Establishment of Strain/Crystallinity Measurement Methods and Evaluation Technique for Fatigue Life for Short Fiber GFRP using Synchrotron Radiation

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K03778
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Meijo University
• Principal Investigator: Shimizu Kenichi 名城大学, 理工学部, 教授 (50294434)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 短繊維GFRP / 高輝度放射光 / 結晶化度 / マイクロメカニックス / 疲労寿命 / 繊維配向

Outline of Final Research Achievements

From injection-molded plates of Glass Fiber Reinforced Plastic (GFRP), test specimens consisting only of the surface layer with fibers oriented in the injection direction were created. The change in matrix stress with tensile loading was measured using X-ray diffraction. As a result, annealing at temperatures above the glass transition temperature led to an increase in the X-ray diffraction peak intensity of the PPS phase, suggesting an improvement in crystallinity. This enhanced the stiffness of PPS, leading to improvements in both the Young's modulus in the injection direction and orthogonal direction of the composite material. Furthermore, the analysis values of the stress-partitioning coefficients obtained by micro-mechanics, considering the variability in fiber orientation, showed values close to the experimental values obtained by X-ray measurement, indicating that the stress-partitioning coefficients could be accurately evaluated.

Free Research Field

材料強度学

Academic Significance and Societal Importance of the Research Achievements

短繊維GFRPの引張試験を行った結果，繊維が負荷方向と平行に配向した材料の方が，直交方向に配向した材料よりも高い引張強さを示した．しかし，マイクロメカニックスを用いて樹脂相応力で比較した結果，両者の破断時の応力は等しいことがわかった．疲労試験でも同様の結果が得られたが，樹脂相応力で比較すると，両者はほぼ同じ寿命を示すことがわかった．これらの結果から，短繊維GFRPの静的強度・疲労強度は樹脂相応力に支配される可能性が示され，高輝度放射光を用いれば，1mm四方以下の微小領域の樹脂相応力を測定出来るので，複雑な形状および繊維配向を有する実際の製品の寿命予測が出来ることを示した．