13th International Conference on Fracture June 16–21, 2013, Beijing, China -9- needed to figure out the reason for this result. 4.4. Wireless monitoring of ACM sensor It was possible to make ACM sensor wireless by using the new wireless device and logarithmical amplifier. Figure 12 shows the output of ACM sensor estimated by wireless and wired systems. Both of them show very good coincidence during three periods (Rain, Dew, and Dry). Moreover, by using the logarithmical amplifier, the electricity in the dry period could be distinguished more remarkably than by multimeter. Thus, it was confirmed that the output of ACM sensor can be transmitted wirelessly by the combination of the new wireless device and logarithmical amplifier. Figure 12. The output of ACM sensor estimated by wireless and wired systems 5. Conclusion In this study, (1) the measurement accuracy of the ion-sputtered metal film on “sputtered smart patch” was improved by changing the shape of the ion-sputtered metal film through FEM. (2) a new wireless device equipped with RFID and ZigBee was developed. By using this device, the communication distance between smart patches was improved to more than 20 m. The wireless communication among 1 receiver and 4 transmitters has been tested and proved to be possible. (3) the existing smart patch was proved to be not applicable to high-stress low-cycle fatigue environment through fatigue experiments because the crack growth rate did not change a lot even through the maximum strain changed, which tendency is quite different from that of the low-stress fatigue environment. Further research is needed to figure out the reason for this result. (4) the wireless monitoring by ACM sensor was realized by combining new wireless device and logarithmical amplifier. References [1] S. Nambu, M. Enoki, Smart Stress-Memory Patch for Fatigue Damage of Structure. Mater. Trans., 48 (2007) 1244-1248. [2] S. Nambu, M. Enoki, Scattering in Fatigue Crack Growth of Thin Pure Copper Sheet for Smart Stress Memory Patch. ISIJ Int., 47 (2007) 1687-1691. [3] Y. Fujino, S. Nambu, M. Enoki, AE behavior of smart stress memory patch after variable amplitude loading. Mod. Phys. Lett. B, 22 (2008) 1105-1110. [4] S. Nambu, M. Enoki, Monitoring of Acoustic Emission Activity of Smart Stress Memory Patch to Estimate Maximum Fatigue Stress for Structural Health Monitoring. ISIJ Int., 51 (2011) 88-92. [5] T. Shiraiwa, M. Enoki, Evaluation of Fatigue Properties of Steel Bar by Smart Stress-memory Patch. ISIJ Int., 51 (2011) 250-255.
RkJQdWJsaXNoZXIy MjM0NDE=