Nondestructive deformation and damage evaluation of engineering plastics based on X-ray diffraction profile analysis

2023 Fiscal Year Final Research Report

• Project/Area Number: 21H01207
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Yokohama National University
• Principal Investigator: Akiniwa Yoshiaki 横浜国立大学, 大学院工学研究院, 教授 (00212431)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: X線 / 回折法 / 高分子 / 非破壊 / 塑性変形

Outline of Final Research Achievements

Diffraction planes suitable for stress evaluation of crystalline polymer materials PE, PEEK, and PP were determined from the perspective of X-ray elastic constants. It was also shown that the diffraction intensity, diffraction line width, and X-ray elastic constant of PE, PP, and POM deformed to the plastic region depend on the plastic strain, and the plastic strain can be estimated from the distribution with respect to the angle from the deformation direction. X-rays penetrate deep into plastic, however damage in localized areas in the surface layer could be extracted by using the constant penetration depth method. Furthermore, by applying the X-ray method to fatigue fracture surfaces, it was shown that the stress ratio and maximum stress intensity factor can be estimated from the diffraction intensity and diffraction line width.

Free Research Field

材料強度

Academic Significance and Societal Importance of the Research Achievements

SDGsの取組み，特に天然資源管理や気候変動対応の観点から，軽量化に対する要求が増しており，高分子材料への期待が大きい．実用に際して，材料の変形損傷の程度を把握することは，製品の安全使用に不可欠である．本研究では，X線法を用いてそれを可能にし，特に機械加工等によって局所化された領域の変形の程度が，侵入深さ一定法によって評価できたことは有用である．さらに，疲労破壊に対して，X線フラクトグラフィーが適用できることが示され，今後の事故原因解明に有効な評価ツールとして期待できる.