Study on mechanical properties and thermal conductivity of 3D short carbon fiber reinforced ultra-high temperature ceramic matrix composites: A novel material performance evaluation model

Conducting precise and consistent research into the mechanical and thermal properties of 3D short fiber-reinforced ultra-high temperature ceramic matrix composites (SC_f/UHTCMCs) is essential for the lightweight design optimization of structures operating under extreme loads. While the current use of one-dimensional elements to simplify fiber solids addresses the mesh quantity and quality issues stemming from the demand for periodic cell size, it fails to accurately predict the mechanical and thermal properties of SC_f/UHTCMCs. This research developed material models featuring fiber volume fractions ranging from 0 to 15%, derived from statistical data on the aspect ratio distribution of short fibers. Addressing the unique characteristics of SC_f/UHTCMCs, we proposed the Material Properties Discount Calculation Method (MPDCM), which leverages fiber distribution to calculate the mechanical properties and thermal conductivity of composite materials. Furthermore, we introduced the Node Heat Transfer Judgment and Coupling Technique (NGTJCT), rooted in fiber diameter, to address the issue of unrealistic heat transfer between fiber nodes and matrix nodes in numerical assessments. Utilizing both MPDCM and NGTJCT allows for a substantial reduction in the required mesh count for composite modeling, while adhering to the dimensional needs of periodic cells and facilitating rapid and precise numerical analysis of 3D short fiber-reinforced composites. The outcomes of this research have the potential to overcome the existing bottleneck in the numerical analysis of SC_f/UHTCMCs, minimize the necessity for complex experimental procedures in material performance studies, and lay the groundwork for engineering optimization design.