巻号一覧
35 巻 (2009)
- 6 号 p. 233-
- 5 号 p. 185-
- 4 号 p. 141-
- 3 号 p. 99-
- 2 号 p. 49-
- 1 号 p. 3-
35 巻, 5 号
選択された号の論文の4件中1～4を表示しています
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研究論文
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林 利光, 若山 修一2009 年 35 巻 5 号 p. 185-194
発行日: 2009年
公開日: 2010/12/21
ジャーナル フリーThe effect of the porosity on the fracture behavior of 3D-woven SiC/SiC composites fabricated by multiple polymer impregnation pyrolysis (PIP) process was focused in this paper. The number of PIP cycles was varied as two, four and nine which yielded various porosities from 13 to 30%. The fracture behavior was examined by 4-point bending tests with the aid of acoustic emission (AE) monitoring. The microscopic observations of cross section after loading showed that the critical stress for the onset of crack formation on the tensile surface was increased with the decrease in porosity. However, the AE analysis indicated that the composite with the lowest porosity showed the earliest crack propagation in the rich PIP-SiC matrix region. The composite with intermediate porosity exhibited the most delayed onset of microdamage accumulation. Regardless of the porosity, the large pores located between fiber bundles did not arrest the crack growth from tensile side along thickness. The effect of the porosity on bending fracture process was explained by both the several crack propagation paths and the stress levels for the initiation of the cracks.抄録全体を表示PDF形式でダウンロード (4887K) -
中村 幸一, 平山 紀夫, 西田 裕文2009 年 35 巻 5 号 p. 195-202
発行日: 2009年
公開日: 2010/12/21
ジャーナル フリーIn general the mechanical properties of FRTPs (fiber reinforced thermoplastics) are inferior to those of FRPs (fiber reinforced plastics). This caused by the length of reinforcing fiber in FRTPs is shorter in FRPs, and relatively low content is available because TP (thermoplastic) resin has much higher melt viscosity than TS (thermosetting) resins which is used in FRP. The main objective of this study is to present an FRTP that has excellent mechanical properties with continuous reinforcing fiber in high volume. For one trial, we investigated an FRTP using an in situ polymerizable polyamide 6 as the matrix for the infusion molding process. This polyamide 6 is converted from its monomer into a TP polymer, by the ring-opening-polymerization of ε-caprolactam during the molding process at 160°C. The obtained FRTP had no voids and unfilled parts because ε-caprolactam has a very low viscosity at 100°C before polymerization. Bending tests revealed that the FRTP exhibited a high bending strength and modulus, compared to a conventional FRTP molded by hot press molding with polyamide 6 films and reinforcing cloths. Furthermore, the results of the bending tests indicate that surface treatment of the carbon fiber is effective at improving mechanical properties of the FRTP.抄録全体を表示PDF形式でダウンロード (2349K) -
林 利光, 若山 修一2009 年 35 巻 5 号 p. 203-211
発行日: 2009年
公開日: 2010/12/21
ジャーナル フリーThermal fracture behavior of the 3D-woven SiC/SiC composites was evaluated by a direct diode laser (DDL) irradiation with shading method. The shading method generated a circular shade at the central portion of square sample during quick heating with the DDL. In order to assess microdamage due to thermal stress, the acoustic emission (AE) signals were monitored during the test. The surface temperature distribution was measured by using infrared cameras and then used as input to compute the stress distribution using FEM. It was shown that the surface temperature near the central portion was kept low while the temperature in the outer region of the sample remarkably increased and that the temperature distribution produced biaxial tensile stress field at the center of the sample. The AE activity was increased with increasing the temperature difference between the central and the outer region of sample. Microscopic observation confirmed that microdamage was accumulated on the specimen top surface where the AE signal with maximum amplitude was located.抄録全体を表示PDF形式でダウンロード (2931K) -
黄木 景二, 矢代 茂樹2009 年 35 巻 5 号 p. 212-220
発行日: 2009年
公開日: 2010/12/21
ジャーナル フリーNew fatigue fracture criteria for the transverse crack evolution in a composite laminate subjected to cyclic loading were proposed using the probabilistic model and energy release rate. First, a time-dependent fracture model that combines slow crack growth (SCG) with stochastic failure was established for a general brittle material. The fracture probability was obtained as a function of the number of cycles and maximum stress on the basis of the Paris law and Weibull distribution. Next, the above probabilistic SCG model was applied to the fatigue transverse cracking behavior to establish a stress intensity factor criterion. Thirdly, an energy criterion for predicting fatigue transverse crack density was shown through the combination of the energy release rate on the basis of a variational approach by Nairn with the SCG model. The predicted transverse crack density under the static tensile and fatigue loading was compared with the experiment result to verify the reasonability of the above fracture criteria. In addition, the transverse crack density rate versus the number of cycles predicted using the two fracture criteria and the Paris's equation proposed by Nairn was compared with the experimental results. The transverse crack initiation life was also derived from the energy criterion.抄録全体を表示PDF形式でダウンロード (606K)
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