2014 年 55 巻 9 号 p. 1464-1470
Fatigue is an important factor of failure of structures such as bridges, buildings, etc. To prevent the failure, a sensing method of fatigue damage is desired. In previous studies, it was demonstrated that smart stress-memory patch is a suitable and effective method for fatigue monitoring, because it is possible to evaluate a number of fatigue cycles and stress amplitude of structure wirelessly. However, there are still some problems on the conductive property. For instance, using the conventional shape of conductive film, it was found out that the crack length could not be estimated accurately because sometimes the resistance of the conductive film was unstable and did not increase monotonically as the crack length increased. Moreover, effects of environment factors such as temperature and strain have not been figured out. The objective of this research is to clarify the effects of fabrication method, shape of conductive film and environment factors on conductive property of smart stress-memory patch and to improve the sensitivity on the crack length measurement. The sensitivity of the smart patch was evaluated by changing the fabrication procedure and the shape of conductive film under strain-controlled fatigue testing. It was shown that the effects of strain could be ignored under atmosphere environment and the effect of temperature could be ignored until around 65°C.
