著者

干川 大和 白須 圭一 岡部 朋永

出版者

一般社団法人 日本複合材料学会

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.48, no.4, pp.142-148, 2022-07-15 (Released:2023-07-29)

参考文献数

20

被引用文献数

1

---

Recent years have witnessed the development of 3D printing systems of continuous carbon fiber reinforced thermoplastics (CFRTP) for use in various applications. In terms of convenience, 3D printing of CFRTP has attracted considerable attention in various fields and industries. In this study, non- and open-hole compressive (NHC and OHC) properties of 3D-printed CFRTP were evaluated. In an NHC test, the compressive elastic modulus and strength in the fiber alignment (0º) direction were obtained with values of 58.1±4.0 GPa and 368.0±33.3 MPa, respectively. A theoretical study of the relationship between compressive strength and the initial fiber misalignment angle showed that the latter was greater than that of conventional hot-pressed CFRTPs, suggesting that the fiber waviness of 3D printing has a negative effect on the longitudinal compressive strength. In an OHC test, cross-ply laminates with center holes were prepared, where the OHC strength was 165.6±1.2 MPa. Both fracture surface and X-ray CT observations showed that kink bands occurred in the 0º layer at the edge of the center hole and that extensive delamination was observed at the 0º/90º interface around the hole. These observations suggest that the voids attributed to 3D printing merged with the delamination derived from fiber buckling near the center hole, leading to rapid expansion of the delamination.

著者

川越 吉晃 小森 翔平 菊川 豪太 白須 圭一 岡部 朋永

出版者

一般社団法人 日本複合材料学会

雑誌

日本複合材料学会誌 (ISSN:03852563)

巻号頁・発行日

vol.48, no.4, pp.134-141, 2022-07-15 (Released:2023-07-29)

参考文献数

26

---

Recently, carbon-fiber-reinforced plastic (CFRP) has been increasingly used in the aerospace industry. To apply CFRP as an aircraft-grade structural material, thermosetting resin is used as a matrix to achieve high mechanical properties and environmental resistance. Additionally, the development of multifunctional CFRPs using matrix resins with functional properties, such as flame retardance, heat resistance, and vibration damping, is ongoing. In this study, molecular dynamics (MD) simulations and experiments were performed to analyze the thermomechanical properties of epoxy/cyanate resins compared with those of conventional epoxy/amine resins, to evaluate the application of this heat resistant resin as an aircraft-grade structural material. This study clarified the properties of epoxy/cyanate resins, which had no cure shrinkage, high glass transition temperature, and low thermal conductivity. These properties are attributed to the characteristic cross-linked structure of epoxy/cyanate resins, which demonstrates their potential as a structural material for next-generation aircrafts.

著者

岡部 朋永 矢代 茂樹

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 A編 (ISSN:03875008)

巻号頁・発行日

vol.75, no.751, pp.304-309, 2009

参考文献数

9

被引用文献数

1 1

---

This study proposes the cohesive zone model (CZM) for fatigue damage growth in the notched CFRP cross-ply laminates. In this model, the damage growth in the fracture process of cohesive elements due to cyclic loading is represented by the conventional damage mechanics model. We preliminary investigated how this model can appropriately express the fatigue damage growth for the circular crack embedded in the isotropic solid material. This investigation demonstrated that this model could reproduce the results with the well-established fracture mechanics model plus the Paris law by tuning adjustable parameters. We then numerically investigated the damage progress in notched CFRP cross-ply laminates under tensile cyclic loading and compared the predicted damage patterns with experiments reported by Spearing et al. (Compos. Sci. Technol. 1992). The predicted damage patterns agreed with the experiment results that exhibited the extension of the multiple types of damage (i.e., splits, transverse cracks and delaminations) near the notches.

著者

西川 雅章 岡部 朋永 武田 展雄

出版者

一般社団法人日本機械学会

雑誌

日本機械学會論文集. A編 (ISSN:03875008)

巻号頁・発行日

vol.75, no.751, pp.287-295, 2009-03-25

---

A numerical simulation was presented to discuss the microscopic damage and its influence on the strength and energy-absorbing capability of short-fiber reinforced plastic composites. The dominant damage includes matrix cracking and/or interfacial debonding, when the fibers are shorter than the critical length for fiber breakage. The simulation addressed the matrix cracking with a continuum damage mechanics model and the interfacial debonding with an embedded process zone (EPZ) model. The fictitious free-edge effects on the fracture modes were successfully eliminated with the periodiccell simulation. The advantage of our simulation was pointed out by demonstrating that the simulation with edge effects significantly overestimates the dissipative energy of the composites. We then investigated the effect of the material microstructure on the fracture modes in the composites. The simulated results clarified that the inter-fiber distance affects the breaking strain of the composites and the fiber orientation angle affects the positions of the damage initiation. These factors influence the strength and energy-absorbing capability of short fiber-reinforced composites.