円周切欠きをもつ熱可塑性プラスチック丸棒の引張りにおける破壊の条件

概要

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The influence of notches on the static tensile strength was studied for selected polymeric materials. The tension tests on the grooved shafts have been carried out for a wide range of notch tip radii and depths. The materials used were the following seven kinds of thermoplastics; PC, PVC, PMMA, ABS, Nylon 66, PP and PE. The sharply notched specimens failed in a brittle manner and the bluntly notched specimens failed in a ductile manner for all the materials except PMMA. All the notched specimens of PMMA failed in a brittle manner. The predominant factor for determining the brittle-ductile transition of the fracture mode was the notch tip radius. The experimental results were discussed in terms of a relation between the maximum elastic stress at the notch tip, σmax, and the notch tip radius. In the case of brittle fracture, it has been verified that the σmax at which the specimen failed is governed by the notch tip radius alone and is independent of notch depth for all the specimens. On the basis of the concept of linear notch mechanics, the experimental results mentioned above could be clearly explained and the limiting condition for fracture of the grooved shafts of rigid plastics was expressed. The condition is applicable commonly to seven kinds of thermoplastics.
社団法人日本材料学会の論文