Identification of Microscopic Damages in CFRP Laminates with Chirped FBG Sensors (original) (raw)
Journal of the Japanese Society for Experimental Mechanics, 2012
In this paper, the propagation behavior of elastic waves generated in CFRP laminates by pulsed laser was investigated both experimentally and analytically. First, the anisotropy in amplitudes of elastic waves generated by pulsed laser were measured experimentally. The anisotropic property was found to vary with different frequencies. Secondly, elastic wave propagation behavior was evaluated by finite element analysis. In this analysis, two cases in which CFRP has anisotropic and isotropic thermal expansion properties were compared with experimental results. As a result, tendency in analytical results of CFRP with anisotropic thermal property agreed well with the experimental results, which confirms that the anisotropic thermal expansion property of CFRP laminates causes the anisotropy in amplitudes of elastic waves generated in CFRP laminates by pulsed laser. Finally, the influence of coatings on anisotropic behavior of elastic waves generated in CFRP laminates by pulsed laser was i...
SPIE Proceedings, 2005
This paper reports damage detection and vibration control of a new smart board designed by mounting piezoelectric fibers with metal cores on the surface of a CFRP composite . Damage to the board is identified on the assumption that the piezoelectric fibers used as sensors and actuators are broken simultaneously at the damaged location. First, the length of the piezoelectric fibers is measured to derive a finite-element method (FEM) model of the cantilever beam. If the fiber length is shortened due to a break, there is a decrease not only in actuator performance but also in the sensor output. Damage detection is based on the computed relation between the input/output signals and the damage position. Furthermore, a reduced-order model that considers only the first mode is derived for the controller design and transformed into a linear fractional transformation (LFT) representation for the gain-scheduled controller design. The position of the damage is the contributing parameter in the variation. Next, the gain-scheduled controller is designed using LFT representation. Finally, the experimental results of the damage detection and the gain-scheduled control are presented. These results show that our gain-scheduled controller can improve control performance when damage causes a break in the piezoelectric fiber.
RGB Sensitivity Measurement Experimentation of Gas phase and Oil Film Flow on Journal Bearing
Transactions of the Visualization Society of Japan, 2017
The gas phase area in journal bearing is associated directly with bearing characteristics. Therefore, gas phase area observation have an ongoing by many researchers. This paper describes a new visualization method which can visualize oil film distribution and gas phase area on journal bearing. The distribution of oil supplied from two sites is visualized by two color oil, the blended color and gas phase area are measured by RGB representation. Moreover, the measured gas phase area compared to one by traditional visualization method. In this study, oil flow of wedge side under flooded lubrication, oil whip and starved lubrication condition are visualized. As results, it is found that the distribution of oil film under oil whip and starved lubrication condition have been changed by changing the amount of supply oil. Moreover, gas phase area by the new observation method agree rather well with a result of traditional experiment. Therefore, it was found that the new visualization method by using two color oil and RGB representation is possible to observe both gas phase area and blended oil color in journal bearing.