Study on the Two-Way Shape Memory Characteristics Induced by Compressive Loading Cycles
The NiTi alloy can be trained by repetitive loading or heating cycles. As a result of the training, a two-way shape memory effect (TWSME) can be induced. Considerable research has been reported regarding the TWSME trained by tensile loading, however the TWSME trained by compressive loading has not been investigated nearly as much. In this research, six types of specimens (one solid cylindrical and five tubular) were used to obtain the two-way shape memory strain and two-way recovery stress and to evaluate the actuating capacity. The two-way actuating strain showed a saturated tendency after several training cycles for the same maximum deformation. A maximum value of the two-way strain was obtained for 7% of maximum deformation, independently of the geometry of the tubular specimens. The two-way strains obtained by the shape memory cycles and two-way recovery stress linearly increase as a function of the maximum deformation and the two-way strain, respectively, and the geometry of specimen affects the two-way recovery stress. Although the results show that sufficient recovery stress can be generated by either the two-way shape memory process or by the one-way shape memory process, the two-way shape memory process can be applied more conveniently to actuating applications.
Joong Hee Lee
Y. I. Yoo and J. J. Lee, "Study on the Two-Way Shape Memory Characteristics Induced by Compressive Loading Cycles", Advanced Materials Research, Vols. 123-125, pp. 1023-1026, 2010