著者

山崎 友裕 西野 博満 片山 大希

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.76, no.762, pp.145-150, 2010-02-25

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Electromagnetic acoustic transducer (EMAT) is applied to resin cure monitoring in manufacturing process of fiber reinforced plastic (FRP) by resin transfer molding (RTM) method. The RTM is suitable for fabrication of FRP products of three-dimensional complex shape. In order to reduce the cost by minimizing the cycle time, cure monitoring is required. Authors have already ensured that the EMAT can detect the resin flow front in RTM process by monitoring the change in reflection coefficient at mold surface due to resin impregnation. The reflection factor is also affected by the resin viscosity. In this study, during the curing process, we measure the attenuation coefficient of standing wave introduced in the mold. Results are compared with impedance of dielectric sensor located inside the mold, showing that the degree of cure can be evaluated by EMAT at outer surface of the mold.

著者

髙井 直樹 元木 信弥 山崎 友裕

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:18848338)

巻号頁・発行日

vol.79, no.807, pp.1632-1647, 2013 (Released:2013-11-25)

参考文献数

9

被引用文献数

1

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The effects of applied stresses on dynamic characteristics of piezoelectric ceramics are analyzed based on the nonlinear electroelastic theory. Piezoelectric ceramics are used in many electric devices as functional elements, where mechanical constraint is usually applied. Estimation of piezoelectric properties under applied stresses is important in designing the devices. However, applied stresses cannot be considered in the basic equations in the linear piezoelectric theory, and the effects of the applied stresses cannot be predicted. In this study, we introduce additional terms related to the dissipation effects, specifically, electric conduction and internal viscosity resistance, and nonlinearity of elastic properties into electroelastic theory. As well, considered nonlinear effects are elastic, piezoelectric and dielectric constants up to 3rd order. Frequency dependence of admittance of PZT disks is measured under applied compressions, showing that applied stresses have certain influences on either of thickness and radial vibrations of PZT. Assuming proper material constants, experimental results can be well explained by the nonlinear electroelastic theory.