高分子切欠き平板の変形と破壊の力学解析と変形構造のX線観察

抄録

Center-notched plates of five kinds of high polymers available commercially, i.e., polymethylmethacrylate, polycarbonate, nylon 6, polypropylene and polyethylene were stretched under monotonic loading at room temperature. The plastic zone size and the opening displacement at the notch tip were measured experimentally during loading. The measured values of the plastic zone size and the opening displacement were found to be predictable using a modified Bilby-Cottrell-Swinden model where the cohesive stress distribution within the plastic zone was assumed to be parabolic. The X-ray diffraction method was found to show a clear difference in structure of the plastic zone ahead of the notch tip and the cold-drawn zone of the stretched smooth specimen. This method was confirmed to yield useful information in explaining the relation between the critical crack tip opening displacement and the tensile fracture ductility.