Zhu Yutian

(College of Mechanical Engineering, Tongji University, Shanghai 200092)

Hagiwara Ichiro  Yasuhiro Mohri

(Department of Mechanical Engineering and Science, Tokyo Institute of Technology, Tokyo 152-8552, Japan)

Abstract: For intelligent materials embedded with shape memory alloy (SMA) wires, a method based on checking the resistance variation of the SMA is proposed. By this method, the strain caused by tensile load can be measured and the damage of the matrix be estimated. The strain caused by the temperature effect is compensated; hence the sensing error is eliminated by using a reference SMA wire. During the self-repair process, generally the temperature state of SMA wires embedded in composites is uncertain due to the ambient temperature, the heat convection, the heat radiation or the external current inputted for heating, to suppress the crack(s) by inducing the SMA phase transformation as fast as possible but not to overheat or burn the matrix or the SMA itself, a dynamic heating/self-sensing method which can detect the beginning and the ending of the SMA phase transformation based on the feedback of the SMA resistance variation is proposed and verified in laboratory experiments. Analytical solutions are compared favorably with the experimental data.

Key words: Shape memory alloy  Intelligent material  Self-repair  Strain sensing  Heating control

CLC No: TP271  TB39

Received 20040302, received in revised form 20040906