著者

西川 雅章 逸見 啓 パク サンチョル 灘部 岳晃 武田 展雄

出版者

一般社団法人 日本航空宇宙学会

雑誌

日本航空宇宙学会論文集 (ISSN:13446460)

巻号頁・発行日

vol.58, no.680, pp.261-268, 2010 (Released:2010-09-27)

参考文献数

15

被引用文献数

1 1

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Carbon fiber-reinforced composites have been recently applied for engine fan blades, because of their high specific strength. In the design of the fan blade, the bird-strike impact is one of the greatest concerns, since impact-induced damage can lead to the engine stall. This study presented a numerical method to analyze the bird-strike impact as a soft-body impact on cantilevered composite panel. Especially, we coupled a stabilized dynamic contact analysis, which enables predicting impact force on the panel appropriately, with laminate damage analysis to predict the impact-induced progressive damage in the composite. This method was verified through the comparison with the experimental results. With the numerical method, we investigated the effect of impact condition, blade thickness and shape on the impact-induced damage in composite fan blade subjected to a bird strike. An intermediate blade thickness and a large blade curvature help improving the bird-striking impact resistance of the composite.

著者

河原 康太 松田 直樹 北條 正樹 西川 雅章

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 (ISSN:21879761)

巻号頁・発行日

vol.83, no.849, pp.16-00582-16-00582, 2017 (Released:2017-05-25)

参考文献数

15

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Formulation based on the eigenfunction expansion is shown for second-harmonic generation simulations at a cylindrical interface. The displacement potentials of fundamental wave fields and second-harmonic fields are expressed as sums of eigenfunctions. The cylinder-matrix interface is assumed to be imperfect and modeled as a nonlinear spring interface for the purpose of considering roughness of the interface. Nonlinear equations in this model are dealt with the perturbation theory. The relational expression on the expansion coefficients of the fundamental waves and the second harmonics is shown. The results for the P wave incidence are demonstrated; although arbitrary incident wave field is available in the present method. As a result, both P and SV second harmonics are generated at the cylindrical interface. The numerical results for the directivity patterns of second harmonics are also given. The results show that the directivity patterns depend on the interfacial stiffness. Moreover the relationships between the interfacial stiffness and the ratio of stress in forward direction to backward direction are investigated in order to discuss the interfacial stiffness dependence in detail. The ratio significantly varies with the interfacial stiffness and the relationships are different by the frequency of the incident wave. Due to these characteristics, the ratio of stress in forward direction to backward direction can be useful for the evaluation of the interfacial stiffness. The influence of the ratio of the transverse stiffness to normal stiffness on the ratio of stress is also demonstrated. It is shown that the ratio of the interfacial stiffness has little effect on the ratio of stress.

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

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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.