, 13, 421; doi:10.3390/ma13020421 www.mdpi.com/journal/materials
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