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A shape memory composite (SMC) was fabricated with a shape memory alloy (SMA) and a shape memory polymer (SMP), and its two-way bending deformation and recovery force were investigated. The results obtained can be summarized as follows: (1) two kinds of SMA tapes which show the shape memory effect (SME) and superelasticity (SE) were heat-treated to memorize the round shape. The shape-memorized round SMA tapes were arranged facing in the opposite directions and were sandwiched between the SMP sheets. The SMC belt can be fabricated by using the appropriate factors: the number of SMP sheets, the pressing force, the heating temperature and the hold time. (2) The two-way bending deformation with an angle of 56 degrees in the fabricated SMC belt is observed based on the SME and SE of the SMA tapes during heating and cooling. (3) If the SMC belt is heated and cooled by keeping the bent form, the recovery force increases during heating and degreases during cooling based on the two-way properties of the SMC. (4) The development and application of high-functional SMCs are expected by the combination of the SMA and the SMP with various kinds of phase transformation temperatures, volume fractions, configurations and heating-cooling rates.

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Experiments were conducted to investigate the deformation behaviors and fatigue properties of a superelastic thin tube (SE-tube) and a high-elastic thin wire (HE-wire) of TiNi alloy under conditions of pulsating-plane, alternating-plane and rotating bending. The main results obtained are summarized as follows. (1) The stress-strain curve of the SE-tube in tension describes a superelastic hysteresis loop with an elastic modulus of 35 GPa. It is thus suited for use as a medical catheter tube with flexibility and shape recovery. The stress-strain curve of the HE-wire stays close to a straight line up to a strain of 4% and a stress of 1500 MPa with an elastic modulus of 50 GPa, and is suited for use as a medical guide wire with flexibility, high pushability and a good torque transmission performance. (2) With respect to fatigue, the SE-tube and the HEwire in air both have a longer life in pulsating-plane than in alternating-plane and rotating bending, whereas the difference in fatigue life between alternating-plane and rotating bending is small. The relationship between the maximum bending strain and the number of cycles to failure in the region of low-cycle fatigue can be expressed by a power function for each kind of bending fatigue. The fatigue life in the body is longer than that obtained in air. (3) The maximum bending strain at the fatigue limit of the SE-tube is 0.8%-1.0% which is close to the starting strain of the stressinduced martensitic transformation. The maximum bending strain at the fatigue limit of the HE-wire is 0.7%-0.8%.