• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.1
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• pp.51-58
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• 2021

In this paper, a multi-scale finite element (FE) modeling methodology for three-dimensional (3D) needle-punched (NP) C/SiC with a complex microstructure is presented. The variations of the material properties induced by the needle-punching process and complex geometrical features could pose challenges when estimating the material behavior. For considering these features of composites, a 3D microscopic FE approach is introduced based on micro-CT technology to produce a 3D high fidelity FE model. The image processing techniques of micro-CT are utilized to generate discrete-gray images and reconstruct the high fidelity model. Furthermore, a subcell modeling technique is developed for the 3D NP C/SiC based on the high fidelity FE model to expand to the macro-scale structural problem. A numerical homogenization approach under periodic boundary conditions (PBCs) is employed to estimate the equivalent behavior of the high fidelity model and effective properties of subcell components, considering geometry continuity effects. For verification, proposed models compare excellently with experimental results for the mechanical behavior of tensile, shear, and bending under static loading conditions.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.200.2-200.2
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• 2016

Carbon-based materials have been known as ablative material and have been used for thermal protection systems. Ablation is an erosive phenomenon that results in thermochemical and thermomechanical changes on materials. Ablation resistance is one of the key properties that determines performance and life-time of the thermal protection material under ablative conditions. In this study, ablation properties of graphite, 3-dimensional (C/C) composites (needle-punched type and rod type) were investigated byusing a plasma wind tunnel which produce a supersonic plasma flow from a segmented arc heater with the power level of 0.4 MW. The mass losses and surface roughness changes which contain main result of the ablation are measured. A morphological analysis ofthe carbon-based materials, before and after the ablation test, are performed through field emission scanning electron microscopy (FE-SEM) and non-contact 3D surface measuring system. Electronic balance and a portable surface roughness tester were used for evaluation of the recession and mass loss of the test samples.