Yoshiki Sugimoto

Two-Way Bending Properties of Shape Memory Composite with SMA and SMP

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.

Fabrication and Two-Way Deformation of Shape Memory Composite with SMA and SMP

The shape memory composite (SMC) with shape memory alloy (SMA) and shape memory polymer (SMP) was fabricated, and the 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 and superelasticity were heat-treated to memorize the round shape, respectively. The shape-memorized round SMA tapes were sandwiched between the SMP sheets, and the SMC belt was fabricated. (2) The two-way bending deformation with an angle of 56 degrees is observed during heating and cooling. (3) If the SMC belt is heated and cooled by keeping the form, recovery force increases during heating and decreases during cooling.

Performance of shape memory composite with SMA and SMP

The shape-memory composite belt with a TiNi-SMA wire fiber and a polyurethane-SMP sheet matrix was fabricated. The bending actuation characteristics of the belt were investigated by the thermomechanical tests. Residual deflection obtained by cooling under constant maximum deflection is close to the maximum deflection. The residual deflection disappears by heating under no load. Both the rates of shape fixity and shape recovery are close to 100%. Recovery force which appears by heating under constant residual deflection is 93-94% of the maximum force. The model of bending-spring constant of the shape-memory composite belt is proposed and evaluated based on the experimental data.

SMA Thin Strip for Rotary-Driving Element

If a shape-memory alloy (SMA) thin strip is applied as an element subjected to torsion, a rotary driving element with a simple mechanism can be developed. The torsion tests were carried out for the SMA thin strip. Torque and recovery torque, both increase in proportion to the angle of twist and temperature. The recoverable strain energy increases in proportion to temperature. The dissipated work decreases slightly with an increase in temperature. A means of opening and closing a door with an element driven by an SMA thin strip is demonstrated.

Rotary Driving Characteristics of a Shape-Memory Alloy Thin Strip Element

In order to develop a rotary driving element with a shape-memory alloy (SMA) thin strip, the torsional deformation property, cyclic deformation property and torsional fatigue property of a TiNi SMA thin strip were investigated. The results obtained can be summarized as follows. (1) During twisting the SMA thin strip, the martensitic transformation appears along the edge of the thin strip and develops toward the central part. The rate of increase in the tensile strain of the edge increases gradually with an increase in angle of twist. (2) Torque increases with an increase in angle of twist. The torsional deformation properties change slightly under cyclic torsion. (3) With respect to the fatigue properties, the number of cycles to failure decreases with an increase in the angle of twist. The fatigue life in pulsating torsion is five times longer than that in alternating torsion at the same angle of twist. (4) The two-way rotary movement of an opening and closing door model was demonstrated. Therefore, a rotary driving element with a small and simple mechanism can be developed by using the SMA thin strip.

Torsional Deformation Properties of Shape-Memory Alloy Thin Strip Element

If a shape-memory alloy (SMA) thin strip is applied to the elements subjected to torsion, a rotary driving element with a simple mechanism can be developed. In order to develop the rotary driving elements with the SMA thin strip, the torsion test, the recovery torque test and the torsion fatigue test were carried out for the TiNi SMA thin strip. The basic characteristics of the SMA thin strip for torsion were obtained. Torque increases in proportion to angle of twist and temperature. Recovery torque increases in proportion to angle of twist and temperature. The recoverable strain energy increases in proportion to temperature, but the dissipated work decreases slightly with an increase in temperature. Fatigue life decreases in proportion to amplitude of twisting angle. The fatigue life of the heat-treated material is longer than that of the as-received material. The fatigue limit of amplitude of twisting angle for the heat-treated material is almost the same as that for the as-received material. In order to develop the rotary driving elements, an opening or closing door driven by the SMA thin strip is demonstrated.