Measurement and analysis of deformation behavior of polyethylene pipe subjected to biaxial repeated loading-unloading

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01667
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 26050:Material processing and microstructure control-related
• Research Institution: Tokyo University of Agriculture and Technology
• Principal Investigator: KUWABARA Toshihiko 東京農工大学, 工学(系)研究科(研究院), 卓越教授 (60195609)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 二軸応力 / 材料試験 / ひずみ速度制御 / 大ひずみ / 塑性 / 材料モデル / 降伏関数

Outline of Final Research Achievements

Third-generation high-density polyethylene (PE100) is being adopted by water utilities across the country due to its earthquake resistance and long-term durability. Although water pipes are subjected to multiaxial stress during actual use, their deformation characteristics under multiaxial stress conditions have not been elucidated. In this study, we performed biaxial stress tests using a biaxial tube bulge testing machine that can apply arbitrary biaxial stress to circular pipes. First, we measured the deformation behavior of a PE100 pipe in linear stress paths (constant principal stress ratio between the pipe axis and circumferential directions). It was found that the behavior can be roughly reproduced using a higher-order yield function. Furthermore, the behavior in nonlinear stress paths was found to deviate slightly from the calculated values based on the material model created from the linear stress path experiment.

Free Research Field

塑性力学

Academic Significance and Societal Importance of the Research Achievements

我が国では地震や津波などが多発し，時に社会インフラが甚大な被害を受ける．その備えとして，ガス管や水道管に多用されている高密度ポリエチレン管（以下，PE管）を研究対象として，地震や津波などでPE管が大きな変形を受けたときに発生する，二軸応力状態における変形挙動を解明し，その挙動を数値シミュレーション上で再現するための適切な降伏関数を同定することができた．これにより，社会インフラの基盤を支えるPE管の変形挙動を従来よりもより正確に予測することができるようになり，その安全性をより定量的に評価することができる．