多孔質炭素材料の応力集中下における変形破壊挙動評価

抄録

Porous carbon materials are expected for applying for heat-resistant lightweight structural materials in aerospace field because they have high strength relative to their low density and heat resistance. In the present study, we studied three-dimensionally networked porous carbon materials (TNPCs) for applying ablators, which are used thermal protection system in space vehicle. Although understanding of mechanical behavior is important for application to actual structures, mechanical behavior of TNPCs under stress concentration are not still well known. In this study, tensile mechanical behavior of TNPCs with three different pore sizes ranging from 3.8 μm to 10 μm were investigated using double edge-notched and open-hole specimen. Experimental results revealed that fracture toughness of TNPCs was relatively large compared with other porous materials. In tensile tests of open-hole specimens, strength was decreased by stress concentration, however, it deviated from calculated value based on linear elastic fracture mechanics. Strain distributions around hole computed using DIC technique and FEM simulation was significantly different. The decrease in strength of TNPSs was not similar in that of bulk materials, and was probably originated from reduction of strain (or stress) concentration.