Thermo-Chemical-Structural Modeling of Carbon Fiber Pitting and Failure Mechanism

The ultra-high temperature environment leads to surface oxidation of the carbon fiber, which could create non-uniform voids and weaken the integrity of the structure. A thorough thermal-chemical-structural coupling is conducted for carbon fiber using the developed new modeling technique. The evolving topology of the residue carbon fiber is captured by the simulation without actual moving grid manipulation. Current results show that for single carbon fiber, surface oxidation can be harmful since pitting can occur at multiple locations on the surface and pitting can penetrate the entire fiber. The variability of surface roughness, or sites, is also investigated by using a Gaussian function. It is found that when the surface is coarser, it becomes easier for carbon to be oxidized. The full coupling study will also be conducted to show that as oxidation continues within the materials, it becomes more vulnerable for the carbon fibers to withstand their loading.