13th International Conference on Fracture June 16–21, 2013, Beijing, China -7- and logarithmical amplifier (AD8304) was proposed. The schematic of the wireless system for ACM sensor is shown in Figure 9. The accuracy was evaluated by two measurement systems. One is wired, consisted of digital multimeter. The other one is wireless, consisted of logarithmical amplifier (AD8304), microprocessor (PIC12F675, Microchip Technology Inc.), Battery (3 V), transmitter ZigBee (IEEE 802.15.4) and receiver ZigBee. To imitate different corrosion conditions in the atmosphere (Rain, Dew, Dry), pure water was sprayed to ACM sensor by different times. 4. Results and Discussion 4.1. Evaluation of the measurement accuracy of the metal film by FEM Figure 10. (a) Electrical potential distributions in the ion-sputtered metal film calculated by FEM (ac=1.3 mm); (b) Relationship between the normalized crack length in sputtered smart patch and the normalized resistance of the ion-sputtered metal film through FEM. The examples of analytical results about the normalized electrical potential ( Φ/Φ0) distribution are shown in Fig. 10 (a). The relationship between the normalized crack length in sputtered smart patch and the normalized resistance of the ion-sputtered metal film is shown in Fig.10 (b). By changing the shape of the ion-sputtered metal film from shape 1 to shape 2, the increase amount of
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