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Volume 39 (2013)
- Issue 6 Pages 212-
- Issue 5 Pages 167-
- Issue 4 Pages 127-
- Issue 3 Pages 89-
- Issue 2 Pages 49-
- Issue 1 Pages 10-
Volume 39, Issue 4
Displaying 1-3 of 3 articles from this issue
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Research paper
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Goichi BEN, Hikaru OZEKI, Koichi NAKAMURA, Norio HIRAYAMA, Masaki NAMA ...2013 Volume 39 Issue 4 Pages 127-134
Published: 2013
Released on J-STAGE: August 05, 2014
JOURNAL FREE ACCESSThe mechanical properties of carbon fiber reinforced in situ polymerizable polyamide 6 resin (I-CFRTP) were investigated by using differential scanning calorimeter (DSC), resin flow tests, three-point bending tests and Izod impact tests for various kinds of molding conditions. The bending strength of I-CFRTP at 160ºC was the highest within all the specimens tested. For Izod impact strength of I-CFRTP, no correlation between the molding temperatures.View full abstractDownload PDF (2271K) -
Akira TODOROKI2013 Volume 39 Issue 4 Pages 135-142
Published: 2013
Released on J-STAGE: August 05, 2014
JOURNAL FREE ACCESSA new electrical potential method is proposed in the present study. Many electrodes to measure electric voltage are mounted on a carbon-fiber-reinforced-polymer beam surface. Direct current is applied and the electric voltage changes are measured at the electrodes. Comparing the measured results with the analytical results obtained from the anisotropic electric potential function, electric conductance ratio is obtained. Using the obtained electric conductance ratio, difference of the electric voltages at the surface is amplified. The difference of the electric potential enables us to know the delamination location and dimension. Uniform doublet analysis enables us to know the relationship between the measured results and the delamination location and dimension. The method is applied to numerical analyses here. The results show that the new method is quite effective for simple delamination monitoring.View full abstractDownload PDF (1086K) -
Kazunori TAKAGAKI, Shu MINAKUCHI, Nobuo TAKEDA2013 Volume 39 Issue 4 Pages 143-151
Published: 2013
Released on J-STAGE: August 05, 2014
JOURNAL FREE ACCESSCFRP pipes are used in spacecrafts to support heavy optical instruments. Low coefficients of thermal expansion and high stiffness of CFRPs improve the performance of the instruments. However, it is known that significant through-thickness strain arises in thick CFRP pipes during the cure process and the operation in low temperature, resulting in delamination failure. This study developed a fiber-optic-based life cycle monitoring system to measure the through-thickness strain development. First, we addressed the mechanism of the strain development by a theoretical approach and finite element analysis (FEA). It was confirmed that geometric constraint arising from cylindrical shapes of pipes causes significant out-of-plane stress in the through-thickness center, and the stress value increases with increase in the thickness and stiffness. A fiber Bragg grating (FBG) sensor was then embedded at the through-thickness center of the pipe during the lay-up process. “Non-axisymmetric strain” change in the FBG sensor was continuously measured using birefringence effect throughout the life cycle including cure process and simulated operation in low temperature environment. It was clearly demonstrated that through-thickness strain and delamination failure can be monitored using the non-axisymmetric strain. FEA and comparison with plate specimen were also conducted, confirming the validity of the experimental results.View full abstractDownload PDF (2754K)
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